Pressure Plate Bolts - What's the deal??

goaztecs · #1 (**permalink**) 10-28-2004, 05:43 PM

I was looking to pick up some pressure plate bolts so I can mount up my clutch tomorrow - and I've gotten nothing but conflicting information. Is anyone an "expert" here?

I am running a 50 oz 157 tooth McLeod flywheel. Should be standard issue 5.0 Mustang replacement Hardware.

Modern Driveline, who sold me the disc and pressure plate says 8MM bolts - Ford PN #N602549-S2.

Speed Merchant, my local speed shop said they were not metric rather 5/16-18 x1". They sold me Mr. Gasket PN #911

I called McLeod, who actually makes the flywheel - all of their "tech guys" are apparently at SEMA, but someone looked up my flywheel (which is PN 453102) and told me they were 5/16".

I called a local Ford dealer, and they said they should be 8MMx1.25x20

I called another Ford dealer and they said 8MMx1.5x20.

I have now rec'd about 5 different answers on this one. I am thinking about buying them all and trying them!

Not looking for more opinions, I am wondering if anyone KNOWS, definitively whether these things should be standard or metric? Would a big name aftermarket mfgs like McLeod change the threads on their flywheels from the factory metric (8MM) to standard (5/16)? Help?

Rick Parker · #2 (**permalink**) 10-28-2004, 06:18 PM

I am certain that the aftermarket products are threaded 5/16ths-18 for simplicity sake, however the OEM original flywheel may very well be a metric application. Be sure to use a small amount of Red Locktite on the threads, but not enough to get under the heads of the bolts.

Rick

goaztecs · #3 (**permalink**) 10-28-2004, 07:14 PM

Thanks Rick,

I finally got home and tried threading the Mr. Gasket 5/16" Ford bolts, they go in a few turns, and then stop. I think they are the wrong size. To be honest, the threads show some signs that I am not the first one who was confused by this. I suspect that my engine builder might have run into a similar problem when balancing the assembly. Since 5/16" is a little bigger than 8MM (8.128MM) I think I am onto something. I am going to test the 8MM bolts tomorrow, and if they work, run an 8MM tap through the threads to clean them up and then use plenty of loc-tite.

Nothin's ever easy.....

stuck · #4 (**permalink**) 02-04-2005, 12:39 PM

I think they are 5/16....the metric ones I got from the dealer buggered mine up!!!!

davidlee · #5 (**permalink**) 02-04-2005, 01:12 PM

If they screw in a "few turns" I strongly suspect you need the 8mm bolts. My factory FMS flywheel took the 8mm bolts. I tried the 5/16th first , they went in a "few turns" and stoped.
David

goaztecs · #6 (**permalink**) 02-07-2005, 10:24 AM

Hi All,

Here is what I learned during that fiasco: The factory Ford late model 50 oz flywheels, use metric 8MM bolts. Dang near all of the aftermarket brands use 5/16.

This is important to note because many builders use a 50 oz 157 tooth "5.0 style" flywheel in their 351W stroker applications. Since the stroke is longer and the counterweights are different, the imbalance is accounted for by using the flywheel with the higher weight imbalance (50oz vs. 28 oz for the "old style"). Then, weight is either added or subtacted from another part of the 50 oz flywheel to come up with the proper balance for the stroker's rotating assembly.

In summary - if you have a windsor stroker, you probably have a "late model" or "5.0 style" 50 oz flywheel. If it is a factory Ford piece, it will use 8MM bolts for the pressure plate. If it is an aftermarket part, it will need the 5/16.

I hope this helps somebody...

stuck · #7 (**permalink**) 02-09-2005, 02:05 PM

I looke dinto it as well, the fms billet flywheel has both 8mm and 5/16th. If you are using a diaphram style clutch, they line up with the 8mm, if you are using the 3 arm type, they line up with the 5/16....

But after asking aound, it seems pretty common for them to strip out regardless...