CJ handling problems after 4" lift

You 'really' need the shims for the front, not the rear....

The longer shackles have destroyed the front end alignment and you either need to shim it or cut the spring perches and move them.

For the rear, you need to get the faces of the yokes in parallel. so they need to look like |=======| or /=======/. Folks use an angle finder or plumb bob to get it.

With 6" shackles, you might have fun trying to shim it right but 'apparently' the lift maker 'thinks' you can do it....

I used stock CJ springs and had them rearched for my lift. My stock shackles were shot and all I could find at the time were 1" longer YJ ones. The Jerk at the 'jeep' shop insisted they would work. Ya right, he figured on making big bucks trying to 'fix' it later. This has me at borderline for vibes and front steering geometry.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's.

Tracy Brooks wrote:

Mike, At the risk of sounding even more stupid...what would I "shim" in the front? The axel?

For the rear, I read an article which stressed the importance of the yokes being parallel. When looking at the output of the tcase, and the iput of the diff, in order for them to be parrallel, I would need to remove the shims on the rear axel. This would then make the driveshaft angle very steep at both ends.

-Tracy

On Wed, 18 May 2005 09:30:06 -0400 in , Mike Romain graced the world with this thought:

Something to add to this, if you aren't accustomed to a lift on a Jeep, it takes a while to get used to. My CJ has a 6" lift, and when I first started driving it, it seemed squirrely as hell, on top of which, any little twitch I made seemed like an overcorrection, probably because of the short wheelbase. Passing someone on a two lane backcountry road scared the hell out of me when both of us were going, say, 50mph (try passing a Dakota pulling a boat, on a two lane bridge with a 45mph speed limit, then check your pants...). It definitely took a few months of regular driving before I realized that for the most part, you have to let the vehicle drive itself, you'll wear yourself out trying to make it steer like a Pontiac. Now, after 15 years of driving it this way, it doesn't even phase me. Of course, if that alignment is off, you'd have to take care of that first, or it won't steer itself terribly well.

80 CJ5 35X12.50 M/T's 258

Figure the shackles tilted the front end down or pinion up big time so the shims would go in the back side of the spring perch to bring the pinion back down and get the castor angles back to something sane.

For the rear, the article was right. The steep angle of the shaft doesn't matter, having the u-joints open and close the same does. If one u-joint opens more on one side than the other, they will be out of sync and jam and vibrations will set in.

Even just with the 1" longer YJ shackles in mine, I get nasty vibes if running with no load and my steering won't self center any more. When a load drops the body down a bit, the angles are ok so the vibes go away.

Mike

Tracy Brooks wrote:

Hey Bill, Have you seen one of these track bars used on a CJ?

-Tracy

6" shackles!!! Take those off and go back to stock, or at most 1" longer than stock. What you want is heavy duty shackles that are a little bit longer than stock, not long shackles that are the same strenght as stock. Shackles are a source of twist and bend in the suspension.

I suspect the shackles have changed the Caster angle to near zero, and you need shims to get the caster back. The trouble is, this will present binding problems for the front drive shaft, MAYBE.

I think you need the shortest possible shackles. This might mean they are longer than stock, but nowhere near 6".

Yes. Just like you shimmed the rear - you shimmed the rear, right? If not, this could explain your vibes.

The centerline of the crank, trans, tcase, and so on needs to be parallel to the pinion. With the lift you have, there is no way in hell you will have parallel lines with out shims. With the double cardan drive shaft in the rear, then this rule is modified somewhat.

Your problem is gonna be on the front. You have so much lift from the shackles that you have lost your caster angle, and the way to get it back will make your driveline angles on the front even worse, and you could be getting vibes from there already. To add insult to injury, one of the corrective actions for the back is to drop the tcase some more, but this will exaserbate the trouble in the front some more. The saving grace is that the front drive shaft is so long that the angle differences will be less significant than for the rear, so the solutions might be workable.

It would likely be better to put in the 1" taller engine mounts and maybe help the angles better that way than a t-case drop.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Yeah, I relied on the 4x4 shop's recommendation for the lift and shackles. Of course, they cater to the extreme crowd....the ones who think a weekend is fun only if it includes at least one roll-over.

The original shackles measured 3" bolt to bolt, mine measure 6". I guess I'll start by replacing the shackles with 4" ones. Do you think that will give the springs enough room to flex.

Thanks,

-Tracy

I know of NO member of the extreme crowd that uses 6" shackles. Indeed, these are a disaster waiting to happen. I have the ConFer heavy duty shackles, and they are just a fraction of an inch longer than stock, I assume this is because the material is so much beefier that they needed the space avoid compromising the strength after they drilled the holes.

The springs should be longer to accomodate the added arch, therefore in theory the original shackles should be fine. As a practical matter, you want the absolute shortest shackle you can get. I'd agree that the stock shackles for that lift would be too short, but there is no question that the 6" shackles you got are way too long. I can't suggest the right shackle, sorry, but the wrong shackle is the one you already have.

I forgot what springs you got, but if you have ProComp springs, they won't flex much no matter how long the shackles are.

On Wed, 18 May 2005 10:49:31 -0700 in rec.autos.makers.jeep+willys, "Jeff Strickland" wrote,

I think it is because they needed to make room for the extra brace in the middle, that the originals don't have.

That could be, the added length is about the size of the bracing.