clutch 9 inch vs 11 inch
 

Have what I think is A 37 truck motor.

It has an 11 inch clutch, fitting a 39 toploader to it for a fenderless hiboy roadster .

Obviusly I do not need the truck clutch for such a light car, but if I leave it, are they are harder to push the pedal, or any other reason to fit a car 9 inch clutch ?

If it is no difference I will leave it as to save changing the flywheel.

Re: clutch 9 inch vs 11 inch
 

I have a 11 inch in my 47 pkp. and it is a little harder to hold say at a stop light then my 39 which has a 9 inch Is your flywheel drilled for a 9 inch SUNSHINE

Re: clutch 9 inch vs 11 inch
 

In city traffic your left leg will get tired pushing the clutch. I would redrill for a 10 inch? IMO

Re: clutch 9 inch vs 11 inch
 

I agree. After double clutching the 11 inch clutch on the tonner in stop and go city traffic for several years I changed to a 10 inch clutch. This thread might be helpful in making your decision: http://www.fordbarn.com/forum/showthread.php?t=97208

Re: clutch 9 inch vs 11 inch
 

Have Fort Wayne clutch build you a 9" clutch,you will not regret it.Phil

Re: clutch 9 inch vs 11 inch
 

Foot pressure on the clutch pedal is one issue, but vehicle acceleration is the one I'm most interested in. The smaller in diameter (and weight) the clutch assembly is the faster the rotating mass can accelerate.

Re: clutch 9 inch vs 11 inch
 

I Agree with trainguy . Plus your left leg will thank you!

Re: clutch 9 inch vs 11 inch
 

Fort Waynr makes a nice 9" and it's much lighter. Now if you had a 302 HP Mustang with a T-5. You'd also have a 9" clutch. However the one thing an 11" clutch and flyeheel will do is:: Burn rubber with the engine turned off.

Re: clutch 9 inch vs 11 inch
 

Haaa! Maybe even spin the spare tire!!

Re: clutch 9 inch vs 11 inch
 

I would rather have a clutch that you don't have to pull the pan to replace.

Re: clutch 9 inch vs 11 inch
 

Thanks all for info.

Think I will change flywheels and go 9 inch.

Truck flywheel is not drilled for both.

Re: clutch 9 inch vs 11 inch
 

Or have your current flywheel re-drilled. However, doing with a new flywheel could allow you to find a lighter one.

Re: clutch 9 inch vs 11 inch
 

I use 9in. in about 90% of my engines (Fort Wayne) If its a real hot engine I have them install stiffer springs the PP, the 9in. is a lot lighter than the 11-10 set up. NOW, this is for street rods mainly. Walt

Re: clutch 9 inch vs 11 inch
 

Walt what flywheels do you tend to use? Stock, turn-downed stock, aluminum with steel insert ?

Re: clutch 9 inch vs 11 inch
 

From someone who has an 11 inch in a fenderless truck use a 9 inch

Re: clutch 9 inch vs 11 inch
 

The aluminum wheel with the steel insert is nice for real light car 12#, but expensive, It's a lot cheaper to turn down a stock wheel to about 20# and have it balanced. If you use a real light wheel in a heavy car it's hard to take off up hill, you have to rev the engine. Remember a Model A engine has a 65# flywheel and 40HP, if the engine dies you can ride home on the flywheel. Walt

Re: clutch 9 inch vs 11 inch
 

Yep, I like the light flywheel/clutch assy in a light (stripped down) car. Just curious about your input.

Re: clutch 9 inch vs 11 inch
 

I have an 11" in my truck, came that way from Ford, I can't tell the difference between it and the one in my 06 Jeep. Neither causes any undue fatigue.

Re: clutch 9 inch vs 11 inch
 

Does the throw out bearing sit in the same place out from end of crankshaft on both the 9 inch and 11 inch ?

Ie, are the flywheels the same thickness and when clamped down, are the fingers in identical positions ?

Reason for asking is the sump is back on and I am wanting to mock up the engine/box /pedals/ tailshaft assembly, and will change the flywheel /clutch when pulled apart again.

Re: clutch 9 inch vs 11 inch
 

What Walt said X2.

Walt, I will bring you a couple extra lipped flywheels for 9" clutches when I come up to see you.

Re: clutch 9 inch vs 11 inch
 

The flywheels are just drilled differently. There is no other difference unless you are dealing with earlier type flywheels. The T/O set up should also be the same.

Re: clutch 9 inch vs 11 inch
 

Thanks so far for answering all my questions.

The last flathead I had was in 67 and I never had to go inside that one.

Flogged it around as a kid and nothing ever broke.

It has been said to remove the outer flywheel lip on the 9 inch flywheel.

I guess this is just for less weight and no other reason ?

How many pounds would it reduce it by ?

And once the flywheel was in the lathe, is it good to shave some more weight off and where from ?

Fenderless A roadster so not much weight to haul.

Re: clutch 9 inch vs 11 inch
 

It is not totality about the weight, it is about weight at a distance on a rotating mass. The inertia changes as the rotational weight changes. What is changing is the ability to accelerate, the less mass the less inertia and the faster the acceleration. Like wise the more mass on the outer edge of a rotation mass the greater the inertia and the slower the acceleration (or any change in the rotational speed).

If you are interested in a stump pulling truck or getting a heavy car started from a stop a lot of inertia in the flywheel is helpful. If you are interested in overall acceleration and the vehicle is fairly light, then a lot of flywheel inertia is not helpful. It is going to try and keep the driveline at its current speed and resist acceleration.

Re: clutch 9 inch vs 11 inch
 

i have found that taking a few lbs. off a 9" wheel and useing 10" springs in my 9" presure plate workd great

Re: clutch 9 inch vs 11 inch
 

Does anyone know if Fort Wayne clutch has any use for flathead pressure plate cores? Or F W clutch phone #.

Got the phone from google.

Re: clutch 9 inch vs 11 inch
 

call fort wayne clutch ask if they can make the 11 to be to feel ligher this way you wount need to drill fly wheel & buy a 9" clutch assembly it,s not ez to find a clutch thats not made in china

Re: clutch 9 inch vs 11 inch
 

You can always change the springs to get less pressure.
Taking away some rotating mass needs machining and a smaller clutch.

Re: clutch 9 inch vs 11 inch
 

Call F W Clutch, talk to Kerry, he will tell you if they need Pressure plate cores. He has built a lot for me. 1-800-258-8243 Walt

Re: clutch 9 inch vs 11 inch
 

I never use China clutch and PP, that why I get all mine from F-W-Clutch. Walt

Re: clutch 9 inch vs 11 inch
 

Walt,
How much did you tell me you turned down a model A flywheel once? You said you weighed the shavings..

Re: clutch 9 inch vs 11 inch
 

I had my Model A wheel copped down to 35# and redrilled for 9in. pressure plate, The clutch pushed so smooth compared to the stock Model A, of course my 31 rumble seat coupe, I built a B engine, hi compression head, bored .060, B trans with 41-48 gears, 3:54 rear gears, cruises 60-65 mph, I cruise 55-60 usually, at 55 mph turns 2300 rpm, listening to my country CD,s up in the ceiling. Walt OH, F-1 steering box, 48 brakes, 16in. Michelan tube type tires tires.