Some Sort of Vibration Noise?

[charles1503]

What's up everyone finally rebuilt my ae86 diff with a new spool, ring & pinion (4.77), and bearings which has been amazing to drive, but with my luck something always occurs after a problem is fixed haha. So I've had the new rear end setup for a couple of days now and have been getting some sort of vibration towards the rear of the rolla while driving straight. When accelerating around 20mph the noise kicks in and gets louder by 45mph, but if I go faster than that it begins to become quieter.

I'm pretty sure the noise isn't a "howl" from a bad pinion, but the vibration sounds similar to as if a pinion bearing was going out. From searching around online this sounds like a drive shaft issue, but not entirely sure. When decelerating from 45mph, if I apply a slight amount of braking it helps to get rid of the vibration. Also, the vibrations definitely were louder on my first "break in" drive on my new setup and are actually a bit quieter now after driving it for a few days. Idk if its just because the diff is still new and I don't have it "broken in" with a few hundred miles on it or if it is my drive shaft u-joint ... Anybody have some input on this?


*And no it is not the welded diff chirping noise thing from making turns

[ga_goosh]

I would check pinion angle that could cause some vibrations. also check your drive shaft support bearing. i had one go out not that long ago and it was pretty noisy. i thought it was my diff too

[KonaTrueno723]

Wow ga_goosh..second one this week? Actually 3rd being mines haha..

charles1503=gaijin_rokurunner also mentioned somethin about shimming the trans to correct pinion angle to help some. It's posted in another topic in here.

[charles1503]

Thanks guys I'll check into it tomorrow so sick of working on my rolla haha. I have a good feeling its the drive shaft bearing ga_goosh mentioned or u-joint. When I was driving around today I put my hand behind the rear console box/ash tray and the vibration felt the strongest in that area. Seems like throwing it in neutral coasting makes it quieter as well braking.

[evanstewy]

Some good advice I got on my vibration problem was to hit the clutch when the vibration was happening. If it stops vibrating right after you hit the clutch then it is probably not your drive-shaft. The only way to fix the pinion angle is like KonaTrueno723 said about shimming the transmission mount or you need at least rear adjustable upper control arms.

Here's a really good write up on pinion angle.

http://www.mestiso.net/forums/index.php?showtopic=325

[charles1503]

Thanks appreciate the info I'll definitely look into that. Is there any danger to drive with this issue?

[KonaTrueno723]

Thanks appreciate the info I'll definitely look into that. Is there any danger to drive with this issue?

In regards to safety? No question, i'd fix the issue. It's a mechanical driven part under load & having that fail on ya' is the last thing you need miles down the road