ebluekeys

I've had a high speed vibration since I purchased this car 14 years ago. I've tried three different sets of rims/tires and results are always the same. The vibrations starts around 55-60MPH and gets worse as you go faster. Seems to be happening at or near the same RPM as the tires, but this is just my subjective judgement. Here's what I've done so far to try to tame it down:

1) Balanced tires/rims.
2) Got alignment done
3) replaced U-joints with heavy duty "precision" brand
4) rebuilt rear (put a trac-loc in while I was at it...)
5) Had driveshaft balanced.
6) replaced tranny extension housing bushing and seal (Nice and true running now!)
7) replaced rear transmission isolation mount.

Vibration does NOT stop by taking car out of gear at speed!

I think this all keeps pointing to the DRUMS (Yeah, I know, 4 of 'em, all the way round).

Is it really possible that the drums being out of balance could create this vibration? It doesn't seem to "come" from any specific direction - the steering wheel doesn't shimmy - the whole car just seems to shake up and down... enough to blur the side mirror!

I bought a bubble type wheel balance at Harbor freight, and I'm going to check all 4 drums. If they are off balance, what's the easiest way to add weight? I have a TIG welder, so maybe I could just spot some washers on the face of the drums near the outside edge, no?

If anyone else has ever had this experience, please chime in!! If I could just fix this one last problem, I'd be happy enough to put on fresh paint and "call 'er done!"

Thanks for any and all suggestions!

Soaring

Obviously, if you take it out of gear and it still vibrates, it's not the engine, transmission, U-Joints or imbalanced drive shaft. Since you have a new rear, then you can rule that out. More information please. Is it the original engine? Just making sure it is not a 28 oz. imbalance problem as opposed to a 50 oz. Have you double checked the rear wheel bearings? Are there any noises other than the vibrarion? Does it seem to be coming from the rear or the front? Yes, you can add balance weights to the drums, but you will need to know exactly how much and where to put them.

ebluekeys

Engine was rebuilt by yours truly. Used same plate and harmonic balancer. It runs like a swiss watch...just lots more horsepower.

Tried all those other fixes before I got inspired to try taking out of gear (duhhh...) probably needed all that new stuff anyway.

Assuming I use the bubble balancer, it's just a matter of getting the bubble in the middle, no? smallest weight, farthest out... or is there some other magic?

Soaring

Yeah, that's about it for balancing the drums, but I seriously doubt the brake drums being out of balance will cause you any vibrations unless you only get it when you step on the brakes. Afterall, they are just spinning freely until you hit the brakes. You most likely have bearings in the rear somewhere that are causing it, or your car was in a wreck years ago, and the rear isn't aligned properly.

ebluekeys

Sounds like a good suggestion. I've already talked to my local tire shop - also a classic car enthusiast... he's agreed to give me a "deluxe" alignment, including checking the diagonals and dialing some extra caster in. I've got the front strut rods out now, getting some extra threads cut (yes, already cut down the body diameter...) so that there is room for extra caster adjustment. There is an ever so slight low shoulder between the old and new section, but deep enough to chase threads. Will double nut the side of the rod facing the rear, just to be sure...

Will be checking the balance tomorrow AM (I work 2nd shift) and I'll post my results back here. If it's not the drums, then perhaps you are right, and the alignment should fix it, hopefully...

PhillyDog88

Actually, you seem to have the same symptoms as me. I'll be following your story until I get mine fixed too

ideal_mustangs

I would say you've got some bad wheel bearings also. I've seen that cause a vibration. By sure to put new races in them so everything will be nice and tight. I've also heard of axle bearings causing this. They will get worn a little and then the axle will have some slack. I assume you changed these when you did the rearend, so thats probably not it.

ebluekeys

Got the balancer. Tried front drums first. Due to bearings/races and the way it fit on the balancer cone, the part was "top heavy" either way, and couldn't get a decent "read" on the bubble. Both fronts have hefty weights still in place from the factory though... Jackstands are under front of car right now while strut rods are out getting threaded... will have to wait till front is back on the ground to check the rear drums. They should be easy.

As for bearings, all were replaced when I rebuilt the rear. Professionals removed/replaced all. Axles were verified "true" as well. Whole rear turns VERY smooth. Problem never seems to change not one iota despite all these improvements. New tires/rims coming in a week or two, and will get full Monty alignment then. Perhaps that will be the cure.

Colorado_Mustang

There are some good alignment places that can balance your tires while on the vehicle (at least there used to be). You might also ask if they can balance a drum.

ebluekeys

replaced rear drums, and this helped a LITTLE. Now when the vibration starts, it is most definitely in the front. Just put on new rims/tires and had a "deluxe" alignment done. Watched the whole thing, so I know it was legit. I'm going to order new front drums and hope that fixes it finally. It's the only thing left that I have yet to change. Ball joints and tie rod ends are in excellent shape and nice tight fit. This is really driving me nuts. Vibration starts at 60 and gets worse the faster the car goes. I'll keep everyone posted after I get the new drums...[X(]