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Old 01-28-2014, 06:19 AM   #376 (permalink)
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Just summing up this thread as I just read the entire thing.

- read pages 1-9, 13-15 ( some ass hats in the middle ask bad questions and are answered with info that doesn't jive with the rest of the thread.)

- read CJ2ota's post on pg.14 he sums it up nicely

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To fix your roll values have you considered increasing link separation at the frame or axles , like CJ2ota mentions on pg14 (separation meaning widen or narrow)
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Old 09-26-2014, 09:07 AM   #377 (permalink)
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So, I have a question for you. I have read this entire thread, purchased a book on suspensions and played with the calculator. Its all really great stuff. But, my question is just how off do some of these numbers have to be to really notice a difference.

For example, my wifes' stock JK's numbers aren't all that great. From the builds I see people do, their numbers are much better. I have not off roaded her jeep but I hear in stock set up, they do quite well.


for example, the role axis on the JK is over 12%. That is pretty high by the standards in this thread. I would love to hear from folks who had to make corrections because the numbers where to high. How far off where your numbers and where did you have to set it before you were happy with it.

Last edited by buildbreakrepeat; 09-29-2014 at 07:10 AM. Reason: typo's
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Old 02-14-2015, 01:23 PM   #378 (permalink)
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Suspension 101 - Rock Racing | Xtreme 4x4 | PowerBlockTV - Full Episodes

easier to just watch a video
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Old 05-31-2015, 07:46 AM   #379 (permalink)
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Thanks for this Cliff Notes version of this thread, appreciate it!
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Old 05-31-2015, 07:57 AM   #380 (permalink)
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super video!
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Old 05-31-2015, 04:22 PM   #381 (permalink)
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super video!
I guess it might seem that way, but mostly it was gibberish for TV.
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Old 09-23-2015, 03:13 PM   #382 (permalink)
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Nice video but of the 17 minutes only a few had anything to do with link placing and adjusting. Practically nothing about 3 link systems. They could have put an hour into this topic easily. For instance I would like to know why factory systems seem to violate most of the rules of thumb. The dodge trucks I see with 4 link suspensions, well correction. 5 link suspensions seem to have plenty of angle on their links which we all know is going to lead to a ridiculous roll center and AD(anti-dive). My problems are getting the roll center to 0 and have any anti dive left on a 5 link. With the vehicle having only an 8 inch lift it is impossible to fit any triangulation into the front.
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Old 10-27-2015, 01:20 PM   #383 (permalink)
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I agree with what you are saying, although I like to think of increasing AS as increasing resistance to suspension compression not "increasing grab" as the normal force on the tires isn't changing under constant acceleration. Your explanation is basically my understanding of why the 70% rule. For the reasons you mentioned I think longer lowers generally makes for best AS change through travel. Although instead of 70% I generally shoot for 80% to help mitigate the pinion angle issue.

Additionally I've always built my own driveshafts and lately I've been using Dana 50 TTB axle shaft ends (1350 series) and I can get some rediculus angles out of them. Additionally I usually point the pinion up so it is pointing above the TC output at ride height. People have told me "you can't do that" for "blah blah blah vibe, u-joint wear, reasons, reasons" and I have yet to change a u joint in either of my DS. Additionally I challenge someone to get in my buggy and tell me what exactly is vibrating

So anyhow pinion angle at full droop has only been an issue for me on my front axle, so I'm considering reworking the front 4 link or possibly making a new front DS out of Dana 60 axle shafts (1480 series). But when it comes to the front axle I wonder whats "the lesser of two evils" pinion angle change and poor DS angle or the castor angle change with travel that would be associated with using longer uppers than lowers.

Edit: Re read and changed top paragraph slightly.
Any chance you can post some tech on the Dana 50 TTB driveshafts? That would be awesome.

Also, have you come to a conclusion on the lesser of two evils regarding the long vs short upper link and driveshaft angle vs castor? I'm in that same boat right now.

Thanks!
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Old 02-03-2016, 06:42 PM   #384 (permalink)
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Bumping this thread up. When linking front and rear axles how important is it to have the links similar lengths front and back to maintain equal driveshaft lengths?

Also I read you want your lower links as close as possible to the output shafts on tcase.

I have a divorce tcase and I can easily move it forward. Current driveshafts are 40" rear and 55" front
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Old 02-03-2016, 09:19 PM   #385 (permalink)
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Also I read you want your lower links as close as possible to the output shafts on tcase.
Yes. You will get optimum droop angle out of you driveshaft U joint if the joint is exactly at your lower link mount point. Make them both move in unisun on the same plane.
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Old 02-04-2016, 07:37 AM   #386 (permalink)
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Yes. You will get optimum droop angle out of you driveshaft U joint if the joint is exactly at your lower link mount point. Make them both move in unisun on the same plane.
If your goal is maximum flex, this is good advice. Your slip joint won't work as hard. As far as the drive shafts being the same length, There is not really any big advantage. Moving the t-case maybe good for drive shafts and links, but not for weight distribution. There's trade offs for everything.
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Old 02-04-2016, 08:22 AM   #387 (permalink)
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The advantage is clear to having equal length shafts. One spare.

Imo, weight bias and gross weight are not concerns of the op. Check his build out. I believe what he is doing is eating the length of the intermediate shaft off the trans and swinging the balance of the long front shaft to the rear shaft.

In any other "buggy" app, equal length shafts ARE a result of BETTER weight bias and a midship is run on the front output.

The lower length of the links front to rear doesn't really effect the drive shafts until the geometry, WB or vertical sep of yokes gets to extreme values. What I mean by this is you can have equal front and rear shafts but different link geometry front to rear. Only have to mind the capability of the u joints. Also the length of the lower links in the X plane (viewed from side) is altered by the horizontal separation of the links in the Y plane (viewed from above). This means you can have 40" links but the further they are triangulated in the Y plane might mean you have a 36.5" link distance in the X plane. 40" axle horizontal separation and 7" at the frame Those are the figures from my rear links. 40" lowers f&r and 25" f&r shaft measurement iirc. 1410 joints, non cv.

X2 what Stubs said
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Last edited by Juicysluice; 02-04-2016 at 08:25 AM. Reason: Change rear lower value at frame
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Old 02-04-2016, 12:56 PM   #388 (permalink)
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The advantage is clear to having equal length shafts. One spare.
I like the way you think. I've always thought it would be cool to build a rig with equal length links, driveshafts and have identical axles at both ends. If you really wanted to go to extremes, get center diffs.
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Old 02-04-2016, 01:37 PM   #389 (permalink)
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Funny you mention the links. I fought hard with link placement, the "#"s and the steering so I could carry 1 spare link in the toolbox to get me home. Steering, panhard, front lowers and rear 4 link are all 40". For obvious reasons the tie rod and front top link are of different length but least likely to fail or suffer a damaging impact. Vetteboy built his TTB buggy around equal drive shafts. Think he only had a 1/2" variance in his design
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Old 02-04-2016, 04:47 PM   #390 (permalink)
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The advantage is clear to having equal length shafts. One spare.
Yep.

All my lowers are all the same length and so are my uppers. Uppers dont bend very often but I am using DOM for my lowers and expect them to bend over time.
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Old 02-04-2016, 09:01 PM   #391 (permalink)
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Vetteboy built his TTB buggy around equal drive shafts. Think he only had a 1/2" variance in his design
Yep. Completely intentional. 100% meant to do that.

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Old 02-04-2016, 09:39 PM   #392 (permalink)
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Thanks for responses guys. I want the design to also help protect the shafts with the links. A carrier bearing could come into play in front as well. The rear I original had a 1350 cv shaft but after dropping a significant amount of lift for better stability I could just run 1350/1410 shaft probably but the rear truss was built anticipating rotating diff for cv. Gotta start crunching some #'s in a calculator
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Old 02-05-2016, 09:56 AM   #393 (permalink)
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Thanks for responses guys. I want the design to also help protect the shafts with the links.
You got the right idea.
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Old 02-22-2016, 07:14 PM   #394 (permalink)
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I always wondered why Ford angled the rear of the leaf up.
I always understood this had to do with keeping the axle centered under compression. What with the curvature of the leaf springs and all. The angle cancels out the extension of the leaf as it goes flat under compression. I guess this would pretty much take care of the roll steer.
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Old 02-23-2016, 04:53 AM   #395 (permalink)
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I always understood this had to do with keeping the axle centered under compression. What with the curvature of the leaf springs and all. The angle cancels out the extension of the leaf as it goes flat under compression. I guess this would pretty much take care of the roll steer.
Strange you would bring this up now. You realize you are quoting me from 3 years ago. In that post, I went on to say that I figured it was for roll steer.
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Old 02-23-2016, 07:01 AM   #396 (permalink)
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Perhaps I'm overthinking it, but I have a question / discussion for the big brains...

What (if any) ill-effects would you see with a setup having the instant center behind the rear drive axle? In other words, a negative IC x-axis.

Playing with it in the calc, doesn't seem to affect anything too greatly slipping from the parallel plane to a negative IC, and I can't come up with anything in my head that would cause any weird jacking in the suspension (assuming proper separation & geometry otherwise)
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Old 02-25-2017, 07:42 PM   #397 (permalink)
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I need some help here boys, Im terrible at figuring out angles without putting them into action first and then re doing my work.

Im putting a buggy together that formerly had toy axles, now going to 1 tons. Suspension geometry was good and would like to keep everything as close to the same as possible. Im trying to figure out my lower lengths right now to run through the calculator and scratching my head. Here is the info I know from before

old Lowers-44
current spacing at frame-12 inches
former spacing at axle (toy) -35 inches (center to center)

New spacing at axle (dana 60) should be 40 (center to center)

to keep my heims straight and inline with the old frame tabs, how long do my lowers need to be? I bought 20* link mount brakets to angle them in as much as possible, but I'm afraid it won't be enough. Any help here? This is probably simple as shit but I just can't put it together tonight.
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Old 02-28-2017, 10:57 AM   #398 (permalink)
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Mark it out on the shop floor, measure for length, then go buy one of these Husky 5 in. Digital Protractor-822H - The Home Depot read numbers, now you have your angle. Send me $5 for my wisdom.
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Old 11-26-2017, 04:16 PM   #399 (permalink)
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hmmmm

Looks like I have a lot more research to do, lots of info here!
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Old 12-21-2017, 02:18 PM   #400 (permalink)
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Smile

Thank you - Great thread
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