Rock Jock vs Pro Rock

[bart]

Yeah, I love the Spider 9s and am suscribed to this thread, so keep it going. I don't have any tech to add, but I would love to build one of these front axles for my TJ.

[TedsTJ]

I have ProRock 60s under my TJ and love them. I used to have a Currie Hi Pinion 9" under the front. Obviouisly the Currie Rock Jock 60 uses an aluminum dif. housing. Most people agree that nodular iron is much stonger especially when the aluminum gets hot. I have heard of people breaking those aluminum center sections quite a bit. Bare in mind that with Curries standard hi9, they use 3" diameter .188 wall tubes. Think about that !. A dana 35 housing and a dana 30 housing use 2.5" diameter, .25 thick wall tubes but the Currie axle uses .188 thick wall tubes which is obviously about 25% thinner walls then the factory axles tubes. Granted, the 3" diameter of the Currie 9" provides about 50% more stifness or resistence to bending as compared to the Dana 30 or 35, but what happens if you slam that .188 wall tubing on a big rock......good chance you will dent it and then you have a weak stop that could bend. .188 tubing is probably fine for hot rods, but way to thin for playing in the rocks IMO. Currie will build the 9" with thicker wall tubing, but its not their standard package and I think you can only go as high as .375 wall tubing. ProRock 60 is 3.5" diameter .50 wall tubing. Also, Currie just recently come out with what they call their "Iron Jock" which is nodular iron. So, is this an admission that the aluminum center section is weaker? If the Aluminum Rock Jock is as strong as say a ProRock 60, then why do they need the new "Iron Jock"? Plus, the front Rock Jock is close to $8000 and you can get a front ProRock for about $6400 with a detroit but that is with alloy shafts not 4340 chromoly. The Tera Flex CDR 60 is good value IMO, a little over $5000 for front and close to same price for the rear with detroit and I think you get Chromoly shafts. I am running 37" Iroks with 5.13 gears and I am glad I went with more gear instead of say 4.88 gears.

Just my thoughts

Rock On

Ted

[Ghetto Fab.]

Wish i had a limitless supply of cash!

Keep posting on the buildup, its allways good to see what other people are doing.

How much were those rockcrusher spindles? Would they take standard front 60 hubs or just rear hubs?

Kevo

[BamaSahara]

I would build some Rockcrushers (Solid Axle now). Lots of them around here and they work well

[bnine]

Originally Posted by Ghetto Fab.

Wish i had a limitless supply of cash!

Me too. That way I wouldnt have had to build 5 rigs this year to pay for my junk But Im patient. I just want to build the last big parts I'll ever need for my rig.

Originally Posted by Ghetto Fab.

How much were those rockcrusher spindles? Would they take standard front 60 hubs or just rear hubs?

Kevo

The spindles are really resonable at 92$ a pop. They except front chev 60 hubs, or rear 14bolts. I was going to junkyard some of that stuff, but changed my mind and am now savin up for RockCrusher rear hub kit. For 750, you get spindles, hubs, slugs, brake brackets, and a few other odds an ends.

You can really do the hubs cheap with boneyard 14b's, but then you shafts get a little more pricy and hard to get due to custom cuttin 35 spline on one end, and 14b on the other.

Doing it yourself, these things actually work out to be pretty cheap compared to a lot of crate axles out there.

After selling my original axles for 4k Canadian, I'll be spending less then 5k Canadian to build both axles with all aftermarket parts.

Not that bad IMO.

[cdc12372]

Originally Posted by TedsTJ

I have ProRock 60s under my TJ and love them. I used to have a Currie Hi Pinion 9" under the front. Obviouisly the Currie Rock Jock 60 uses an aluminum dif. housing. Most people agree that nodular iron is much stonger especially when the aluminum gets hot. I have heard of people breaking those aluminum center sections quite a bit. Bare in mind that with Curries standard hi9, they use 3" diameter .188 wall tubes. Think about that !. A dana 35 housing and a dana 30 housing use 2.5" diameter, .25 thick wall tubes but the Currie axle uses .188 thick wall tubes which is obviously about 25% thinner walls then the factory axles tubes. Granted, the 3" diameter of the Currie 9" provides about 50% more stifness or resistence to bending as compared to the Dana 30 or 35, but what happens if you slam that .188 wall tubing on a big rock......good chance you will dent it and then you have a weak stop that could bend. .188 tubing is probably fine for hot rods, but way to thin for playing in the rocks IMO. Currie will build the 9" with thicker wall tubing, but its not their standard package and I think you can only go as high as .375 wall tubing. ProRock 60 is 3.5" diameter .50 wall tubing. Also, Currie just recently come out with what they call their "Iron Jock" which is nodular iron. So, is this an admission that the aluminum center section is weaker? If the Aluminum Rock Jock is as strong as say a ProRock 60, then why do they need the new "Iron Jock"? Plus, the front Rock Jock is close to $8000 and you can get a front ProRock for about $6400 with a detroit but that is with alloy shafts not 4340 chromoly. The Tera Flex CDR 60 is good value IMO, a little over $5000 for front and close to same price for the rear with detroit and I think you get Chromoly shafts. I am running 37" Iroks with 5.13 gears and I am glad I went with more gear instead of say 4.88 gears.

Just my thoughts

Rock On

Ted

Ted, As far as the Currie Rock Jock weaker than a ProRock well...... everyone has their own opinion. As far as Rock Jocks breaking "quite a bit" I like to see a picture of a broke one. As far as I know the Rock Jock is not recommended for really heavy rigs (4k +), it was design and build with lighter weight rigs in mind. As far as the Iron Jock goes I think is a big assuption to say that their is something wrong with the aluminum center section that is why the have an iron one. Some people will not buy the Rock Jock just because it is aluminum even if they like the design. So why not offer another product for the people that have a heavy rig and do not like aluminum. If you were building a light weight rig how would you like to save 50 lbs on a center cention alone!!!! Rock Jock 35 lbs VS Pro Rock 85 lbs.
I believe this is more a case of using the right part for the propper application.

[fordnut]

awsome axles keep the pictures coming.

[bnine]

Another qucik question. Just to confirm, there is no crosspin in a 9" detroit right?

Be nice to be able to pound a busted shaft out from the other end if a guy where ever in that predicament.

[TedsTJ]

Originally Posted by cdc12372

Ted, As far as the Currie Rock Jock weaker than a ProRock well...... everyone has their own opinion. As far as Rock Jocks breaking "quite a bit" I like to see a picture of a broke one. As far as I know the Rock Jock is not recommended for really heavy rigs (4k +), it was design and build with lighter weight rigs in mind. As far as the Iron Jock goes I think is a big assuption to say that their is something wrong with the aluminum center section that is why the have an iron one. Some people will not buy the Rock Jock just because it is aluminum even if they like the design. So why not offer another product for the people that have a heavy rig and do not like aluminum. If you were building a light weight rig how would you like to save 50 lbs on a center cention alone!!!! Rock Jock 35 lbs VS Pro Rock 85 lbs.
I believe this is more a case of using the right part for the propper application.

Granted, coming out with the "Iron Jock" is probably not an admission on the part of Currie that nodular iron is stonger..........that would be a stretch, but rather most likely an effort to be competitive with the other nodular 60's available. However, IMO the .188 wall tubing on the Hi 9" is a poor choice as their standard tubing for their 9". The 9" I purchased was $5000. How much more would it have cost Currie to use say .375 wall tube or maybe even .25 wall tubing? Probably not but a couple of bucks cost to them. Also do you really want to start welding on that .188 wall tubeing? What if you want switch the axle from a TJ to a YJ and you have to cut off all the pirches and brackets and weld on new ones. .188 wall tube is not much material to work with. A Currie management representative relayed a story to me in which a jeep was running one if their 9" axle in a front application of a mud racing vehicle. The vehicle got extremely stuck so they took a chain rapped it around the axle tube and hooked it up to a Front End Loader and pulled the vehicle out. In doing so, they bent the 9" .188 inch tube. Granted, they should have hooked up to the frame, but had that been a tube from a 60 most likely they would have pealed off a control arm bracket way before they bent the tube. Why not make it stupid strong when it doesn't cost anymore or take more time? After all, when it comes to breaking stuff, few sub-cultures are more creative than hardcore offroaders. IMO, Currie just doesn't build their stuff strong enough.

Ted

[bnine]

Great story Ted.

Any chance you ran a detroit in that 9", and did it have a center pin ???

[CCJC]

Hey Bnine, are you wondering if a detroit for a 9" has a center pin, because I thought I read that you were?

[truehi9]

The 35 spline 9" Detroit is open inside. So yes, pushing an axle out should be easy.

On the left side, of the second pic up from the bottom of this http://www.truehi9.com/thrustblock2.html page, is a 35 spline 9" Detroit.

[crusty1007]

Bnine,
This is bellocchi.
anyways, have you checked out the iron jock? or are you looking for weight savings by going with the rock jock....? is this going in the rubi?

edit: excuse my ignorance, i didnt read the whole thread.

[soilantgreen]

TrueHi9: It occurs to me that if all vendors were as honest, open, and forthcoming about the perceived defects in their products, then I and (how many?) others wouldn't be heading to Dothan, AL at the end of this month. I look forward to dealing with you when it's time to go HP on my Currie 9s. ('Happy to do that testing for you on your improved aluminum centers in my DD TJ, BTW. :wink

[jonnyjeeps]

In my opinion currie makes ambitious products that don,t hold up well over time and the parts for repair are proprietary. I have run lots of axles that I pieced together thinking of the money and it never paid off till I scrapped up enough for my rear tera cdr60 I've been running it real hard for almost two years with minimal service and no problems I will definitely be upgrading the front to the same btw I am running 39.5s and 4.88s

[bnine]

Originally Posted by BamaSahara

I would build some Rockcrushers (Solid Axle now). Lots of them around here and they work well

I went through that. It would cost me almost as much for the front axle as it does for two 609's, and, a well built rockcrusher front weighs in at 700lbs.

My 609 will be lucky to break 350.

I weighed my knuckles with the unit bearings attached last night.

50lbs per side, for 100 total
Housing will be 50lbs once its cut
According to Truhi, 9" 3rd with detroit, 70lbs on the hi side
brakes, 50lbs
axles, 40lbs, call it 50 with slugs?

Thats 310lbs, another 40lbs in some light trussing and link tabs is generous.

A 609 on 37's has the pumkin clearence of a 60 on 40's. Half the weight. About 2 3rds the cost.

Once these guys showed me the 609's and I started researching, the decision was pretty easy.

[bnine]

Originally Posted by truehi9

The 35 spline 9" Detroit is open inside. So yes, pushing an axle out should be easy.

On the left side, of the second pic up from the bottom of this http://www.truehi9.com/thrustblock2.html page, is a 35 9" spline Detroit.

Thanks Truhi, as usual.

First order for a 3rd is coming next week.

[bnine]

Ordered my rear axles, hubs, and 3rd member yesterday. The rar should be going together by the end of the month.

In the mean time, anyone want to drop some tips on welding the Chromo spindles into the non chromo steel tubes?

Anyone here ever do these? How much interference did you use? 5 thou sound good? We are going to turn the inside of the axle tubes a few thou to true them up a bit, then turn the spindles down to match. Just wondering what a good interference fit would be to go with.

Also, another qucik question. How much play do I want in a full float shaft? 1/4" ok?

[mrblaine]

Originally Posted by jonnyjeeps

In my opinion currie makes ambitious products that don,t hold up well over time and the parts for repair are proprietary. I have run lots of axles that I pieced together thinking of the money and it never paid off till I scrapped up enough for my rear tera cdr60 I've been running it real hard for almost two years with minimal service and no problems I will definitely be upgrading the front to the same btw I am running 39.5s and 4.88s

That's a great opinion, why don't you get back to me when you actually run some of their stuff?

I've been running an aluminum Rock Jock in the rear with 4:88's and Red Label Krawlers in the 39" flavor in JV exclusively for the last two years plus and have had exactly zero issues with it.

As far as proprietary goes. That is in response to the majority of their customers requesting the 5 on 5.5 bolt pattern on most of their "proprietary" junk. I know I have no interest in running 8 lug stuff when I already own two sets of 5 hole beadlocks.

I've also been running one of the 609's in the front with it's poor pathetic little .188 wall tubes that I welded brackets onto and have had exactly the same service out of it. Flawless.

Almost forgot, I'm also running their aluminum knuckles.

BTW Zach, I'd like to see a picture of what happened to the truss on that axle that stripped out the tubes. The one that goes from side to side that bolts up to the welded lugs to slow the tube spin down.

[mrblaine]

Originally Posted by bnine

Ordered my rear axles, hubs, and 3rd member yesterday. The rar should be going together by the end of the month.

In the mean time, anyone want to drop some tips on welding the Chromo spindles into the non chromo steel tubes?

Anyone here ever do these? How much interference did you use? 5 thou sound good? We are going to turn the inside of the axle tubes a few thou to true them up a bit, then turn the spindles down to match. Just wondering what a good interference fit would be to go with.

Also, another qucik question. How much play do I want in a full float shaft? 1/4" ok?

If you tig it, don't use Chromolly tig rod. Use whatever you would use for mild steel. We've found that the tig has a tendency to crack down the middle of the weld if you mix metals. The normal tig rod and normal mig wire seem to do much better.

On that diameter of stuff, it's going to be pretty hard to press in with that much interference fit. Back it down to about .003 or so. You might get by with .005 if you heat the tube. Your weld will take care of holding it in, the fit is just for alignment.

[bnine]

Thanks for popping in, and for the advice Blaine.

Good point on the alignment, no point in bustin our nuts on that if we dont need to.

[CCJC]

So I was over at Bnine's house last night and those housings and knuckles are freakin' AWESOME and they have a very nice bling factor to them too. I can't wait to see the 3rd members

[WHITE RHINO]

Have have two buddies one with rock jocks front and rear and the other has pro rocks front and rear. neither have had a problem with either. I have seen rock jocks have sealing problems. when currie was pressing the tube in they made a deep score on the aluminum which allowed the gear oil just to leak out at a good rate. I personally like rock jocks and prorocks but if i was going to put one under my rig it would definitely be the pro rocks just for strength of the housing

[WHITE RHINO]

if you want a super stout axle that will "never" break get a front dana 80 from dynatrac that would be nuts

[bnine]

Last big decision I need to make.

A hi 9 rear pinion is 2 an 1/8" offset. If I run equal length shafts, that mean my pinion will not be center and I will be compounding two angles.

If I center my pinion, I cant run equal length shafts, which would be a nice plus for shit like carrying spares.

Not having anyexperience with a pinion offset that far, I dont know how bad it would be.

Vertical angle will be a minimum because of ride and driveshaft height. With my wheelbase stretched 6 inches, and a yoke conversion on my t-case, I should get about 20-22 inches of driveshaft.

My rig wont see a lot of road duty, but a little here and there wont be out of the question either.

Anyone run this much offset on a pinion and get away with it?

I've gotten away with .5- maybe 1 inch on 44's and 8.8's I've set up on short shafts around 16 inches long, but never pushed it this far.

If anyone can shed some light on this one, it would be greatly appreciated.

The ability to run equal lengths would be nice. Also cheaper since I can get them off the shelf in the width Im shooting for. No special request.

Thanks