Little End Bolt Failure

See also Little End Bolt Failure; Second Thoughts

I wish to bring this piece of information to anyone contemplating rebuilding their engine.

First I heard a small metallic noise like a bolt falling off from the body work [it does happen], the next time the sound was heard a closer look, much revving of the engine found nothing, the third time 'Bang' and the engine was sounding very sad, luckily we had just arrived at my works and I was able to wait there until the 'nice man with a lorry' could take Ruby and me home.

little 1
Once home, I set too. It turned out to be a failure of a small end bolt which was of the original type, I hadn’t replaced them thinking that they were fine.




So the advice is this: if rebuilding your engine REPLACE the little end bolts [as if they were gaskets] the cost of the bolts is small compared to the cost of the damage!!

However please ensure that the bolts are :-

The correct grade The letter 'R' should be stamped on the head of the bolt which indicates a higher carbon steel bolt [stronger].

That the bolt is the full length of the thread in the conrod, this will mean a little bit of filling of the bolt to ensure that the correct length is gained.

Tony Leslie at Holmesdale Sevens was very helpful and informative on this matter.


This article, written by Mike Davies, originally appeared in Seven Focus Nov 2002 pp21-22. 

See also:

Camshaft Bush Modification

Crankshaft Conversion

Every Piston Tells a Story

Front Main Bearing Retaining Lip

Gearbox Oil Seals

Good Sump Joints

Gudgeon Pins and Little-End Bearings from The Practical Motorist, August 17, 1934

Overhauling the Gearbox

Replacing a 3-speed gearbox with 4-speed

Synchromesh Set-up