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Old 01-18-2018, 01:17 PM   #1
daveymc29
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Default Pressure plate adjustment

Here's the problem. Clutch slips, brand new engine rebuild by reputable mechanic. Clutch and pressure plate was replaced by him. Engine was installed and the clutch slipped. I had a friend bring the car over and I drove it. Adjustment was engaging at the top of the pedal. The clutch slipped badly. Felt it by hand and 1 inch free play. Adjusted to gain two inches of free play and drove it again. Anytime, in any gear, the clutch will slip if I step on the gas hard.
Now the solution appears to be to adjust the fingers of the pressure plate as that seems to me to be problem. Can they be adjusted through the inspection Access? Or is it necessary to remove the engine or transmission?
Thanks for any replies.
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Old 01-18-2018, 01:34 PM   #2
Tom Endy
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Default Re: Pressure plate adjustment

The fingers of the pressure plate can be adjusted through the window, however it is a difficult task. Much easier with the transmission removed.

See attached article.

Tom Endy
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Old 01-18-2018, 01:40 PM   #3
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Default Re: Pressure plate adjustment

Quote:
Originally Posted by Tom Endy View Post
The fingers of the pressure plate can be adjusted through the window, however it is a difficult task. Much easier with the transmission removed.

See attached article.

Tom Endy
Tom. I had one that I had to adjust and it was tough to hold the screw and break the nut loose when they were staked. Have you ever seen a tool that makes this job easier? Really hard if one tried to do it thru the floor boards and the inspection cover.
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Old 01-18-2018, 02:35 PM   #4
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Default Re: Pressure plate adjustment

Just a simple question. Have you adjusted the clutch with one inch of free travel?
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Old 01-18-2018, 04:00 PM   #5
daveymc29
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Default Re: Pressure plate adjustment

#4 Started there and it slipped badly so I adjusted to 2+ inches of free play and absolutely no difference. It will hold if one eases the clutch out and accelerates real slowly. I once heard a load pop from a diaphragm clutch cover in my Austin Healy. The clutch cover dish shaped spring had split and if I tried to accelerate in a normal fashion the engine just spun up and the car remained in place. I very slowly released the clutch and drove miles out of my way to approach my house from above it as I could us a long circuitous route to arrive above it, but approaching below meant going up a short but steep incline.

So from Tom Endy's reply I understand it is doable and will be a pain.
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Old 01-18-2018, 04:19 PM   #6
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Default Re: Pressure plate adjustment

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I did one once thru the inspection cover, but as Tom said, it is difficult and trying to get them all the same takes patience. And trying to turn the screw while holding the nut is a pain. Probably not what you want to hear. I have to adjust my driver right now, but will probably just bite the bullet and pull the rear end and trans and do it.
Good luck with yours.
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Old 01-18-2018, 07:51 PM   #7
Patrick L.
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Default Re: Pressure plate adjustment

As mentioned the plate can be adjusted without removal, but, I don't think that will work in your case. I'm thinking the assembly needs to come out and go to the bench. I'm wondering if the flywheel was turned/cut correctly. Regardless I think it needs to come and looked at.
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Old 01-18-2018, 08:53 PM   #8
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Default Re: Pressure plate adjustment

Luckily for me it's a friends car. Unluckily for me it's a friends car and I'll end up doing a good portion of the "pulling."
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Old 01-18-2018, 09:34 PM   #9
Tom Endy
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Default Re: Pressure plate adjustment

Quote:
Originally Posted by zzlegend View Post
I did one once thru the inspection cover, but as Tom said, it is difficult and trying to get them all the same takes patience. And trying to turn the screw while holding the nut is a pain. Probably not what you want to hear. I have to adjust my driver right now, but will probably just bite the bullet and pull the rear end and trans and do it.
Good luck with yours.
I have done a bunch of them with the flywheel resting on a work bench and me sitting on a stool. A fellow club member, friend, and neighbor has done it several times through the bell housing window. He is much younger than me and much more limber. I would never attempt it.

There is a myth in the Model A kingdom that new pressure plates come already factory adjusted. Don't you believe it. The pressure plate should be adjusted to whatever clutch disk you are going to use installed in the pressure plate.

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Old 01-18-2018, 09:46 PM   #10
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Default Re: Pressure plate adjustment

Tom. I have also heard that myth, but always doubted it. You made a good point. Thanks for your input. Mark.
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Old 01-18-2018, 11:12 PM   #11
Marshall V. Daut
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Default Re: Pressure plate adjustment

Just so we're all on the same page here, is it a Model A clutch or a V-8 clutch mounted on a lightened Model A flywheel, such as the combo sold by numerous vendors? The reason I ask is because in the last couple years, two such V-8 pressure plates in two separate vehicles began slipping fairly soon after I installed them. Re-adjusting the fingers provided only temporary improvement before the clutch began to slip again. I finally yanked the engines in both and replaced the V-8 clutches and lightened flywheels with a standard Model A pressure plate and flywheel. That solved the slipping problem.
I am nervous anymore about using vendors' V-8 clutch/flywheel combos after these two frustrating - and expensive - experiences. I seem to recall shortly afterwards that someone else posted similar problems with his V-8 clutch right out of the box. I wonder if there was a run of bad V-8 clutches sold during this time period because I never read or heard about this problem prior to my experience.
So, can you please verify that you have the standard Model A pressure plate before we all continue with our SWAGS?
Marshall

Last edited by Marshall V. Daut; 01-18-2018 at 11:27 PM.
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Old 01-19-2018, 01:21 AM   #12
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Default Re: Pressure plate adjustment

Marshall, I have no idea what is in there. I didn't do any of it, A friend did and has brought it to me after the problem became apparent which was the first time he drove it. I'm guessing it is stock model A. Haven't seen the build sheet, if there is one. A well respected authority on this work did the engine for him.
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Old 01-19-2018, 02:03 AM   #13
Tom Endy
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Default Re: Pressure plate adjustment

Another consideration, if it is a stock Model A clutch set up, is the step that the pressure plate sits in. The dimension of this step to the clutch surface of the flywheel is 1.123". When the clutch surface is machined the same amount of material should be taken off the step to maintain the 1.123". If this is not done and the surface has been machined several times it will affect the operation of the clutch.

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Old 01-19-2018, 08:16 AM   #14
Patrick L.
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Default Re: Pressure plate adjustment

Marshall brings up a good point, which clutch is it ? A look thru the inspection cover should show which it is. 3 finger or 6 finger.

When I mentioned the cutting of the flywheel in post #7 I was referring to the proper cutting of the 'step'. That seems to be over looked at times.
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Old 01-19-2018, 09:52 AM   #15
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Default Re: Pressure plate adjustment

What Tom said is what I was going to add, about the step.
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Old 01-19-2018, 05:50 PM   #16
daveymc29
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Default Re: Pressure plate adjustment

The engine is being removed sometime soon. After the Turlock meet I should have some answers. Stay tuned. Thanks for all the input, I have learned something. (I hope)

Dave Mc Arthur
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Old 01-20-2018, 09:27 PM   #17
Chuck Sea/Tac
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Default Re: Pressure plate adjustment

If it’s this style of clutch with the type of pressure plate that has a smaller id, then these rivits can keep the clutch friction from being sandwiched tight between pp and flywheel. I used a backing object and punched down about .100”. No slipping after that. My friend had the same problem.
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Old 01-20-2018, 10:06 PM   #18
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Default Re: Pressure plate adjustment

Quote:
Originally Posted by Marshall V. Daut View Post
Just so we're all on the same page here, is it a Model A clutch or a V-8 clutch mounted on a lightened Model A flywheel, such as the combo sold by numerous vendors? The reason I ask is because in the last couple years, two such V-8 pressure plates in two separate vehicles began slipping fairly soon after I installed them. Re-adjusting the fingers provided only temporary improvement before the clutch began to slip again. I finally yanked the engines in both and replaced the V-8 clutches and lightened flywheels with a standard Model A pressure plate and flywheel. That solved the slipping problem.
I am nervous anymore about using vendors' V-8 clutch/flywheel combos after these two frustrating - and expensive - experiences. I seem to recall shortly afterwards that someone else posted similar problems with his V-8 clutch right out of the box. I wonder if there was a run of bad V-8 clutches sold during this time period because I never read or heard about this problem prior to my experience.
So, can you please verify that you have the standard Model A pressure plate before we all continue with our SWAGS?
Marshall
I think at least some of the new V8 clutches are made in China. That may not be good. Also, some were using 8N tractor clutches, which do not have the flyweights to tighten the pressures by cyntrifical force at speed.
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