What size are bolts used to connect a 1958 FE long style pressure plate to flywh

[brushwolf]

Have run into this before, but previously I have just used original Y block clutch bolts after searching high and low but never finding any new or ARP versions. Don't have any original bolts left (or I have 2 bolts, not enough...).

This is an FE 184 tooth flywheel of unknown year only tapped for an 11" long style pressure plate. There are also 12 untapped 0.333 diameter holes around the perimeter. I presume those are holes which could be tapped for some unknown year diaphragm style pressure plate, but that is another issue and I have the long style pressure plate already. Anybody knows what year FE diaphragm clutches would fit if those holes were tapped, please chime in...

The pressure plate bolts for the long style pressure plate are not 5/16th bolts, they are slightly smaller with a shaped unthreaded shoulder near the bolt head which matches the 6 countersunk drilled and tapped holes in the flywheel to center the clutch plate. So,these 6 bolts were both the fastener and the locating pins in one unit. Typically I found them on original assemblies with a small lock washer on them also (the days before loktite...).

Tons of listings for the 5/16" or 3/8" new or ARP, but that is not what the bolt diameter is with the long style pressure plate. They are just a 1/2" head and my caliper shows them to be 1.043" overall length, 0.820" overall shaft length, 0.50" thread length with the remaining shaft length comprised of the shoulder of about 0.32" in length and 0.310" in diameter. Outside diameter of threaded section appears to be 0.302"

Pretty sure when I used the saved bolts before that they all came from 54-62 Fords. Probably were all off of Y block pressure plates.  Is this the same size and type of shoulder bolt that was used on flathead motor pressure plates that look to be the same design?

[59meteor]

The factory pressure plate bolts ARE 5/16". On my 428, I am using ARP pressure plate bolts, which as you mentioned, use a shanked portion to locate the pressure to the flywheel, as well as handle the shock loads. The flywheels have  countersunk holes for the pressure plate bolts, to accept the bolt shoulders. I am not aware of any factory FE that came with a diaphragm style clutch.

[brushwolf]

Looks like the multiple packages of aftermarket bolts I have and which I thought were ordered for a 390 a few years back are all 3/8" size,  so larger but still with the locating shoulder. Must be for a 5.0 or something..  Well then, I will send for some ARP 5/16" and see what happens.

Thanks for the feedback.

[brushwolf]

I looked up every 5/16 ARP pressure plate bolt listing for vehicle equipped with a 352, 390 or 428 prior to my original post. Every time the part selection message consistently came back with the message "this part does not fit your vehicle".  When I went to Pioneer PP bolts it did come back as fitting all the earlier Ford V8's... But apparently the part is the same and fits despite the erroneous "does not fit" messages...

[lalessi1]

The factory pressure plate bolts ARE 5/16". On my 428, I am using ARP pressure plate bolts, which as you mentioned, use a shanked portion to locate the pressure to the flywheel, as well as handle the shock loads. The flywheels have  countersunk holes for the pressure plate bolts, to accept the bolt shoulders. I am not aware of any factory FE that came with a diaphragm style clutch.

x2. I do have (2) flywheels though, one is drilled for a 12" clutch and came from Ford Performance, the other is a Mcleod 28 lb one (internally balanced) that is drilled for an 11" clutch. I simply bought ARP bolts as well. I have a 12" LUK diaphragm clutch on the "Ford" flywheel.