CyprusMustang

just rebuilt engine and cant get to the bottom of this problem.

when i am driving low rpm's and hit 30mph, the car kinda shakes, then when i pass 35mph, shaking stops.

not quite sure what the problem is, do you guys think its a timing problem?

peteman

are your u-joints good on your drive shaft

Stepman

I have to go with that. You have a bad U-joint.

Gun Jam

at least you can drive thought it...so I'm guessing its not a balance issue.

U joints is a good place to start.

-Gun

CyprusMustang

how would you inspect to see if the old U joints are faulty? when i removed the tranny i dissconnected the driveshaft from the rear u joint. i didnt notice anything unusual but then again i wasnt looking. what do i look for.

67mustang302

Either a jacked u-joint, depending on how the engine sits after being put back in the slip yoke angle might be wrong, and if it's the same driveline and din't have that problem before we can assume that's fine, unless something happened while it was out that might have dented/bent it. Sure it's not an out of balance wheel?

kalli

welcome to the shaker's club!

the first thing to do is to check if it happens no matter what gear or no matter what engine revs to find out where it's coming from.

if it happens at that speed no matter what engine rpms it's something from the gearbox backwards (wheels included)
if it happens at a certain rpm then it's engine related (or engine, engine parts hitting your chassis)

Stepman

Put the car in neutral, block the wheels, then get under it and twist the driveshaft back and forth. Any play you see in the joint means it is bad. It may also be that you didn't get it centered when you put it back in, over torqued it, needs grease, or maybe try and turn it 180 degrees and reinstall.

If it was a tire balance issue, the vibration would steadily get worse as speed increases. A "classic" symptom of a U-joint is that it vibrates at 30-35 mph. (you can set your speedo to it)

CyprusMustang

actually i took stang out today for a ride noticed that its only when hill climbing, not on straight away. Goes away after 35mph. ill do the driveshaft inspection tomorrow. also now that i remember, in the u joint there were little bearings (needle like rods) and i noticed that on one of the joints there were missing half. are they supposed to be full all the way around or are there supposed to be half.

anyone have any ideas about the hill climbing theory?

Gary H

Needle bearings should go all the way around :-)