How Hot the Shock?

[irb4ur]

I have heard that Baja shocks get super hot. Can anyone put that in degrees F for me?

[Shaffers Offroad]

I have heard that Baja shocks get super hot. Can anyone put that in degrees F for me?

I have had my shocks get over 400 degrees:eek:

But at about 275 -300 they start to fade

[irb4ur]

I have had my shocks get over 400 degrees:eek:

But at about 275 -300 they start to fade
Ouch! I thought that maybe I could check the temperature by applying my tongue--maybe not.

Do the seals hold up okay at those temperatures? And, do external bypass cylinder oil coolers help?

[TRD]

Mr Shaffer.

Where (on the shock) and how are you measuring those temps?

*and what shocks? Brand, Size, Style

Thanks

[JESSE_at_TLT]

There was a good discussion about this over on RDC a while ago. Here's a link (http://www.race-dezert.com/forum/showthread.php?t=16591&highlight=shock+temp).

[Beat95YJ]

There was a good discussion about this over on RDC a while ago. Here's a link (http://www.race-dezert.com/forum/showthread.php?t=16591&highlight=shock+temp).

Thanks.

Mike,

Are you using temp strips or something more sophisticated to determine the temp of the shock?

Also Where on the shock are you recording temps?

[65Chevy4x4]

the shocks bodies on my shocks easily reach 200 but the res stays around 150 or less.

[Lance]

I'm sure he's using a laser temp gauge.

[TRD]

Nice link Jesse!

I cant believe someone was using emulsion shocks in the desert :laughing:

[MIKE S]

Thanks.

Mike,

Are you using temp strips or something more sophisticated to determine the temp of the shock?

Also Where on the shock are you recording temps?

When we pit we will have someone check with a temp gun. Not the best way but it would tell us if changes we had made was for the best or not.

[Beat95YJ]

Thanks. What brand of shocks are you running? According to the post on rdc the heat gun may not work well with Bilsteins or newer SAW. I always use temp strips because that's what I have access to. I do not like the fact that they only show peak temp. I will be adding realtime data logging to a truck at work for this very reason.

You may want to have your guy check them near the rodguide as that seems to be the hottest part when we are durability testing shocks.

[irb4ur]

Heat strips sound like a good choice, but Max. Temp. only measurements. The reason I asked is that I had one shock that I rebuilt that showed evidence of a hot spot: about 1/4" Dia. area of the brass rod bearing was melted. Brass melts at almost 1700 F. The shaft and seals were okay, so the hot spot must have been confined to a local spot only. It looked like the heat was trapped and couldn't dissipate to the outside. I plan to machine cooling fins into the housing that holds the brass bearing.

[MIKE S]

Thanks. What brand of shocks are you running? According to the post on rdc the heat gun may not work well with Bilsteins or newer SAW. I always use temp strips because that's what I have access to. I do not like the fact that they only show peak temp. I will be adding realtime data logging to a truck at work for this very reason.

You may want to have your guy check them near the rodguide as that seems to be the hottest part when we are durability testing shocks.

I had bilsteins 2.5's but now i have 3"Radflo's on the front

[BigLittleToyota]

There's no way a shock got even remotely close to 1000, not to mention 1700 degrees. It was warped/damaged because the temp was increased and there was rubbing.

Another thing, reservoirs are not intended to cool the shocks down.

You rockcrawler guys should stick to the rocks and leave the highspeed man stuff to us. When you guys are grown up enough, come on over to www.dezertrangers.com

[JESSE_at_TLT]

You rockcrawler guys should stick to the rocks and leave the highspeed man stuff to us. When you guys are grown up enough, come on over to www.dezertrangers.com
Grown up....................................dezertranger s?

[fj40forlife]

Yes they get hot. I had to change a tire. and the tire was next to the shock. And gave me a litter burn

[Weasel]

There's no way a shock got even remotely close to 1000, not to mention 1700 degrees. It was warped/damaged because the temp was increased and there was rubbing.

Another thing, reservoirs are not intended to cool the shocks down.

You rockcrawler guys should stick to the rocks and leave the highspeed man stuff to us. When you guys are grown up enough, come on over to www.dezertrangers.com

stuff it, so what are they for. Looking cool?

[JESSE_at_TLT]

No, I think he's right about the temperatures and he's definitely right about the reservoirs.

[JESSE_at_TLT]

Most shocks would shit their pants when the temperature gets up past 400 to 500-degrees and reservoirs have a dividing piston in them to keep the shock fluid from mixing with the nitrogen, not to keep the shock cool.

[MIKE S]

There's no way a shock got even remotely close to 1000, not to mention 1700 degrees. It was warped/damaged because the temp was increased and there was rubbing.

Another thing, reservoirs are not intended to cool the shocks down.

You rockcrawler guys should stick to the rocks and leave the highspeed man stuff to us. When you guys are grown up enough, come on over to www.dezertrangers.com

So are you racing the 1000?

[Lance]

You rockcrawler guys should stick to the rocks and leave the highspeed man stuff to us. When you guys are grown up enough, come on over to www.dezertrangers.com

:shaking: :shaking: :shaking:

[Chase2]

You rockcrawler guys should stick to the rocks and leave the highspeed man stuff to us. When you guys are grown up enough, come on over to www.dezertrangers.com


Typical Dezert Ranger "Flatbiller" playground smack. DGAF except to talk crap.

[Weasel]

Most shocks would shit their pants when the temperature gets up past 400 to 500-degrees and reservoirs have a dividing piston in them to keep the shock fluid from mixing with the nitrogen, not to keep the shock cool.

I'm not saying he isn't right, but if you want to spout off crap you should atleast explain it to back up your smack.

Why not put the piston in the shock? Moving it to a reaservoir does what, increases the oil capacity of the shocks?

[MattyB4x4]

It seems that the extra oil capacity would, in the end make a cooler shock. however i don't know shiat, but just throwing that out there.

[JESSE_at_TLT]

Sometimes they do put the dividing piston inside the shock. That's called an internal reservoir as opposed to an external reservoir. The biggest difference is that if the shock is using an internal reservoir, the eye-to-eye dimensions of the shock must be longer.

[TRD]

Resi adds oil capacity and frees up length inside the shock (Longer extended length = more travel or a shorter shock with the same travel). The divider cup takes up significant space inside the shock.

[JESSE_at_TLT]

These Donahoe bolt-in coil-overs for Tacomas use an internal reservoir with a dividing piston and it's just as effective as an external reservoir.

http://www.trailslesstraveled.com/content/techarticles/52/13.jpg

[JESSE_at_TLT]

Some people have set up their shocks with two hoses going to the reservoir. They use a check-valve to make sure that shock fluid is actually recirculated and then the reservoir does actually help keep the shocks cooler. Here is a picture of the Baldwin TT's rear suspension and here is a link to a discussion about that truck on RDC.

BIG Picture of recirculating hoses (http://www.race-dezert.com/forum/attachment.php?attachmentid=1653&d=1049774463)

[JESSE_at_TLT]

I also found these pictures of Donahoe's Stock Full Superduty (http://www.donahoeracing.com/project_detail.php?projectID=10). Those are 4.5" diameter bypass shocks and they also have dual hoses, but I don't remember if they used check-valves.

http://www.trailslesstraveled.com/content/news/ORE_05/ore_05_12.jpg

http://www.trailslesstraveled.com/content/news/ORE_05/ore_05_11.jpg

[Beat95YJ]

I also found these pictures of Donahoe's Stock Full Superduty (http://www.donahoeracing.com/project_detail.php?projectID=10). Those are 4.5" diameter bypass shocks and they also have dual hoses, but I don't remember if they used check-valves.

http://www.trailslesstraveled.com/content/news/ORE_05/ore_05_12.jpg

http://www.trailslesstraveled.com/content/news/ORE_05/ore_05_11.jpg

One hose has a check valve in one direction. From the examining I have done with these systems they often cause valve lag due to slow response time. (think of a small reservoir hose.)

Also with respect to the DR Tacoma shock above, there is no difference between it and an emulsion shock as far as the ability to radiate heat. A shock with ifp will always have more consistant damping as the oil will not emulsify and fade (emulsion shocks are complete crap for any off road vehicle) If you were to add a reservoir to the Tacoma shock it would have increased surface area to dissapate the heat, and would run cooler.

[JESSE_at_TLT]

Radflo is developing a bolt-in replacement shock for Tacomas with a remote-reservoir shock, but I thought the benefits would be negligible. You think it would help much?

[Beat95YJ]

Radflo is developing a bolt-in replacement shock for Tacomas with a remote-reservoir shock, but I thought the benefits would be negligible. You think it would help much?

Yes, it will make a large difference in cooling ability.

[irb4ur]

There's no way a shock got even remotely close to 1000, not to mention 1700 degrees. It was warped/damaged because the temp was increased and there was rubbing.

Another thing, reservoirs are not intended to cool the shocks down.

You rockcrawler guys should stick to the rocks and leave the highspeed man stuff to us. When you guys are grown up enough, come on over to www.dezertrangers.com
Melted - Melted - Melted, not wear! I do failure analysis for a living (26 years). The hot spot was between the brass rod bearing and its press fit aluminum cap (at the OD of the bearing, not the ID). I was shocked :) The oil between the shaft and bearing amazingly prevented scoring of the shaft and bearing. The bearing cap aluminum was too thick to dissipate heat outward and thus trapped rising heat in a concentrated zone, albeit a very small zone, but melted nonetheless.

And, by the way, not all rock crawlers go slow. I didn't get hot shocks driving on and off the trailer. As far as growing up . . . I really don't plan on it anytime soon--I'm having way too much fun.

As for resevoir cooling, I have heard claims that they might provide some cooling, but you're right, there is not sufficient oil circulation and volume for a remote resevoir to provide much cooling. You might need a more elaborate circulation system through an oil cooler to do much good.

[TotalImmortal]

There's no way a shock got even remotely close to 1000, not to mention 1700 degrees. It was warped/damaged because the temp was increased and there was rubbing.

Another thing, reservoirs are not intended to cool the shocks down.

You rockcrawler guys should stick to the rocks and leave the highspeed man stuff to us. When you guys are grown up enough, come on over to www.dezertrangers.com
shut the fuck up.

[Beat95YJ]

Melted - Melted - Melted, not wear! I do failure analysis for a living (26 years). The hot spot was between the brass rod bearing and its press fit aluminum cap (at the OD of the bearing, not the ID). I was shocked :) The oil between the shaft and bearing amazingly prevented scoring of the shaft and bearing. The bearing cap aluminum was too thick to dissipate heat outward and thus trapped rising heat in a concentrated zone, albeit a very small zone, but melted nonetheless.

And, by the way, not all rock crawlers go slow. I didn't get hot shocks driving on and off the trailer. As far as growing up . . . I really don't plan on it anytime soon--I'm having way too much fun.

As for resevoir cooling, I have heard claims that they might provide some cooling, but you're right, there is not sufficient oil circulation and volume for a remote resevoir to provide much cooling. You might need a more elaborate circulation system through an oil cooler to do much good.

I have seen this type of failure only after a seal failure, the seal burning up and the rod going metal to metal. I agree that no functioning shock could hit this temperature.

[irb4ur]

I have seen this type of failure only after a seal failure, the seal burning up and the rod going metal to metal. I agree that no functioning shock could hit this temperature.
I can understand everyone's skepticism. I called it like I saw it, just as I described. The seal was a Parker double-lip BS series U-cup urethane, and the upper lip was burned--damaged, but the seal was not leaking, probably because the lower lip was still intact; and below that seal was a backup double-lip Nitrile wiper. The BS seal design also greatly reduces side loading to help prevent metal-to-metal contact, but has some disadvantage of greater breakaway friction.

[TRD]

That must have been a pretty thick rod guide for it to reach 1700 degrees at the OD but remain less than 300 at the ID

[Beat95YJ]

I can understand everyone's skepticism. I called it like I saw it, just as I described. The seal was a Parker double-lip BS series U-cup urethane, and the upper lip was burned--damaged, but the seal was not leaking, probably because the lower lip was still intact; and below that seal was a backup double-lip Nitrile wiper. The BS seal design also greatly reduces side loading to help prevent metal-to-metal contact, but has some disadvantage of greater breakaway friction.


My experience with parker urethane (including the 4300 series) is that it hardens at 250degrees f and will suffer premature wear and fail. This even though my seal vendor says it will hold to 300 deg F. I am thinking that he means short term and I am discussing steady state.

I have seen another failure similar to your description a few times. Somebody welds on a vehicle chassis with the ground strap on the axle, suspension link or some variation of this. The shock becomes the ground strap and arc's thru the du bearing. This will cause a small failure in the du and an eroded spot on the rod.

I am not saying what you described is impossible, but it sounds extremely unlikely given my testing/destroying of shocks in a lab enviroment over the years.

[Beat95YJ]

Typical Dezert Ranger "Flatbiller" playground smack. DGAF except to talk crap.


For us old timers wtf is dgaf, dilgaf and buna? help an old fart out.

[Beat95YJ]

Why not put the piston in the shock? Moving it to a reaservoir does what, increases the oil capacity of the shocks?


A shock is a simple thermo example. A shock converts linear energy into heat energy (simplifying) Most shocks have similar wall thickness and tube materials, so neglecting that cooling capacity = surface area. A reservoir dramatically increases the surface area of the shock allowing for much more heat transfer. Typically when run hard for extended periods the reservoir area with oil in it gets damn close to the temperature of the working area of the piston. The hot spot is usually where the dynamic seal is.

Most of my exeprience with this is in the lab. I am not exactly sure if these results are reflective of field testing. I would expect similar results though.

We are picking up a truck tomorrow for some field testing. We will be putting data acquisition on the shocks to continuously monitor temps. When we have some more info I will post up our findings.

[TRD]

dgaf = Dont give a fuck
dilgaf=??
Buna=????????????????????????????????????????????? ??????????????????????

[Beat95YJ]

dgaf = Dont give a fuck


Dammit. I must be slow witted...Or there is already too much random crap floating around in my head.

[TRD]

Dammit. I must be slow witted...Or there is already too much random crap floating around in my head.
I'm gonna go with slow :flipoff2:


:laughing:

[65Chevy4x4]

dilgaf is suposed to be dilligaf= does it look like I give a fuck
buna= Matt Helton's term for something that's cool, well built, up to par, etc... Pretty much means it's good and acceptable, kinda like bueno.

[irb4ur]

I am not saying what you described is impossible, but it sounds extremely unlikely given my testing/destroying of shocks in a lab enviroment over the years.
These were the conditions: 18" stroke, up to 80 mph, jumps (etc.), 12 hours near continuous driving in Arizona desert. Yes, I'm from Georgia, but I get around some--nothing in GA but trees, dirt and termites--very few trails--no Baja.

P.S. Buna is short for Buna-N, same as Nitrile (a polymer), the most common compound for O-rings and seals (black). Buna is short for Bueno? I've been in GA too long.

[Beat95YJ]

dilgaf is suposed to be dilligaf= does it look like I give a fuck
buna= Matt Helton's term for something that's cool, well built, up to par, etc... Pretty much means it's good and acceptable, kinda like bueno.


Thanks, I don't feel anywhere near as stupid now.

[irb4ur]

That must have been a pretty thick rod guide for it to reach 1700 degrees at the OD but remain less than 300 at the ID
1/8" wall thickness.

[Weasel]

A shock is a simple thermo example. A shock converts linear energy into heat energy (simplifying) Most shocks have similar wall thickness and tube materials, so neglecting that cooling capacity = surface area. A reservoir dramatically increases the surface area of the shock allowing for much more heat transfer. Typically when run hard for extended periods the reservoir area with oil in it gets damn close to the temperature of the working area of the piston. The hot spot is usually where the dynamic seal is.

Most of my exeprience with this is in the lab. I am not exactly sure if these results are reflective of field testing. I would expect similar results though.

We are picking up a truck tomorrow for some field testing. We will be putting data acquisition on the shocks to continuously monitor temps. When we have some more info I will post up our findings.

I did know the purpose of a remote reservoir. We need a sarcasm smiley. :D I'm learning more about shocks and continuing to read the Shock Absorber Handbook and would like to get into valve/shim testing and design. We started with airshocks on our baja rig last year and learned a ton about them and tuning them to increase suspension performance. Still have a bunch to still learn though. We have a Data system we are going to use as well to hopefully record some velocitys that we can relate to our dyno tests. Haven't had a problem with heat yet.

[Beat95YJ]

I did know the purpose of a remote reservoir. We need a sarcasm smiley. :D I'm learning more about shocks and continuing to read the Shock Absorber Handbook and would like to get into valve/shim testing and design. We started with airshocks on our baja rig last year and learned a ton about them and tuning them to increase suspension performance. Still have a bunch to still learn though. We have a Data system we are going to use as well to hopefully record some velocitys that we can relate to our dyno tests. Haven't had a problem with heat yet.

Some days I just don't catch the sarcasm, my bad. Also I feel like I shouldn't assume in these threads as you never know.

btw we have a sarcasm smiley...It is :flipoff2:

[jahwarrior1423]

sayin' a emulsion shock is crap is false...they can be used also with a bypass and work fine...

[Beat95YJ]

emulsion shock damping changes so fast from static, that no one can convince me that they are worth a shit. A bilstein 5100 is a better shock (more consistant) than a fox 2.0. Unfortunately It is difficult for most people to revalve a 5100, so the fox's are more popular. Put identically tuned emulsions and standard monotubes on a car/truck/mtb/atv/pogo stick and it is obvious that they are complete garbage.

Edit: It appears that you are speaking of them as a secondary coil carrier type shock. Eh...It would be better to use a monotube with ifp if you are running damping in the shock.

[BigLittleToyota]

I only got on here to talk a little bit of trash back to all of those 4x4 guys that bashed me every time I asked for a little help with IFS. I built a set of LT arms for my truck and I run SAW 10" C/O, SAW Tripple Bypasses and deavers in the rear. Every time I would ask a simple question I had every idiot with a Kragen 110v arc welder that has turned out some "dang 'ol nice stuff" on the ranch telling me I was an idiot. I just wanted to stir the pot since Dezert trucks are my forte and I am in my element.

Reservoirs hold more oil so the capacity can be increased in the shock to decrease "shock fade" as the shocks heat up. They don't "cool" the shocks, but they do allow for more oil to flow and can keep the temps in a more fitting range. It used to be that racers would run up to 4 emulsion shocks per corner and they would have to replace all 4 every time that they pitted. emulsion shocks are garbage for high speed driving. Fine for rock crawling and daily driving.

No, I'm not running the 1000 next month, but I did help change tires and empty a few cold ones with a team that just finished the PRIMM 300 and will be running a 1600 in the 1000. I have school that is stopping me from pitting with them.

That's right, I am a flat-biller. Plain and simple. DILLIGAF!!!

[TRD]

I only got on here to talk a little bit of trash back to all of those 4x4 guys that bashed me every time I asked for a little help with IFS. I built a set of LT arms for my truck and I run SAW 10" C/O, SAW Tripple Bypasses and deavers in the rear. Every time I would ask a simple question I had every idiot with a Kragen 110v arc welder that has turned out some "dang 'ol nice stuff" on the ranch telling me I was an idiot. I just wanted to stir the pot since Dezert trucks are my forte and I am in my element.

Maybe you deserved the trash talking for being an idiot :confused: :flipoff2:

Reservoirs hold more oil so the capacity can be increased in the shock to decrease "shock fade" as the shocks heat up. They don't "cool" the shocks, but they do allow for more oil to flow and can keep the temps in a more fitting range.



You are contradicting yourself here.
Reservoirs do help cool shocks. If the fluid in the reservoir is hotter than the ambient air then there is cooling going on.

I dont think emulsion shocks are ok for comp vehicles or anyone that wants to do even mild prerunning.

[Lance]

I only got on here to talk a little bit of trash back to all of those 4x4 guys that bashed me every time I asked for a little help with IFS. I built a set of LT arms for my truck and I run SAW 10" C/O, SAW Tripple Bypasses and deavers in the rear. Every time I would ask a simple question I had every idiot with a Kragen 110v arc welder that has turned out some "dang 'ol nice stuff" on the ranch telling me I was an idiot. I just wanted to stir the pot since Dezert trucks are my forte and I am in my element.

Reservoirs hold more oil so the capacity can be increased in the shock to decrease "shock fade" as the shocks heat up. They don't "cool" the shocks, but they do allow for more oil to flow and can keep the temps in a more fitting range. It used to be that racers would run up to 4 emulsion shocks per corner and they would have to replace all 4 every time that they pitted. emulsion shocks are garbage for high speed driving. Fine for rock crawling and daily driving.

No, I'm not running the 1000 next month, but I did help change tires and empty a few cold ones with a team that just finished the PRIMM 300 and will be running a 1600 in the 1000. I have school that is stopping me from pitting with them.

That's right, I am a flat-biller. Plain and simple. DILLIGAF!!!

If you were trying to build an IFS for rock crawling, you ARE an idiot... Plain and simple. Just ask Walker Evans. :laughing:

[Weasel]

You are contradicting yourself here.
Reservoirs do help cool shocks. If the fluid in the reservoir is hotter than the ambient air then there is cooling going on.


I think what he meant f that the main purpose of reservoirs is not cooling, it's a side benifit. Maybe not...

Plain and simple. Just ask Walker Evans. :laughing:

What ever happened to that thing? Did he just scrap it?

[Beat95YJ]

I think what he meant f that the main purpose of reservoirs is not cooling, it's a side benifit. Maybe not...



What ever happened to that thing? Did he just scrap it?

It turned into the Redbull Rockit 1.

[Weasel]

It turned into the Redbull Rockit 1.

I always though it would have been a fun rig to through hydros on, not for comp but just to screw around with.

[KSL]

It turned into the Redbull Rockit 1.

the Redbull Rockit 1 was Walkers old truck prior to the independent truck. They did put solid axle under it soon after the first coulple of runs.

[BigLittleToyota]

All that I wanted to know was if anyone had ever used the SAW torsion bars on their rigs. Instead of someone seeing my question and not answering, I had about 40 posts telling me that I was an F***ing idiot before one guy said, they worked for him and that this site was just for a bunch of rude people that want to unload on everyone with a question. Whatever to them.

The fluid isn't cooled by the reservoir like people think. There are some companies that have built bolt-on fins that help cool the shocks, but that was an afterthought of the reservoir design.

This is just beating a dead horse now. I'm out!

[Whitewater]

All that I wanted to know was if anyone had ever used the SAW torsion bars on their rigs. Instead of someone seeing my question and not answering, I had about 40 posts telling me that I was an F***ing idiot before one guy said, they worked for him and that this site was just for a bunch of rude people that want to unload on everyone with a question. Whatever to them.

The fluid isn't cooled by the reservoir like people think. There are some companies that have built bolt-on fins that help cool the shocks, but that was an afterthought of the reservoir design.

This is just beating a dead horse now. I'm out!

Well hopefully those people have opened their minds and expanded their horizons.
Now, let a dead horse lie and join in the constructive conversation here. The board is bound to be a great resource! :beer:

[BigLittleToyota]

Cheers to that.

[Beat95YJ]

TRD did some testing for you.

Shock heat thread (http://www.pirate4x4.com/forum/showthread.php?t=526226)

[irb4ur]

Since I started the thread, maybe I can have a final word. I was thinking about the heat in this shock that melted a small spot in the bronze rod bearing (1750 F melting point). There is a chance that the installer did welding on the buggy by grounding on the axle and welding on the frame. The shock would complete the circuit via the rod bearing if the buggy was in a stage of assembly that provided no other grounding path, which would make this issue a no-brainer. I just can't be sure that is what happened, but it makes good sense.

[TotalImmortal]

enough to melt buna. buna is the shit so pretty hot.

[cajunsuzukispider]

just put on cooling fins, build a little chamber around each of them, and pump the A/C through it.
what? you guys don't race with the A/C on?:laughing:

[HoupPhotography.com]

just put on cooling fins, build a little chamber around each of them, and pump the A/C through it.
what? you guys don't race with the A/C on?:laughing:

If the Herbst shark car can change nitrogen while driving, Anything is possible. :D
BTW - that is big :grinpimp:'n

[Beat95YJ]

Desert trucks with liquid cooled shocks, nothing new...

[HoupPhotography.com]

Desert trucks with liquid cooled shocks, nothing new...

It may not be "new" but still cool!!!
Why can't someone figure out a quick change system for pit stops if it's an issue.
hypothetical-tap the top and bottom of the shock, the truck comes in to pit and have a "quick flow" mechanisim that sucks the hot oil out and puts fresh cooler oil in at the same time.... I'm sure there may be more to it than that

[Beat95YJ]

It may not be "new" but still cool!!!
Why can't someone figure out a quick change system for pit stops if it's an issue.
hypothetical-tap the top and bottom of the shock, the truck comes in to pit and have a "quick flow" mechanisim that sucks the hot oil out and puts fresh cooler oil in at the same time.... I'm sure there may be more to it than that

Jiffy Tite/Russell quick disconnects would be fine for that (used in nacar on radiators to pump cold water in during pitstops.)

[COMPLAINE]

elaborate contraptions are cool, but isnt the point of really getting a shock to perform well is to tune it for a stable oil viscosity at a temperature that the shock could maintain under even the hardest beating. Basicly an oil that functions well at a high enough temperature where the heat loss at that temperature is great enough to maintain that temp in the shock even when it is 100+ outide. Surface area of the shock, and air speed over the shock would play pretty considerable factors.
The way i see it, if your beating a truck bad enough, even with fresh cool oil it will be hot again in less than an hour or so i imagine. So what good does changing the oil do unless it got too hot at one point and burnt it?
Hell if its not burnt, why not just spray the shock down with liquid nitrogen at pits, that'll cool it down.
Just my take on it, but maybe im wrong

Ian-

[Beat95YJ]

elaborate contraptions are cool, but isnt the point of really getting a shock to perform well is to tune it for a stable oil viscosity at a temperature that the shock could maintain under even the hardest beating. Basicly an oil that functions well at a high enough temperature where the heat loss at that temperature is great enough to maintain that temp in the shock even when it is 100+ outide. Surface area of the shock, and air speed over the shock would play pretty considerable factors.
The way i see it, if your beating a truck bad enough, even with fresh cool oil it will be hot again in less than an hour or so i imagine. So what good does changing the oil do unless it got too hot at one point and burnt it?
Hell if its not burnt, why not just spray the shock down with liquid nitrogen at pits, that'll cool it down.
Just my take on it, but maybe im wrong

Ian-

You are correct. I think the original poster was refering to a cooling jacket on the shock. I believe that the Kudela designed Baldwin truck has such a system on it.

[Curious1]

You are correct. I think the original poster was refering to a cooling jacket on the shock. I believe that the Kudela designed Baldwin truck has such a system on it.

I'm not sure if Kudela did it, but I've "heard" of another builder doing it. I can't remember his name right now, but he was one of the designers that did an all independent trophy truck. Was that a vague enough bit of info?

[skullver]

My old Jeepspeed buddy re-routed his windshield fluid nozzle, put a y and a misted his shock bodies with the press of a button, not sure it helped any but thought it was an interesting idea as he did not have a windshield to begin with.

[Curious1]

I'm not sure if Kudela did it, but I've "heard" of another builder doing it. I can't remember his name right now, but he was one of the designers that did an all independent trophy truck. Was that a vague enough bit of info?

I finally remembered the name of the designer I was thinking of. Nye Frank! I know he designed Dale Dondel's all Trophy Truck, but I couldn't find anything with liquid cooled shocks. It does sound like a great idea though. You'd have shocks that would run at a constant temp whether running hard or just cruising (in theory). It would seem like a great thing for doing valving.

[Bomber52]

Nye Frank did design some air shocks used in short course racing a number of years ago that used a water jacket around them to maintain a constant temperature. They were routed through the radiator system of the vehicle if I remember correctly.

Glenn

[Beat95YJ]

FYI,

I was in Barstow today in my Soccer Mom SUV playing around. The front right hit a peak temp of 400deg F. The other 3 shocks were in the high 300's. We weren't pushing the car that hard, we just were not giving it a break. Next time we might prerun a whole course to see what happens.

Oh and for fun here is a pic of the F-150 at home. The shocks on it hit 360deg F peak. (all temps recorded with temp strips)

[COMPLAINE]

Sick. You must have been chasing that soccer ball for quite some time to get the shocks up to temp in that thing. Why are you still using temp sticks? Are they more accurate than my impression of them(which isnt very accurate)? Whats stopping you from putting a Longer shock body on a shorter shaft and welding in a bung for a thermocouple? to take the temp of the mixed oil. Too elaborate? Too much money?

Ian-

[Beat95YJ]

Huh, I have never had anyone challenge the accuracy of a temp strip. (Never really thought about it though) It would be easy to check on the dyno as we have thermocouples on all of them.

I recently ordered some oil temp guages from autometer in an attempt to get real time temps from inside the cab for the F-150. The truth is they have not arrived yet.

At some point we will be installing a quickdata to record shock temperatures, chassis accelerations, and a few other things I am dreaming up. It just hasn't been the highest priority yet. I do have some real concerns about the longevity of some of the sensors in the dezert. The really durable ones tend to be very expensive.

We drove each vehicle for about 1 hour and 15 min to achieve these temps.

[COMPLAINE]

I actually don’t know what kind of temp sticks you are using, but I just don’t trust things that read temp from the outside. I picture the motorcycle temp stickers that guys put on there cylinder wall and trust that it is giving them accurate engine temp. Im sure they will never give a reading that is too high, so I guess it will give an upper limit which can be useful. Id would be interested to see if you stuck one on a shock on the dino and recorded temps from both the thermocouple and the temp stick to see how much they deviate, if at all.
Setting up sensors on a car that gets beat in the desert im sure is expensive, and finding durable components that weren’t just made to be used in a lab is not easy or cheap.
A real time data recorder would be cool. I do have one idea that im going to throw out there incase it is useful. I have thought about using a rotational potentiometer on suspension links. For example on the ford, there would be one on each beam pivot. This would plot angle through time which then you could get suspension position using geometry, and using a program like matlab, could then get velocities and accelerations at the shock or tire. Of coarse all of these would be relative to the chassis, but sometimes it hard to get relative data, and I am sure it could be usefull. When compared to accelerometers on the car, the absolute acceleration of the car and tire can be known, and of coarse the relative. That kinda gives you everything. And I know it gets you nowhere for leafs.
This is where stopped because I have no idea what could be done with all of this data
i.e. could you actually use this to tune or design a car?:confused:

Ian-

Disclaimer- See kids this is what happens when you spend too much time in a class room and not enough time being a hillbilly beating old trucks to death out in the backwoods. Be smart and don’t go to school, just build sick trucks and haul ass (just kidding):homer:

[Gordon]

it seems to me all you really need is a pair of accelerometers, one near each shock eye. from those data you (or labview) can calculate the shock velocities very acurately and get a reasonable estimation of position. and accelerometers can take a pounding.

I know most people who have done telemetry on desert cars have used potentiometers to read position but it doesn't make sense to me why you would need to. maybe to tune bumpstops or bypasses, but if you have bypass shocks the accelerometer data are going to show exactly where the piston passes the bypass tube and also where you hit the bumpstop.

What am I missing?

[Weasel]

This is where stopped because I have no idea what could be done with all of this data
i.e. could you actually use this to tune or design a car?:confused:


Yes, Something we have talked about for years with our mini baja, setting up a data acc. system and it might actually get done this year. Using the data you can help validate any models you may have of the system or simulations (we used Adams and Carsim). I'm not sure if anyone does this or not. Also would think you would be able to look at shock velocities and compare them to you dyno testing?

[Weasel]

I know most people who have done telemetry on desert cars have used potentiometers to read position but it doesn't make sense to me why you would need to.

What am I missing?

Well don't they use position vs force graphs for shock tuning? More accuracy on the position? We don't tend to use them as much as force vs velocity but at our comp on of the Honda suspension judges latched onto the position vs force graph and had all kinds of questions but pretty much ignored the Force vs velocity.

[Beat95YJ]

Well don't they use position vs force graphs for shock tuning? More accuracy on the position? We don't tend to use them as much as force vs velocity but at our comp on of the Honda suspension judges latched onto the position vs force graph and had all kinds of questions but pretty much ignored the Force vs velocity.

Force-position curves are fairly useless compared to force-vel.

Gordon,

One of the items I am going to try is to put pressure sensors in the top and bottom of the shock to closely allow me to calc the loads (and derive the velocities) as well as determine how much cavitation is actually occuring. I have on occasion discussed it with our data acq guys. The concern now goes to sampling rate. The events are extremely brief in this type of testing.

[Weasel]

Force-position curves are fairly useless compared to force-vel.



Thats what I thought but this guy was stuck on them. Dunno.

[Gordon]

sure but you have the accelration of the shock as a function of time by subtracting the accelerometer values and then you just take the first derivitive for velocity. that part is pretty much going to be dead on. then you can take the second derivitive and get a ball park for change in position that should be OK as long as you recalibrate it once and a while by jumping(topping out the suspension) or hitting the bumpstops. At least it should be good enough to tell you if it is packing up in the whoops.

Some of the judges at those student competitions are morons. Heck they even invited me to be a judge for FSAE competitions a few times.



With shock tuning I think there are two goals. 1) maximize road holding power and 2) maximize ride quality.

2 is pretty straight forward if you have an accelerometer on the chassis. try to make the accelerations small. If the accelerations are high cause you are always bottoming out make the shocks stiffer if they are high because you are not using much travel make sthe shocks softer. If the accelerations are out of wack at a particular shock velocity you can adjust that with different valving configurations.

1 is complicated in the big picture with how the low speed shock valving controls corner entry and exit characteristics etc but if we are just talking about maintaining control on a rough road then all you can do is try to make the contact force between the tire and the road as consistant as possible. that contat force can be plotted as a function of time from the two accelerometers too.

I have not seen it done for a form of racing where the tires leave the ground often, but I am sure the rally car guys do it. You would need to add a little bit of software to make the graph look right when the tires were in the air but it could easily be done, I think.

[Gordon]

Frank, the pressure sensors are a great idea! you should be able to do it with a strain gauge based pressure sensor. I have some small strain gauges that I have used at up to 100Hz and been able to validate their accuracy. The sample frequency is funny some of the expensive equipment can't go as fast some cheap stuff. I used some cheap almost homemade stuff from dataq? that could sample like 600 points per second. It was nice cause it would write right to USB memory sticks so you didn't have to torture test a lap top.

[COMPLAINE]

One of the items I am going to try is to put pressure sensors in the top and bottom of the shock to closely allow me to calc the loads (and derive the velocities) as well as determine how much cavitation is actually occuring. I have on occasion discussed it with our data acq guys. The concern now goes to sampling rate. The events are extremely brief in this type of testing.

How do you plan on knowing when it cavitates? Will the whole region of oil on one side of the piston be below vapor pressue? What about localized cavitation.
I take it the problem lies that the sampling rate would have to be very high like 1000 samples/sec, but they would have to be taken over a long amount of time which would be tons of data to store and sort through.


Thats what I thought but this guy was stuck on them. Dunno.
Maybe that had nothing to do with the shocks, but more suspension geometry and spring rate, and they were interested to see how the geometry manipulated a linear spring, or in your case how non linear the air shocks are. Just a thought.


Ian-

[Beat95YJ]

How do you plan on knowing when it cavitates? Will the whole region of oil on one side of the piston be below vapor pressue? What about localized cavitation.
I take it the problem lies that the sampling rate would have to be very high like 1000 samples/sec, but they would have to be taken over a long amount of time which would be tons of data to store and sort through.

Ian-

Theoretically during cavitation you would have negative pressure on one side of the working piston. By monitoring the pressure on both sides I could largely detect this in either direction (I would assume that a zero pressure reading was actually vacuum)

All theoretical at this point, but it makes one think.

[irb4ur]

(I started the "How Hot the Shock" thread last October and concluded that my customer's hot shock problem that melted his brass rod bearing (1700 F) was most likely caused by him welding on his frame while using the shock as an intermittent ground path.)

Acceleration and strain data are great if you can ultimately apply them to shock design and setup changes with the goal to improve suspension performance and longevity. Is the shock manufacturer working with you? Obviously heat is the big shock killer. So, reduce/eliminate the heat causes. Just some thoughts:

1. Piston shaft surface area/side load force: a small diameter shaft produces high localized heat due to side load force concentrated over a small area. A large shaft distributes the load over a larger surface area, reducing surface pressure and galling.
2. Shaft speed: lean the shock to gain as much geometric advantage possible (but consequently higher spring force/gas pressure needed). Straight up and the shaft speed = vertical wheel speed. Leaning, and shaft speed slows as an angle function relative to wheel movement and speed.
3. Maximize airflow at the heat source--the rod bearing: The rod bearing support member could use a thin wall and possibly heat dissipating fins.
4. Increase oil volume and circulate flow at the rod bearing if the design allows. (There has already been a lot of this discussion).
5. Ensure that the shocks have no side-load binding at full stuff and full extension. I've seen this many times where shocks deflect at the mounts to the point of binding. Breaking the bolts and mounts is as much a concern as the subsequent side force that is being conveyed to the rod bearing and piston--instant scuffed bearing and cylinder, followed by increased friction and heat. I even had a customer return a shock with the shock body almost completely worn away from tire contact. He wanted to know why the shock lost pressure and failed.

After reading these postings, it is clear that most of you are already way ahead of the game. Are you scientists or racers? Both?

[Beat95YJ]

clear that most of you are already way ahead of the game. Are you scientists or racers? Both?

I drive a train. I blow the whistle at intersections. :D

[Gordon]

After reading these postings, it is clear that most of you are already way ahead of the game. Are you scientists or racers? Both?

I'm a wannabee racer and a gladimnot scientist. I used to be an engineer but now I just push paper.

[Weasel]

yeah same here, wanna be racer and engineer sorta out of school.

[irb4ur]

After reading these postings, it is clear that most of you are already way ahead of the game. Are you scientists or racers? Both?

From a kid to a machinist to an engineer to quality assurance to business owner. Now I just want to play in the dirt again. These group confessions release emotions--I think we should hug.