Hello all,

I'm getting some nasty vibration in my '70 4-door (225 hydraulic lifter engine, 904, 7 1/4 rear with highway gears) when under load (stops when I ease off the throttle). I'm thinking worn u-joints or trans mount (I haven't had a chance to climb under and check it out yet). It used to be that I'd get some vibration around 70 mph, but then it'd "break through" and smooth out around 75 or so. Now it's doing it around 45 and again, only under load. Any thoughts? If it is the u-joints, how do I go about replacing them? Anything else I should have a look at?

Thanks,

Nat

_________________
1970 four-door Dart, 225/A-904/2.45 gears. 0-60 in twenty three minutes!

Could also be the tires

_________________
Excuse me, does this smell like chloroform to you?

Tires are only about two months old and I've only noticed the increased vibration the last week or so. Pressure is even all across the board. Alignment was just done and the car tracks nice and straight, so I'm sure it's not a front end thing. I know the motor mounts look pretty tired, so I can only assume the trans mount isn't much better.

There is an audible "clunk" when switching from "D" to "N" which has gotten louder in the past while. Not sure if any of this helps, but you now know about as much as I do in regards to the problem.

Thanks,

Nat

_________________
1970 four-door Dart, 225/A-904/2.45 gears. 0-60 in twenty three minutes!

you should check the tranny mount. when i finally replaced the original mount in my car, the new mount praised the rear of the tranny 1/2"-1". have you ever had your driveshaft balanced? i know mine was way out.

zedpapa

_________________
1970 dodge dart w/225 /6 bored .040" over, holley 390cfm w/vac. sec., compcams 252s, clifford shorty headers w/2.5" exhaust w/flowmaster, f-body 11" front discs, aluminum A-833OD, 8 1/4 w/3.21 SG
soon to have 5 gears!!!

It is sounding like the drive shaft. To be sure, take a flashlight and look at each u-joint from a safe distance, while you have someone shift from drive to reverse and back to drive a few times at an idle. If you see movement in the u-joints they are bad.

To replace u-joints you need at least one of the following:
Ball joint press
Hydraulic press
Big vise
Big Hammer

I prefer a ball-joint press, I find it easier to handle. Maybe someone can post some pics of how to press them out and back in.

Good luck
TopHat