issue with vibration at 60 mph

[rhturbo]

Hi everyone,
Just discovered this site yesterday. Some great info here. I am new to the Turbo world and just bought a 1987 GN last week. I am having a couple of issues one of them being when I reach speeds of 100kmh (60mph)  I get a bad vibration in the steering wheel and front end seems to be shaking. If I push it past 120kmh (70mph)  it gets better and seems to almost disappear but is still somewhat there. If I go below 80kmh all is good.


I don't believe the rotors are warped because when I apply the brakes its very smooth with no vibration plus that would only show up when braking

The car had a safety inspection before I bought it last week and it passed which means they supposedly checked the front end.  I took it into a different garage to have it looked at. They examined front end and couldn't find anything wrong.  They suggested the wheels needed balancing. Seemed reasonable so I had them do it but problem is still there. They then suggested that I replace the two front tires as possibly one of them had a flat spot or other issue. I replaced both front tires and still same problem.  So $500 later I am no further ahead


I am taking it to a different shop next week that specializes in both  classic cars and high end cars and hoping they can help. Can you think of what might be causing this ? I was thinking maybe a damaged rim (there is nothing visibly wrong) but if that was the case wouldn't that show up when balancing ?

[Scoobum]

If you have access to 2 other tires and rims...throw them on and give it a whirl. If it straightens itself out...then you know you've got a tire or rim that's fubard. If it remains...then it's a front end issue. Sure the  front shocks are okay?

[rhturbo]

Thanks for your reply. I have been watching your video. excellent info. Cant say for sure if front shocks are o.k but am assuming that both garages it went to would have checked that ? My back tires are a different size so I don't think I can move them to the front. Hoping the shop i take it to Wednesday can figure this out.

[nocooler]

If you want it fixed do it yourself or take it to a place that you can trust.

Are you sure it’s not a driveline vibration?

How long has the car sat? Are the brakes stock? Suspension? Stock wheels? Radials tires on all four corners? How’s the alignment?

[Steve Wood]

If the car has been parked for a few years, check the tires.  they do take a set after awhile and run like they are square at speed.  A good balancer should show them to be out of round.

Also, check the u-joints

[rhturbo]

Thanks everyone, Tires on Front are brand new. Just replaced them to try and solve the issue. I thought about the possibility that  the drive shaft was causing the issue but when the problem starts I put it into neutral and coasted and the vibration did not go away until i gt below 60 mph. Stock rims all around . Brakes are stock all around. brake pads were changed last week on front rotors. Hoping the shop can measure run out on rims to see if that's an issue.

[TexasT]

Did you get under there and tug that drive shaft around? The ujoints could be original. They spin with the axle as the car is moving. I would swap the front n rear tires and see if the vibration moves. If the backs are wide dont do any real sharp turning while conducting this test, and really a different known good set of tire on the rear would be better.


Did you let us in on your location? Might be some one local who could help with some part swapping to see if you can track down the prob.


I just looked. Bunch of guys in the GTA, what part are you in?

[Scoobum]

GTA. Where's that?

[TexasT]

Yes Brad, where is that? Haha

[rhturbo]

I haven't checked the drive shaft. I will check it tonight

[1KWIKSIX]

I had a similar problem with vibration some years ago, spent a lot of time chasing my tail.


My transmission shop found my transmission Tail Shaft bushing was sloppy, allowing too much up / down movement of the front yoke, so he replaced it.

Finally took the drive shaft to a drive shaft specialty shop and here's what they found:
1) drive shaft had a slight bend / bow to it....they straightened it out in a hydraulic press
2) front u joint was not centered in the yoke
3) they replaced both U joints with Spicer (no grease fitting)
4) re painted the drive shaft black





Problem cured.......No more vibrations!

[daveismissing]

In the old days we might have pulled the shaft out and had our buddy tow us a bit as a test

[nocooler]

I'd check the u-joints and then re-index the shaft 180*, sometimes that's all they need.

[rhturbo]

Starting to think that it might possibly be the driveshaft as some have mentioned. So far everything else seems to check o.k

[rhturbo]

Gave up on trying to figure this out myself. I dropped the car off at the shop this morning. I will let everyone know the outcome when I hear back.