Can anyone tell me the thread type commonly used on crossflows?

I want to bolt my gearbox/bellhousing to the engine block, but I've only got the metric bolts that came with the Sierra box and the Xflow is Imperial.

I have some studding that fits the block and that's 3/8" dia, but I have no idea whether it's BSW, UNC or Unified Cycle Gas Thread

I'm guessing that it's going to be UNC, but advice would be appreciated.

It's only the 2 top bolts that screw into the block - the rest are through holes which could be done with M8's without pain.

cheers,

David

For vitually all the components that interest us there are only three types of thread that you are likely to come across-metric, unc or unf. Generally unf (fine) are used when bolting into steel, and unc (coarse) when bolting into softer material such as aluminium eg rover v8 engines. Metric is usually inbetween. If the studding you have is 3/8 then look at the thread. Is it finer than metric then it will be unf.If not, then unc.
John
PS a Zeus book and a thread gauge (ask at the bolt and nut shop) are very useful

Many thanks!

It's what I suspected - the thread looks identical to the M8, so I reckon it's UNC.

These threads are going into the iron block, so this seems right as well.

cheers,

David

Take it to a hardware shop (B&Q?) they'll be able to tell what the thread is and supply you with new bolts for about 30p each.

I would go to a proper bolt and nut stockist, there's at least one in most cities. You are unlikely to find unc at a B&Q. Even if you did it would be a basic quality version

John

PS Don't forget the Zeus book and thread gauge

All sorted - got them from Namrick.

I also managed to work out the bolts I really needed - 2 of 3/8" UNC to go from gearbox flange to the engine, and M10s for all the rest (they go from the engine to metric holes in the Sierra gearbox.

cheers,

David

why not drill n tap em all out to a suitable metric size ?

much cheaper.......

Already got 'em from Namrick!

Gearbox fitted to block, and everything into the chassis.

I now have room in my garage, as the engine hoist and stand have been folder away for a while.

David

P.S. If I could get this site's photo archive upload to work, I'd post some pictures!

same here, still can't upload pics.......