Help - Clutch Pedal Jumps

[ronstang94]

69 mustang 302 3speed

Rebuilt the motor last summer after the car had sat in the garage for 20 years, and still haven't got the car out on the road due to this clutch issue. I did a complete engine bay restoration. Replacing anything that couldn't be cleaned or refinished. I tried to find a new clutch disk to use with the original pressure plate. I could not get the clutch disk by itself so I had to just get the kit from Autozone. This came with a new diaphragm style pressure plate. Since I had to pay for it I decided to use it.

Now the clutch pedal is very strong right at the top, making the pedal hard to push down at first, and then gets much easier 1/3 of the way down. When releasing the clutch, the pedal wants to jump up right at the end. This makes for a very jumpy acceleration from a stop. It is impossible to not spin a little tire.

On a previous post, people seemed to think the problem was the large spring connected to the top of the clutch pedal underneath the dash. I removed this spring, and it was not the problem.

I disengaged the adjustment rod from the clutch fork, to test out the pedal and z bar and bushings. The pedal gos up and down nice and smooth with no effort at all. So the problem is definitely not a bushing or anything involved with the z bar.

Someone at a car show was telling me that the problem is most likely that new diaphragm pressure plate and that I should put the original 3finger back in. Something about a difference in physical thickness of the two different pressure plates.

So my question... Do you think this is the problem and I should re-install the old 3finger pressure plate? and will the new clutch disk work with the old pressure plate?

I don't get paid well at work and my dad has been laid off for 9 months so throwing money at the problem isn't an option..

please help

 

[2+2GT]

The assist spring under the dash is too powerful for your new pressure plate. Pity you didn't look at the Glazier/Nolan catalog. They list your disc as G06245.

http://www.mustangbarn.com/catalog.pdf

 

[ronstang94]

The assist spring under the dash has been removed. It is not the problem.

I had a few different catalogs that I was using. Unfortunately Glazier/Nolan wasn't one of them.

Thanks

 

[2+2GT]

Hmmm… Perhaps your equalizer (Z bar) is distorted. How are the bushings in the clutch pedal? How much movement of the pedal do you have before the release lever contacts the pressure plate?

 

[ronstang94]

Z bar looks perfect. It did not look bent. I cleaned it up and repainted it. I installed new bushings and felt washers on buth ends. With no springs or anything hooked up to it, it swings back and forth really smooth. There is no binding at all.

What ever the problem is, I really think it is inside the bell housing. Just hoping some one has an idea of what the problem may be

Thanks

 

[horseballz]

What transmission did you put in? If it is a T5 or other trans with an aluminum front bearing retainer (the piece that the throw out bearing rides on) there is likely a groove worn around it that the throw out bearing is catching/binding on. Most aluminum units are replaceable with steel ones. Even a steel one may be heavily worn enough to cause this, but not as likely, unless a throw out bearing went bad at some time and spun on the retainer. I realize you don't really want to pull the trans out, but..............
HTH
Gene

 

[2+2GT]

… I had to just get the kit from Autozone. This came with a new diaphragm style pressure plate. Since I had to pay for it I decided to use it.

Someone at a car show was telling me that the problem is most likely that new diaphragm pressure plate and that I should put the original 3finger back in. Something about a difference in physical thickness of the two different pressure plates.

So my question... Do you think this is the problem and I should re-install the old 3finger pressure plate? and will the new clutch disk work with the old pressure plate?

If the disc is the same diameter and thickness as the one you removed, and the old pressure plate was working well, put it back in. Put the assist spring under the dash back in, too. It's easy and safe if you know the tricks.

 

[v8only]

Upgrade to mustang steve clutch cable setup...wont give u that problem..sounds.like a.mechanical issue somewhere in the clutch.pedal.linkage

Sent from my SPH-D710 using Tapatalk 2

 

[Rusty67]

Is this problem the same if the car is running or off ?

Gene said to check your front bearing retainer, good sugestion.

Did your replace the pilot bushing ? If you didn't you should have but that isn't what is causing this. Side note, if you do pull it all out put a pilot bearing in as they are much better then the bushings.

You need a second set of eyes (or feet), someone needs to actuate the clutch pedal while someone else looks at the linkage for a flexing rod or to see if the shaft the z-bar rides on is not sturdy. If you have compliance issues with weak metal it could cause wierd pedal feel issues.

Does the car make any wierd noises while idling ? Do you hear any odd noises when the car is running and you clutch in ? Do you get full release ?

 

[Couped Up]

Are you sure that your pedal support doesn't have elongated holes where the pedal pivots?

 

[Rusty67]

Good call. Check the pedal pivot to make sure it is good and also check the nylon bushings.

 

[ronstang94]

I fixed the problem quite some time ago, life just got too busy and I forgot to get back on here. But I wanted to post the solution for anyone on here in the future that comes across the same problem.

As I originally suspected, the problem was the new pressure plate. I pulled the transmission and put the original pressure plate back in. Bolted everything back up and the problem was solved!

Now I don't know if this (Autozone) part was not meant for this car or if it was just a piece of junk. Everything fit well with it, like it belonged there, but it was not right.

So, if the original part is not broken, do not replace it with a new model.

 

[2+2GT]

Good news. One other thing, IIRC, Glazier'Nolan can have your own clutch reconditioned. That certainly removes any problems with fitment or configuration.