I know this has been covered a long time ago as part of another thread but I can't find it. I have an 8ba flywheel and a 11" clutch disk/pressure plate assymbly... I'm about to take the flywheel down to be lightened. I also have a much lighter 9" clutch/pressure plate assembly, from a '40 ford I believe... The machinest said he could drill the flywheel for the smaller clutch if I wanted to save a bit more weight... My question is, would the combo work in an 8ba mated to a '39 trans? The pressure plate looks pretty close to the 11" one but it may be a fraction shorter. The clutch disk is close too but the metal 'snout' is a bit shorter on the flywheel side.
It should work fine. 9" clutch is pretty light pressure generally (though it can be equipped with more and different springs), and it belongs in a light car. For a heavier big car, like late thirties up, consider a 10. The 11" is a heavy monster that belongs only in working trucks. '49 up type Long pressure plates cannot be used with early trans because they are made for a very small throwout bearing. On late engines, the only stock pressure plates usable in early Fords are the '49-50 Merc Borg and Beck and those used on trucks with the early Ford based 3 and 4 speed transmissions. Most of the Long types for '49-up were 9 1/2 with no direct crossover for early cars. Only a few taxis and such got 10's that could take a '48 Ford plate.
Bruce, you never cease to amaze me, you anwered it even better than I would have...... Kilroy, Bruce nailed it, the 9" will work fine for a lighter car, and one that won't be driven too hard. If you do plan on some harder launches, maybe a day at the drags, go with the 10"..... I personally use 10"'ers in everything with a flathead, but that's cause of my driving.....LOL
Well I just talked to the machinist and he's changed his tune a bit... Instead of a minor deal, he now wants $85/hr including setup time... So it may not be worth it after all... Does the 10' clutch/preasure plate bolt up in the same holes as an 11"? It is a heavy beast... But it's the beast I got... Thanks again Bruce!
Oh, there will be launches... I was actually thinking it would be better for the clutch to slip than for the gears to launch through the case... But this is a model A roadster, so it might not be that big an issue?
Tell your machinist he's too high, many, many shops do it around here, for between $45 and $55 and hour. The setup isn't hard, would only take him 25-30 min total. Tell him to suck it up if he wants any repeat business...... cause once you go with a flathead, you tend to stay with them....and they can be so addictive that price is not an object. I do believe the 10" and 11" mount in the same hole. Could be wrong.... and don't worry about being hard on the gears, they are tougher than anything you can buy today....
Well if a 10" will bolt up to the 11" flywheel... Maybe I'll just have it lightened at my usual machinist... They refered me to a guy that doesn't do car parts as his primary business, because they didn't have a fixture to redrill the flywheel. This is Austin and it's hard to find good services here...
Well I just got back from all the reputable machine shops I know of in town, and the best price I found was $150 drilled and lightened... But it looks like I need a new ring gear too.... I didn't notice that untill I had the wheel on their bench. So I dragged the whole kit-n-kabootle home to ponder on it and find a ring gear. So I'm easing up on the price of a new Fidanza aluminum flywheel... As a side note, it seems like the going hourly rate for machinework here in austin is $80...
I have used the steel flywheel from Flathead Jack on the last couple of motors I did. Comes drilled for a 11 and 10 inch. You won't be happy with an 11. Also the 11s I sell have have a larger bolt pattern than the 10s.
My 40 Ford has an 8BA with the 8BA flywheel, 10 inch Ford clutch, 49-51 Merc pressure plate and stock 40 throwout bearing with stock 40 trans. As i recall it all bolted together with no drilling required.
the 10" disk is pretty hard to find at least around here.... id just go with a 9.5 they are plentiful and cheap the weight difference would be very little vs. cost to redrill, liten, balance and ringgear dont make sence to me...
I have the 11" clutch that came with my French Flathead engine installed in my '37 4door and it works fine. Pedal forces are acceptable.
Basic Ford clutch facts: 1) On all early Ford flat (1942-48) flywheels, two size clutches were offered: 10", and 11" diameter. The earlier cars (1932-41) used the 9" clutch in a flywheel with a 9" pocket on its friction face. No other size will fit in there. The 11" was for trucks. 2) On all late Ford flat (1949-53) flywheels, three size clutches were offered: 9.5", 10", and 11" diameter. The 9.5" was for Ford cars. The 10" was optional for the Ford cars and standard on 49-51 Mercury cars. The 11" was for the trucks. 3) All used their own flywheel bolt holes> different bolt pattern for each! 4) As stated above, the 9.5" clutch (1949-53) will not work when hooking up to the early trannies with the large diameter clutch spline. The release fingers are closer together at their tips, and will cause damage to the early style throw out bearing & hub. 5) The 1942-48 V8 flywheel with 10" clutch spacing will NOT work on the 49-53 late style engines. Starter ring gear will not be aligned properly. Keep the 42-48 flywheels with the 42-48 motor, and keep the 49-53 flywheels with the 49-53 motors. 6) Ford did offer an optional 10" clutch on the 49-53 passenger & truck Fords. It was the LONG style pressure plate. The bolt pattern appears as three separated pairs of holes in the flywheel. 7) Ford used the 10" Borg & Beck style clutch in the 1949-51 Mercury cars. This one can be recognized by the six equi-distant bolt holes in the flywheel. The common question comes up about using a 10" clutch on a 49-53 flathead V8, along with a '39 style transmission (large diameter input spline used from 1932-48 on cars/trucks and up to 1952 on pickup trucks). You can do this in one of three ways: a) Have your 49-53 stock car flywheel (9.5" clutch) redrilled for a 10" Long style pressure plate......b) Use a 49-53 Merc flywheel with its 10" Borg & Beck clutch.....c) Find and use a 49-53 car/truck flywheel that was drilled for the 10" Long style clutch. Finding someone who can redrill the flywheel is getting harder to do. Some shops can't/won't do it. Also, the Mercury B&B pressure plate is not mfr'd anymore (not even in reproduction). You have to find a decent used core and get it rebuilt by a clutch shop. The 10" clutch disc with the large diameter spline (1-3/8" x 10 spline) is the same whether used on the 42-48 Ford/Merc or the 49-51 Merc. Doesnt matter if the pressure plate is the Long style or the B&B style. Hope this helps!......................Mac VP ([email protected]) www.flatheadv8.com
A recent article in Hot Rod Deluxe (article was on adapting SBC to Ford transmission) gave current ordering info on a diaphragm clutch setup from one of the big performance clutch places that will interchange with the departed B&B. As I said, the only EASY ways are the Merc (pressure plate must be '49-50 one) and the monster 11". The current replacement for the Merc B&B will please a lot of people. The other option if you have access to a rebuilder would be to get different arms in the common 9 1/2 and a special rebuild on a plate to adapt 9 1/2 plate to Ford hub. The 10" Long late flywheel is essentially non-existant.
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