Ok, so my car shook pretty bad when I first bought it. I replaced all four tires and had them balanced. That helped A LOT. I recently replaced all four springs, shocks and struts. I also replaced all of the steering components to include, ball joints, tie rods, center link, idler arm, sway bar links, etc.. All with rubber bushings. Took the car down and had it aligned at the shop. Noticed a big improvement right away. However, when I reach 65+ on the freeway the car still shakes some. What should I be looking at/inspecting next? I want to be able to take the car on long road trips but the shaking bugs me.
Thanks...

 

When my car was shaking itself apart at that speed, I found the culprit to be the driveshaft. Went from stock to an aluminum one, and no problems since.

 

Did you replace the strut mounts also?

 

I agree with Manic Z, try replacing your driveshaft with an aluminum one. That was a huge problem with my car for the longest time, couldn't go over 70mph without worrying the car was falling apart! Look up "SPOHN EXTREME DUTY DRIVESHAFT" for f bodies, they're a bit costly (mine was about $450 and some change) but you get a very high-quality piece that is a little wider than the stock one, about 15-20 pounds lighter and will withstand more torque if you put mods into your engine! Best of all, shaking completely cleared up, has never driven smoother!

 

Yep, forgot to mention new strut mounts too. I will look into the driveshaft issue. that would never have crossed my mind? Can they be balanced or should I just look at replacement?

 

According to their website those extreme duty shafts are chrome moly, not aluminum.? probably won't get much weight change with that will I?

 

Just grab an aluminum one from Hawks:

http://www.hawksmotorsports.com/82-9...s/driveshafts/

 

+1 on the aluminum driveshaft. It will make your car accelerate slightly faster (due to the lower rotating mass), should help gas mileage a little bit (again, lower rotating mass), and should clear up your vibration problem. I'm using a stock used aluminum driveshaft behind my LS1 swap, and its been great.

 

Yes, that was my mistake. It is chrome moly. It is still lighter than then the stock one by quite a bit, though... maybe not as light as the aluminum but it is indeed way stronger... again, pick your choices based on what you plan to do with your car in the future. You never know... take it from me, I was only looking to convert mechanical to hydraulic clutch, and now the engine is out and getting rebuilt. In my case, I'm glad I got the spohn shaft! ��

 

If that doesnt solve it look into brakes. Warped rotors or sticking drums might be the cause, as well as wheel bearings.

 

First thing to do is, figure out whether it's a drive line problem or a wheel speed problem.

VERY EEEEZY to identify: drive line at 65 mph goes hmmmmmmmmmmmmmm, wheels go wubbawubbawubbawubba. You have NO CHANCE WHATSOEVER of fixing it until you start at least working on the right part of the car.

If it's a wheel speed vibe, check for separated tires (borrow a known good wheel & tire that will fit your car); bent wheels (jack each front up by itself and spin it, watch for runout); bent axles (put the rear axle up on jack stands - NOT just a jack - put the car in gear and watch for runout, then if there is any, swap the wheels left to right and see if it moves or stays).

Pretty straightforward really.

 

Does the car have any wheel spacers, including the factory thin spacers in the rear. Is the car lowered? Factory wheels, if not is the center hole in the wheel a tight fit to the hub? When you put the wheels on tighten the lugs in a star pattern not in a circle. You may also want to look at the Diff to see if there is any play in it. Does the rear axle have any in/out play? Check the transmission mount also, though usually if its bad it will tump against the tunnel under hard acceleration.

The rear brakes if drums check make sure all springs are in tact, nothing is trapped in them, and that the drums fit right (if it has play around the hub center or lugs up/down/front/back) it could be out of center or warped. Warped brake parts such as rotors etc. U-joints in the driveshaft. One last thing is look at the front rotors in the internal fins I've seen things get stuck in those and cause out of balance issues.

Butler tire does on car wheel balancing, their equipment may help identify it, I'm sure you can find a local place that can do on the car balancing.

 

I put in a 4th gen aluminum driveshaft and it fixed all my vibrations. I would start with that.

 

My car had a vibration problem from 68 - 73 MPH. The first thing I did was to rotate the drive shaft 180 degrees and that took care of most of it. Later I found a small oil leak on the driveshaft pinion, so I swapped my rear end for a 4th gen and that took away the vibrating issue completely.

 

It has the thin little spacers. I assume those are stock? Car not lowered, has factory wheels, and the fronts are hard to get off when the lugs are off so I think it fits pretty tight on that hub. Brakes are new all the way around including new rear drums. Brand new tires all the way around.

I noticed last night at about 70 it shook really bad but smoothed out quite a bit at 75..??

 

Are they interchangeable without modification?

 

Yes the thin ones are stock, but your rear wheels should fit without them. Give it a try.

The 4th gen drive shaft is a direct bolt in.

The wheel shouldn't be hard to get off though, is there crossion or is the hub and wheel surface clean.

 

One other thought are your tires directional?

 

Rear wheels have no spacers. Not so much hard to get off as a good snug fit I'd say. Have to check on the tires but I believe they are.

 

You said it had thin spacers, are those on the front? I could be wrong but every 3ed gen I've seen they are on the rear not the front from the factory. At any rate if your wheels will clear without the spacer remove them and test drive it, make sure you tighten the lugs in a star pattern not around in a circle. Then do final torque with partial weight on the tire using the star pattern. If the tires are directional make sure the are all turning in the right direction.

If your factory wheels have different offsets (GTA wheels do) I've had tire shops insist that the rear wheels are front and vice/versa and move them around with the spacers... obviously that is usually the last time I deal with that shop since its stamped on the back of the wheel. Back/front. Saying this to say... make sure if different offsets the fronts are on the front and the rears are on the rear.

You can swap the front tires to the back with no issue but the rear wheels on the front will hit the tire rod end unless it has spacers. That is If you put the thin spacer on the front with the rear wheels on the front they will barely clear the tie rod end... and I mean just barely.


If you can't find a 4th gen drive shaft google drive shaft balancing for your area, 4x4 shops and 18 wheeler shops usually can do this. It may be cheaper to get the drive shaft balanced than buying a new one... though the 4th gen is substantially lighter so there is that.

 

+1 4th Gen Axle. Whole car would vibrate 55+ mph, original thought was pinion angle was severely off. Steel shaft was old/packed full of dirt//rust//out of balance. Found a Parted out LS1, took drive axle and complete rear suspension. What a difference. Smooth to 85+ (speedo stopped there )