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Cam followers and Crank end float!
Locost82 - 17/8/05 at 08:01 AM

Quick overview

1 of my 8 cam followers has worn away to around half it's original length and destroyed the cam in the process! NICE!

I'm replacing the cam in the engine and noticed considerable end float in the CRANKSHAFT, around 1/8th inch. This is obviously outside the design tolerance. Does anybody know whether the wearing away of the cam follower could have led to the destruction of the crank spacer, or are the 2 unlikely to be linked? I was thinking of contaminated oil.

James - 17/8/05 at 08:12 AM

What engine?

Cheers,
James

Locost82 - 17/8/05 at 08:32 AM

Good point!

1300 x-flow Locost Racing engine.

It's gone from minor to major endfloat in about 10 races.

viatron - 17/8/05 at 09:49 AM

When you say half its length i take it you mean from the end that the pushrod sits it? In which case i would check the rocker on that follower, cant remeber ever seeing one wear on its length, they normally wear on the od of the follower or wreck the bore that the follower sits in.

Mac

MikeRJ - 17/8/05 at 10:49 AM

quote:
Originally posted by Locost82
I'm replacing the cam in the engine and noticed considerable end float in the CRANKSHAFT, around 1/8th inch. This is obviously outside the design tolerance. Does anybody know whether the wearing away of the cam follower could have led to the destruction of the crank spacer, or are the 2 unlikely to be linked? I was thinking of contaminated oil.


I suppose it's possible, but unlikely IME. The crank thrusts are only under any serious pressure when you have you foot on the clutch, as if they have worn that badly from contaminated oil, the rest of the engine is almost certainly scrap metal.

One possibility is that one or more of crank thrusts were fitted backwards. This means a steel-steel bearing surface, and will very rapidly score the thrust face on the crank. I've seen this happen several times, and the crank is nearly always scrap.

Bob C - 17/8/05 at 11:24 AM

My mate's chevanne had this much crank movement when he pressed the clutch.
Amazingly, he drove it for years without any trouble.......
Bob

Locost82 - 17/8/05 at 11:32 AM

Viatron, the cam follower has worn from the cam end. The mushroom part of the follower is no longer there!

Bob C, I removed and replaced the thrush washers when I rebuilt the engine over the winter, looks like that could be the culprit!!! Out of interest is there an easy way to make sure they're fitted the correct way round?

Locost82 - 18/8/05 at 08:45 AM

It was the thrust washer. Appears to have been thrown out and did a quick lap of the engine, destroying the cam follower, before depositing itself in the sump. Result: new cam and followers, new crank, less fun money in the bank.

Bugger!!!

Nitroustoy - 18/8/05 at 12:06 PM

Locost82,
Thrust washers are fitted with the steel back against the block and cap, the bearing surface goes against the crank.
Make sure all four are the correct way round oil grooves too crank.