What clutch would you use?

[1941Pony]

Hi, I’m building a 59a, 4” merc crank, 60 over with a 1007 b cam and will have a 39 3 speed. This is going in a 41 pickup that is going to be street driven. I have the flywheel that came with this engine when I bought it which is a 11” clutch. I read that they are too heavy though, that they are for big trucks. I have a 9” clutch from another flathead that was in my pickup. It’s a little crusty and has a little wear on the ring gear but I think it would be okay.

The ring gear on both flywheels match up though so I should be good to use either. When I weighed them, the 11” was 35lbs and the 9” was 38.2. Stock for stock, I’m not seeing any weight savings.

I’ve seen recommendations about removing the lip on the 9” to reduce weight which I recall from other posts was around 12lbs. When I look at the 9” flywheel it seems it had weight removed (see holes next to lip on 1st image). My thought is this was to balance it and if I remove that lip, the balance of the flywheel will be off. Seems more of a headache as well to find a machine shop that would remove this lip for less than the cost of a new one.

Is the concern with the 11” clutch, the actual clutch weight itself? It’s seems the 9” and 11” would be roughly the same weight. I’m thinking resurfacing the 11” flywheel and run the 11” clutch is the way to go. Or have that 11” flywheel drilled for a 10” clutch. Here’s what I’m working with. What would you do?

[JSeery]

It all depends on how you want to drive it. The weight issue is the distance from the centerline, the further you are out the more inertia. If the rate the drivetrain accelerates is not a concern, then the inertia is most likely not a concern to you. The other issue is the leg effort required to operate the clutch, again, depends on what you want/like. I would never use an 11 inch clutch/pressure plate in any non-heavy truck application, but that is me! On the balance, any clutch/pressure plate/flywheel assembly should be balanced before installation. Bottom line, the concern with the 11 inch clutch is most people really don't like driving them ( but some do). As long as you understand what you are going to end up with and willing to except it, then go for it.

Now, if it was me, I would want the flywheel as light and clutch assemble as small in dia as I could get it. And, it would all be balanced as an assembly.

[Aarongriffey]

Yup. Same as JS says.
I wouldn’t even use an eleven inch clutch in a big truck.
The nine inch will handle the power.
Back in the fifties guys preferred the nine inch clutch on their cars because they said they were easier to control and were less likely to chatter.
I had nine inch clutches in all of my three early V8 cars. No problem, never wore one out.
I put a new 10 inch made in China clutch in my ‘51 pickup back twenty years ago.
It has chattered with a drive line snapping chatter ever since. More like a grab.
Finally broke a tooth off first gear and now just sits waiting for me to find a T5.
So the story of the moral is: stay away from made in China clutches.
I

[Lanny]

I agree with both the above answers.
Get the 9" flywheel as light as possible and use a good brand 9" clutch.





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[cas3]

i have pretty much the same as the OP, 59a, 4" crank. i cut the lip off the 9" flywheel, bought new PP and disc from FT Wayne, had the assembly balanced, and i can make it slip at low RPM's. high RPM when the centrifugal force starts on the fingers, it will not slip. so, to go that route i would explain to Ft Wayne what you are doing and get some slightly heavier spring pressure. or, really a 10" flat flywheel and clutch is what a 59a would have used in a car, and 11" for trucks

[Lawrie]

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I have a 99a with 4 in and .040 over, stock cam and 97 carb, it would slip a 9in clutch no mater what springs I put in it.
go with a 10in and you wont have any problems
Lawrie

[19Fordy]

Like Lawrie says, 10 inch is best if you can do it.

[Bored&Stroked]

I'd just go with a 10" long style clutch, have the lip machine off of the flywheel and have it drilled for a 10" clutch, balance the assembly and be good to go. I'd probably go to Ft Wayne and have them build your clutch and disc assembly - per the specs you and them agree too.

[marko39]

Originally Posted by Bored&Stroked

I'd just go with a 10" long style clutch, have the lip machine off of the flywheel and have it drilled for a 10" clutch, balance the assembly and be good to go. I'd probably go to Ft Wayne and have them build your clutch and disc assembly - per the specs you and them agree too.

Is the "long" style any better than the Borg & beck?

[Gene1949]

I bought a 10" Centerforce II, PP, disc and flywheel dropped shipped from JEGs [on sale] for about the same price as having an old wheel cut, balanced and shipped.
Same with the PP and disc (having them rebuilt and shipped)
You'll love the Centerforce. Smooth, easy on old knees

[1941Pony]

Thanks for all the replies. I read them all last night and started searching 10” again. I found a good deal on a modern driveline billet flywheel & their diaphragm clutch and decided to go with that.

I’m sure it’s overkill for a weekend coffee shop cruiser but my leg will be happy and was roughly the same price as the Chinese stuff. I have had a long style only once before and I remember my leg hated it, switched to the diaphragm and my knee stopped feeling like a bucket of bolts. Hopefully this will help with the enjoyment of driving it whenever I get to that point. Haha

Appreciate the help.

[JSeery]

If you didn't like the heavy clutch feel in the past it's good you decided against the 11 inch, it is super hard on the old knee joint.

[cas3]

i was under the impression no one had figured out a borg n beck style clutch for the 59a flywheel. is that not true?

[Pete]

A 9 inch can easily be made to handle 400 hp at home.
Be sure to have the assembly balanced on the crank you are going to run.

[Lanny]

A 9" clutch would let your flathead rev up a little quicker...

I have a 10" Centerforce setup in my 550 hp Cobra.
I'll guarantee you, this clutch DON't slip...

.Click on Picture to Enlarge

[cas3]

That's quite a car there Lanny, could i borrow it sometime for a date?

[Lanny]

Hey cas, I gotta pass on that, but we'r almost neighbors, so
come on up and we can take it for a little joy ride.

Wait till the snow has melted thow. haha


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[Brian]

A bit off topic, but an old hotrodders trick was to use an Auburn clutch. I use 9" Auburn clutches in all my builds, they will not slip: [I have backed up a 284 with one with no issues], and they are so light, much nicer than a Long style. Superior design; the springs never see any heat.

[cas3]

not off topic at all Brian, i'd like to hear more

[Tim Ayers]

Originally Posted by cas3

not off topic at all Brian, i'd like to hear more

Me too.