as of my diagram since the driveshaft is parallel to car, I just assume that the u-joint center are both the exact equal height. in any case I won't get any further without dropping the engine, I understand that. So I'll go from there and read that article. if i raise the tailshaft a bit and lower the pinion angle I am in the normal straight thought design if i can get all angles matched up. I can always shim the rear up and down a bit, so I'll play with the one/two degree offset, but i think we all agree, the tailshaft angle must be changed first to have a hope of working angles of less than 5 degrees per joint

 

well I ordered half inch lowering motor mounts today (ron morris performance).
I haven't measured, but if it's lets say 40 inch from transmission mount to motor mount, that half inch should cause the transmission to raise by .75 of a degree. not much ... expected more. would have loved 2 degrees. well I'll only see when they're in. but even with 1 degree up at trans, one down at diff it should shift the driveshaft a bit, so I might just run 6 degrees total instead of 10 ... will be a surprise alright

 

I can only speak to my experience, but if be willing to net that if the vibration is really bad at speed you got a bad driveshaft.

Before you install those pricey motor mounts, inspect your driveshaft really well. If there are any dents or if it is out of round at all, go get a new aluminum driveshaft.

I chased a driveline vibration for two years and for all the work I did lowering the tranny, replacing the yoke and output shaft bushing, and axles, nothing worked. Granted the problem got better but it was never solved.

Turns out that the small dent in the driveshaft, 1/16" deep and 1" long, that I thought didnt matter did.

With the aluminum DS that I got from street and track the car is now smoothe as glass at all speeds up to 120.

If I were you, I'd return those mounts, save up a few more bucks and spring for a new DS.

Good luck...

 

Well, should I risk getting my *** handed to me and answering another driveshaft post? yea, I don't give a **** so why not...

My son has a 70 mph vibration that developed in his "old" truck, he assumed that the driveshaft shop screwed up the shaft they cut so he replaced it with a junkyard shaft and guess what..... no change at all.

The driveline is almost automatically suspect in just about every vibration issue, problem is the problem ain't always there.

He hasn't worked on the truck since, so I don't have a possible resolution, but I do have an opinion, that is, judging from your picture and comments, the driveline angle(s) ain't your problem. Driveline balance, maybe, but I doubt it, bent driveline, more likely but,,,, ummm.

bent axle,
bent wheel,
out of balance brake drum etc...

 

hiya all,

the driveshaft is the only thing past the trans that isn't new. used a shaft from a 66 auto and I have no idea if it was a good one.
new moser axles,
new ford racing disc brakes
new wheels and tyres
everything is centered same distance measured from left and right of chassis.
sicne the angle is a bit off (total working 10 degrees) I said I replace the mounts first, if that doesn't cure it the driveshaft is next (yes, new alum it will be).
the angles were never right because the rear axle was welded incorrectly to perches, it was 4 degrees down instead of 4 degrees up to start with (8 degrees out). I adjusted with cutting and welding and another 2 degrees with shims

I'm going to tackle this thing, no matter what ... sick of it :-)

but ya, friend of mine has a 69 chevelle with 55mph vibration and I have my money on bent axles. can see them wobbling a bit (at the flange) when driving wheels off car lifted in back

 

Hey Kalli
why dont you rule out the tailshaft before making any more changes?
I'm not saying buy a new one.

Just take the one you have to a tailshaft place and get the u-joints and balance checked out. Shouldnt cost more than a few pounds to rule it in or out.

if its crook, it may well be repairable at a fraction of the cost of a new one.

 

I have the stock height RMP adjustable mounts. They are nice. I will say this. You may have oil pan to crossmember clearance issues if you drop the motor. This probably depends alot on what oil pan you have. I went out and looked at mine and there is not much room there.

I got my aluminum driveshaft from Inland Empire. http://www.iedls.com/

I would go with Spicer U joints.