Light Flathead Flywheel question

[CTFuzz]

I have two flathead flywheels, one with a 9.5" clutch and the other with a 11" clutch. Problem is they are both the same except for the pressure plate mounting holes. I allways thought the truck flywheel is heaver than the car wheel. Anyone have any ideas what I have?? Bottom line is, I was looking for the light flywheel when I got the car wheel.

CT.

[286merc]

Only difference is the clutch mounting between the 9 1/2, 10 & 11" wheels. Some aftermarket were multi drilled.

A little fuzy on details but I believe there was one, maybe aftermarket, that used the 337 Lincoln 12" clutch.

[Mr 42]

I think the weight difference is in the pressure plate. Since th 11" is bigger the flywheels are the same as far as i know.
If you can lighten it it will make big difference, the engine is more crisp, revs faster...

[CTFuzz]

Thanks......I'm gonna reface it so I'll see how much I can safely take off. Funny, I always thought truck flywheels were heavier..live and learn.
thanks.
CT.

[Flat Ernie]

I would probably use the 9" over the 11" - the pedal effort is quite high on the truck clutches...

http://www.jalopyjournal.com/ubbthreads/images/graemlins/cool.gif

[286merc]

If you are going to have a hot cam with minimal low end and/or a highway rear I would go with the 10" at a minimum.
I dont know why everyone says the 11" is too stiff; my 54 Y block F350 has one and it is far from being a problem.

That extra surface goes a long way to minimize slippage and extend clutch life.

[Flat Ernie]

Carl,

Do you think the linkage in your truck has a better pedal ratio? I've driven a car with the 11" clutch & it was heavy - nothing like my old Mustang w/3000lb P/P, but much heavier than the 9". Don't know that I've driven a truck w/11" though - maybe the linkage is different?

I agree on running a 10" if it's an option - especially with the combo you mention...

http://www.jalopyjournal.com/ubbthreads/images/graemlins/cool.gif

[286merc]

Ernie, someone mentioned pedal ratio difference between car and truck a long time back. I do not have a 50's car handy to compare; my 53 is still in storage. That has a 10" and has always felt wimpy. The other 5 of mine from the era are trucks. Does anyone have car measurements?

The flatheads are a 46 1/2 ton and a 51 F5; the latter I know is 11" as that is all that was offered. A 11" will not fit inside the earlier cast-in bellhousing blocks.

The 54 is a fresh clutch/plate/flywheel rebuild behind a warm 292 and I drive it regularly. The 5.14 rear encourages constant shifting! Before that I drove the stock 239 for almost 5 years with a 11" also.

Something else I havent looked into; are there different PP spring options for these antiques? I should think that a rebuilder could come up with whatever you want.

[Flat Ernie]

I take it back I might have driven a truck w/11", my 51 F1 Panel may have had 11", but I just don't remember now. That was back when I was younger and dumber - yanked the flattie/3spd for a 351W/C6 http://www.jalopyjournal.com/ubbthreads/images/graemlins/confused.gif and then, even more stupidly GAVE away the flattie/3spd for free! http://www.jalopyjournal.com/ubbthreads/images/graemlins/blush.gif

You're right! I'm sure a good clutch rebuilder could put any springs you wanted in there.

I guess use whatever you've got is the rule (unless money is no object - sadly, I don't fall into this category!) - I don't think the 11" is required in early cars unless you're making pretty good HP & racing - even then, the 10" should work I would think...it's early in the morning, I'm just rambling now...

http://www.jalopyjournal.com/ubbthreads/images/graemlins/cool.gif

[286merc]

945 AM is early? I was up a 5!

The one problem with a real grabbing clutch in a car is the ability to snap axles unless the rear has been updated.

I used to snap axles on a regular basis in shoeboxes; no one told us back then that the 49-early 50 were dogs and Ford changed them!

Time to ask some questions at the rebuilders, I suspect the one in the 53 is nearing its end anyway and I have a bunch of 11" wheels.