High speed vibration

[SupraRed]

Im not sure if this has already been asked, I tried to find it but couldnt seem to locate a thread. If there is one please link it to me.

Anyways, I have an 86.5 7MGE and Im currently trying to restore it but I have a high speed vibration coming from my driveshaft/rear end. It vibrates when I take my foot off the gas for a split second when im up around 100km/hour and then if my foot is completely off the gas it doesnt vibrate at all so its only when im lightly pressing the pedal. right now I notice a leak coming from my rear Differential so I'm going to order a seal for it and check the bearing inside there while Ive got the drive shaft out.

I replaced the center support bearing yesterday and that seemed to reduce the vibration but it didnt eliminate it.

I was wondering if anyone out there has heard or this or has had this problem before and knows what it could be.

[mrnickleye]

Swap the tires front to rear and see if that helps, or shifts the vibes to the front.

U-joints ??? Axle joints ?? Grab hold of the pinion and see if you can move it up/down at all to check the bearings. S/B no movement.

Driveshaft balance???

[supradaddy0803]

I had the same problem and found that the jerk that had mine before me didnt put the balance points back to line up there should be a matchmark every where the drive shaft comes apart because at this point in your cars life it has probably had new u joints look at ever flange and try to see if there is a white mark and line them all up. I just got done fixing mine today and no vib all the way up to 145 so its good.

[SupraRed]

yeah apparently the guy who owned the car before me did the same thing but there are no marks on it, so I replaced the steady bearing (center support) and all three U-joints so now I think im gonna take the driveshaft in to get rebalanced. I did some trial and error with the drive shaft and I still cant get the vibe out so I think I'll just take it in to get looked at.

thanks for the input. I should have it workin 100% in no time.

[rnoswal]

Try jacking up the rear end of the car and see if you can wiggle any of the back tires. If so then the bearing needs to be replaced. That is my problem, a high speed vibration. The driveshaft and carrier bearing are all in good shape, but when checking the rear wheel, I noticed that I can wiggle the passenger side but not the driver side. I haven't replaced it yet as I am doing the head gasket and a few mods, but when I finish I will let you know if that cures my vibration.Russ

[theWeezL]

usually you can just repack the bearings and not have to replace them...torque'ing them to proper spec is important.

[f00g00]

Try to turn one half of the driveshaft 1/4 turn and re-try it. keep trying till the vibes go away or you turn it 3 times like that. I had some mechanics change my center bearing and they got it back together wrong.
One half had to be rotated to get the vibes out. It takes a shop with a special machine to balance a driveshaft which all automakers seem to have but very few machine shops. You will need to find a shop that specializes in drivelines who can do it.
I just tried having a one piece shaft made from steele here in Kuwait. The shaft weighed 14 pounds but no one has a way to balance and it had vibes at 100KPH and up so Im out about 100 dollars and back to my heavy two piece.
Good luck with it.

[Jeff887]

Hi, I have a similar issue to SupraRed. When I partially release the throttle, (like trying to maintain constant highway speed) at about 80k and up, I get a strange vibration coming from the rear. It gets worse when I drive faster then that. If I drive up to 120k then throw it into neutral, it vibrates until about 70k. If I'm driving and putting a load on, it doesn't vibrate... (either foot fully on the gas, or completely off). Any ideas? I had it "looked over" at the shop today, and they couldn't find anything obvious.

thanks.

[supracurtis]

check your axles. ..