Author Topic: Rod/Main Bearing Bolts Reusable? (Read 5249 times)

NitroRustlerDriver · « **on:** November 28, 2011, 12:01:59 AM »

Tried searching on this and came up with nothing. Are the stock M42 rod and main bearing cap bolts reusable, or are they stretch bolts that need to be replaced after use?

Thanks.

dude8383 · « **Reply #1 on:** November 28, 2011, 04:37:13 PM »

Give Jim Rowe a call at MM... guy knows everything there is about BMW engines.

Going to search around as well... I could have sworn I saw something before

Avtovaz · « **Reply #2 on:** November 28, 2011, 05:02:37 PM »

stretch bolts, and there is two differrent types, make sure you measure yours first or give chassie number when ordering!

wazzu70 · « **Reply #3 on:** November 29, 2011, 01:26:25 AM »

The 12pt rod bolts pictured here are reusable (early cars). The mains are just regular bolts, not TTY.

If you have the ability to look at the bolt, a TTY bolt will be "necked down" in the middle. A sure fire indicator.

You can see the shaft of the bolt is smaller right after the threads, this is where the bolt stretches.

Warsteiner · « **Reply #4 on:** November 29, 2011, 06:51:53 AM »

Mains : you can re-use

Connecting Rods: you replace everytime! Can you guarantee that they are stretched perfectly everytime? And if one lets go, then what? You guessed it....Ventilated block!

Cheers,
~Ralph

wazzu70 · « **Reply #5 on:** November 29, 2011, 04:15:52 PM »

Very true, its very cheap insurance to replace them.

When I slapped my engine together I reused the old bolts. I wasn't planning on the engine lasting long anyway. Now I wonder why I didnt pony up a few bucks for new bolts. Oh well, lll post pictures of the carnage if it ever happens.

Engine has survived a track day and daily beating so far. Probably a ticking time bomb though!