How is your rear alignment? I found that I have almost the same problem however my rear alignment is off. The car shakes really bad above 4krpm.
Major drivetrain vibration/shudder at 85mph
- Thread starter tekdeus
- Start date
Is it possible the rear trans slip yoke bushing is worn? You mentioned being able to move the drive shaft up and down in the tail housing. I have always wondered, wouldn't a one piece drive shaft accelerate wear on this extension housing bushing from the added weight of the drive shaft/having the drive shaft weight pull down at an angle?
The slip yoke had very little play. I drove it again this evening at the speed that creates the vibration (87mph), and I noticed that mostly the rear of the car and chassis shakes, but the shifter itself does not. It seems to me that if the shaft began to shake at a harmonic frequency, the shifter would be shaking more than the chassis, but that's just my assumption. I'm thinking there may be something in my subframe or CV joints contributing... my car is 6" wider than stock, so who knows how that affects it as well.
UPDATE: On SF it was recommended to rebalance the wheels with a RoadForce balancer: http://www.gsp9700.com/index.cfm After looking into it, it does solve problems for a lot of people.
I just had all 4 tires rebalanced at a shop with the roadforce machine, and they said they are better balanced now than before, but the wheels are not perfect (I got them used), and also the tires are not perfect either.. "lumpy" they call them. I wasn't too happy to hear that, considering that they are the top street tire by BF Goodrich that I bought brand new 2000 miles ago. (2 years ago now)
But the car is much smoother at higher speeds now. A little vibration still at 85, but totally smooth beyond that. I can live with it for now. Don't like the thought of having to buy new custom offset wheels and tires!!
However: They pointed out that my right rear wheel bearing has play. I checked it, and the edge of the tire does move maybe 0.5mm, compared to the others which have no play at all. BOTH rear and 1 front bearings were replaced 2000 miles ago. Could the offset of the rear wheels wear out a new OEM bearing that fast??
I just had all 4 tires rebalanced at a shop with the roadforce machine, and they said they are better balanced now than before, but the wheels are not perfect (I got them used), and also the tires are not perfect either.. "lumpy" they call them. I wasn't too happy to hear that, considering that they are the top street tire by BF Goodrich that I bought brand new 2000 miles ago. (2 years ago now)
But the car is much smoother at higher speeds now. A little vibration still at 85, but totally smooth beyond that. I can live with it for now. Don't like the thought of having to buy new custom offset wheels and tires!!
However: They pointed out that my right rear wheel bearing has play. I checked it, and the edge of the tire does move maybe 0.5mm, compared to the others which have no play at all. BOTH rear and 1 front bearings were replaced 2000 miles ago. Could the offset of the rear wheels wear out a new OEM bearing that fast??
This page http://www.gsp9700.com/pub/search/findgsp9700.cfm shows where there is a machine in your area. National Tire Wholesale here in Delta is the closest for you and me Dave
