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Had a vibration in my rear!

A

Anonymous

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At the track Wed, as soon as I got on track I noticed a vibration that started above 4,000rpm and was at its worst at 5,500. Since it rained on me while on track, I wasn't able to diagnose where it was coming from.

I removed the rear tires and the vibration was still there. Took the drums off and still there. Touched a pc of chalk to the driveshaft in 3 locations, that was it. Took the driveshaft out and ran it and the vibration was gone. So I got 2 new U-joints, replaced them and put the driveshaft back in, vibration gone.

The U-joints didn't show any noticeable wear nor were they loose, but changing them sure fixed the problem. They've been on the car for 7 years with just 6 years of drive time. Most of the drive time was track time though. I guess 6 years is one too long between replacements for track usage. Another consumable to add to the list!
 
Heck I was going to suggest you use a lower voltage battery in your man toy but guess that wasn't the problem.

:craz :ep :lol
 
"Moostang" said:
So in conclusion, playing with your shaft fixed the vibration in your rear.
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Always does [nb]that seems sooo dirty saying it to a woman on the interwebnet[/nb] :lol :lol
 
I was tracking down a similar driveline vibration recently. I was feeling vibrations in the car especially through my shifter handle at 75+ mph in any gear. Did some exploring with my dial indicator. Found my "balanced" driveshaft that came as part of my tranny upgrade was out almost 30 thousandths near the rear U-joint. Had an aluminum one made by Dynotech and installed it last weekend. Vibrations now gone.
 
Mark: in those seven years of use, did you ever once lubricate your u-joints?
 
"Midlife" said:
Mark: in those seven years of use, did you ever once lubricate your u-joints?
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They were non-greasable supplied with the driveshaft from Denny's Driveshafts. I replaced them with greasable ones!
 
"silverblueBP" said:
They were non-greasable supplied with the driveshaft from Denny's Driveshafts. I replaced them with greasable ones!
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And that's the rest of the story. Thank you...for the nicely lobbed softball. Folks, avoid non-grease-able parts at all costs. They were designed for the non-mechanically inclined owner who takes their car in for service at the proscribed intervals and have their wallets deflated. These parts are an abomination to the industry!
 
Agree, I asked him why they used that type, but it's been so long I have no memory of what he said.

For $30, it's just another consumable for a track car.
 
"silverblueBP" said:
They were non-greasable supplied with the driveshaft from Denny's Driveshafts. I replaced them with greasable ones!
Click to expand...

Did you by chance orient the grease fitting such that the when the joint is under load the grease fittings area is under compression versus tension? Supposedly they are less likely to break under compression.
 
I installed them so I could get the grease connector on them from under the car.
 
I had a 66 I built in 1980 and I went through U joints weekly. I carried all the tools and an extra U Joint everywhere I went. I had a 76 F250 I put a built 460 in and had the same issue. It had the tool box on the lower right side of the bed and there you found all the tools and a couple extras. I've changed many U joints on the side of an orange county CA freeway.

I found that in the truck, when I got tired of changing them out, I got some lifetime guaranteed U joints and never had another problem. They even looked a bit stouter.

I guess my point is get the stoutest U joints you can get to fit even if they don't have the fitting and you will likely even in a track car have good results. Do you carry grease with you? If so, grease them even if you have to take them out, just before you go out on the track.

Mel
 
"Midlife" said:
And that's the rest of the story. Thank you...for the nicely lobbed softball. Folks, avoid non-grease-able parts at all costs. They were designed for the non-mechanically inclined owner who takes their car in for service at the proscribed intervals and have their wallets deflated. These parts are an abomination to the industry!
Click to expand...

I'd agree, except for the time I spent working in auto repair. At the time (early '80s), nearly everyhing was greasable.

NONE of the mechanics I worked with ever took the time to clean the zerks before greasing them. The result is dirt pushed into the part, and premature wear. I worked at several differnet shops, and at one, the owner told me to stop wasting his time by cleaning the zerks.

So, when the parts people say non-greasable last longer than greasable, I believe them - for 90% of the cars. Those cars got the quicky grease jobs, and dirt pushed into the part. Hence, part failure before a sealed part would fail.

Now, if you clean them before greasing and keep the grease gun tip clean, parts will last a long time. I always try to get the greasable component, but I know how those parts are being greased.
 
Follow up:

I was going over the car Sat making sure it was ready for Wed track Day. [nb]that will def get rained out[/nb] I had it up on the stands and ran it up, video taping it and when I went back and watched it I noticed the driver wheel had a wobble to it.

I switched tires around and the wobble followed the same tire. Took it into my tire guy to check the balance and sure enough it was off. He re-balanced the tire (fo free) and I brought it back home. Mounted it up and the wobble was gone.
 
No shart, I doubt I'll even hitch up the trailer. WTF is the world coming to.
 
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