A better clutch disc for a souped-up flathead ??

[Robert Dip]

Well, the ’39 Coupe’s souped-up flathead is roaring, but, with now more power being delivered to the drive train, clutch is beginning to slip in high gear. I ordered a new 10” disc from Mac’s, and the one I received is like the original size. Having said that, my buddy also has a spare new disc, but, it has more ‘meat’ to it. I like that! The width of the facing on a standard flathead disc is 1 5/8”. The other is 2”….which, in my opinion would be much better for grabbing.
Question….has anyone had experience using the 2” wide disc…good or bad. Chatter comes to mind, but, maybe not.
After seeing/having this 2” wide disc, I am very reluctant to use the original 1 5/8” wide disc.

 

[rotorwrench]

The disk is only part of the equation. The quality of the springs in the pressure plate, the width of the pressure plate friction ring, and the proper adjustment of the pressure plate & fingers all have an effect on the friction capability of your clutch.

I use Fort Wayne Clutch's services when getting a clutch PP & disk rebuilt. They rebuild a lot of clutches for people in the hobby and likely have the most experience when setting one up. They have all the information required to insure you have the correct springs and replacement materials & parts for Long type and Borg & Beck type clutches used by FoMoCo back in the day

 

[Robert Dip]

Thank you rotorwrench, however, taking into consideration all that is required in spring pressures and related components, there still remains the question...why not use the full width 2" wide disc since the pressure plate is about 2 1/8" wide. Why leave out usable surface that helps in the 'clamping' process? Comments from the experienced would be appreciated. Robert

 

[trainguy]

Contact Fort Wayne Clutch and the will custom build a clutch and pressure plate.They are such a pain to change,why take a chance with the imported stuff. I had them build upp a 9" clutch for my 41 sw with a warmed up 59a.The previous new clutch slipped under load.No problem now.Phil

 

[Bassman/NZ]

Contact Fort Wayne Clutch and the will custom build a clutch and pressure plate.They are such a pain to change,why take a chance with the imported stuff. I had them build upp a 9" clutch for my 41 sw with a warmed up 59a.The previous new clutch slipped under load.No problem now.Phil

But that's not what he's asking. Sorry Robert, I cant help. It sounds like a good idea, and I see no reason why it wont work.

 

[rotorwrench]

There aren't as many clutch rebuilders around as there used to be. Most of the ones in my local area specialize in big trucks and tractors. An older shop will usually have the specification books for clutches that date back a long way. These references are difficult if not impossible to find and I've tried. The damn books are willed to the owners kids when they keel over. Without this type of reference, I couldn't tell you which width was OEM to your car. There were a lot of different clutch facings made by aftermarket sources even back to only 10 or 20 years ago. Most of the soft asbestos related stuff is long gone. There are even specs on the waffers that go in between the facings on some disks. Putting a 2-inch wide clutch face disk in the stack up might be the hot smokin tip and it might not. I sure can't tell you without the spec books. All I can tell you is to call a rebuilder that has about 40-years of experience and all the old spec books and ask them for the straight skinny.

 

[flatjack9]

That disc will work just fine, but as noted I would also replace the pressure plate. I doubt that the extra friction surface would eliminate the slipping or it might just be a stopgap and a little further down the line it will start slipping again.

 

[Robert Dip]

Thanks Bassman/NZ....you got that right, no one so far is answering my smple question....and yes, everything will be NEW, PP, release bearing, etc. I have a dozen flatheads, rangeing from early 21 studs, 59 series, 59AB series, 8BA to '53 Merc, and all the ones with 10" discs have the narrow width. I even have brand new 11" clutch setups, 11" drilled flywheel, PP and discs....but I do not believe I will need the truck 11", but I want too use the best 10" setup I can. This is what this forum topic is all about...for me to learn and to share info that possibly many of us can use. Robert

 

[FlatheadTed]

I do a few clutches and I don't see a problem with wide face ,you wont get chatter so longs as the pressure plate is set up as stock .