Random Shaking at Speed (Vintage Prep)

[EIP11]

Hey everyone,

I've managed to get my E28 ready for my first ever Vintage with ONE major exception. Randomly when driving at highway speeds I can feel the car begin to shake and it only gets worse if I try to brake. Every suspension component on the car including shocks and springs are brand new quality parts. The front brakes have been upgraded to E32 components with all brand new parts. The car also has brand new tires (225/45r17) mounted on 17x8.5 ET13 Borbet Type As. This only happens randomly and other times the car cruises at highway speed smoothly and also brakes smoothly. I'm completely lost in regards to what this could be. Therefore I'm hoping you guys can think of something that could be the issue? Any help will be appreciated!

[dsmith]

UCBs, unless something is obviously loose or brakes are sticking.

[EIP11]

UCBs, unless something is obviously loose or brakes are sticking.

At this point I'll try/check anything. I'll pull the upper control arms and check the bushings, if that's not the problem I may just replace the calipers all together.

[dsmith]

I would leave them alone until you can install moosehead or HD bushings properly. You won't be able to visually tell.

To test the brakes, replicate the issue on a safe road, pull off to a safe flat spot and try to roll the car by hand to see if something is locking up.

[EIP11]

I would leave them alone until you can install moosehead or HD bushings properly. You won't be able to visually tell.

To test the brakes, replicate the issue on a safe road, pull off to a safe flat spot and try to roll the car by hand to see if something is locking up.

In regards to the control arms, they currently have Meyle HD bushings installed with less than 1,000 miles. I'm going to pull them off and reinstall them in case that they were installed improperly. (I didn't install them, I had a shop install them)

To test the brakes should I pull of by crusing to a stop or should I actually brake to come to a stop?

[Mike W.]

Check the tires, they might look like it but the aren't always round. I forget if spec is .060 or .080" but not an awful lot. It's more important on the shoulders than in the middle.

[demetk]

Borbets need centering rings?

[EIP11]

Check the tires, they might look like it but the aren't always round. I forget if spec is .060 or .080" but not an awful lot. It's more important on the shoulders than in the middle.

I never knew that about tires, that's pretty interesting. These tires have less than 200 miles on them, and I had the same issue with my previous wheels and tire setup so that's why I think it's more suspension/brake related.

Borbets need centering rings?

As far as I know they don't. I also had the same issue with my previous wheel and tire setup. (OZ Fittipaldis)

[EIP11]

One more thing that I think could be wrong. My steering does have some sloppiness to it. I adjusted the nut in the drivers foot-well and it helped a lot. Could sloppiness in my steering gearbox possibly be causing this? I have yet to adjust the actual steering box mostly because I've been too scared to try to possibly ruin something.

[dsmith]

Anything loose can cause it, so yes, check that first. Raise left front and wiggle at 3 and 9 and 6 and 12. Same for the right front. Any movement needs to be fixed. You don't need to remove the control arms. Just loosen the bushing bolts, load the car properly and retorque.

I have never experienced tires that have a brake shake, unless they had a slipped belt that shows up as a buldge in the tread. Worth checking.

I would focus on the brake shake first. Just come to a safe stop in a parking lot or something. You want to check within a minute of stopping before the heat subsides and they release.

[EIP11]

Anything loose can cause it, so yes, check that first. Raise left front and wiggle at 3 and 9 and 6 and 12. Same for the right front. Any movement needs to be fixed. You don't need to remove the control arms. Just loosen the bushing bolts, load the car properly and retorque.

I have never experienced tires that have a brake shake, unless they had a slipped belt that shows up as a buldge in the tread. Worth checking.

I would focus on the brake shake first. Just come to a safe stop in a parking lot or something. You want to check within a minute of stopping before the heat subsides and they release.

I did get a chance to check the brakes. I got out 15-30 seconds after it had shaken and pushed the car. While it was hard to do since it's a heavy car it didn't feel like it had any resistance (besides the weight of the car). I'm going to put the car up on ramps or a 4-post lift and loosen the bolts and retorque like you said. If that doesn't fix it then I will mess with the adjustment on the gearbox. I want to do that last since I'm honestly a little scared of doing it.

[dsmith]

The steering shaft lash is not the pitman arm lash. AFAIK, it won't affect your symptoms. It is risky too. I can drive by and take a look on Thursday, about 9-10am, if you are available. Just send me a PM with details.

[EIP11]

The steering shaft lash is not the pitman arm lash. AFAIK, it won't affect your symptoms. It is risky too. I can drive by and take a look on Thursday, about 9-10am, if you are available. Just send me a PM with details.

PM sent. Thanks!