Driveline vibrations that is.
I'm trying to get the lift install on my 96 Cherokee wrapped up as quickly and as cheaply as possible. Running Rusty's 3" HD springs up front, IRO adjustable LCAs, OME CS033RB leaf springs in back, yielding about 4" of lift front and rear as it sits now. Jeep goes in today for an alignment and to get my new tires mounted, which just leaves the nasty driveline vibrations yet to deal with.
Basically, I'm just trying to develop a plan of attack that doesnt involve firing the money cannon at it because the money cannon is low on ammo. Im closing on a house in a little over a month and need to wrap things up and stop spending money on the damn Jeep. Which means I'm really trying to avoid doing an SYE right now, even if that means band aiding for now until I can put one on in a few months time.
Backing up a step, the OME leaves are known to give a good bit more lift than advertised in many cases and had initially left me with nearly 5" of lift in the rear. Initial test drive in this state yielded horrible vibrations at all speeds, so I pulled the 3rd leaf from the top to reduce lift down to the current 4", per OME's instructions. Drove it again, and vibes were still there but significantly reduced. Rear pinion was definitely pointing up a bit, so I ordered 4 degree shims and installed them last night. My precision calibrated eyeballs tell me the rear pinion angle is pretty good now (gonna grab an angle gauge today to verify), but the vibrations are most certainly still present. I have yet to mess around with the front at all (pinion angle is a bit lower than driveshaft angle, but pretty close), nor have I isolated the problem to the front or rear yet. It feels to me like the vibes are origionating from the vicinity of the transfer case, fwiw.
My thinking is step 1 is to isolate the problem front to rear by pulling the front shaft. Next, start going through the u joints in the rear. I can definitely feel some play in the t case end u joint on hte rear shaft perpendicular to the axis of the driveshaft, though the pinion end seemed tight upon cursory inspection. If this doesn't solve it, then what? I don't see a transfer case drop helping, as the shims should accomplish the same thing. Am I forced to go SYE at that point?
Any thoughts, suggestions, or experience would be much appreciated.
U joints can feel tight in the vehicle but be junk. Seen this many times.
Also there ate some darn good apps for cell phones that you can use to measure the driveshaft angle.
Because the vibration got better by decreasing the angle in the rear I would continue looking there.
In 2 high, the front drive shaft should be freewheeling and not cause any issue.
Well I pulled the front shaft to no discernable effect, so it's definitely the rear. "Front" u joint on the rear shaft definitely has play, rear feels OK but I think I'm gonna go ahead and replace both anyways. Hoping that solves it, otherwise I should probably bite the bullet and buy a sye and double cardan shaft, thus making the $40 worth of u joints essentially a waste.
Toyman01 wrote:
In 2 high, the front drive shaft should be freewheeling and not cause any issue.
Because the later XJs have no disconnect at the or anything the shaft should still be turning in 2wd. Regardless of whether there is any torque going through it, I would think the rotational forces could still give rise to vibrations. Make sense?
How Sure are you it's the driveline? Sure it isn't old bad tires or unbalanced tires or even bearings?
From reading your post you haven't put on the new tires etc right?
I guess the next logical thing would be to pull the rear shaft and try it in fwd only and see what that nets you.
Isn't there an old lifted 4×4 trick that goes along with adjusting the pinion angle, which is to also lower the rear of the transfer case a bit?
So that if the rear axle pinion angle is raised a certain number of degrees, the angle of the output shaft is effectively lowered a similar number of degrees.
Most XJ's over 3in of lift need a SYE.
Antihero wrote:
How Sure are you it's the driveline? Sure it isn't old bad tires or unbalanced tires or even bearings?
From reading your post you haven't put on the new tires etc right?
New tires were installed today, no improvement.
I'm fairly positive it's the driveline. Shows all the right symptoms and it's a known issue when lifting XJs.
HappyAndy wrote:
Isn't there an old lifted 4×4 trick that goes along with adjusting the pinion angle, which is to also lower the rear of the transfer case a bit?
So that if the rear axle pinion angle is raised a certain number of degrees, the angle of the output shaft is effectively lowered a similar number of degrees.
Yup, that's a transfer case drop. I would rather not do one because a) it's counter productive to the point of a lift in that youre sacrificing ground clearance and b) added stress on the motor mounts. The angled shims should accomplish the same thing anyways. Checked the pinion angle today withan angle gauge and it's barely off, maybe a degree or so.
MrChaos wrote:
Most XJ's over 3in of lift need a SYE.
As I understand, the general internet wisdom seems to be that 3-4" or so of lift is a crap shoot as to whether it needs an sye. Which rear axle, tranny, and transfer case you have seems to affect the susceptibility (ax15<aw4, d35<8.25, 231<242, 95 and earleir<96 newer in terms of susceptibility to issues, so I'm about middle of the road being a 96 manual np231 8.25), but it is a total YMMV thing.
I'll throw the front shaft in and pull the rear tomorrow just to see what that does.
The real question at this point I think is going for be whether it mames sense throwing money at u joints or if I should just suck it up and buy the sye. May just end up doing a hack n tap and junkyard shaft.
wvumtnbkr wrote:
What is sye?
Slip Yoke Eliminator
If either u-joint breaks, the driveshaft will be free to slide out of the transfer case along with the lubrication.
The SYE eliminates this situation and allows you to drive safely on the front driveline.
I did a 4in lift on my 98 xj and got lucky i didnt need a slip yolk eliminator or transfer case drop but sounds like you need one or both. And idk if the one inch drop of the tcase would do much for ground clearance considering the axle is still way lower.
If your ujoints have play in them, you should replace them asap regardless of the vibration :)
I had about 5" with ROR's add-a-leaf(s) and shackles (still incredibly soft and flexible) and had that set-up with the Dana 35 then a factory Dana 44 with a mini-spool with zero vibration. And this is 90% street driving including some highway miles.
The extended shackles tilted the differential slightly toward the transfer-case. I doubt that'd help much.
U-joints are cheap insurance anyway so replace both and see what if any improvements you get. It's a lot less labor-intensive than an SYE.
Well I bought the u joints, got home, and crawled under the Jeep again only to discover what I thought had been play in the front u joint actually seems to be play between the yoke and output shaft. It seems there just isn't enough engagement of the yoke in the splines of the output shaft. Guess it's time to stop kidding myself and buy the slip yoke eliminator. I'll probably go with the Iron Rock hack n tap kit, I've been pleased with their double shear track bar and lower control arms for the price.
Hack and Tap. Budget friendly and works well enough. Throw new joints in the shaft that goes on and make sure the splines are greased well and tight.
That will solve the issues, and allow you to still use the Jeep without worry offroad.
In reply to Ross413:
That's the plan, IRO hack and tap kit ordered last night and I'm planning to head to the junk yard Saturday in search of a front driveshaft from a 5.2 ZJ. Not happy about spending the additional money right now, but at least it should be dealt with for good. I'm not really planning on any heavy duty rock crawling so I expect the H&T should hold up fine.
