New (not so good )Vibrations on the YJ

[JeepinMaxx]

Vehicle Background:
90 YJ with Rusty's 4" lift, SYE, and Tom Woods CV shaft

No vibes after the SYE/Woody install. No vibes until on the ride too and from Rocktoberfest (with hard doors, spare axles, tools, Powertank, etc.. on board). Vibes on acceleration up to ~45MPH. Came home from the trip and they seemed to go away. Yesterday I put the hard doors back on and today I loaded up with a bunch of equipment to go to the range. Those vibe are back. It seems to be weight related (anytime I add hard doors and tools/passenger). Also with the hard doors and equipment on board - the rear tires scrape on the flares on every bump :evil:

Question is - can loading up affect the pinion angle?
When I had it jacked up by the frame yesterday it looked like the pinion angle improved quite a bit.
Could the recent spring flexing activities (Coy, Ramp at GAJR, Rocktoberfest) cause my cheap Rusty's springs to sag? :swear_mad: (also notice it's been about a 1/2 inch lower on the frame to the ground on the drivers side for a while now - probably due to the driver's substantial ballast :frown:

If so - could an add-a leaf or new springs correct the pinion angle like I think it would? (plus keep me from scraping the tires on the flares when loaded up)

Sorry for long post and all the questions - just want to give as much info as possible.

I appreciate your input :wink:

Thanks

Frank

 

[NomadJeep]

I have been through more spring pinion changed than I care to admit.  I have had issues with load, with accell only with decell only... and it all comes down to angle.

Now that you have a SYE, it IS the easiest style to check angle.  Yes springs can sage and effect angle. Even mine have gone down a lot and required a smaller shim.

Sometimes you can do the MM lift and that will bring you just in line, however the first thing to do is put the $8 angle finder on the shaft, and on the back tab of the diff.  Find those to numbers and we will know what the deal is.  Also when you did your SYE, remember that sometimes a new u-joint will hide a vibe a little bit.  However this bad angle will quickly wear out the joint, and then a vibe appears.  I need to redo my shims again because I went from a perfect 2 degree below the drive shaft to now a 2 degree above.  I get a small vibe now, but as soon as a put a new joint in, I get a few weeks before it gives me grief.  I am just doing the ujoints until I finally get up the time to fix the real problem.  Also check your angles loaded.  (if you dont want to deal with it now, just change the pinion u-joint and you will be back the way you were, at least for a short time)  :mrgreen:

 

[NomadJeep]

edited it so it read better, sorry Frank I was still asleep when I typed that this morning.

If you want to have a pinion angle Wrench down, we can curse, throw wrenches, and swear repeatedly together as we work on them both... :mrgreen:

 

[JeepinMaxx]

Thanks Damon- I called Rusty's today and the tech I talked to was really helpfull. He asked how long I had the lift, what tire/wheel combo I have and asked for measurements from the center of the wheel to each stock flare at all 4 wheels. I checked my records and I've only had the lift since summer '04 (right before I joined NEJeep :wink He seemed concerned I had tweaked springs in just two years :question: Hopefully Rusty's will have a solution to the tweaked springs. If I need a add-aleaf- maybe I can check the pinion angle then and add shims if needed
The tech said he would call me back with a solution tomorow...

BTW - On past issues - Rusty's support has been great!

 

[beaker]

Stay with the tech, I've talked directly with rusty and it only took them 3 friggin months to send me some add a leafs to fix the sagging in my lift springs.

I'm glad he's good with some people but not always.

 

[JeepinMaxx]

Stay with the tech, I've talked directly with rusty and it only took them 3 friggin months to send me some add a leafs to fix the sagging in my lift springs.

I'm glad he's good with some people but not always.

Beaker - did Rusty's charge you for the add a leafs or did he send them free of charge?

BTW I haven't got a call back from Rusty's tech yet...

 

[beaker]

I got them for free, but I had to call a dozen or so times. Rusty kept forgetting to send them out etc. I never wait for return calls. The customer service takes care of the "squeaky wheels" first so I squeak.

Mine look like the Mc D's arches without the add a leafs and the add a leafs are starting to look like them too. I'm just putting new leafs on with what ever I do for axles.

 

[JeepinMaxx]

Update - I spoke with the Rusty's tech today. He told me they forwarded the data I gave them to their spring manufacturer (he said the springs are manufactured by the same company that makes Fabtech & Rubicon Express). I might have to wait a week or so (because most of their crew are at the SEMA show this week) :sad:

I hope I don't need to wait 3 months like Beaker did for a warranty solution :swear_mad:

I hate to have that kind of downtime...

So - I'm thinking of buying some add-a-leafs now (and wait to see what Rusty's does for warranty...)
Or changing the axle shims and adding a 1" body lift and/or cutting to fit my TJ flares I have sitting in my shed

 

[beaker]

Fab up a torque arm. Ensures proper pinion angle without shims. No more spring wrap as well.

 

[toyworx]

Frank,

I've got add-a-leafs in the garage for a YJ. Also, beaker is correct. I ran the CJ spring over with crappy 5 year old leaf packs and NEVER had a problem. I ran the M.O.R.E. track bar.

 

[ctgranite]

i didn't read every post in detail but i have had a problem with spring wrap. i had rancho 2" lift springs (old) and added a chevy 350. the springs stayed in a permant "s" shape. replaced them with RE spring over 1.5" springs with a 6 leaf pack. fixed.

 

[NomadJeep]

however, he has spring under.  He really sould not need a track bar.  

Frank, if you are trying to correct the un even level, or think that 1 pack is shot, then add a leaf or get a new pack. (warrenty)

For the vibe, I thought when we last talked you said you did the SYE, and left the old 8 degree shims in, and have not checked it since.  Thus once you did the SYE, you would have to change out the 8 for something less, like me I went from 8 to 6. Either way, the angle needs to be checked, so the right shim can be put in.

Fix your leaf pack, then get you set up with the right shim/ angle. Becuase to set it now, and then change around the pack is doing the job twice. get level, then vibe free. :wink:

 

[beaker]

I wasn't refering to the track bar, that controls axle left and right position. I was refering to a torque arm. A front to back orientated bar to control pinion angle. The leaf springs just bend a little to follow the pinion angle set by the torque arm. It's far less bend than you'll get with uncontrolled spring wrap such as when your on the throttle in 4 low.

Setting the correct pinion angle with shims is important otherwise using the torque arm will cause a continuous stress in the springs.

 

[JeepinMaxx]

however, he has spring under. He really sould not need a track bar.

Frank, if you are trying to correct the un even level, or think that 1 pack is shot, then add a leaf or get a new pack. (warrenty)

For the vibe, I thought when we last talked you said you did the SYE, and left the old 8 degree shims in, and have not checked it since. Thus once you did the SYE, you would have to change out the 8 for something less, like me I went from 8 to 6. Either way, the angle needs to be checked, so the right shim can be put in.

Fix your leaf pack, then get you set up with the right shim/ angle. Becuase to set it now, and then change around the pack is doing the job twice. get level, then vibe free. :wink:

Nomad - Thanks for the input (and your SUA experience). Toywerks is letting me borrow some YJ add-a-leafs, and I hope to borrow some axle shims (do you still have some 5 degree shims hanging around?) to dial out drivetrain vibes. No worries on the fenders rubbing - sawzawl or body lift will fix that... I'm more concerned with the vibe's than lift/fender rubbin'

 

[toyworx]

I wasn't refering to the track bar, that controls axle left and right position. I was refering to a torque arm.

Sorry...thats what I meant. I meant to say "traction bar" which is old school lingo for the torque arm you are referring to.