Vibrations -Not the good kind!

knightsm · 06-15-2006, 03:43 PM

Hey all you grease monkeys help/advice needed. Recently change the rear gears to 4.10's, set the backlash at the lower permissable setting, .oo4", it turned sweetly. Now with 650 miles on the clock, ( a change at 500), there is bad vibration above 90mph which gets worse the faster we go. The rear is filled with Penziol and GM additive. Although I'm sure I replaced the prop shaft in the position it was originally I keep toying with the idea of spinning it 180. Anything else I should try? The rear seems to be working correctly no noises whines etc, the only whine is from her indoors as it's technically her toy! Help!!

Crabs · 06-15-2006, 04:01 PM

It sounds like a balance issue of some kind. Have you had the rear tires balanced lately?
Failing that, I'd take a good hard look at the U-Joints and Drive Shaft. Could you have knocked any balance weights off of the drive shaft when you did the rear end?
I can't imagine that's a gear or rear end problem, I'd start with the easy/cheap things first.

Good luck!

TomC
'90ZR1 #792

FU · 06-15-2006, 04:29 PM

LTPWS sensors fall apart ?

Crabs · 06-15-2006, 05:54 PM

Quote:

Originally Posted by FU

LTPWS sensors fall apart ?

Ahh yes...
Can't forget those.
Have you made any high speed runs lately?
The wheel sensors are known to fail at high speeds.

Good luck!

TomC
'90ZR1 #792

knightsm · 06-16-2006, 05:00 AM

Thanks for the response

, unless you are chronic insomniacs by the time you read this I will have put her,(the Z not Louise

), over a pit and checked out the whole drive area. I will re-post with a positive response soon I hope.

knightsm · 06-18-2006, 06:02 PM

Progress in the right direction, spun the prop shaft 180, after noticing there are marks on both sides of the U-Joint yoke, thanks GM/whoever! Much better, however still a slight buzz which wasn't present on the car before. I replaced the old U joint bolts on one side for new ones but when they arrived at my local parts store from the good old US they were the same thread rate but a larger head(not 5/16ths) and longer. I cut them down and installed two on one side and as the other side was ok just replaced the old ones. You know what I'm thinking now, even though the weight difference is very slight, one side of the U J is heavier than the other and something at the back of my mind from school many years ago tells me the faster the drive shaft spins the weight difference will be magnified, hence the inbalance. What 'cha think? It's over the pit again for a bolt weighing session, if I can't get the correct ones before next weekend I will machine the replacements so all weigh the same.

LoTu5 · 07-06-2006, 08:42 AM

Mark,how did things go with the vibration?it was good to get aquainted at the Nats with you and your lady.

Rob 93ZR-1 · 07-08-2006, 10:38 AM

Any progress on this issue. I think I may be in the same boat.

Bigvmaxx · 07-08-2006, 03:36 PM

I am having the same issue also... however... as you mention about U joint bolt lenth and weight. IMHO it hardly matters when the bolts in question are so close to the centerline of rotation. Especially if all 4 bolts are the same lenth.
How much to long are the bolts ?
How much difference in weight between these bolts ?
It seems the amount of weight in question is so minimal that it would be hard to get a vibration from it.
You have me wondering now... maybe I better order some new bolts because I have been swapping bolts around. Also a good time to check everything and make sure it is tight to spec.

Could spline wear in the spindle cause this problem ?

Let us know if you find out anything...