Spring tension on new pressure plates

[alexiskai]

I mainly do Model A stuff, but I'm starting to put together the parts for a V8 transmission modification. I had heard murmuring about the reproduction three-finger pressure plates. I was able to procure both a NOS pressure plate assembly and a brand new reproduction. Both are the correct type with the counterweights, not the tractor type.

Upon comparing them, I noticed that the pressure required to depress the fingers was different. I used a bathroom scale and drill press to do some crude measurements. I found that the average force needed to move the fingers from the rest position to horizontal was about 30% higher on the reproduction plate than on the NOS plate (roughly 70 lbs per finger on NOS, roughly 100 lbs on repro).

This has likely been covered before, but I wanted to post here because I hadn't previously seen actual numbers.

 

[Kube]

You will need the specifications to test which plate, both or neither, are correct.

The springs are tested to a specific pressure at a specific height of compression.
Without those specifications, I am afraid any crude testing worthless.

 

[alexiskai]

OK, what are the specs?

 

[Kube]

OK, what are the specs?

Logical question indeed.

I'm certain any QUALITY clutch rebuilding shop has them. If they don't, they are not a quality shop.
Of course, why they would consider sharing them is beyond my imagination.
I'd bet heavy that the Benson Ford Research Center has the drawing with those specifications available.
Check out their website. You will need the part number of the assembly and there is a fair fee to obtain the information. Still, most likely your best bet.

 

[alexiskai]

Logical question indeed.

I'm certain any QUALITY clutch rebuilding shop has them. If they don't, they are not a quality shop.
Of course, why they would consider sharing them is beyond my imagination.
I'd bet heavy that the Benson Ford Research Center has the drawing with those specifications available.
Check out their website. You will need the part number of the assembly and there is a fair fee to obtain the information. Still, most likely your best bet.

Are all 9,400 of your posts spent telling people that their efforts are worthless and you can't help them, or is it just me?

 

[Kube]

Are all 9,400 of your posts spent telling people that their efforts are worthless and you can't help them, or is it just me?

It's just you.

I applaud you for your efforts and if you desire you can continue down the path you started on.

I gave you the information you need to get the specifications required to get meaningful results from any tests you may wish to perform. Did you want me to obtain them for you as well?

Yeah, I'm certain it's just you.

 

[tubman]

I for one appreciate these efforts. With all of the strange clutch problems folks have been experiencing lately, this approach may be rewarding. There is certainly something strange going on.

So keep up the good work; hopefully it will lead somewhere useful. I went through a similar exercise evening out the height of pressure plate fingers : https://www.fordbarn.com/forum/showthread.php?t=227626&highlight=shim.

And don't mind Mike; doing too many 1000 pt restorations can give you a little different point of view from most of us.

 

[Kube]

I for one appreciate these efforts. With all of the strange clutch problems folks have been experiencing lately, this approach may be rewarding. There is certainly something strange going on.

So keep up the good work; hopefully it will lead somewhere useful. I went through a similar exercise evening out the height of pressure plate fingers : https://www.fordbarn.com/forum/showthread.php?t=227626&highlight=shim.

And don't mind Mike; doing too many 1000 pt restorations can give you a little different point of view from most of us.

I found out about the height of the fingers after TWO very tough lessons. TWO remanufactured assemblies installed (same car) and both didn't work properly. Pulled some hair out, scratched my ... and finally figured out the issue.
I ended up making a plate as the assembly had to be drawn done to a specific height to check the height of the fingers.

 

[alexiskai]

It's just you.

I applaud you for your efforts and if you desire you can continue down the path you started on.

The goal of figuring out which plate, if either, has the correct spring tension is one you introduced. That's your goal. You don't know what my goal is because you didn't ask, which is consistent with your condescending tone.

Swapping a V8 clutch into the Model A engine has been a common modification for decades, and it was originally done because the V8 counterweighted pressure plate required less force than the stock A pressure plate. However, anecdotal reports in recent years have indicated that the force required for new reproduction pressure plates is greater than expected. If true, this could make the modification not worth the cost for A owners.

My experiment correlates with these reports but, as you noted, doesn't prove things either way. More investigation is needed. My goal in posting to this forum was to see whether the community was aware of the discrepancy or had any information that might be pertinent.

You don't seem to have any relevant information on this topic, so maybe commenting here isn't a good use of your time.

 

[Bob C]

Page L7 of the shop manual shows the springs on the 09A-7563 clutch plate are brown and 145-153 lbs. at 1.562 in. free length 2.250 in.

 

[Kube]

The goal of figuring out which plate, if either, has the correct spring tension is one you introduced. That's your goal. You don't know what my goal is because you didn't ask, which is consistent with your condescending tone.

Swapping a V8 clutch into the Model A engine has been a common modification for decades, and it was originally done because the V8 counterweighted pressure plate required less force than the stock A pressure plate. However, anecdotal reports in recent years have indicated that the force required for new reproduction pressure plates is greater than expected. If true, this could make the modification not worth the cost for A owners.

My experiment correlates with these reports but, as you noted, doesn't prove things either way. More investigation is needed. My goal in posting to this forum was to see whether the community was aware of the discrepancy or had any information that might be pertinent.

You don't seem to have any relevant information on this topic, so maybe commenting here isn't a good use of your time.

Rest assured I will not attempt to help you in the future.
Condescending? I was attempting to help you.
Perhaps a good use of your time is to have someone explain my signature to you.

 

[Kube]

Page L7 of the shop manual shows the springs on the 09A-7563 clutch plate are brown and 145-153 lbs. at 1.562 in. free length 2.250 in.

That's great information. Thank you!

 

[Kurt in NJ]

I was just looking up something else and noticed that the 9” was said to 850 lbs pressure on the disc from the service bulletins when they were talking about the new available larger heavy duty clutch