The diagnostics prize goes to Jon Tilson.

Once the car was on the hoist and lit underneath by a bright light, the
shiny mark on the prop shaft was obvious. The front silencer had been
rubbing on the prop shaft because the front exhaust bracket (the one that
anchors the joint between the front pipe and the intermediate pipe to the
rear of the gearbox) had given way. Under power the engine twists slightly
on its mountings and maintains clearance. Decelerating, the engine twists
slightly in the opposite direction and the clearance between exhaust and
prop shaft reduces to almost nothing. Turning left while decelerating causes
centrifugal force which causes the exhaust to swing outwards slightly, and
just enough to cause the front silencer to rub on the prop shaft. By
replacing the exhaust mounting, the problem went away.

Many thanks for all the suggestions of what to look for. It has been an
education

Jim

On Wed, 30 Jul 2003 22:14:58 +0100, "Jim Warren"
wrote:

The diagnostics prize goes to Jon Tilson.

Once the car was on the hoist and lit underneath by a bright light, the
shiny mark on the prop shaft was obvious. The front silencer had been
rubbing on the prop shaft because the front exhaust bracket (the one that
anchors the joint between the front pipe and the intermediate pipe to the
rear of the gearbox) had given way. Under power the engine twists slightly
on its mountings and maintains clearance. Decelerating, the engine twists
slightly in the opposite direction and the clearance between exhaust and
prop shaft reduces to almost nothing. Turning left while decelerating causes
centrifugal force which causes the exhaust to swing outwards slightly, and
just enough to cause the front silencer to rub on the prop shaft. By
replacing the exhaust mounting, the problem went away.

Many thanks for all the suggestions of what to look for. It has been an
education

This is very good news. Although I haven't been able to contribute to
this thread (the grinding noise on my Triumph 2000 was a worn UJ but
you'd discounted that early on) I was following it with interest.

It's amazing what you can do when you have the right equipment!


Best Regards
John McCabe

To reply by email replace 'nospam' with 'assen'

"Jim Warren" wrote in message
...
The diagnostics prize goes to Jon Tilson.

Whahay...its good to know the time I spend on here is sometimes put to good
use....
When all else fails, including the obvious...think laterally.
I'll now spend the rest of the day feeling a smug git...:-)

Jonners

I'll now spend the rest of the day feeling a smug git...:-)

Jonners



Well, I hope you ask his permission first???......

Jon Tilson wrote in message
...

Whahay...its good to know the time I spend on here is sometimes put to
good
use....
When all else fails, including the obvious...think laterally.

There is an interesting aside to this problem. Under normal circumstances,
an exhaust rusts into holes and is replaced every few years, and when it is
replaced it is normal to use new clamps and hangers.

I fitted my Triumph with a stainless steel exhaust about 10 years ago. The
exhaust has lasted, but the clamps are not stainless and had rusted away.
Something for those with stainless steel exhausts to keep an eye on.

Jim

Jim Warren wrote:
Jon Tilson wrote in message
...

Whahay...its good to know the time I spend on here is sometimes put to

good

use....
When all else fails, including the obvious...think laterally.


There is an interesting aside to this problem. Under normal circumstances,
an exhaust rusts into holes and is replaced every few years, and when it is
replaced it is normal to use new clamps and hangers.

I fitted my Triumph with a stainless steel exhaust about 10 years ago. The
exhaust has lasted, but the clamps are not stainless and had rusted away.
Something for those with stainless steel exhausts to keep an eye on.

I have the same problem with my Scimitar - the mild steel
U-bolt clamps on the front downpipes only last a couple of
years before they rust through and start to rattle in a
most uninspiring way.

The exhaust itself is stainless, at least 10 years old
[it was on the car when I got it] and has done 120,000
miles in my ownership.

Does anyone know of a source of stainless-steel U-bolt
clamps at *sensible* prices?