Bad vibrations in my Fastback 65 - Ford 9 inch rear end

Well I take a shotgun guess.

Check the driveshaft balance. Might try repositioning the driveshaft on the differential (but with all the checking and replacing you've probably done this already)

Does it have drums? Can those go out of balance? Mine have what look like weights attached. Some shops can balance wheels on the car taking consideration of all the rotating mass.

How about the condition of the axle bearings.

Worn shocks, leaf springs, and/or bushings could magnify an imbalance.

Is the vibration constant or does it change as you move from accelerate to float to decellerate? How about a neutral coast down (move the shifter to neutral and allow the car to slow on it's own)?

Mr Nospam opined

........

Clue is "the 9 inch"

Maybe it was installed wrong.

It's imperative that, at rest - normal ride height- the pinion shaft and trans tailshaft be aligned at the same angle with respect to grade...that is the pinion shaft should NOT point directly at the tailshaft, note the tailshaft doesnt point at it.

An imaginary line extended from the center of each shaft should be equal distance apart at both ends.

Also if the driveshaft was "built" make sure the u-joint ears are aligned properly with regard to each other, IIRC.. it's 90deg, not zero

That is one of the things I plan to do.

Yep, doesn't help.

Yes it's drum breakes, you're right the drums should be balanced as well!

new..

quite new.

One thing I forgot to say clearly about the play in the rear part of the gearbox.. There's some play in the mounts, not in the gearbox itself. Could that be something?

Thx!

Sverker

There is not much of a difference whether I accelerate or decellerate.

In neutral or with cludge down, the vibrations seems to increase slightly.

Thx!

Sverker

The Ford 9 inch was probably not on the car back in 1965, since I read that only those with the high power engine had it. So someone put it in and it's hard for me to tell if they did it right. Looks like fine job, though I haven't looked at those angles you mention. How much would be appropriate?

The front u-joint is symmetric. The rear one is not but can only fit one way. 1 1/8" cap for the rear end and the smaller 1 1/16" at the drive shaft. The overall width is 3 7/32"

Thx!

Sverker

On Sun, 24 Oct 2004 15:23:17 -0700, Mr Nospam rearranged some electrons to form:

What's a cludge? Maybe you meant "clutch".

Mr Nospam opined in news: snipped-for-privacy@posting.google.com:

Looks like fine job, though I haven't looked

I dont think you understood...read what I wrote about that... it is NOT a stated angle... it refers to two planes. Clarified: "...imaginary lineS extended from the center of each shaft should be equal distance apart along their lengths"

Look here..

Not what I meant but I was wrong... it's zero... (just did a search)... that is let's say you were to remove both u-joints from the driveshaft on each end the ears would remain. The ears should be at the same side of the driveshaft as you sight along it. not 90 deg or at a random angle ...

Yes that's what I meant.

/Sverker (swedish mother tongue)

First things first...get the transmission mount repaired/replaced. If the tailshaft is moving side to side it's intoducing another angle that the U-joints have to contend with and aren't designed for.

bradtx