Strawboss

Hello All,

I have done some searching on this, but want to get some other ideas/feedback. I have an 84 Z28 that I did a fair amount of work on a few years ago. Since I put it back together I have a driveline vibration that I cannot figure out. The vibration gets noticeable around 57-58 MPH and get worse the faster you go. It makes the seats shake and rear view mirror shake. It is a drumming vibration that feels like it is coming from the rear of the car. It is so annoying I hate driving it down the interstate at 65-70 MPH. If you go faster the vibration gets harder/more pronounced. The frequency to me seems more driveshaft speed related than wheel speed related, but I could be wrong. Here is some history……..

Car: 355 CID, rebuilt world class T-5 (rebuilt by professional trans shop), new clutch (balanced), stock driveshaft, 3.73 Yukon Gearset (Randy’s Ring and Piston), Eaton Limited Slip diff, all new bearing in rear end except for outer axle bearings, stock axles, stock rear end housing/axle, TA differential support cover, stock rear lower control arm and drag link that have been boxed in, stock wheels, Firestone Firehawk tires (235/60-15), stock brakes, all energy suspension bushing front and rear except for motor mounts (NAPA stock replacement), Hotchkis springs all around (1” lower), KYB shocks/struts, custom subframe connectors, stock torque tube, stock trans crossmember, stock brake drums………….

What I have tried:
- Vibration stays the same if you push in clutch and/or put the trans in neutral with the vehicle at the above speeds
- Rebalanced tires after they were install by Firestone
- Switched tires front to rear
- Put brake drums on balancer and they were under 1 gram of imbalance
- Driveshaft was balance and then double check a year later
- New u-joints front and rear. I made sure to knock them back so they are not binding or tight
- Tried known good driveshaft out of 83 Camaro with slip yoke
- Tried know good pinion yoke from 4th gen
- Measured driveshaft angles (about 2.8 degrees at curb height, slip yoke and pinion yoke within 1 degree of each other
- Measure axle hop/runout (less than 0.010”) , wobble (less than 0.004”), and radial freeplay (less than 0.006”)
- Measured the pinion gear runout off the center machined into the gear and it was around 0.003” when installed in the vehicle with the driveshaft off.
- Removed 1/8” thick preload shim from energy suspension rear trans mount per Spohn’s website advice.
- Measured the pinion gear runout with the gear supported in centers in a lathe at 0.003” on the big bearing, 0.005” on the small bearing, and 0.006” on the pinion yoke seal surface (just turned gear and not lathe chuck so there should be not runout from lathe). I did this with a stock GM 3.42 gearset from a 4th gen and the numbers were almost identical

None of these things have eliminated the vibration or even seemed to affect it much. I am at a loss here. I can’t figure this one out and it is really frustrating!!!!! Does anybody else have any ideas or things to try? I was thinking about trying to have the Eaton rear differential balanced.

Thanks a ton for any advice!!

Ryan

jmd

iTrader: (4)

Some things I've run into:

Properly balanced tires that were not round (they were Goodyears.) - trade all 4 wheels with someone who has a 2nd gen, a G-body, 2WD S10 or small wheel pattern 77-90 B-body. Drive the car to rule out tires.

You didn't mention anything about the slip yoke into the T5. The tailhousing bushing is the first thing that should wear / cause problems. I'm sure you've visually checked the slip yoke already when you had the DS out. See if the slip yoke has any lateral play when installed in the trans. Is the slip yoke the original correct length?

3.73 rear, I assume?

Strawboss

Hey JMD,

Haven't tried switching tires yet. I can do that after I put the gears back in.

My slip yoke is original and looks to be engaging properly. I measured the OD and there is 0.003" difference from the largest OD to smallest so I don't think that is the problem. No major grooving or wear visible either. Also the other DS i tried had the OE slip yoke on it too. There is some radial play in the slip yoke which I am not the most comfortable with. However the tailshaft bushing was replaced during the trans rebuild. I also checked with a different local trans shop and they said if you get that bushing too tight you will spin it right out of the housing. Any ideas on what amount of measured radial freeplay is acceptable? I don't think I actually ever measured it, but I can.

Yes it is a 3.73 Yukon Gearset from Randy's Ring and Pinion. I have an OE 3.42 gearset from a 4th gen I was going to try and I still have the the stock 3.23 set out of my rear end.

Thanks for the ideas!

Ryan

Burnout91

Take a look at this thread:
https://www.thirdgen.org/forums/tran...ration-my.html

Bill

Strawboss

Bill,

Thanks a bunch. Any other advice/experiences like this is much appreciated.

Ryan

JamesC

iTrader: (5)

Some members have reported issues even after removing the pre-load plate.

JamesC

Confuzed1

iTrader: (4)

Went through the same thing after doing even more than you have so far trying to fix it. I noticed you even got your original driveshaft balance checked twice. I had mine checked 3 times. I even thought I had it figured out for a week or so.

https://www.thirdgen.org/forums/tran...em-has-me.html

mh82camaro

same problem here...have eaton posi, 4.10 gear, es trans mount and torque arm mount, new u-joints.etc my vibration/noise was at 60-65 then i removed the preload plate and it changed from 70-75....faster i go above that i have a vibration/noise.....gets louder/faster ...the faster i go....so i feel your pain

Strawboss

Hey Guys,

I had time to do more reading on this forum last night. Looks like many people have had success with OE aluminum driveshafts from so equipped third gens and fourth gen cars. I might try that. I have a buddy with a fourth gen ls1 firechicken. We put 3.90's in his car in my shop so I think he will let me try his driveshaft out before I throw down coin on one!! He sorta owes me that I think!! ha-ha!!!

Also don't think my driveshaft was high speed balanced and they definitely did not balance it with the slip yoke installed.

I will keep you guys informed of what I find out. Thanks for all the feedback/information.

Ryan

RuinDeckard

I have the same issue with my 88 T-tops 5.0l Camaro. Horrific shakes like a sick puppy at anything above 55mph. I replaced the rear lower control arms and original panhard bar with Founders Performance (Made a big difference in handling). Also tried 3 different pairs of rims and tires (I went out and purchased brand new rims and tires that were balanced and filled with nitrogen). Brand new KYB struts all around yet the problem persists even after alignment. There is no way its the tires or rims. Just as stated before no steering wheel shake. These upgrades were something I was going to do anyways but I was hoping it would resolve the problem. Ive been a vulture on on thirdgen.org and so many people have this problem. I thought it may be related to the T-Tops stability (My fathers 85 IROC has no shake at all). I want to resolve this issue before I put an LT1 into the car and finish painting it (Its in the primer as shown below). Going to see if I can find a aluminum drive-shaft which I really really hope solves this issue.

http://i337.photobucket.com/albums/n...d/IMG_0031.jpg

Strawboss

Hello All,

I just thought I would post an update. I found a driveshaft from a 99 Camaro LS1 that happened to be a 6 speed car. The local dealership told me all 98-02 LS1's auto's with 3.23 gears and manual's with 3.42 gears have the same driveshaft part number. There was actually a LS1 manual car with 2.73 gears which has a different OE driveshaft part number (not sure why anybody would actually want this combo other than if GM needed this for some sorta fuel mileage rule or something).

Anyway, I wanted an OE driveshaft from the LS1 car that had the vibrational dampner as part of the slip yoke and the 3" OD aluminum which I was sure came on the 98-02 LS1 powered cars. I am not really sure what came on the 93-97 Camaros for driveshafts.

So I installed the driveshaft and took it for a test drive. Took my car up to 80 MPH and no vibration!!!! AWESOME!!! This problem has been driving me crazy for about 3 years. However, not so awesome is that the driveshaft is hitting something in the tunnel near the front of the driveshaft when you start to pour the coals to her. It is ok under light load, but hits when you start to get the vehicle under load. Haven't had a chance to jack it up and look yet, but I hope it is something easy to fix. It was a tight fit in there with this 3" aluminum driveshaft, especially past my 3" flowmaster exhaust, but I got it together. I hope to work on this tomorrow night and figure it out. Until then, good luck with everybody else wrestling with the driveline vibration problem!!

RuinDeckard

Just purchased an LS1 drive shaft and when I receive it, I'll post to tell you if it fixes my shakes.

RuinDeckard

Put the ls1 driveshaft in and..... It still exists.

Don't get me wrong though, no more clunking when taking off and feels more responsive due to the faster spooling. Doesn't take 6 years to take off in drive. So it was worth it but I lost my job so when I get the money, it's time to try the springs or another rear end (I want posi!).

Some shake was reduced. I'll see if I can get it balanced since I haven't yet. The 3" driveshaft has the original dampers but who knows.

squatingeagle

check your rear wheel bearings. Strawboss, you said that was one of the things you didnt replace when you did your axle. replace them. gm service manual says vibration in the year is caused by rough rear wheel bearings. test them by grabbing the rotor top and bottom and try to pry/pull in and out. you should get NO play AT ALL. if any its a worn out bearing. ive got the same problem and ive replace everything you can think of only to find out yesterday its bad bearing. let us know updates

JamesC

iTrader: (5)

Because the axles are held in place by C clips, there will be some in/out play whether the bearings are bad or not.

JamesC

Confuzed1

iTrader: (4)

Funny how switching to a 4th gen driveshaft solves it when you had your stocker balanced....I couldn't believe the difference either on my car, but I was out of things to check and was actually getting ready to strip the car for parts and take the loss if that didn't solve it!

squatingeagle

not the whole assembly sliding in and out but the top and bottom rocking in and out. or even any up and down indicates a worn bearing

Confuzed1

iTrader: (4)

RuinDeckard - I'd "think" that if the rear bearings are sloppy enough, you'd see some leakage from the rear seals?? Any leakage? Worth a check though.

Sounds like you've ruled out tires, and front end issues since there's no vibs in the steering wheel. I might try moving that new driveshaft 180 degrees and see if anything changes. Should'nt hurt anything.

squatingeagle

finished the bearings. rides like a dream apart from the 20 years/170xxx. didnt have any leaks. but when i got the passenger bearing out it had a bent cage. new bearings and axle shafts my car has never driven so smooth.