Put a post up awhile back about a drive line vibration I had, It was suggested by Byrant and Derek 5oComet that I check drive line angles they were indeed out so I figured the issue was resolved. I shimmed the pinion up and now have it running 1.5 degrees down in relation to trans, took car out still vibrated, so thought I would start back at beginning. Car is 69.5 Maverick with 87 roller motor t5 9 inch all fresh less than 4 thousand on all parts. its not in the engine run car up to 50 stick it in neutral or depress clutch has a shudder type vibration, can be felt under load as well but seems less or maybe masked by all else. I run 28x10.50 Mickeys on the car thought maybe tires so swapped to the stock 14 inch michelins and rims off my 4 door comet no difference. Pulled drive shaft checked ujoints (spicers) all seemed fine the (the t5 is fresh as well including the rear bushing where the slip yoke goes in) Swapped out drive shaft to one I had in a 5.0 Mustang that drove fine went for a short drive no vibration couple hours later go for another drive it is vibrating again. With car running on jack stands can make it vibrate but can,t see anything wrong. Not sure where to go from here its not bad enough to park car but its annoying and just not right. Any suggestions appreciated
i would be looking at the yoke on the thirdmember. i see a lot of them that have had a bearing cap spin and eat away the tabs that center the yoke and even a grove in the saddle of the yoke. if this has happened the ujoint cant stay centered. that may explain why the mustang shaft was good at first then had the vibration later. also dont over tighten the u joint straps. i will put blue lock tite on them and just tighten them to when its hard to hold the shaft by hand against the twist. if you over tighten them they get distorted and will wipe out the u joint.
The yoke on the third member is a new one no wear at all it is one of the big cap ones making it a little less prone to over tightening u joint straps and yes I just snug them up and use blue thread locker. The 5.0 shaft and temporary stopping of vibration has me baffled.
does the slip yoke have any perceivable slop in the back of the trans? i have encountered bent out put shafts on several different transmissions over the years. is their any chance the centerline of the motor/trans is not centered in the car or that the rear end is not square in the car? this is a very hard thing to truly test. about the easiest way is to check the side operating angels of the drive shaft to see if they match.
Is the pinion nut tight? Is the preload on the pinion bearings correct? Either of these ( if not correct ) can cause vibrations.
The slip yoke has no more play than any other cars I have I can move it a bit but we are talking minimal amount,Bent output shaft was something I had considered a possibility as well may wind up pulling trans or swapping out t5 from my Falcon, engine and trans appear to be square I will check the side operating angles of drive shaft. Yes rear end is square in car
Pretty sure pinion nut tight will double check,correct bearing preload not sure as I did not assemble third member but another thing to check. How do you do multiple quotes from different people in one post?
I know when I had a roller motor, I accidentally used the wrong flywheel and it caused vibrations at medium to high rpm.
I can stick it in neutral and coast with it idling and it vibrates and when not moving rev it up no vibration, definitely a speed thing
I would check the pinion nut. I had the exact same symptoms as you on an '84 Trans AM, and fought it for a while before I was laying under the car one day and realized I could shake the drive shaft up and down at the rear end, pinion had so much slop in it. Have never had it happen on a Ford rear end, but I suppose it's possible. Click the little button with quotations on it next to the quote button on each post you want to quote. Then hit the post reply button at the bottom instead of using the quick reply.
