Clutch disk size?

[Ivan_B]

Searched the forum but cannot find a definitive answer. Is there a way to determine the clutch size I have in my 40 Ply sedan without taking it out? The manual lists 9", 10", and 11" clutches... Why would anyone make things complicated like that? 😅

[Sniper]

Well assuming it is still all original I bet the IBM card from the Chrysler historical society would help you figure it out. Short of that I don't know. But typically heavy-duty applications like taxi service had a bigger clutch

[Ivan_B]

I do have a service card record, but that does not seem to list the clutch size...

On a side note - are the flywheels all the same? Can I just get, say, a complete 10" clutch kit and assume that it will fit? 🤔

Edited October 8 by Ivan_B

[Plymouthy Adams]

it is easy to assume anything....winter is coming, odds are your car will be down for bit of time, heck even a hurricane can place you in an immobile period.  suggest you take the time to investigate....it is a manner of time now or time later, time now, tear it down and be sure....time later try to install after ordering to find your assumption was wrong,...roll of the dice on what best suits you....maybe there is a shop near you that can rebuild your disc and resurface/tweak your plate, have you checked it this option is available?  Time to return an item and get credit before they ship another can sometimes be a bit lengthy.  

[Young Ed]

Could you get a rough measurement just by pulling the inspection cover?

[Ivan_B]

29 minutes ago, Plymouthy Adams said:

winter is coming

FL is an all-year-round classic car season 😉

The old clutch is still working. I am just trying to stock-up on some wear and tear parts while they are still available.

 

29 minutes ago, Young Ed said:

Could you get a rough measurement just by pulling the inspection cover?

Good idea, I'll try that.

[Loren]

1940 is a little early for my experience but most I have seen are 9 1/4 inch.

For a project I am working on I drug out a couple of flywheels I had surfaced a while back and discovered both were drilled for the 9 1/4 and the 10 inch clutch.

I bought a flywheel from Vintage Power Wagons for a 251 ( government surplus ) and it was only drilled for the 10 inch. However it’s intended use was for a truck.

A car could be for private use ( 9 1/4 ) or a taxi ( which we know had a 10 inch clutch as part of the taxi package ).

9 1/4 might be cheaper and 10 last longer, your choice. I would call A B and ask them as they have both. However get your throw out bearing NOS somewhere else.

[Sniper]

On 10/8/2024 at 9:43 AM, Ivan_B said:

I do have a service card record, but that does not seem to list the clutch size...

I'm not as familiar with the call-outs with the early Mopar era stuff but the later cars will tell you what the transmission code is and then that will tell you the clutch application.

[Dartgame]

I'd pull the inspection plate and see if it is drilled for another pattern. If its stock size now, probably 9 1/4. Next size up is 10". 10" stuff is kind of hard to locate.

 

For throw out bearings get an oem part number and cross it to alternate brands. I just did this for my car, low and behold mopar used the same throw out bearing and sleeve from about 1950 into the 80's. Lots of choices. I went with a self aligning type. I couldn't find an angular contact bearing with out doing a lot more research. I'm sure timken or SKF has one, but you'd need all the specs for the bearing itself, search through a bunch of bearing part numbers to find it; and then have to press off the old bearing and press on the new yourself.

[rustyzman]

With my C1D, it turned out to have the optional 11" clutch.  The standard truck 10" clutch bolt pattern was in fact different than the optional 11" clutch and would not have fit.  Just FYI.

 

If you take an old timey caliper and spread it across the flywheel OD through the inspection cover and measure that caliper off-car, you can then measure the distance from the edge of the flywheel to the clutch disc edge, multiply by two and subtract from the flywheel OD.  You'll have the disc diameter then.  

 

You could also feed a rope around the pressure plate at the bolts, mark it and measure it off car and divide by Pi.  Tape it, rotate the engine until it comes back around.  Another quick measurement from the pressure plate edge to the clutch disc edge, times two, subtracted from the diameter you got from the rope would get you the disc diameter again.  

 

Not super easy, but still easier than pulling the trans.

 

Also, if they are compatible, Vintage Power Wagons has 10" clutch kits.

 

I also had to machine a spacer for the backside of the throwout bearing sleeve on my truck too.  Mine was definitely wrong for the application and was too short.   Clutch release lever was bottoming out on the frame and barely releasing.  Works great now.

[Ivan_B]

8 hours ago, Sniper said:

later cars will tell you what the transmission code is and then that will tell you the clutch

Here is my built card. I do not believe there is anything useful on it, though

 

35 minutes ago, rustyzman said:

You could also feed a rope around the pressure plate at the bolts, mark it and measure it off car and divide by Pi.

Oh my god, I chose liberal arts thinking that I'll never have to deal with math, again. And now, here we are... 😅

 

 

7 hours ago, Dartgame said:

If its stock size now, probably 9 1/4.

I'll take the cover off, and see what it looks like under there. I might even be able to pull a part number off a pressure plate, too 🤔