Thread: Drive line setup

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I need some help. I had someone else install my trans an 4 link I have had some vibration when you let off the gas. The drive shaft runs good an true. I'm not a drive line person but now I'm thinking my angles are off. Trans is down 8 degrees rear is up 6 degrees this is setting at ride height. With the shaft in it is going down hill towards the trans 3 degrees. Dose that make sense to anybody?

Your trans yoke must be lower than your rear pinion. I think I'd raise the trans but make sure the intake is level. you could lower the angle of the rear a bit. You may have to re figure your entire drive line.

It is will this be a major problem

Like Charlie said, get the intake manifold level first which should leave the transmission about 3 degrees down.....then lower the pinion to about 3 degrees up....

Ok, thanks

The engine/trans and pinion should be set at the same angle. Anything more than 3 degrees would be unusual.

How are you measuring the angles? Also measure the angle of the driveshaft.

Off the yoke face an trans input face

If you are measuring angles relative to the ground level----you are doing it wrong--it should be the angle of the drive shaft relative to the angle of the trans tailshaft and pinion c/l----the shorter lengths in most hot rods make the angles more than longer drive shafts in modern stuff--------

http://www.iedls.com/asp/admin/getFi...&TID=28&FN=PDF

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Ok, I got my trans down bout 2.8 deg pinion up 3.0 deg another question my drive shaft at the rear and center is about .014 runout at the trans it hard to tell. My in an out clearance is 1.125 slip but I can take the drive shaft and move it up and down or back an forth till it's plum off the indicator I got + or - .04 on my indicator. I'm sure you should have some but is that normal?

Are you saying that with a dial indicator on driveshaft you're getting 0.014" runout at the back, 0.014" at the center, but able to drive it off scale, exceeding 0.040" at the transmission end? If my understanding is right, and if you have your u-joints properly seated in the rear yoke it sounds to me like you may have a bad pinion bearing, and at the front end maybe a bad output shaft bearing. That said, you may have a driveshaft that's bent or has a yoke installed funky. Have you had your driveshaft checked at a good shop, like Inland Empire if you have one near by? If not look for the place that services big trucks and they generally do car & jeep shafts, too.

I had the shaft checked by the people that made it they said it was good but I didn't see it my self. I don't think it's pinion bearing. It was biult by someone I know very well it only has bout 500 miles on it. The drive shaft was worse than that at the back I turned it 180* to get it within .014"as for the trans bearing I will have to get it checked

Are you sure you've got the right front yoke for your transmission output shaft? Could be the tooth count is right, but the ID of the yoke is a little large and you're only getting partial engagement of the splines? Just thinking out loud here. With the driveshaft out can you wiggle the transmission output shaft?

The shaft coming out of the trans will move around about .050"

Originally Posted by 39 Chevy

The shaft coming out of the trans will move around about .050"

Seems to me that the output shaft bearing shouldn't have that kind of play in it, but then I'm not a tranny expert by any means. Maybe one of the other guys will jump in a bit later and offer some solid advice.