I have an '88 TA w/ the 305 and 102k miles. About 5-6 yrs ago I started noticing a vibration coming from the rear of the car while driving on the freeway. I did some work on it back then, but this car is stored a lot so I never got it fixed. Well now I"m getting ready to get her painted and I wanna do all the mechanical stuff 1st.

Anyway, my sister has an '86 IROC that doesn't have any vibration problems, so I've been able to swap out a lot of part to try to narrow it down. I've tried 3 sets of tires and 2 sets of rims, different driveshaft, and different brake drums. I've also lubed all the bushings. I thought possibly the rear springs were sagging and changing the driveshaft angle (causing the U joint to bind slightly) but the distance from the top of the rear tire to the quarter panel is roughly the same as the top of the front tire to the fender. Is there any better way to check this?

I should also mention that, after installing my sister's driveshaft, the car was quieter. Not soon after that, I realized I needed a new U joint. That eliminated the low-pitched rumbling noise I was hearing, but it didn't do anything to the vibration.

It's also been suggested that the tailshaft in the transmission could be the culprit -- do I have to take the driveshaft out to feel any excessive play? I looked at it w/ the driveshaft still in and it seemed fine. Beyond that, the only other thing I can think of is to open up the rear end and check for a bad differential gear, axle bearing, bent axle, etc.

The other clue that might shed some light on this happened while I was swapping out parts. My sister's car has aluminum brake drums that are lighter than my steel set. The vibration was lessened when they were on the car. Likewise, the 2nd set of rims I put on the car were lighter than the 1st set, and this reduced the vibration as well. The lighter weight is the only thing I can think of they would have in common. That suggests to me that the problem is either a bad axle bearing or bent axle. None of the other things I've tried have had any effect on the vibration.

Ideas? Comments? Suggestions?

 

anybody?

 

The first and least expensive thing I would try next is replacing the tailshaft housing bushing and seal. see what that gets you. Otherwise, it will then have to be in the rearend with either a carrier bearing or and axle bearing gone bad.

 

Well I found a better way to check it. While my dad was cleaning up the basement, he found an old package of rubber spring spacers that are designed to temporarily support sagging springs. So we threw them on and the rear end picked up about 3/4". I took it for a ride and it made a hell of an improvement. It may not be the whole problem, but I"m gonna order new heavy-duty springs today.

 

how are the bushings all around?
tranny mount?
motor mounts?
shocks?

all of these as well as slight axel bends and warps can make the little vibrations

if it's in the steering wheels, that's usually front end related
up through the feet and seat is usually driveline related

also having mis-matched tires can sometimes cause it too

 

UPDATE: I can't believe I'm still fighting w/ this problem I ordered and installed the heavy-duty springs and went for a short ride on the freeway. She felt good for about the 1st mile, but then it started coming back and getting worse. I drove about 120 miles the next day, and the vibe was as bad as ever by the time I got home.

I took the driveshaft out to check the trans tail shaft. My dad knows a guy who owns a good trans shop, and he said there would be trans fluid leaking out if the tail shaft was bad. There was no fluid and the shaft had very little play. While I had the driveshaft out, I noticed there were chatter marks all the way around the yoke. I took it to the trans guy and he said the marks would only be on 1 side if the driveshaft was out of balance.

We put the car on the hoist and ran it to 70mph. We checked the driveshaft and the pass wheel and didn't see any wobble (the driver wheel wasn't spinning). Then he noticed that the driver's side of the axle was hanging down farther than the pass side. He suggested that I get new shocks. While we were looking at the shocks, he noticed that the driver's side e-brake cable was rubbing on the rim! Turns out the clip that holds it in place was rusted and it broke while I was installing the springs. The cable chewed the lead weight right off the tire.

So I installed new shocks, replaced the cable, and got the tire rebalanced. I also noticed that pinion seal was leaking, so I checked the differential fluid level and it was probably 1/2 full. I replaced the seal, inspected the pinion, and filled the fluid.

I took her for a drive last night and... THE VIBRATION IS STILL THERE!! My dad watched from behind as I drove and it doesn't look like I have a bent axle. We also replaced the rear brakes and inspected the axle shafts... there's no run out that would indicate a bad bearing, and the guy from the trans shop said that a bad bearing wouldn't cause the vibe I have.

The only thing left is something inside the differential, so I thought about a gear that lost a tooth and was out of balance. But then I found another post from a guy who said that he lost a tooth back there and it vibrated becuz the gears weren't meshing correctly. That would explain why it didn't seem to vibrate when we had it on the hoist -- there was no load on the gears so it was ezr for them to mesh.

 

I bet your flux capacitor failed. That would cause youre muffler bearings to overheat and you probably lost a lot of driveshaft fluid in the process.


Sorry thats my standard answer to all seeminly impossible problems


Seriously though, im thinking its something in your rear end. If it wasnt vibrating on the lift, you could be onto something with your no gear load theory. Did you weld your spider gears? The only reason i ask is because i had a buddy of mine with an 82 z28 and he welded his, one weld broke and the broken pieces of weld were practically vaporized by the gears. It didnt lock up the rear end thankfully, but it did cause a hell of a racket. Does the vibration get worse when you get on the gas?

 

Yet another update... I decided I better look at the differential, so I pulled the rear cover. The gears were fine... in fact, they looked pretty good for 104K miles. There's also a magnet in there to collect metal shavings, and there was barely anything on it. My dad's buddy suggested a trans mount or torque arm bushings. So I changed the mount (and managed to break 2 of the crossmember bolts in the process, so a 20 min job took over 6hrs ) But when I got the old mount out, I discovered it was torn. I really thought I was on to something, but it didn't fix it The vibration feels different though... not quite as severe and it seems to come on and go away as I speed up/slow down different than it did before. My guess is that the vibration caused the mount to tear, rather than the other way around.

While I was under there, I inspected the torque arm bushing and there was nothing wrong it. I have 1 on order, but I don't know if it's worth $20. Besides, it's a pretty severe vibration... I can't see how the torque arm bushing could cause that. Could any of the other bushings cause it? I've inspected and lubed them, but then again, I never would have seen that tear in the trans mount until I pulled it out.

Another thing I should mention is that, when I changed the shocks, it seemed to change to more of a side-to-side wiggle rather than up and down.

I really don't think the rear end is the problem... there's no grinding, run out in the axles, or metal shavings to indicate a bad bearing. And there's no wobble in the tires to indicate an bent axle -- my sister's '86 IROC had a bent axle that was quite visible and even that wasn't enough to cause a vibration. My tire wear is normal too. And the diff gears look perfect (and no, I"ve never welded anything -- that's the 1st time the rear end has ever been opened up). It's a lot of time/$$/effort to replace and I have absolutely no reason to believe that the rear end is the problem.

 

Things to check if you havent already...


Sway bar bushings, panhard bars....



After that, it is possible that your frame can be out of wack slighty... it costs more than I'd want to pay to have it put on a frame rack to check for straightness, but if you're willing... I'd do that lastly...


and if the frame is straight, my suggestions for subframe connectors... it'll make the car drive like a cadillac when installed properly

 

Torque converter out of balance?
Total guess, sorry.

 

Yeah we thought about the frame being tweaked too... we measured the distance between the tires w/ a tape measure and they were w/in 3/8". I don't think that would be enough to cause the problem... and I'm not getting any funny tire wear. What does changing the subframe connectors do?

Well that's something I hadn't thought of. But I have tried shutting the car off while going at freeway speeds... would that stop the convertor from rotating?

Another thing I was thinking of is some kind of aerodynamic force. The rear spoiler is cracked and splitting, and I wonder if that could cause enough turbulence to shake the car. I tried moving the car back and forth by grabbing the spoiler w/ my hand, and it doesn't take as much force as u might think. That would explain why it doesn't shake on the lift, cuz there's no air flow. Seems pretty unlikely, but at this pt, all the remaining options seem pretty unlikely

 

take off the spolier and take the car for a drive, if that fixes it then you got your problem

 

You'd actually be installing subframe connectors (unless you have some already?). They stiffen the frame and prevent it from flexing as much. While I doubt that it would help your high speed vibration, it is a modification that everyone with an F-Body should do when they get the funds.

 

Sycopath I have bad vibration problems as well and the spoiler won't do anything. I have, had actually, a '91 aerowing spoiler was flopping around like a fish out of water. I thought what you thought 'maybe the loose spoiler is creating a turbulence" well the spoiler was removed and the vibes are still there. I think a loose spoiler is just that, a loose spoiler.

Have you tried the see the condition of your sway bar endlinks?

I also rotted off rear endlinks for the rear sway bar. I had my tires balanced and it didn't improve anything, it did however move the vibes from 75mph on up to 82mph and up. I will see if they can redo it and then my car also needs an alignment as my driver tire is going bald on the outside.

After that I'm going to swap out my 2.73 rear for a complete disc to disc & swaybar w/ endlinks rear end.

At that time I have an aluminum DS so that can't be a culprit but maybe the universal joints have worn down.

If still vibrating, it's time to check the motor mounts.

Sorry for my plan of attack, but I feel your pain. It seems like a long road to smoothness.

Good luck to both of us.

 

sorry not to post this earlier.... but how are your wheel bearings?

 

I've been fighting a similar problem for months. One thing you didn't mention, though, was the TYPE of vibration.

I actually have two. One is clearly engine-related. From 2200 to 2400 rpm, there is a vibration. It even happens in neutral, with the car parked, so it is clearly from the pressure plate-forward. I took the belt off, so no accessories were turning, and the vibration is still there, so I can rule out alternator, power steering pump, etc. I'm thinking I've either thrown a spring off of my pressure plate or my harmonic balancer is bad.

I have another vibration that is clearly driveline-related. It starts at around 75 and gets progressively worse as I go faster. It's a rhythmic, "thrumming" sort of vibration (thrum, thrum THRUM, thrum thrum THRUM). I had the driveshaft checked and balanced, the guy said it was twisted and he straightened it. It still vibrates, but the vibration is different now, so I think it's definitely driveshaft-related. I bought an aluminum 3" driveshaft from an 02 SS Camaro off of ebay and have it out being balanced today (by another driveshaft shop). We'll see.

If the vibration is still there, I'm thinking it's an axle bearing, carrier bearing, etc. I won't put any money into this rearend, as I want to swap to a 4th gen rearend for the disk brakes and to be able to put my SLP Firehawk rims on the car without having to use spacers.

I really don't think you're going to cure your vibration with bushings, etc. Most of the time, they are caused by something in the actual driveline being bad, bent or out-of balance. If you've swapped driveshafts and ruled out the trans tailshaft, it's probably going to be in your rear end.

Does it vibrate in neutral, at speed? If so, it's probably not the trans tailshaft.

Is it a constant vibration, or does it "modulate"? A constant vibration would probably be a tire. If it modulates, it's probably mechanical.

Have you checked your axles/axle bearings? Put the car on jackstands and take the wheels and brake drums, off. Put the car in gaer and observes the axles rotating. They should not wobble at all. If they do, you probably have a bent axle and/or bad axle bearings.

I came across a tool for isolating vibrations not long ago, but have lost the link to it. Maybe someone knows what I'm talking about. Anyway, it was too expensive for me to buy, but I was thinking of emailing them to see if they knew of a driveline shop in my area that had one.

I know this afternoon whether the new driveshaft fixed my problem, wish you good luck with yours.

 

Got my car back, and the driveline vibration is gone! I'd bought the driveshaft on ebay from a seller with nearly 100% feedback, so I was pretty sure it would be ok. I decided to have it checked out on a balancer and have new, heavy duty u-joints put in, anyway. It just didn't make sense to put it in and risk having to pull it out again later.

The guy at the driveshaft shop said it was straight as an arrow and only needed a little bit of weight added to correct a slight vibration over 3100 rpm. He also said the vibration damper put on later 4th gen driveshafts is junk and strongly recommended I not use it. I took his advice and it appears he was right. I took it out and ran it till the speed limiter kicked in at 106, no driveline vibration at all.

I still have the engine vibration between 2200 and 2500; I'll track that down, next.

syco, I know you've already swapped out the driveshaft, but I'd still suggest you have it checked on a balancer and put NEW universal joints in it. I told the guy at the driveshaft shop about your problem and what you'd done to try and fix it. He said that once tires were ruled out, 90% of the time vibration problems came from the driveshaft or u-joints. He also agreed that the next best place to look would be the axles.

 

It’s probably the actual engine… I’ve noticed similar with every factory 350 that I’ve paid attention to, they all vibrate some at that RPM (you have to realize that these things are not balanced from the factory, they just use matching parts and hope for the best).

that’s a harmonic, not a vibration. That is the natural frequency for the driveshaft and it actually flexes/bows at that speed causing it to feel like a vibration. I’d bet that it would go away after you got significantly past that speed and would come back at 2x that speed.

Going to an aluminum driveshaft, one with a different diameter, wall thickeness… will change where the harmonic happens. No amount of balancing will totally get rid of it.

It’s more common for 4th gen guys to complain about this because it’s more common for them to have steeper rear gears that put them at a driveshaft speed to see this sooner.

 

I don't think it's that simple. The engine was vibration-free, for more than a year under my ownership, then started vibrating one day. Something had to change to cause it.

It's a harmonic vibration. Operative word; vibration. Again, it wasn't there one day, and was the next. When the first driveshaft shop found it was twisted and straightened the shaft, the vibration changed. Clearly, the shaft was bad. I'm thinking I twisted it during one of my marathon G-Tech sessions.

I have 3.42 gears in my car. I've run it up to 4500+ in 4th gear with the new shaft, moving slowly up the rpm scale, looking for any vibration or harmonic. None there.

In the words of Seigmund Freud: "sometimes a cigar is just a cigar". As I looked for the source of my driveline vibration, I've had every possible implausable theory thrown at me; everything from faulty brake shoes to transmission tailshafts to harmonics in the exhaust (an actual, possible explaination for the engine vibration that still exists between 2200 and 2500 rpm. it started sometime around my header and exhaust install).

I believe in Achem's Razor (The law of Parsimony): "All things being equal, the simplest answer is probably the correct one." More often than not, a driveline vibration can be narrowed down to the tires, driveshaft or rearend. I had the tires balanced, I checked the axles as I described in an earlier post; the next most likely culprit was the driveshaft. After it was straightened and the vibration changed, I was sure I had found the problem, regardless of what anyone else said.

When you work through the possible causes for something, you start with the most probable explainations, eliminate them as possibilities and move on to the next-most-probable one. It works in cars, it works in poker.

 

perhaps this is too simple... harmonic balancer shot?

 

That was the first thing I thought. I had it looked at and was told the balancer was ok. However, this vibration started right around the time I did the exhaust and changed the timing chain. That leaves me pretty suspicious. It's been more than a year since this particular vibration started, and it hasn't changed at all. I'm thinking if the pressure plate had puked a spring, it would've gotten worse or even gone out completely by now. Since I'm not about to mess with my high-priced, custom-made, mandrel-bent exhaust unless I absolutely have to, I'm back looking at the balancer again. I'm going to swap it out and see what happens.

 

Well I finally got a chance to get her out this summer... took my gf cruising in a nearby town. As soon as we got on the freeway, it felt like being on a vibrating bed. It was so bad that we started humming and u could hear our voices fluctuate w/ the vibration. It was much worse than the last time I drove her in Sept 2005 (before the repaint).

I never did check the sway bar links, but that's a good idea... I broke 1 of the front sway bar mounts a few yrs ago, so it wouldn't be surprising if the rears weren't in the best shape either. But given the fact that the severity of the vibration changes depending on weather or if it's a Tuesday or whatever, it's probably a bearing. If it was something bent, broken, or out of balance, it should always be the same.

So now I'm looking for a new rear end. Anybody got 1?

 

it seems as though you have been extremely thorough searching for this problem, but I have two more ideas to help you out as I myself have had vibration issues in the past.

1. Torque converter lockup. I have seen torque converter clutches go bad and cause a vibration at high speed. This is usually easy to diagnose as you will notice that the vibration happens everytime the converter locks up.

2. U-joints. I know you said that you have had the u-joints changed already, but let me share an experiennce of mine: I recently had new u-joints put in my 89' to fix a vibration problem that I could not figure out. Well after they were changed, the vibration continued - of course... So I got under my car and inspected their work to find out that they actually forgot to add the retaining clip that holds the caps in on 1 side, which caused a vibration @ 55-70 mph. After I reinstalled the clip - problem solved.

oh - and one more thought is that you may want to take the driveshaft to a driveline shop to actually have it balanced as things may appear okay to the untrained eye - but they can eliminate small harmonics on even new factory shafts by balancing to a higher speed. Jst a thought, let me know if it helps.

 

Well I can shift the car into neutral and let off the gas at freeway speeds and the vibration remains. I assume the falling revs would disengage the lockup, but that's something I'll pay more attention to next time I drive the car.

As for the U-joints, I also took the driveshaft out of my sister's '86 IROC and put it in my car. She doesn't have any vibration problems, but the vibration remained w/ her driveshaft in my car.

 

ttt

 

I just realized that it's been almost 2.5 yrs since I started this post and I still haven't solved the problem. I spent most of last weekend replacing the rear axle assembly, torsion bars, and panhard bars -- and it didn't make a damn bit of difference

Some1 also mentioned sway bar bushings -- I took the old ones out during axle replacement and they were in really good shape. I also put new good-quality bushings in.

Since this is such a long post, I’ve decided to summarize it to make it ezr to review…

This is a vibration that seems to come from the rear of the car. U can just start to feel it at 65mph and it’s most noticeable at about 75mph. The vibration seems to change sometimes… I don’t know if it’s becuz of weather or how long the car has been sitting or what.

1. Tried 3 sets of rims and tires. I also had my rear tires rebalanced recently.
2. Tried the driveshaft out of an ‘86 Camaro w/ no vibration problems
3. Tried the rear brake drums off the Camaro as well
4. New rear springs
5. New rear shocks
6. New trans mount
7. New spoiler (eliminating possible aerodynamic turbulence)
8. Rear axle assembly from car in junkyard. Complete w/ torsion bars, panhard bars, and sway bar. Installed new sway bar bushings as well.

Other things that have been suggested that I haven’t tried yet:
--tailshaft bushing
--motor mounts
--frame out of whack
--torque converter out of balance/lock-up clutch bad

For each of these, I have reason to believe that they are not the problem. But at this pt, I’m willing to try it. So how do I investigate each of these? Is there a way to access the tailshaft bushing? For the motor mounts, I was thinking about wedging some boards under them to keep the engine from rocking at freeway speeds. I know that would increase vibration from the engine, but would it be ok to run it like that for about 5 miles just to diagnose the problem? The frame would have to be done at a frame shop. As for the torque converter, wouldn’t shutting the engine off stop that from spinning? Also, is there an electrical plug I can disconnect to keep the clutch from locking up?

One more possibility I’ve been thinking about… what if the vibration that I was feeling was originally caused by the bad universal joint that I had replaced. So when I put the other tires, rims, and/or brake drums on, I actually eliminated the vibration but didn’t notice it becuz the U-joint was still messed up. So I then replaced the U-joint thinking that was the whole problem, but it only fixed part of the problem – I still had the bad rim/tire/brake drum on the car so the vibration remained. The ez solution would be to toss my sister’s rims and drums back on, but she hasn’t driven her Camaro in about 3yrs and I’m not sure if her tires are still ok.

 

Well I inspected my sister's tires and they looked to be in good shape. It also turns out that she drove her car about a month ago. So I tossed her rims and brake drums on my car -- didn't make any difference.

I bought a cheap set of motor mounts for $20, so I'm gonna try that next. I also remembered that the handle on the engine oil dipstick started rubbing on the AC condensor many yrs ago -- but I'm pretty sure it didn't do that when I 1st got the car. That could indicate that the mounts have deteriorated and allowed the motor to shift. So that gives me a little hope anyway... I hope changing the mounts isn't too hard of a job...

 

Is there any possibility that a something in the front (like front rims or rotors) could cause this vibration? It doesn't seem like it would, but I need to cover all the bases. I have a minor vibration that I feel in the steering wheel at lower speeds (like 45mph), but I don't feel the vibration at 75mph in the steering wheel.

 

Why the hell are you wasting our time with this if you don’t want to listen to the answer?

I said it before and I’ll say it again, it’s a driveshaft harmonic, replace it with one that has a different harmonic frequency (different diameter, different material…) and it will go away, it has nothing to do with balance or anything else.

****, there have been assorted TSB’s about this from the 80’s till ’98 when all the f-bodies got aluminum driveshafts.

 

Well it's not that I'm not listening, I guess I just didn't understand the intricacies of your suggestion. I have tried a different driveshaft, but since it was out of an '86 Camaro, u'r saying that it's made out of the same material and will have the same harmonic properties?

Interesting suggestion... I've noticed posts on here before about going to an aluminum driveshaft, but I always thought it was just for lighter rotational mass and therefore better acceleration. I'll search on here and try to figure out how much an aluminum driveshaft would cost. Thanx!

 

If you have a steel shaft in there, it is reaching "critical speed" which means it will not stay within balance tolerances at higher rotation speeds. The steel will tranmit vibration propeties much more than aluminum.

Length and weight BOTH come into play. You could go a larger diameter steel shaft to help with rotaion stregth and increase critical speed, BUT the heavier weight on the same lenght shaft will increase tailshaft bearing load. the longer the shaft, the more previlant this becomes.

Longer shafts generally require lighter material.
Critical speed generally requires lighter material or a shorter shaft.

Now, with that all said, another benefit to different materials is that aluminum does not transmit frequency vibration as much as steel. To go further, Carbon FIber does not transmit frequency vibration as much as aluminum.

 

That is not necessarily the cause of his problems. I changed my driveshaft out to an aluminum one from a LS1 Camaro, had it balanced just to be sure, and it did not solve my problem.

That could easily be the case with him, too.

 

Any chance a 4th gen driveshaft would fit my car? I'm finding prices of $400

Also, are the aluminum driveshafts lighter, or are they just stronger at the same weight?

 

Any chance a 4th gen driveshaft would fit my car? I'm finding prices of $400

Also, are the aluminum driveshafts lighter, or are they just stronger at the same weight?

Well considering how much other stuff I've changed, I think there's a good chance that this is the problem. At least I sure hope it is!

 

Aluminum driveshafts are lighter, although not necessarily stronger; especially the factory ones. They are as strong as the stock steel ones that come in our cars,though.

You can find 4th gen Camaro or Firebird driveshafts on ebay; they'll bolt right up. Pay no mre than 125.00. With shipping, I have 140 and change in mine. Another 100 to have it checked for true, balanced, and new Spicer u-joints put it in my car for under 250.00.

Aftermarket driveshafts are stronger, but will run you from 350-500.00

 

Well the only performance mods I have are a chip and a K&N air filter. I'm lucky if I'm pushing 180HP, so I need lighter a lot more than I need stronger

I found a junkyard that has 1 out of a low-mileage 4th gen for $125, so that's probably what I'll end up w/.

 

3rdgen steel shafts and 3rd gen aluminum shafts have the same rotation mass. The aluminum shaft will not show any gain in acceleration.

The aluminum shaft is lighter by a few pounds, BUT it is larger in diameter so the rotaion mass is harder to turn the larger diameter even though it is lighter. It not just what it weights, its also about polar movement.

So basically, a steel shaft is heavier but the weight of the walls is 1 1/4" from the center rotation. The aluminum walls is lighter weight but is 2" from center rotation. Its like spinning in a circle with you arms extened outward as opposed to spinning in a circle with you arms to your sides. You can spin faster with your arms to you sides. Thats less polar weight.

 

Well I installed it yesterday... didn't fix it

However it did substantially reduce the vibration. It still has the same rhythm, occurs at the same speeds, etc, but it's about 50% lower in amplitude. This follows the pattern -- the vibration decreases when I go to lighter rotating parts. The car came w/ 15" steel rims, and the vibration decreased when I put the stock 16" rims on. It had steel brake drums, and the vibe decreased when I put on the aluminum drums from my sister's IROC. And now it has decreased w/ a lighter driveshaft.

So this leads me back to 1.tailshaft bushing 2.motor mounts 3. frame out of whack.

1. If the steel driveshaft was flexing at speed, that could cause excessive wear on the bushing. But wouldn't a bad tailshaft bushing allow excessive play in the shaft that would damage the seal and cause trans fluid to leak out? I don't have any trans leaks.

2. I did a visual inspection and the mounts looked fine. We also tried jacking up the engine to see if the motor was loose or if the mounts allowed excessive play. But what I didn't realize at the time was that the front wheels were on blocks -- so as we raised the engine, the suspension decompressed and raised the car w/ the engine. So I guess I'll have to check that again to be sure.

3. The car has never been in an accident, but I do remember leaving the passenger front wheel up on a jackstand for a couple of days. 1 of our neighbors said not to do that becuz it could twist the frame. The car has T-tops, so it would be more vulnerable to that. But on the other hand, the T-tops fit well and don't leak. Plus we measured the tires as accurately as we could and they seem to be in alignment -- there's no weird tire wear either.

 

I will save you the trouble right now.
2) Its not motor mounts
and 3) its not the frame out of wack.

I suggested long ago to just replace the tailshaft bushing and seal because they are chep and cheerful and a quick fix. If they are probably original anyways and even if they do not fix the problem they are probably close to being in need for a few inexpensive bucks.

You still never tried this.

If it is not that

Then...

It is deffinately ethir a wheel bearing, pinion bearing OR it is a motor vibration that is tricking you. Check if it is rpm related (meaning does the vibration occur at the same rpm range) whether you are in 1st gear, 2nd gear, or 3rd gear(drive)- forget about O.D. it can diappear or be very faint.

 

1/3rd of the vibrations issues on trucks (not too many RWD cars come in these days) we get in the shop is the tailhousing bushing and/or yoke. 1/2 the time they aren't leaking, just abnormally worn. you mentioned chatter marks? THAT is probably your vibration my friend. Replace the bushing and the yoke at a minimum. Keep in mind, a couple times I've had to replace the housing itself with another used piece because it had been beat up for so long it just wasn't in round anymore, therefore not properly supporting the yoke. i'd just go get a junkyard housing with a good looking yoke you can take some small-grit sandpaper to, install a new seal in it, then swap it out for the old one. it'll only take about an hour to do, and only that because of the yoke.

 

Are u talking about the yoke on the driveshaft? That's pretty new, becuz I just replaced the DS. Or is there another yoke for the tailshaft?

Does any1 know what trans I have in an '88 TA w/ the 5.0L TBI? The tech pages are down right now, or I would look it up myself. And how about a general set of directions on how to do this?

 

Are u talking about the yoke on the driveshaft? That's pretty new, becuz I just replaced the DS. Or is there another yoke inside the trans for the tailshaft? Is this part the same on all Camaros and Firebirds, or do I have to check to make sure they have the same trans?

Any chance I could get a general set of directions on how to do this?

 

You have a 700r4 in your car if it's an automatic, a T-5 if it's a stick. As long as you get a tailhousing off of the same type of transmission, you will be fine. You can also get a tail from a 4L60E if you have a 700r4, it will work fine also. If you get a tailhousing from a 4L60 you will need the splash shield that is on the trans output shaft inside the tailhousing. It's just a metal cup.

If your driveline came with a new yoke then you're probably fine, but polish up the surface that bears on the seal when you have it out, it will add much longevity to that rear seal (remember the seal rides on a wide area because the driveline will go in and out of the tailshaft by a decent margin when you're rear suspension is compressed)

It's all very easy. This is the kind of stuff I'd be doing when I first started R&Ring transmissions. Mark your driveline in relation to your pinion yoke on the rear end. Simply unbolt the driveline straps at the pinion on the rear end with a 3/8" wrench and remove the driveline. Remove the speedo cable or sensor (depends on the year) from the tailhousing, then remove the tailhousing with a ratchet and extension. I believe there are six 15mm bolts around the base of the tailhousing.

Put a new rear seal and speedo seal in it, these are common to leak later on and REALLY cheap.

Then simply swap it onto yours, install everything, and cross your fingers. I'd consider installing the driveline 180 degrees around from how it is installed right now also, it may help tremendously. If not, it takes all of ten minutes to put it back around if it causes a worse vibration (doubt it if it was balanced). Good luck with that vibration.

 

I had a vibration in one of my thirdgens that turned out to be the spare tire. It wasn't fully tightened up and at certain speeds would start vibrating. Tightened up the wing nut and everything was fine after that.

 

Awesome This gives me a much better idea of what I'm in for. And that's a good tip about the speedo seal -- I planned on replacing the rear seal, but I didn't think about the speedo. And isn't there a gasket from the housing to the main part of the trans that would have to be replaced?

I'm thinking about getting a new part... my dad gets an employee discount, so I can get it for about $150. When I pull the old unit out, will it be pretty obvious if the bushing is worn?

I've tried switching the driveshaft 180*, but it doesn't make any difference. Anyway, it's gonna be about a week before I get the part and some time to swap it, but I'll let u know.

 

Yes, there is a gasket between them, but I always use RTV. It's not under pressure so you can do whatever you like. It just pee's a small amount of fluid out the back hole when the car is running and the pump is moving to "splash lube" the tailshaft.

Keep in mind to have a shallow bucket handy, cause you might lose up to a quart of fluid

 

Will I be able to tell if the tailshaft bushing is worn when I pull it out? If I'll be able to tell, I'm gonna take it apart before I buy the new unit. If it's ok, then I'll just put it right back together. On the other hand, if I won't be able to tell, then I'll just have to bite the bullet and replace it... and in that case, I'll buy the part 1st so I can install it when I pull the old part out.

 

Well I swapped out the tailshaft bushing yesterday... didn't make any difference. Once I got the old unit out, I could see the bushing pretty well and it didn't look bad at all. But I couldn't be 100% sure, and I had already bought the new part ($170 GM employee price). So I threw it in and hoped for the best, but once again I was disappointed.

I don't even know where to go from here... what else can I try or what have I missed???

 

$170? Are you frikin kinding me.

A tail shaft bushing and seal + install of them into the tailshaft is flipping someone $20 max at a tranny shop.

I am hoping this was a misprint and you bought the bushing for $1.70.

Anyways, you need to go to my next step and check the virbration at rpm speeds regardless of gear. If rpm related, then its very wellyou dampner. If not then its a pinion bearing or a wheel bearing on the rear axle.

 

My camaro does the same thing but mine only dose it if I run it in OD. I am thinking mine is in the tranny.