very stiff cluth pedal

[wildturkey46]

I have a 8BA flathead hooked to a 39 box in my 32. It has a 3 finger pressure plate I believe came from Speedway, hooked to 32 pedal, stock appearing throwout bearing lever, straight connected to pedal, no binding The clutch is VERY VERY stiff to push. It is very hard to hold the clutch in for any length of time. Any ideas how to make it softer? Someone told me to use a slave, but I don't see how that would help. Is there a diaphram type pressure plate made?Thanks for your ideas. Dale

 

[Charlie Stephens]

My first thought is that the pressure plate from Speedway may be intended for racing application and too stiff for the street. My second thought is the clutch arm on the transmission may be too short. Can you measure the length of the clutch arm?

Charlie Stephens

 

[DICK SPADARO]

I am going with charles stephens on this one. If you are using a 39 case in a 32 you must use the 32 clutch shaft release arm to get the 32 pedals to index correctly. If you are using the clutch shaft arm off the 39 trans inconjuntion with the 32 pedal assembly you are actually pushing the cltch release rod at an angle not in a straight line and my be the source of your high pedal pressure.

 

[rotorwrench]

I agree with previous entries on the 32 type linkage & clutch operating lever but to add for the question about clutches, I've added further info.

Diaphragm types can be set up to work but most are set up to mate to the Borg & Beck style bolt pattern and are closer to 9.5 inch. The 49 through early 51 Mercury flywheel will work for this since they had the 10 inch Borg & Beck clutch or have an 8BA flywheel re-drilled . The Mercury clutch pressure plate wasn't too stiff since three of the possible nine springs were removed on them. The 10 inch Long type clutch is a direct cross over to the 8BA using 1 3/8" 10-spline inputs but they are mostly used in pickups, station wagons, and police cars in the 8BA era so a re-drill of the flywheel would be likely. I am relatively familiar with Speedway stuff for flatheads but am not aware of any new manufacture clutches for 8BA types except the Center Force types which are diaphragm types. I hear they have a heavy pedal pressure too. Its easier to get a clutch shop to set one up from a mid 70s Chevy but the diaphragm fingers also have to be set up to work with the big throw out bearing.

Kerby

 

[DavidG]

Adding to Dick's comments above, beware of the relationship between the two holes in the clutch release shaft (for the arm on the end and for the fork in the center). On some reproduction shafts, this relationship is incorrect thereby robbing much of the leverage and travel of the original design.

 

[PeteVS]

An article in Hot Rod Deluxe awhile ago talked about putting a diaphragm clutch behind a C----- engine with an early Ford transmission. They talked about how a guy at Ram Clutches recommended the 401 pressure plate because it would accept the larger snout on the Ford transmission. (C---- transmissions have a smaller snout diameter.) So, I bought the Ram 401 and IT WOULDN'T FIT!! The fingers came in contact with the snout on the transmission where the throw out bearing slides. I called Ram and talked to the same guy referenced in the article and he said, "It wouldn't fit." I wound up taking about 1/6" off the end of each of the fingers with a die grinder, measuring each one so they'd all be the same. (Ram didn't endorse this method.) Seems to work OK now. If you have a clutch with coil springs in it, it just gets more load on the pedal the further the pedal goes. With a diaphragm spring, (and I'm assuming here,) the load can be tailored to give a good force when the clutch is engaged, but can offer lighter pedal pressure when the pedal is down.

 

[Walt Dupont--Me.]

I have a 8BA flathead hooked to a 39 box in my 32. It has a 3 finger pressure plate I believe came from Speedway, hooked to 32 pedal, stock appearing throwout bearing lever, straight connected to pedal, no binding The clutch is VERY VERY stiff to push. It is very hard to hold the clutch in for any length of time. Any ideas how to make it softer? Someone told me to use a slave, but I don't see how that would help. Is there a diaphram type pressure plate made?Thanks for your ideas. Dale

I use the 9in. long style in all my street rod flathead engines, There all light cars and don't need a heavy duty clutch set up. They are lighter the the bigger set up's. i have mine made Whyne Indina cutch. If it's a stock car engine I have them put some heavier springs in the pp. I have the 10-11 in. wheels redrilled and balanced for the 9in. setup. I understand they will take 400HP. how much hp does your flathead have? Walt

 

[TerryOH]

You didn't give the size of the clutch assembly but the flywheel would most likely have to be redrilled for the smaller 9". I have seen the larger pressure plates with every other spring removed. This does lessen the pressure but usually not a lot.

 

[rotorwrench]

Most of the 8BA family have the 9.5" Long type but they were only made for 1" 10-spline shafts. As was mentioned the old style 9" can be made to work and are probably the most plentyful one out there. The 10 inch Long is a bolt up for the early ones but the flywheels are getting hard to find for them and pressures are a little stiffer. The 49/E51 Merc 10" B&B is a bolt up too but they are also harder to find like the 10" Long types. Ft Wayne clutch just did a Merc set up for me at 200 bucks. I don't know what they charge for a 9 inch but it's probably not too far off from that.

The Center Force set up will work but they want to sell you a flywheel and I've heard the pressure is a little stiff on those. The Mercury B&B flywheel will work for the Center Force or other Chevy type 9.4" diaphragm types if someone wants to go that route. The Chevy pressure plate would have to be set up similar to the Center Force one to work. Clutch shops are easier to find in the big cities but most work on big truck clutches now so a fellow would save a lot of time and energy just getting the 9 inch Long set up to fit the 8BA type flywheel. If some enterprizing company would set up a plane jane 9.4 inch diaphragm clutch for the flatheads and gear it toward the average use of these old machines ie manageable pedal pressures & such, it would likey be the most inexpensive way to go as far as cost of the PP & Disk. The flywheel would need the initial mod for this or use a Merc flywheel so it wouldn't be any easier than drilling for a 9 inch but it might be less costly down the road if parts availability for the old ones ever gets to be a problem.

Kerby

 

[wildturkey46]

Re: very stiff clutch pedal

I am going with charles stephens on this one. If you are using a 39 case in a 32 you must use the 32 clutch shaft release arm to get the 32 pedals to index correctly. If you are using the clutch shaft arm off the 39 trans inconjuntion with the 32 pedal assembly you are actually pushing the cltch release rod at an angle not in a straight line and my be the source of your high pedal pressure.

Here is a pic of the likage setup, the clutch arm is about 6 inches in length, it looks pretty straight push to me, Dick do you see a problem here? thanks Dale

 

[DavidG]

The rod between the pedal and the clutch release arem is much longer than stock, which suggests that the clutch release arm, while evidently long enough judging from the photo is canted too far forward and much of the leverage has been lost as a result.