heefner Posted September 5, 2008 Report Share Posted September 5, 2008 I swapped a rebuilt rear with 3:90 gear set (I pulled the torque tube and check it while I had the rear out) and now I have a wicked drive line vibration. I also pulled the companion flange off the torque tube without making a mating mark. I've read in the manual that if you have over .001 run out that you need to re index the companion flange so I did this. I rotated approx 180 and still looking at the drive shaft near the rear u-joint it looks to have a tiny wobble. I haven't had the car back out on the street but I'm pretty sure I will still have the vibration. When I put in my new drive shaft and rear companion flange in a few months ago, I didn't have any issues with vibration. Any ideas how to remedy this? Link to comment Share on other sites More sharing options...
Shelby Posted September 5, 2008 Report Share Posted September 5, 2008 ok so the vibration was not there untill the 3:90s same drive shaft etc , same tourqe tube but diff carrier when and at what tourqe load is the vibration present did you check for a stiff u-joint while the shaft was down you sure ALL the frt diff mounting spacers are there and none fell out i had a real problem with drive line moveing when i first did the 3:90s,,the trans would ride up and the drive shaft would get out of proper working angle and try to whip it's self up and down , realy beat the crap out of the trany mount untill i realign'd the entire drive line and limit'd the trans mount movement basicly i had wheel hop but at the trans not the wheels going to lower gears is sort of like going from a 6" wratchet to a 12" wratchet same tourqe equals more tourqe load to the wheels few yrs ago Chip broke a u-joint at the gainesville track , i manage'd to get a new joint in to the yoke but the shaft was twist'd and vibrate'd bad , it was not twist'd enought to see with the naked eye but was enought out of alignment to see it when installing the last brg cap Link to comment Share on other sites More sharing options...
heefner Posted September 5, 2008 Author Report Share Posted September 5, 2008 The vibration is present with and with out torque applied ( accelerating and coasting). U-joints seem fine. Is it possible that the torque tube and or rear can be misaligned causing this? It's almost like a wheel vibration, its worst at 40mph and then settles a little then as speed in creases the frequency increases. Link to comment Share on other sites More sharing options...
Komeuppance Posted September 5, 2008 Report Share Posted September 5, 2008 Not to doubt your skills, but are all your lugnuts tightened?? I swapped in a 6 bolt rear end in freezing 20 degree weather... I guess I wasn't thinking straight being halfway frozen and dead tired from wrenching and never torqued my lugnuts enough. Went out for a test drive, seemed ok. Then I took it on a 100 mile round trip... and it started vibrating really bad. I thought I had a bad axle. I bought a new set, waited two weeks for them to come in... and went to lift the car up and take off a wheel. Turns out... my lugnuts were all loose in the rear. -Robert Link to comment Share on other sites More sharing options...
heefner Posted September 5, 2008 Author Report Share Posted September 5, 2008 I didn't take the wheels off but it's easy enough to check. Link to comment Share on other sites More sharing options...
Shelby Posted September 5, 2008 Report Share Posted September 5, 2008 Heff i have lost count of the quest drive shafts i've drop'd and not once did i scribe mark any of them on the diff yoke,, now the shaft ujoint yokes that diff, if you can put the car up on stands with the rear axles as close as you can get them to the position they are in on the ground , meaning don't let the wheels hang down, remove the tires , now run the drive line at the same speed your geting the vibration and look at the drive shaft , and both rear axles, it's very posible for a c-v joint ball to fall out of place when the axle was being remove'd or install'd we tend to for get the rear axles shafts have joints in them also, and can cause the same problems a bad ujoint can , and just like the drive shaft the only real way to check the joints is to remove the shaft and check the joints by hand one other thing diff size rear tires can cause the lsd clutchs to slip even while both are turning in the same direction , this could translate into a vibration type of feeling Link to comment Share on other sites More sharing options...
Indiana Posted September 5, 2008 Report Share Posted September 5, 2008 Does it growl or just vibrate? the shims put the load on the bearings, who set it up? you swap in an entire carrier that the diff was already setup in or just put a diff into the carrier you had? Link to comment Share on other sites More sharing options...
heefner Posted September 5, 2008 Author Report Share Posted September 5, 2008 I ran the car in first gear with the rear of the car jacked up but wheels were hanging. I'll try again tonight with the wheels closer to ride hight levels. ( hope I can scrounge enough jack stands) Is it possible to have the axle flanges out of center if you tighten up the bolts in a weird pattern? I set up the rear a few years ago, ran it and then swapped back to stock sometime after the trans swap. I put new ring gear in pinion on a used diff with new bearings, It was fine when I took it out. Link to comment Share on other sites More sharing options...
Shelby Posted September 5, 2008 Report Share Posted September 5, 2008 just like the drive shaft yoke the axles have a recess and flange that centers and aligns them ,,it sounds imposible but you don't have a 6 bolt diff with 4 bolt axles do you Link to comment Share on other sites More sharing options...
heefner Posted September 5, 2008 Author Report Share Posted September 5, 2008 Ok, So I raised both wheels so that they were at ride hight, car running in 4th gear at idle maybe 10mph emergency break set just so that there is a tiny load on drive line. While running I can stop the passenger wheel while the drivers side continues to spin. I let got and eventually the passenger side starts to spin and you can hear some klunks in the rear diff. If I try to stop the drivers wheel the engine dies. I suspect something in the clutch pack is worn, dry or not functioning correctly. Like I said its been sitting for a few years. I did add friction modifier when I added new royal purple gear oil. Is this common? ...I don't however think this is related to drive line vibrations. I have some video I'll post up later. Link to comment Share on other sites More sharing options...
heefner Posted September 6, 2008 Author Report Share Posted September 6, 2008 I took it out for a spin after some slow figure 8's and then lit them up with the line lock and both wheels started to smoke at the same time so I think the diff is ok. I just have to figure out the drive line. I plan to loosen all mounting blots from the torque tube back, make sure everything is lined up then re tighten from front to back. Link to comment Share on other sites More sharing options...
heefner Posted September 6, 2008 Author Report Share Posted September 6, 2008 just like the drive shaft yoke the axles have a recess and flange that centers and aligns them ,,it sounds imposible but you don't have a 6 bolt diff with 4 bolt axles do you No six bolt rear and axles and spindles. Link to comment Share on other sites More sharing options...
Shelby Posted September 6, 2008 Report Share Posted September 6, 2008 for one wheel to spin freely some thing has to be out of place in the carrier pac , redo your test and see if one wheel will still spin freely how ever i have had one diff to act like that for a few days after a long set up in my g-sons 86 any way just how bad is this vibration mild, slight , or moderate Link to comment Share on other sites More sharing options...
heefner Posted September 6, 2008 Author Report Share Posted September 6, 2008 for one wheel to spin freely some thing has to be out of place in the carrier pac , redo your test and see if one wheel will still spin freely how ever i have had one diff to act like that for a few days after a long set up in my g-sons 86 any way just how bad is this vibration mild, slight , or moderate when I drove the car the vibration started off pretty slight after I got on the gas a few times it seemed to get worse. After 5 or so miles I was glad I was back in the drive way b/c even at slow speeds (30 or below) it seemed like a tire severely out of balance. After dinner I went back out to loosen all mounting bolts and make sure everything was happy then re-torque things and found the passenger side diff mount where it mounts to the chassi was only finger tight. Hopefully that was the root of my problem. It's starting to rain here <hurricane Hanna> so I don't know if I'll get a chance to test it before going to the track on Sunday. Hopefully it will hold up for at least a few passes. If nothing else if something breaks it will be easier to diagnose. Link to comment Share on other sites More sharing options...
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