My wife uses our automatic '88 Vette as her daily driver. It is bone stock with over 157,000 miles. The tires have been balanced - twice. She complains that at speeds above 75 MPH, the car starts to "vibrate". A few years ago I replaced the U joints on both half shafts (rear axles). They were dried out and making crunching noises. The U joints on the drive shaft are original. I will replace them because of their age and miles even though I'm not sure that will fix the problem.
While under the Vette doing an oil change, I took a look at the drive shaft for accessibility. Of course, the big fat exhaust pipe runs directly under it! The pipe is welded in. I want to do the work myself but I've never done any welding. What's the best way to get the exhaust pipe out of the way AND re-install it without welding? Can I cut the pipe and clamp it back together?
What words of advice do you have for someone replacing the U joints?

Thanks in advance for your help.
Greg (Canyon Lake, California)

 

how old are your wheel bearings?

 

We bought the Vette in 1989 when it had about 15,000 miles on it. I am sure all wheel bearings (front and rear) are original. Do you think the wheel bearings are more likely to cause the vibration than the U joints?

 

they definitely can do it, you should check them for play

 

I just changed the driveshaft U-joints on my '87 yesterday, and surprisingly, I was able to get the drive shaft out and back in without removing the exhaust!

Yup, it is a tight fit, but you can do it. Going back in was even easier. In my case, it turned out that the driveshaft U-joints were still in pretty good condtion, but the axel joints were toast, and the cause of the vibrations.

FWIW, for changing the axel joints, the shop manual says to disconnect the support link at the differential, and to mark the cam-bolt. Instead, I never touched the cam-bolt; I disconnected the support link at the knuckle, so I didn't have to worry about adjustments. Also, by dropping the outter end of the link it gives you more room to work on the outer u-joint.
:chevy

 

This is exactly the kind of info I was hoping for. As long as I know someone has actually removed the drive shaft without removing the exhaust, I'll be a lot more willing to try and wrestle the drive shaft out of there. Is your's a manual or automatic? I wonder if it makes a difference as far as clearance is concerned. I'm assuming the automatic uses a shorter drive shaft which could affect clearances. Also, do the manual and automatic transmissions use drive shafts of equal diameter?

 

I would focus on the wheel bearings before the u-joints. 157k is way beyond the expected lifetime (like 2.5 times) of the bearings! As someone mentioned above, jack up the car and check them for play. Loose units can definately cause vibrations similar to unbalanced tires. Good luck.

 

Thanks for your input. Will the bearing slop be obvious when I jack up the car and do a push / pull or do I need to use a dial indicator? Is there a spec on bearing slop? How are the rear wheel bearings lubricated? I'm assuming they are packed in grease similar to the fronts. I seem to remember an earlier thread in this forum that said the rear bearings are like $240. Is that per wheel or for both wheels?
Thanks again,
Greg

 

You can use a dial indicator, but it isn't crucial. Just do the push/pull on 12 and 6 o'clock. You will be able to hear and feel a loose bearing...feels a little bit like loose lugnuts, sort of rocks back and forth. If you can actually feel it wobble, go ahead and replace it. The C4 uses sealed wheel hub/bearing assemblies so they need to be replaced as a whole unit (can't repack them).

Pep Boys offers lifetime warrantee on front/rear bearings for your year...about $140 per wheel. Supposedly the supplier is the same one that GM uses. HTH.

 

I had my wheel bearings replaced for just over $600 a couple of months ago (both rear wheels). Interesting I get the same vibrations you are experiencing which is why I had them replaced. I have also replaced the ujoints in the half shafts, front rack and ball joints. My driveshaft was good. But I still have the same vibrations. The only difference is sometimes it vibrates and sometimes it is fine. I am about ready to just give up.

joe

 

Mine is also an automatic with welded exhaust - I think it should be identical to yours. I disconnected the drive shaft from the pinion, shoved it forward as far as it would go, then I still had to rotate it about 1/8 turn to clear the pinion so I could drop the end down and to the left. Be sure the E-brake is OFF so you can push down on the cable. Slide the shaft back and to the left (driver's side). There was one spot where it was tight and I had my doubts ... but a little tug and it came on out. If it does seem to hang, rotate the shaft a little; there is a balancing weight on the side of the shaft that may catch on stuff on the way out. Before you take it all the way out, note the orientation of the shaft relative to the trans. and diff. Worse case, you *could* disconnect the exhaust hangers and put a jack-stand under the exhaust to support it; you would only need to drop the rear of the pipes a little bit to gain the clearance you need and there should be plenty of flex in the pipe to do that without disconnecting from the exhaust manifold. But I didn't need to do that. Wheel bearings: that sounds like dealer prices, EACH. Discount price at the dealer is closer to $200 if I remember right, but it has been over a year since I did that job and I can't find the receipt now. Plan ahead, and order the bearings from Pep Boys (they don't normally stock it) and the cost will be closer to $100 each. You can also get Brute Force U-joints at Pep Boys for $13.49 each. p/n 1-0153BF for the drive shaft U-joints, and 2-0053BF for the axel U-joints. Best bet, is to do the axel U-joints and the wheel bearings at the same time. With the half-shafts out of the way, it would be a lot easier to get to those 55mm torx bolts that attach the bearing/hub assembly. If you don't have one, well, Pep Boys has the 55mm Torx sockets too! :yesnod:
:chevy :chevy :chevy


[Modified by Prospector, 5:10 PM 1/23/2002]

 

Jason,
Thanks for the info. Looks like it's time to jack up the ol' Vette and get my hands greasy!

 

Wow! Thanks Prospector for all the info. This will make the whole procedure a lot less intimidating. This forum has been indespensible for keeping my Vette going!

Thanks for taking the time to fill in all the blanks.

Greg

 

I've got vibration on my 84' Vette at around 72 MPH.
Gets worse as speed increases.

I've had wheels/tires balanced three times with a standard spin balancer.
Two times with the Hunter GSP-7000.
Vibration still there.

Had new BF Badrich Radial T'A's installed.
The old tires were so worn out when I got the car that it pulled and tried to follow every variation in the road.
Had some small vibration but not so bad I couldn't run up to 120 or so with the old tires.

Anyway , put a set of those BF Goodrich Radial T/As on it.
Vibration was so bad I thought the sun visors were going to break off.
Had the place I bought the tires do the spin balance on them TWICE.
Vibration still there.

Had the wheels/tires balanced two times with the Hunter GSP-7000 or whatever the heck that super wheel/tire balancer is.
Paid both times.
Vibration still there.

They replaced 2 tires at the first place that balanced them with the Hunter GSP-7000.

The next place replaced 2 more tires for Road Force Variation.
They had me change the two front wheel bearings.
Got them from Ecklers.
One NEW wheel bearing was SO bad (worse than the old one I was replacing) that I had to send it back to Ecklers for another "exchange" one.

BTW: Ecklers would NOT drop ship me another one and send a pick up tag for the bad wheel bearing. I had to send them the bad NEW bearing FIRST.
What a PITA.

Anyway I replaced BOTH fron wheel bearings. ($159 each).

Vibration still there.

All the tires have now been replaced.
New tires swapped for more new tires which I had to pay for,
Vibration still there.

Three of the tires I had to pay for AGAIN (the tires were NEW to start with)
(I'll NEVER buy BF Goodrich tires again)

Anyway, the vibration is STILL there.

I'm about at my wits end with this vibration.
I LOVE this 84' Vette but this problem is driving me baZonkers!

Supposedly they would have discovered a bad wheel when they did the balance with the Hunter GSP-7000.
I asked them specifically if a wheel was bad and they said "no".
I ask them to check the U-joints.
They said the U-joints were fine.

Wheel bearings?
Drive Shaft?
Main Drive Shaft U-Joints?
Half Shaft U-Joints?
Rotors?
Flex Plate/Torque Converter?
Variation in sun/moon alignment?


The toll so far has been I've bought 2 sets of tires, two wheel bearings and paid for FIVE balance jobs.
Vibration still there. :mad :mad :mad

I don't know what to do, but I don't want to throw any more money at it just hoping for luck.
There has got to be a scientific way to determine what is causing this vibration.

I have checked the rear wheel bearings with the 12/6 oclock test.
There IS "some" play there but it is VERY SMALL . . .not enough to cause this large a vibration.
I have a dial indicator I can test the actual movement with . .anybody know WHERE to measure at and HOW MUCH movement there should be?

Front wheel bearings have NO play.

The vibration seems to occur more at the "wheel speed" level than the "driveshaft speed" level, if that makes sense.

Anybody got a really good idea what might be causing this?

:confused: :confused: :confused:
:mad


[Modified by VetNutJim, 8:16 AM 1/24/2002]

 

I have BF Goodrich ta's on mine as well and I have vibrations. Does anyone else have Goodrich on their car? Or experierience with them?

joe

 

try putting the car in neutral when its vibrating.maybe its your torque converter or transmission causing a vibration?it could even be in the engine??? :confused: good luck.

 

Hmm, lots of different problems here. This may be oversimplifying things but I got rid of the vibration in my 88 by putting the wheels on the correct sides. :):) The previous owner apparently felt that the giant LEFT SIDE ONLY ,RIGHT SIDE ONLY cast into the wheels was for everyone BUT him.:) As far as the vibrating 84, do you know any other Vette owners that would let you swap wheels so you at least isolate that part of the equation? My BFG's made the car vibrate and it drove me nuts. My new Kumhos are like glass.

 

I had a vibration problem that eluded me. I checked every thing I could find . I had the new Kumhos rebalanced, I was ready to try Equal in the tires to balance them. Then one day after a hard turn passenger side rear started making loud cracking and clicking noises.
Turned out to be U-joints. One cap cracked, I guess the hard turn was the final straw. All 4 drive axle U-joints were totally shot. Linear grooves were worn into the trunions. The grease was gone and some needles were powder. Kind of scary since 2 weeks before I got it up to 105 mph.
Replaced all and problem solved! No more vibrations.
I would check out the U-joints, actually pull out the passenger side outer and check. I think thats the one that gets the most wear.
Barrier :) :)

 

U-joints could be the problem. Jim stated that he had a little movement from the rear. There should be no movement, chances are the bearings are gone. One way to check the rear is to jack up the rear and use horses to stablize the car. Then have someone put the car in drive and get it up to speed while you watch the wheels and drive shaft. Hope this helps.

 

fastguy,

Thanks, no I don't know anyone I can switch tires with, however this is a great idea, I wish I did. Given what some folks on this post have said about BFG, I think I will post another topic. BTW your 88 looks great. I can't believe your wheels were switched, sounds like my luck.

joe