I'm Cursed!!!

[gone huntin]

Well, I put in the 5* shims to correct my pinion angle(was 9*, now 4*). This took care of the vibration that I had above 55 mph. Everything was great for a few days until today. On the way home for lunch I noticed a very bad vibration while coasting, if I give it gas it goes away. Now, on the way home from work I noticed a slight vibration during decelleration, but not nearly as bad as when coasting(lightly lifting of the gas). I'm beginning to wish I'd left the wimpy 10 bolts in this thing, atleast with them I had no vibrations. Here are all of my anglesinion is 4*, measured at the front bolts holding the pinion carrier in, transfer case output shaft is 5* measured on the flat side of the slip yoke, and the driveshsaft itself is 13* with a length of 55 1/2". I spent 30 minutes on the phone with the guy at the driveshaft shop today and he had a computer program that tells you if your angles are good or not and mine shows fine, should not vibrate. I have replaced both the transfer case output shaft bearing and bushing within the past week.
veh:'90 Suburban with a 14bff swapped in

 

[Wingnutt]

Sounds like it's U-joint time. The bad angles that you had previously probably killed the joint at the yoke. For $15, and about a half an hour, it's worth checking.

 

[gone huntin]

Thanks for replying, but it's got new u-joints in the rear shaft.

 

[cegusman]

Check your yoke on the rear axle for any slop, could be a bad/failing bearing.

 

[diesel4me]

loose pinion nut?

I had a severe vibration in an old cougar I had when coasting from highway speeds coming off an exit ramp...I found the nut holding the rear U joint yoke to the pinion shaft was very loose--a qiuck blast with the 1/2" impact at a gas station,and presto--no more vibes!....I'd look and see if your yoke nut is loose,or if you can move the pinion up and down--your previous vibrations might have chowed the pinion bearing(s)...

 

[gone huntin]

Thanks for responding guys. The nut is tight at the rear yoke, I just replaced the pinion seal a few weeks ago, but I did check it again today. Also, there is no slop in the pinion bearings, all tight. I did put on a new slip yoke and front u-joint today just to try it and it helped slightly, but not much. This is the type yoke that slides into the t-case. I added a couple of washers just over 1/4" thick under the tranny mount just to see if 5* might have been too much on the shims, but it changed nothing.

 

[dave_90_blazer]

Thanks for responding guys. The nut is tight at the rear yoke, I just replaced the pinion seal a few weeks ago, but I did check it again today. Also, there is no slop in the pinion bearings, all tight. I did put on a new slip yoke and front u-joint today just to try it and it helped slightly, but not much. This is the type yoke that slides into the t-case. I added a couple of washers just over 1/4" thick under the tranny mount just to see if 5* might have been too much on the shims, but it changed nothing.

did you check for slop where the yoke slides into the t-case?

 

[mouse]

I've got the vibs while decellerating like you've mentioned, but its only barely descernable. I have a new HAD driveshaft coming which I hope will fix it. I have a little slop in the old shaft and the TC yoke - both being replaced. Hopefully the pinion bearings are OK in the 14BFF. I'll let you know if this fixes mine.

 

[gone huntin]

did you check for slop where the yoke slides into the t-case?

Yes, and there was a little there, that's why I replaced the slip yoke. I had already replaced the bushing in the t-case tailhousing two weeks ago.

 

[gone huntin]

Are you getting a shaft with a cv joint in it?

 

[mouse]

Yup, 1350 CV, and the 1410 with u-bolt for the 14 bolt pinion. I have just a little slop in the t-case, in the slip spline of the old shaft, and the pinion. I think my problem is the combination of all the little slop, combined with the out of balance condition of my driveshaft. The old drive shaft has a few dents and is no doubt out of balance, plus t-case angle is 17 degrees, with a pinion angle of 3 1/2 contribute to the problem. I have about 5 1/4 lift in the rear (4 in spring, 1 inch zero rate, and a 3 degree shim).

 

[mouse]

New shaft is in, it drives smoother than ever. I can swear by the butt dyno that acceleration is better - I guess the old shaft was binding. As hard as I tried to make it vib, the new shaft refused to. Now all I feel are the tires...HAD did a great job fixing this for me.

Take a look at old versus new...

 

[gone huntin]

Glad to hear it, can't wait to get mine.