I have noticed that I get a really bad vibration when I hit the brakes from highway speeds. The vibration isn't as bad if I am still in gear. I dont feel a pulsing at low speeds indicating a drum out of round. I just replaced both U-joints.
Any ideas what it may be?

_________________

Sounds as if it might be related to pinion angle. Where do you feel the vibration? In the brake pedal, or in the whole car? Did the vibration exist with the old U-joints?

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

I don't feel it in the brake pedal and it was the reason I replaced the u-joints.
It feels like it is coming from the rear of the car. I don't feel it in the steering wheel either.

_________________

Can you cause the vibration by cruising at highway speed, taking your foot off the gas and downshifting to second gear without touching the brakes?

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

My two cents- if it wasn't there before you replaced the u-joints, then you either didn't get the drive shaft clocked into the same position as removed (did you make alignment marks before you removed the balanced drive shaft?), or one of the new u-joints got damaged as it was installed- like a roller dropped out or dropped sideways. I did that to myself on my van u-joint. Unfortunately, to check the condition of the u-joints almost requires pressing them back out, which means they are not re-usable and must be replaced again with new. Bummer. Pat

_________________
"Louise", a 1976 Dart Custom project, (now sadly reverted to being just an "organ donor" to our other project Darts.)

I'll give that a try Dan. This problem is in the Volare with an 833-od so It would ba an od to 3rd shift. I don't think I feel it unless I put on the brakes.

_________________

The car isn't as smooth at highway speeds as our other cars. There is always a small vibration but it really shakes when I hit the brakes. it dosen't matter if I'm in third, overdrive or in neutral. As it slows down it gets less violent until I'm under 30 mph where it totally goes away. If I just let off the gas it dosen't vibrate. I think its bearings in the rear or perhaps rusty ring gear and pinion.

_________________

I don't think it's a rusty ring and pinion -- those make a lot of noise. Bearings...mmmmmmaybe, but I don't think so. Those make a lot of noise, too. I'm still thinking your pinion angle is incorrect. Does it happen whether you're in gear or in Neutral while braking?

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Would having one sagging leafspring cause this? There is almost 1 1/2" ride height difference between the left and right rear wheelwells. The vibration is any time I apply the brakes over 30 mph, and its worse as speed increases. I don't hear any kind of bearing whine.

_________________

The spring can throw the geometry off. I would say that that could certainly make the vibration a lot worse. If its Broken and sagging then that is most likely the problem.
Frank

_________________
Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

The spring isn't broken it is just really sagging.

_________________

check wheel balance....lugs tight????

if it were tire balance or loose lugs it would vibrate all the time, not just when the brakes are applied and over 35mph

_________________

wheel balance will start at 35-40 mph smooth out about 75-80

but wheel balance is ALL THE TIME not just under braking.

_________________