Centerforce clutch problem in my gt500

[kevingt500]

My 20 year old clutch was starting to slip so I decided to have it replaced before it quit on me. My mechanic recommmended that I put a centerforce clutch in the car, so he order one and installed it. The clutch/prssure plate kit is DF559033. After 60-70 miles I was out diving shifting between 2 & 3 and couldn't get it in gear and the pedal stayed on the floor. Had the car towed back to the shop....he ordered another kit....Installed it and I picked it up today...drove it home 4 miles.....then later went to go take it for a spin to start breaking it in and the pedal only comes half way back and the clutch seems to be still engaged even though the pedal is depressed all the way. The fly wheel was machined, the clutch spring under the dash has been removed, and the bell housing clearance appeared to be fine. Has anyone else installed this clutch in their car...successful or unsuccessful....any recommendations are welcome as the car is going back tomorrow....Oh by the way it is a 68 GT500 with 428, 11+ clutch 10 spline ....
Thanks Kevin

[zrayr]

'68's have a z-bar ? is it bent ?

Z. Ray

[Texas Swede]

Have heard that this is a quite common problem
with the centerforce clutches. The reason being that the
clutch return spring is made for the original type, i.e. fork
clutches. Don't remember for sure what the solution is
but I think you need to remove the return spring.
Texas Swede

[crzy4shelbys]

Hi there,

I don't have a big block... my experience is limited to a small block '65 Mustang FB. I run Centerforce clutches, though. The first one went in back around 1989 or 1990. From what you describe and my experience with the z-bars and clutches, zray is right on (z-bars are also referred to as equalizer bars). Did your mechanic state if anything was visually wrong with the first clutch he took out? I'm not exaggerating when I say that I bent 3 z-bars in one year when I was driving my fastback daily (I was young and dumb and hot-rodded it everywhere, which didn't help). What you've described is exactly what happens when the portion of the bar that comes up over the steering column "rolls over". The clutch pedal quickly goes to the floor without releasing the clutch. Once it's bent and fatigued, it just happens faster when you try to take it up in the clutch adjustment, which is essentially what your mechanic did when he replaced the clutch. I'm not sure if your mechanic explained what's different about Centerforce clutches or if you already know, so excuse me if this is redundant info, but they are diaphragm style pressure plates with a lighter spring, but they have the holding power of a high spring rate clutch because there are weights that are distributed around the pressure plate fingers that use centrifugal force to exert force on the fingers to apply additional pressure to the clutch disc. Basically, the pedal pressure is lighter at lower RPM's and increasing with the rotational speed (RPM's) of the pressure plate.

Once I switched to Centerforce clutches, my z-bar problems went away because of the lighter pedal effort required when the clutch would generally be depressed. If, however, your z-bar was already starting to roll over on you, nothing is going to stop it from continuing to fail now. Additionally, if you're hitting the clutch at higher RPM's, aside from probably needing a scattershield for safety, that would put a lot of stress on the z-bar.

It's very easy to tell if the z-bar is bent. Open the hood and look at the part that doglegs over the steering column. If the part where the linkage from the clutch pedal that comes through the firewall attaches to the z-bar is not in line with the long axis of the car, it's toast.

I always thought somebody should make a heat treated equalizer bar to add strength and stiffness since they are such a weak link. I installed a hydraulic clutch in my GT coupe just because I didn't want to deal with Ford's linkage.

Hope that helps,
Josh

[zrayr]

Consider ponying up for a reinforced Z -bar at the least, or a complete "rollerized" clutch linkage.

I'm using this one and have had zero clutch issues (also am using the Centerforce clutch)





Z. Ray

[Boss302]

All you have to do is remove the spring (the big one) under the dash. This is very common with Centerforce.

[zrayr]

Originally Posted by Boss302

All you have to do is remove the spring (the big one) under the dash. This is very common with Centerforce.

see the first post, he has already done that.


Z

[kevingt500]

It is possible the zbar is bent. I had the assembly under the dash rebuilt 2 years ago, but was not told it was bent. While over at the shop yesterday it does appear that the rod is not sitting exactly where it should.
Thanks for the help.
Kevin

[zrayr]

Originally Posted by kevingt500

It is possible the zbar is bent. I had the assembly under the dash rebuilt 2 years ago, but was not told it was bent. While over at the shop yesterday it does appear that the rod is not sitting exactly where it should.
Thanks for the help.
Kevin

Can't tell if you are referring to the z bar or not. The z bar is under the hood, not under the dash. And unless you know what an "unbent" z bar looks like, you might not be able to tell if yours is bent. But from your original description of the problems, it's likely that it is.

Again, reference my post above, if you do replace the z bar, go with one that has been reinforced. You might not need reinforcement with a Centerforce clutch, but it does offer some peace of mind.

Z. Ray


Z.

[Boss302]

Originally Posted by zrayr

see the first post, he has already done that.


Z

I am sorry.

[zrayr]

Originally Posted by Boss302

I am sorry.

whoa, I wasn't meaning to slam you. we're all just trying to help out & keep these cars on the road.


Z. Ray

[Bob Gaines]

I had experienced a similar problem where the pedal would stay to the floor on a 68 GT350 after installing the center force two clutch and pressure plate. The solution for me was the upper clutch spring was replaced with the heavier big block upper return spring (upper Z bar spring)and it solved my problem . Putting a heavier upper return spring on will be easy to do a quick check to see if it helps any way. I hope it works for you like it did for me.Bob

[kevingt500]

I am installing a new zbar...the old one is definetly bent....Hoping it corrects the problem...Thanks for the help.
Kevin