Is my clutch pedal not returning because it's a (new) diaphragm clutch?

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killerplymouth

killerplymouth

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Hello FABO,

my clutch pedal is not returning all the way and (I think) it stops before the clutch is fully engaged, so I need push it all the way up by using the back of the pedal:


I had the car at a shop recently and they recommended a diaphragm clutch (a McLeod street clutch) so I said ok and they put it in; it had a 3 finger clutch in it before and it wasn't doing this.

I see the other recent thread about this topic, the resolution was to remove the Over Center spring. And the pinned thread about removing the OC spring when you change to a diaphragm clutch. Is it clear from my video that is definitely the same issue I'm having with my pedal? Because I have a diaphragm clutch and still installed OC spring?
Should I take out the over center spring? If I do take it out, is it necessary to make a return spring? Also, since the shop didn't know to take out the OC spring, do you think it's likely that the rod adjustment is not correct?
Should I try to adjust the fork rod with the adjusting nut so the clutch fully engages a bit lower in the pedal travel?
Is there any other reason why this would happen I could check? could I have worn the basically new clutch down enough to cause this?

If anyone can give me any advice, I really appreciate it.
 
Last edited:
killerplymouth said:
Hello FABO,

my clutch pedal is not returning all the way and (I think) it stops before the clutch is fully engaged, so I need push it all the way up by using the back of the pedal:


I had the car at a shop recently and they recommended a diaphragm clutch (a McLeod street clutch) so I said ok and they put it in; it had a 3 finger clutch in it before and it wasn't doing this.

I see the other recent thread about this topic, the resolution was to remove the Over Center spring. And the pinned thread about removing the OC spring when you change to a diaphragm clutch. Is it clear from my video that is definitely the same issue I'm having with my pedal? Because I have a diaphragm clutch and still installed OC spring?
Should I take out the over center spring? If I do take it out, is it necessary to make a return spring? Also, since the shop didn't know to take out the return spring, do you think it's likely that the rok rod adjustment is not correct?
Should I try to adjust the fork rod with the adjusting nut so the clutch fully engages a bit lower in the pedal travel?
Is there any other reason why this would happen I could check? could I have worn the basically new clutch down enough to cause this?

If anyone can give me any advice, I really appreciate it.
Click to expand...

That is probably it. Depress the pedal, install spacer washers and remove the spring. It sounds like you have studied the subject. You know what you have to do.
 
I have the same issue. I removed the spring with washers. Still does it. McLeod diaphragm :popcorn: clutch.
 
The over center spring works both ways. It assists holding the pedal down and at a point in the pedal travel up pulls the pedal up against the stop. Typically the over center spring, with either a diaphragm or no clutch at all, will pin the pedal too the floor and not come back without assistance.

What I see in your video is everything acting the way it should with all the slop built in from the factory. If anything your clutch may need adjustment.

I too have a McLeod Street clutch, and on my car with no over cent spring, I added a return spring under the dash to bring the pedal up. I did this out of preference to my driving style and body ergonomics so you'll need to decide what works for you after proper adjustment.
 
The Borg and Beck (three finger) is correct for your application. You let a shop that obviously knows nothing about Mopars put an incorrect clutch in. If you want it to work as "correctly" as it can with the incorrect clutch, you need to remove the over center spring from the clutch pedal. If it was mine, I would just make the shop put the right clutch in it. They were WRONG in their "recommendation.
 
The diaphragm clutch doesn't need as much departure clearance as the B&B. Adjust the diaphragm setup so the pedal returns all the way, and you will over center the clutch. I have a diaphragm in my 65. The advantage is less pedal pressure. I put a block of wood under the carpet to reduce travel, and replaced the over center spring with a lighter one. Comes up all the way, and returns properly.

Only problem with my Centerforce Dual Friction clutch is that it bites so hard I'm afraid to speed shift it - pretty sure something will break. Not so good for drag racing. But just for regular driving in stop and go traffic, or cruising on country roads and running through the gears, it's a lot easier on my left knee than a heavy duty Borg and Beck.
 
That's why I went to the Diaphragm style. Easier on my knee.
What lighter spring did you use? I put mine back in and didn't notice much difference.
 
Kendog 170 said:
That's why I went to the Diaphragm style. Easier on my knee.
What lighter spring did you use? I put mine back in and didn't notice much difference.
Click to expand...
I don't know, just dug around in my parts pile and found one the same length, but smaller diameter and put it in. Since it's not visible unless you crawl under the dash, I didn't bother painting it.

1744051673305.jpeg
 
The diaphragm pressure plate does not need an over spring at all.
 
Killerplymouth, are you able do drive it this way ? The problem is that you have to pull it back up with your foot-right, because it sticks to the floor.
 
i installed hydraulic slave cylinder with my diaphragm mcleod clutch. removed overcenter springs. i have had no problems. works great
 
I have put no less than 15 clutches in my car over the years everything from ones that would have your legs shaken in traffic to factory replacement diaphragm spec. I only ran one diaphragm clutch and it never was right. But I may have had some other issues with linkage at that time. I now run ram competition or HD Borg and Beck style exclusively. Everything lines up perfect as far as pedal height and adjustment rod. I still run the factory over spring. It's a little Stout but it will hold my 275 drag radials and that's not easy.
 
RustyRatRod said:
The Borg and Beck (three finger) is correct for your application. You let a shop that obviously knows nothing about Mopars put an incorrect clutch in. If you want it to work as "correctly" as it can with the incorrect clutch, you need to remove the over center spring from the clutch pedal. If it was mine, I would just make the shop put the right clutch in it. They were WRONG in their "recommendation.
Click to expand...

Incorrect clutch? LOL!

A diaphragm clutch is no more incorrect on a Mopar than a Holley 4 barrel carburetor is. The clutch in question is literally built for a Mopar.

The only thing the shop did wrong was not remove the over center spring when they installed the diaphragm clutch.

I’ve used B&B and diaphragm clutches behind the 340 in my Duster, both work just fine if everything is adjusted properly. The diaphragm clutch was used when I had an 833 and manual linkage, I have a B&B in there with the T56 and hydraulic set up.
 
72bluNblu said:
Incorrect clutch? LOL!

A diaphragm clutch is no more incorrect on a Mopar than a Holley 4 barrel carburetor is. The clutch in question is literally built for a Mopar.

The only thing the shop did wrong was not remove the over center spring when they installed the diaphragm clutch.

I’ve used B&B and diaphragm clutches behind the 340 in my Duster, both work just fine if everything is adjusted properly. The diaphragm clutch was used when I had an 833 and manual linkage, I have a B&B in there with the T56 and hydraulic set up.
Click to expand...
The FSM shows the B&B style.
 
i am the type of person to complain about anything. but i have zero complaints about american powertrain & mcleod.

my factory clutch setup on my barracudas in the eighties were atrocious compared to now. the clutch setup back then is what i hated most about my cars. now it feels like im driving a honda very smooth
 
do you have the distance between the the throwout bearng and diaphragm fingers at the correct height?
 
dadsbee said:
Is it spring yet?? You guys would argue about which way to unroll a rubber.. ffs..
Click to expand...
I'm not arguing. I'm only stating what the FSM says. You've restored some Mopars. Have you ever removed an ORIGINAL diaphragm style clutch?
 
RustyRatRod said:
I'm not arguing. I'm only stating what the FSM says. You've restored some Mopars. Have you ever removed an ORIGINAL diaphragm style clutch?
Click to expand...


What these guys don’t get is the B&B cover is stronger than the birth control cover. That’s just the fact.

They also don’t grasp that if you use the same disc with a B&B cover you can and should reduce the plate load so you don’t break parts. And it’s easier on your leg.

If you really want a clutch that works and will run with as little as 500 pound plate load, you use a sintered iron disc.

I know this because I’ve done it. I still do it except I have a B&B/Long cover. On the street I use right at 1200 pounds of plate load and when I get to the track I suspect it will be around 550 pounds of plate load and at 7k another 250-300 pounds of counter weight for a of 800-850 pounds of plate load.

Your leg will never get sore with plate loads like that. And you’ll have the correct pedal ratio with OEM parts.

I refuse to use diaphragm pressure plates. They are a cheap clutch with a much higher profit margin than most other covers.
 
I put a diaphragm clutching my 74 Cuda years ago.
When I had this problem it wasn’t the clutch or any springs.
It was the nylon bushings in the Z bar were worn out.
 
65 Cuda 340 said:
True, but I tried it with no assist spring at all, like it better with the light spring that's on there now.
Click to expand...
I agree with RRR that you don't need it but I tried it both way with only a slight differece. I try a lighter spring if I have the ambition.
 
Thanks to everyone for these replies. It is very encouraging to talk to people that understand what I'm trying to say and actually have experience with this.

RustyRatRod said:
The Borg and Beck (three finger) is correct for your application. You let a shop that obviously knows nothing about Mopars put an incorrect clutch in. If you want it to work as "correctly" as it can with the incorrect clutch, you need to remove the over center spring from the clutch pedal. If it was mine, I would just make the shop put the right clutch in it. They were WRONG in their "recommendation.
Click to expand...

I agree.
I was a little disappointed, that shop calls themselves experts in high performance and American muscle cars, they told me they were experts at spec'ing out a clutch, and the McLeod was a good choice. I believe it is a good clutch, but the fact that they didn't know to remove the OC spring, I don't think that screams expert. It was an expensive shop too so I was hoping for more.

I also should have done the research before approving it with them, so part of the blame is mine of course. I am planning to call them and see if they would work with me or consider cutting some kind of a deal at least for putting a B&B back in it. I liked the feel of the B&B better so if I can do that for a reasonable price I will, otherwise I'll get the OC spring out.

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Dart Frog said:
I have put no less than 15 clutches in my car over the years everything from ones that would have your legs shaken in traffic to factory replacement diaphragm spec. I only ran one diaphragm clutch and it never was right. But I may have had some other issues with linkage at that time. I now run ram competition or HD Borg and Beck style exclusively. Everything lines up perfect as far as pedal height and adjustment rod. I still run the factory over spring. It's a little Stout but it will hold my 275 drag radials and that's not easy.
Click to expand...

The 3 finger clutch had my leg shaking sometimes, it felt right for the car to me though. It was fun, I like it being authentic to how they came from the factory.

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72bluNblu said:
Incorrect clutch? LOL!

A diaphragm clutch is no more incorrect on a Mopar than a Holley 4 barrel carburetor is. The clutch in question is literally built for a Mopar.

The only thing the shop did wrong was not remove the over center spring when they installed the diaphragm clutch.

I’ve used B&B and diaphragm clutches behind the 340 in my Duster, both work just fine if everything is adjusted properly. The diaphragm clutch was used when I had an 833 and manual linkage, I have a B&B in there with the T56 and hydraulic set up.
Click to expand...

Yeah, the shop did a pretty good job on most of it, and it's kinda tough to find anyone who will work on my car. I can't fault them totally. I have an 833 and manual linkage.

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TF360 said:
Killerplymouth, are you able do drive it this way ? The problem is that you have to pull it back up with your foot-right, because it sticks to the floor.
Click to expand...
Yeah I can drive it, that is the problem. I stalled it a few times on a hill start before I realized the pedal wasn't coming all the way up though so I think the clutch is not fully engaged unless I push it up to the top. I'll test that out some more to confirm that because I could be wrong, and maybe it's nothing to worry about.
 
Last edited:
killerplymouth said:
....and maybe it's nothing to worry about.
Click to expand...
It is something to worry about. The OC spring is on the wrong side of center and influencing your diaphragm clutch cover.
Either pull the OC spring and just let the pedal flop or devise something to pull the pedal to the other side of center.
 
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