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Re: 69 TR6, Rear End Wobble

To: dbrunk@mhv.net
Subject: Re: 69 TR6, Rear End Wobble
From: Bob Lang <LANG@ISIS.MIT.EDU>
Date: Tue, 03 Jun 1997 11:15:09 -0500 (EST)
Cc: triumphs@Autox.Team.Net
Hi,

Here are some observations based on my experience.

1. Check the tire for runout. I had a belt let go on a steel belted 
radial and it caused about 1/4 inch of radial runout on the tire.

2. If your mechanic suggested that the axle is bent, have him setup a 
dial indicator and measure it. I suspect that what he meant was:

3. The wheel flange is bent. This will cause the wheel to wobble. This 
can be measured with a dial indicator. The most common cause of this is 
an over-zealous mechanic either installing new lugs (or removing the old 
lugs) or someone trying to rebuild the hub. As you may read on this list, 
the hub is attached to the stub axle with a taper joint, and those 
suckers can really get "married", meaning that they are tough to separate 
and can get bent in the process of getting htem apart. I have had this 
problem too.

4. Your comment about the vibration getting worse when you downshift to 
third... This is curious, but I'll offer an explaination. I'll bet you 
have a bent input shaft on the transmission _or_ the "spigot bush" that 
the transmission input shaft rides on at the flywheel/crank/clutch 
interface is out of round. I have seen "spigot bushes" that get out of 
round and cause vibrations. I have experienced this problem also.

Note: I realize that your tires are new, but all it takes is either a 
nasty pot-hole or a minor manufacturing defect to cause belt failure. If 
your tires are new-old-stock redlines, I'd be suspiscious of steel belt 
failure.

Also note: vibrations are usually from things that are out of balance, but 
they can also come from bearings that are in the process of failing. So, 
you probably want to try to isolate the problem via observation. I 
mention this becasue I read a JK Jackson article somewhere where he 
chased an annoying vibration problem down, the sound was apparently 
coming from the back of the car. Eventually, it was discovered to be a 
bad bearing in the _water pump_. So, get out you stethescope and have at it!

Good luck.
rml
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Quote: How many Triumphs do you own??? One that runs, two that don't and 
one that isn't.
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