The Ford Barn

flatheadfan · 09-04-2011, 06:39 PM

I think both you and Bruce are right about the size, I measured an original Ford bolt and came up with a measurement of 0.780". That is the shaft length not the shaft and cap length. The Ford book I have shows 25/64" or 0.390". I belive the 0.390" is only the threaded portion of the shaft. The balance is the shoulder length below the cap.

Hopefully this makes sense!

Tom

Bruce Lancaster · 09-07-2011, 09:51 AM

On the need for shoulder...these bolts have to locate the PP as well as clamp it on, hence the need so that the bolts can also function as dowels to get the thing in the right place. Obviously they are highly stressed items with really bad potential failure modes, so buy something made for the purpose or a bolt from a serious supplier like an industrial supply.
Lines on bolt heads mean very little if bought at the corner dime store...there is no enforcement of SAE grade standards and the Chines have learned we like lines on our bolts!
Originals are of course not lined...they predate that system, but Ford made very high standard fasteners.

jdl · 09-07-2011, 10:24 AM

Has anyone used these bolts? they seem to be the right size. ARP has a good reputation for high quality bolts. I have always re-used the original Ford p plate bolts. just trying to help...

http://www.summitracing.com/parts/ARP-250-2201/

V8 Bob · 09-07-2011, 12:03 PM

[QUOTE=jdl;269480] I have always re-used the original Ford p plate bolts..../QUOTE]

The problem with using old rod, head, main cap and clutch/flywheel bolts, with no known history, is whether they were properly torqued when installed, and how many cycles they have gone through. Better safe than sorry on critical bolts, and ARP bolts are my first choice. IMO.

09-04-2011, 06:39 PM	#21
flatheadfan Senior Member Join Date: May 2010 Location: West Michigan Posts: 1,218	Re: pressure plate bolt size? I think both you and Bruce are right about the size, I measured an original Ford bolt and came up with a measurement of 0.780". That is the shaft length not the shaft and cap length. The Ford book I have shows 25/64" or 0.390". I belive the 0.390" is only the threaded portion of the shaft. The balance is the shoulder length below the cap. Hopefully this makes sense! Tom

09-07-2011, 09:51 AM	#22
Bruce Lancaster Member Emeritus Join Date: May 2010 Location: Madison, NJ Posts: 5,230	Re: pressure plate bolt size? On the need for shoulder...these bolts have to locate the PP as well as clamp it on, hence the need so that the bolts can also function as dowels to get the thing in the right place. Obviously they are highly stressed items with really bad potential failure modes, so buy something made for the purpose or a bolt from a serious supplier like an industrial supply. Lines on bolt heads mean very little if bought at the corner dime store...there is no enforcement of SAE grade standards and the Chines have learned we like lines on our bolts! Originals are of course not lined...they predate that system, but Ford made very high standard fasteners.

09-07-2011, 10:24 AM	#23
jdl Senior Member Join Date: May 2010 Location: California Central Coast Posts: 931	Re: pressure plate bolt size? Has anyone used these bolts? they seem to be the right size. ARP has a good reputation for high quality bolts. I have always re-used the original Ford p plate bolts. just trying to help... http://www.summitracing.com/parts/ARP-250-2201/

09-07-2011, 12:03 PM	#24
V8 Bob Senior Member Join Date: May 2010 Location: Granger (Northern) Indiana Posts: 1,520	Re: pressure plate bolt size? [QUOTE=jdl;269480] I have always re-used the original Ford p plate bolts..../QUOTE] The problem with using old rod, head, main cap and clutch/flywheel bolts, with no known history, is whether they were properly torqued when installed, and how many cycles they have gone through. Better safe than sorry on critical bolts, and ARP bolts are my first choice. IMO.