Hello all,

Piecing my stock driveline back together and I ran into a dilema...I am not sure if I need a 10" or 11" clutch. I have a stock 3 speed with a floor shifter and the stock V-8 Flathead. I wish it was as simple as just measure the dimensions of the old clutch but I dont have the old clutch.

Are there some measurements I could take on the flywheel to narrow this down?

The truck is a half ton, is it as simple as all 1/2 tons were 10" or did some use 11"?

Can I just measure the OD of the flywheel from outside of ring gear teeth to outside of the ring gear teeth?

Thanks in advance, Dave

 

I just measured the contact area of the old clutch disc on my flywheel and it is definately 11". Mac's selld 2 different 11" pressure plates though. I tried taking the measurements they reccomend but it is within 1/16" and I am landing about right in the middle.

Here is the smaller 11" Pressure Plate Ford Pickup Truck Clutch Pressure Plate - 11" Diameter - 6 & 8 Cylinder - MAC's Antique Auto Parts

Here is the larger 11" Pressure Plate Ford Pickup Truck Clutch Pressure Plate - 11" - 2-1/4" Diameter Opening Between The Fingers - 6 & 8 Cylinder - MAC's Antique Auto Parts

The smaller Pressure Plate has a 1 7/8" center hole between the 3 fingers and the Larger Pressure Plate has 2 1/4" center hole between the fingers.

Is 1 more common than the other?

Is there a better place to order a clutch through than macs?

 

Dave, check the bolt measurements in the links against your flywheel. I'm guessing the one with the larger opening. I can measure one tomorrow if you want.
The PP diameter can be slightly larger than the disc, it won't hurt anything

I would check with NAPA or local parts store in case you have to return or exchange it.

 

I checked everywhewre local today, No one has the clutch. Advance listed one and I had them transfer it in and it is clearly not even close.

If you could measure one that would be great!

Thanks!

 

A 3-sp in an F-1 should have a 10" clutch. F-2 with the HD 3-sp and the spur 4-sp got the 11" as did larger trucks. I have 9" and 10" flywheels off engines in my garage, if you want measurements. Like Tinman says, the PP is usually not exactly the size of the disc.

I just measured them:

I think what I have are 10" and 11" flywheels.
10": actual disc diameter = 9.5", PP bolt circle = 11"
11": can't tell disc diameter, PP bolt circle = 11-3/4"

 

What is the most accurate way to measure pp bolt circle, I can go measure it right now.

 

I just went down and looked at the flywheel again, the contact area from the clutch disc is definately bigger than 9.5", its about 10 7/8". I am assuming the clutch set up I need is the 11" setup. The original transmission was a 3 speed column shifter but I am putting in a transmission from a 48 panel that is a floor shifter.

Now that we are discussing this, something just rung a bell.....I know the guy that I bought the truck from did say the motor wasnt the original one, it is the 8BA though, it is stamped right on the head.

Is it possible the motor in my truck is from a F2 or larger? The motor could have also been behind a 4 spd spur at 1 time I guess. I bought the truck running and driving though so I know the engine did work with the column shift 3 speed.

Its driving me crazy trying to figure out what has been done to this truck over its 60 year history!!!

 

Order both, a 10" and an 11", and return whichever one does not fit properly.

 

If I could get them local that's what I would do. If I order 2 then I have to pay shipping for 2 and pay shipping to send 1 back. I am sure it is the 11" clutch, I am just just confused why macs lists 2 different 11" pressure plates but lmc and Dennis carpenter only list 1.

 

Dave, any combination of clutch's, trans and flywheels could have been swapped in over the years. 11" clutch was commonly used in pickups and big trucks. My 3spd is out of a panel and uses a 9' clutch......

I will measure a pp in the morning....

 

I think you're worrying too much. My 48 F1 came with a HD 3 spd floor shift. The clutch is 11" or rather the pp is 11". The clutch disk is slightly smaller.

If your contact area is 10 7/8" then you have an 11" setup.

The bigger clutch will be slightly harder to depress, but still not bad. It will also be more firm on launch. As heavy as these trucks are, I prefer it that way. I don't get any chatter or slip when starting out, even in 2nd gear.

 

A 9" clutch would be a car clutch. Entirely possible with all the parts swapping that went on that a flywheel from a car got into a truck.

I am under the impression from previous discussions that the 11" clutches are not particularly smooth, because of their larger inertia. AFAIK flywheels can be re-drilled for a different clutch/PP, if the new holes are in between the old holes (staggered 60 degrees).

 

I am probably worrying too much, I just dont want to get everything together to find out its all wrong and then needs re-done all over again. I like doing something right the first time and not having to fix things down the line. Thanks for all of your help!

 

C5TZ-7550-D (replaced COTT-7550-B, B6D-7550-D, 81T-7550) .. 11" Clutch Disc.

Applications: Myriad 1948/53 trucks / 1954/60 F100/600 223 I-6, 239/256/272/292 / 1961/64 F100/600 223/262 I-6 & 292 / 1961/64 C500/600 262 I-6 & 292 / 1965/72 F500/600 240 I-6.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
COTT-7563-A (replaced B7Y-7563-A, 51-7563, 51A-7563) .. 11" Pressure Plate.

Applications: Same as clutch disc.

OP: The problemo is...you're asking for these parts for the original 1948/52 F1 application. As you can see, the parts fit faaar more than that.

So, you have a much better chance of buying these parts from local autoparts stores, if you use one of the later applications.

 

Well, I measured.....all of the PP I have are 2 1/4 circle between 3 the fingers, they are all from trucks or pickups I have owned over the years.

Hope that helps.....