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SP vibration

kent sutton
Posts: 46
Joined: Tue Feb 23, 2016 10:15 pm
Location: Townsville QLD

Re: SP vibration

Post by kent sutton »

Dear Chris
By using the clutch the only moving part that changes it's position is the driven plate. Accordingly is it possible for a portion of the friction material to have become separated from the plate and upon engagement and disengagement obviously adopt a different position to the flywheel, pressure plate driven plate combination causing the imbalance?
Kent Sutton

chrisrichards
Posts: 14
Joined: Sat Aug 20, 2016 11:05 am
Location: East Sussex

Re: SP vibration

Post by chrisrichards »

Thanks for the response Kent. You have confirmed what I suspect to be the case too. I'll post again when I've had the gearbox out and discovered something. Hopefully!
Chris

daimlersteve
Helpful Person
Helpful Person
Posts: 496
Joined: Wed Mar 09, 2016 11:20 am

Re: SP vibration

Post by daimlersteve »

Did a clutch many years ago for a guy ( SP) Vibration immediately after , removed gearbox, flywheel and clutch , both balanced , replaced, vibration still there . never resolved as a lack of acceptance that something else was amiss. My assessment was the harder new mounts made the problem obvious . 9 the old mounts were very oil sodden.
steve

Ian Hastings
Posts: 163
Joined: Tue Mar 15, 2016 3:00 pm

Re: SP vibration

Post by Ian Hastings »

I fitted a new clutch, Healey upgrade clutch plate, cover and bearing.

The new cover had a 24 deg run out over the 50 mm or so wide plate that the bearing pressed against.

It didn't half rattle things a bit and wrecked the thrust bearing in under 200 miles!

Always remember when fitting 'new replacement' bits to classic cars that just because it is 'new' doesn't mean it is right. :o :o

chrisrichards
Posts: 14
Joined: Sat Aug 20, 2016 11:05 am
Location: East Sussex

Re: SP vibration

Post by chrisrichards »

Been a long time since I posted on this but finally found the answer!
I eventually decided to strip the engine down but still could not find anything obvious as the engine had been rebuilt shortly before I purchased the car.
I decided to send it of to my local engineering shop and get them to check everything and balance the engine at the same time.
They discovered that when the engine had been rebuilt under previous ownership the engine builder had not used a deck plate when re-boring the cylinders and consequently the block had twisted slightly and the pistons had an excessive gap between them and the cylinder wall.
They made up deck plates which are used to stop the block twisting during re-bore and keep everything true and re-bored to +40.
They reckoned the the extra usage I had given the car had finally caused the pistons to move around enough to get the vibration but that it was intermittent as the the position of the rings would vary the level of the vibration!
With new pistons and rings of the course the engine is now as sweet as a nut!!

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