Wanted: Alternative clutch plates, '39-'52 Series 50, '39-'55 Series 40

5

'51 Special

Active Member
The "crown spring" pressure plate used on these Buicks remains available, provided you have a rebuildable core (or $275+ or -). We know that the pressure plate used on a 1989 Jeep Cheroke 4.0 ltr. six, with 5spd, bolts right on, because that application is described by Rande in his post last year about installing a T-5 behind a 1950 263. The Jeep pressure plate is available for less than $50. I would like to hear from anyone who has used a Jeep pressure plate (or any other pressure plate) as a direct replacement in for the crown spring pressure plate in an otherwise stock Buick?
Also, can anyone point to a 10" friction disc from any non-Buick application that fits the 10 spline 1 1/8 inch main gear drive on these Buick transmissions?
 
The disc should be pretty easy, as the 10 spline 1-1/8" was widely used by GM going back at least to the 1930s. It is less common on later models as the hi-perf cars went to 26 splines starting in the 60s and some of the T-5 applications are 14 spline.

I would start with a 283 Chevy disc or something similar. Don't forget the light trucks, as they also used the same spline. The one thing to watch out for would be interference between the hub or spring cage and the flywheel bolts.

The pressure plate bolt pattern is standard 10", so almost any 10" or 10-1/2" diaphragm or coil spring (except Long type) pressure plate will bolt to the flywheel. However, you need to make sure that the finger height is compatible with the stock Buick release bearing. If you know the Jeep PP works, I can't see any good reason not to stick with that one.

Ray
 
I use a Jeep Pressure Plate too and the Boltpattern doesn't fit on my old 38 Flywheel.
Not like wrote in older Post from ??.. I can't remember.
Now I have let built me from a Machineshop a new Flywheel with a new starting Ring shrunked on (from Bob) for my Dynaflow Crank with the Jeep Boltpattern.
The rest Meassurements are the same like the 38 (incl. 3 Kg less Weight),the Disc is my old One rebuilt.
My Releasebearing is the original One.
A Insert for the Crank (for the Pilotbearing) i let make too.
And it all works very fine.
 
Jenz38 said:
I use a Jeep Pressure Plate too and the Boltpattern doesn't fit on my old 38 Flywheel.
Not like wrote in older Post from ??.. I can't remember.
Now I have let built me from a Machineshop a new Flywheel with a new starting Ring shrunked on (from Bob) for my Dynaflow Crank with the Jeep Boltpattern.
The rest Meassurements are the same like the 38 (incl. 3 Kg less Weight),the Disc is my old One rebuilt.
My Releasebearing is the original One.
A Insert for the Crank (for the Pilotbearing) i let make too.
And it all works very fine.
Click to expand...

Jenz-
The original '38 clutch release (throw out) bearing is different from any of the later clutch release bearings. I just don't know how it is different. My later clutch release bearing has an ouside diameter of about 2.8125 (2 and 13/16ths) inch, and a contact patch diameter range of from 2.09375 (2 and 3/32nd) inch to 2.3125 (2 and 5/15th) inch.
I'm trying to determine if I can fit the Jeep pressure plate into a stock 1950 Buick Special bell, using a stock 1950 flywheel and mounting a stock clutch release bearing mounted on a stock bearing support. All stock, except the Jeep pressure plate and just about any GM based 10 inch friction disc for a 10 spline 1.125 inch shaft. My problem is that I cannot get my hands on one of those Jeep pressure plates without actually buying it.
If you know (or anyone else has such a pressure plate to measure), can you tell me (1) the inside diameter of the circle formed by the fingers of the pressure plate, and (2) the distance from the tip of those fingers to the flywheel, both measurements when the pressure plate is relaxed.
Much obliged for the help.
'51 Special
 
'51 Special said:
If you know (or anyone else has such a pressure plate to measure), can you tell me (1) the inside diameter of the circle formed by the fingers of the pressure plate, and (2) the distance from the tip of those fingers to the flywheel, both measurements when the pressure plate is relaxed.
Click to expand...

51 Special, sorry to give you the bad news, but the finger height cannot be accurately compared between different types of pressure plates when the springs are relaxed. You have to bolt the pressure plate to the flywheel (or a fixture) with a stock thickness disc (or ring) in between. This is because the fingers don't move inward the same distance on different designs as the springs are compressed.

Ray
 
Last edited:
@ '51 Special
In the old Post from Rand he descript that he usw a Throwout Bearing from a inline 6 300cui Ford Engine,if I remember right.
I have orderd it and it will doesnt fit to my Arm,that the Reason why I use my good Old One and I have luck that its fit also good.
Sorry but I can't give you the Measurements but the Clutch is now in the Car.
Look out for the old Post from Rande.
And think the same like Ray about Measurements from a relaxed Pressureplate doesnt happen.

Good Luck
 
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