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I just installed a 72 f100 9" and now I have a vibration at 15 to 25 MPH.
I replaced the brakes, wheel bearings, installed a new drive shaft, reversed eye springs, short stacked the springs and installed new shocks.
That about covers how I messed it up, now how do I fix it.
BTW it now has a choppy ride - before it has just hard.
any help will cause great admiration.
Last edited by 56extcab; Aug 20, 2004 at 04:40 PM.
Reason: sp
The angle of the driveshaft to the transmission output shaft must be the same as the angle of the driveshaft to the pinion gear shaft of the differential. If they are not the same angle, it will vibrate.
I'll give odds that they're different, and that's what's causing the vibration.
Wheels and tires are known to be good I assume? After you read the article on Niolon's site and verify pinion angle, I would have the driveline shop have a quick look at the driveshaft. I believe you that they are reputable but mistakes can be made of course. I've had a slightly different experience than Paul regarding pinion angles. I accidently installed my 4* spacers in backwards briefly and can't really say I noticed a vibration. I think you can get by with a few degrees sometimes. But you certainly must be pretty close to correct.
I found the transmission shaft sitting at 0 degrees. (90 degrees from level)The differential, however, was setting at 8 degrees. (98 degrees from level) I got a set of 8 degree shims from a 4x4 shop and brought the diff to 0 degrees.
There is about a 3" rise in the drive shaft and that seems to be OK.
Again thanks a bunch.
Last edited by 56extcab; Aug 26, 2004 at 04:47 PM.