Sprint Clutch Woes

[GrahamFountain]

Running backwards undoing impellor screw?

Rubbish...

If its touching enough to undo you will already have had far worse problems....

Jonners

I've never seen it myself, that's just what I was told by one of the guys who used to rally Sprint engined cars and who's built and rebuilt several engines for me over the years, Nick Dixon of MND Motorsport - "Don't let the engine run backwards, it unscrews the impeller bolt".

I thought it made sense, since I thought the helical cut gear on the jackshaft turned the way that draws the pump shaft down when running - so it would try to push it up in reverse. But if I'm wrong about which way it turns, then it must be rubbish.

If it does turn that way then, IIRC, the impeller bolt only gets 10 thou clearance from the cover, from the gaskets, and that's before torquing the cover down. So, given the amount the gasket compresses, it wouldn't have to lift the impeller far for the bolt head to touch - 2-3 thou? And, if it did, the cover would try to unscrew the impeller bolt. I assume the consequences would be at least unpleasant if it did.

But I'm not sure what else would happen if there was a few thou side float in the pump's ball race, etc., since the jackshaft should pull the pump shaft down, and pull the impeller against the seals when running. What else do you reckon it would do?

Graham

[GrahamFountain]

If you do decide to fit a braided clutch hose Graham,Goodridge do one.

I've ordered one from S&S, at a less than grimmer price.

Graham

[Jon Tilson]

Fair enough....

I handnt thought about the possibility of the pump shaft moving up if the gear goes round the other way....

It does make some very nasty noises if it has no clearance going round correctly....

Jonners

[GrahamFountain]

Well, like I said, I've never actually seen it or heard of it from anyone else. So it may only be a theoretical risk. I'll still set the tickover lower than I want, to stop it running on though.

Graham