Bolt sizes for pressure plate and bell housing
 

I am restoring a 1953 M250 classic (basically a 53 F250) with a 239 flat head and 4 speed transmission. I have the opportunity to get some hardware from a work site that is being closed. I was wondering if anyone knew the size and thread pitch of the clutch pressure plate bolts and the engine/transmission bell housing mounting bolts. Any of the hardware sizes would be great and I could take the opportunity to get some new fasteners.

Re: Bolt sizes for pressure plate and bell housing
 

Get them all.

The pressure plate bolts are 5/16 UNC (if the same as the earlier ones) and are about 1" long with a portion of plain shank. The thread is short it is not a standard bolt but you can shorten some longer ones.

I don't know about the bellhousing bolts but if the same as the earlier ones they are 3/8 UNC by about 1".

But seriously if they are going begging, get them all. You never know what you are going to need in the future.

Mart.

Re: Bolt sizes for pressure plate and bell housing
 

Bell housing to engine bolts with cast housing are 7/16-14 x 1-1/4"

With pressed steel housing 7/16-14 x 1"


The pressure plate bolts are special 3/8-16 x 3/4" with appox. 5/16" that is not threaded.

Re: Bolt sizes for pressure plate and bell housing
 

For flywheel and / or pressure plate bolts, I'd recommend getting a set from ARP from any of the big speed parts vendors. They'll be the right size, proper shank diameter and "tougher than nails."

Re: Bolt sizes for pressure plate and bell housing
 

The non threaded area is for alighnment. G.M.

Re: Bolt sizes for pressure plate and bell housing
 

Be carful with the pressure plat bolts. A friend of mine ordered some and they were WRONG!! these bolts should have a shoulder on them that match the flywheel. Sometimes you get the wrong part???

Re: Bolt sizes for pressure plate and bell housing
 

That shoulder is very important.... And it could be same diameter as the unthreaded area of a regular bolt. But in a HD truck like an F250 in granny gear with a load, and dump the clutch heading uphill, think of the shear on those 6 rather small bolts!

Re: Bolt sizes for pressure plate and bell housing
 

Not too bad on the pressure plate bolts due to the large diameter of the bolt circle but the flywheel bolts see a lot of shear! And, half of the torque being applied to the clutch disc is coming from the flywheel direct, only the other half from the pressure plate.