V-8 Pressure plate for Model A

[Don/WI]

What is the diameter of the clutch plate and the number of the V-8 Pressure Plate that is normally used when the Model "A" flywheel is lightened to use a V-8 Pressure Plate? Vintage Auto Parts lists a #PX 5102 which is a 9" but is listed as used for a tractor. I have read or heard (I believe on this site), that the tractor pressure plate is too heavy (high spring forces) for Model "A" use. Also, what is the bolt size used for the V-8 pressure plate? All information is appreciated. Thanks. Don/WI

[Jim Brierley]

9" is the most common V8 clutch used, from 1940 Fords, probably other years too but the earlier V8's used a clutch similar to the Model A. The V8 bolt size is 5/16" and should have a shoulder on them that fits down into the flywheel, acting somewhat like a dowel. There are 6 of them. The tractor clutch does not have stiff springs, the main difference is that they don't have weights on the outer end of the fingers, so have no additional gripping force at high RPM's, OK for a stock Model A but I don't recommend them for a high performance A. Some are now going to a more modern diaphram type of clutch, Ford Times did an article on them a few issues back. I do not know part numbers.

[dfish2931nc]

What is the difference between a 9 inch Model A clutch and a 9 inch V8 clutch? I just got a lightened flywheel from Dans4banger, and a v8 pressure plate to go with it. I plan on using my new 9 inch Model A clutch disc. Am I messing up? Thanks

[JoeWay]

Originally Posted by dfish2931nc

What is the difference between a 9 inch Model A clutch and a 9 inch V8 clutch? I just got a lightened flywheel from Dans4banger, and a v8 pressure plate to go with it. I plan on using my new 9 inch Model A clutch disc. Am I messing up? Thanks

The Model A clutch cover--or pressure plate--is made to fit into the 1-1/8" step of a stock A flywheel. The V8 clutch cover bolts onto a flat flywheel.

The same disc can be used with either cover, so you're good there.

Joe

[Ron in Quincy]

The person you got the lightened flywheel from should have tapped the flywheel for the V8 Pressure Plate. Use a grade 5 bolt and lock washer (6 ea.) to mount the pressure plate. Also good idea to have flywheel and pressure plate balanced; usually flywheel first, then bolt on pressure plate and balance together.

Ron

[Don/WI]

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Originally Posted by Ron in Quincy

The person you got the lightened flywheel from should have tapped the flywheel for the V8 Pressure Plate. Use a grade 5 bolt and lock washer (6 ea.) to mount the pressure plate. Also good idea to have flywheel and pressure plate balanced; usually flywheel first, then bolt on pressure plate and balance together.

Ron

I am lightening the flywheel myself and need to know which is the right V-8 pressure plate to use so I can get the correct bolt pattern. Thanks for the info I have received to date. Don/WI

[James Rogers]

Originally Posted by Don/WI

I am lightening the flywheel myself and need to know which is the right V-8 pressure plate to use so I can get the correct bolt pattern. Thanks for the info I have received to date. Don/WI

Don, you need a pressure plate from a 1932-1948 Ford V8. The bolt pattern is 5.375" diameter. Be careful as a national supplier has the plates but, the bolt pattern is not consistent by 1/8" and will cause fit problems. I have gotten them with the same stock numbers and identical boxes but different bolt patterns.

[A Michigander]

I believe the bolt pattern diameter is 10.375". making the radius 5.1875". Each pair of holes are 32 degrees apart.

[JoeWay]

Originally Posted by James Rogers

Don...Be careful as a national supplier has the plates but, the bolt pattern is not consistent by 1/8" and will cause fit problems...

I've seen this problem several times. This is one of the reasons why I STRONGLY recommend against using a pressure plate as a drill guide.

Joe

[Jim Brierley]

Not '32-'48! The early V8 PP's are like the Model A. The '46-'48 are 10". Ask for one for a '40 Ford 85 horsepower engine.

[Chris Haynes]

Originally Posted by Jim Brierley

Not '32-'48! The early V8 PP's are like the Model A. The '46-'48 are 10". Ask for one for a '40 Ford 85 horsepower engine.

Jim always comes up with the good information.

[Milton]

Bratton's Antique Auto Parts

Works great with my 27 lb. wheel and no core required.


V-8 STYLE PRESSURE PLATE
For Year(s): 28-31

V-8 PRESSURE PLATE - Helps reduce the amount of pressure needed to depress the clutch pedal by about 2/3rds. To use this, the crank must be counterbalanced and the flywheel must be machined. No changes in the way the clutch pedal is adjusted. NO EXCHANGE NEEDED. Uses the same clutch disk (11400) as the stock one.

Part #11460 V-8 STYLE PRESSURE PLATE $ 95.00

[Milton]

Originally Posted by dfish2931nc

What is the difference between a 9 inch Model A clutch and a 9 inch V8 clutch? I just got a lightened flywheel from Dans4banger, and a v8 pressure plate to go with it. I plan on using my new 9 inch Model A clutch disc. Am I messing up? Thanks

No Sir, you are on the money. See the last sentence from the Bratton website in my previous post. However, once you have the wheel and pressure plate, get them indexed and balanced.

[Kurt in NJ]

32-34 had a 9"PP that it same style as original A
35-41 had a 9" PP with centrifugal flyweights ---this is the one used for "A" conversions.
42-48 had a 10" with centrifugal flyweights.
Trucks had 10", and 11 "

It is easy to tell if you have the PP with the centrifugal flyweights in your car --push down the clutch, rev up the engine, if the clutch pedal pushes back more as you rev it you have the flyweights, if the effort stays the same = no flyweights

[1930ABONE]

Has anyone installed this conversion without having the crank counterbalanced?
If so how did it work out for you?

[dfish2931nc]

Thanks for all the help with the clutch disc Guys. The flywheel and pressure plate are at the machine shop being balanced. Pick them up in the morning. 1930ABONE, I have a lightened flywheel on a totally stock engine in my other model A. The difference is surprising. I have had no problems at all with this combination. That flywheel has 20lbs. removed from it, faster acceleration and even going up hill is better.

[Don/WI]

Originally Posted by A Michigander

I believe the bolt pattern diameter is 10.375". making the radius 5.1875". Each pair of holes are 32 degrees apart.

Your information is correct for the two pressure plates that I just received. I did a drawing on Auto-Cad last night and then dimensioned the "x" and "y" coordinates for each of the holes. This morning I went to the machine shop and drilled and tapped a test plate as a double check. The pressure plates bolted up with no problem.

Jim Brierley, where do I get the bolts with the shoulder on them? I asked the guy from NAPA where I got the pressure plates from and he said he did not list a special bolt for them.

[Don/WI]

Originally Posted by fordgarage

The pressure plate special shoulder bolts used to be available at better auto parts stores in blister packs from Mr.Gasket. They were the correct english size., 5/16-18 as I recall.

I found a source for the correct pressure plate bolts with the special shoulder to be used for mounting the V-8 Pressure Plate on the "A" flywheel. As stated above, they are in blister packs from Mr. Gasket. I found them at "Advanced Auto Parts" in my area (Appleton, WI). They were not on the shelf, but were at the store in two days. They are 5/16-18 x 1" long with lock washers included. Don/WI

[just plain bill]

Originally Posted by Don/WI

I found a source for the correct pressure plate bolts with the special shoulder to be used for mounting the V-8 Pressure Plate on the "A" flywheel. As stated above, they are in blister packs from Mr. Gasket. I found them at "Advanced Auto Parts" in my area (Appleton, WI). They were not on the shelf, but were at the store in two days. They are 5/16-18 x 1" long with lock washers included. Don/WI

Some of the V8's used 3/4" bolts 1" would bottom out. I think Brattons list them as 3/4" long for use on the "A" pressure plate.

[Don/WI]

Originally Posted by just plain bill

Some of the V8's used 3/4" bolts 1" would bottom out. I think Brattons list them as 3/4" long for use on the "A" pressure plate.

If the flywheel is lightened on the inside to a 11.5" inside diameter there is no problem with the 1" long bolts bottoming out as the mounting holes are drilled and tapped through to the inside. The area is thick enough that the bolts do not protude into the inside. The ones that Brattons lists do NOT have the unthreaded shoulder under the bolt head. Don/WI