Topic: '65-'66 under dash clutch pedal assist spring?

[5F08KGT]

My understanding as of late is that this spring SHOULD be retained when using the original 3 finger style pressure plate.
I in fact have the 3 finger type pressure plate and during restoration the under dash assist spring was left off saying the clutch worked better without it.
I really don't think Ford would have installed these for no reason, so I think I'd like to get and install one.
Comments/suggestions?   (My car is a '65 K GT Convertible with THE original disc and pressure plate)

[Bossbill]

I'm not sure many people know, but the clutch pedal and spring is an over-center type assembly.
When you push down on the pedal, it resists your foot pressure by applying around 8 pounds of pressure against it. This is why you can have free travel -- you have a spring that acts against your foot.
When about half way down, after it has gone over center, it pulls the pedal toward the floor with about 12 pounds of pressure. Spring assist for your foot.

So, it both helps return the pedal to the top and assists your foot in going toward the floor after it has gone over center.

I can't see any reason this has to do with type of clutch pressure plate.

And yes, I put a complete assembly in a vise and used a pull scale.

[5F08KGT]

Thanks Bill!! I really for the life of me can't understand why a professional restorer would intentionally leave it off.
Like its name implies its an ASSIST spring.
Thanks very much for your explanation.

[Bossbill]

A friend of mine forgot to put his in after installing a new clutch pedal. Don't ask me how he got the pedal  out. But he never got it back in and bought a lighter spring.

If I remember right the only way to install this hefty spring is to pull the pedal away from the support 3/4" or so and swing it forward. If the support is in the car you can't swing the pedal forward enough to easily get the spring in there as the firewall is in the way. So you really need to have the support out of the car. Others can be more clever than me and get it in there.

Maybe that's what happened. They forgot to put it in and didn't want the pain of removing the support.

By the way, when I tested this I cheated and used a 67/68 support I have fully assembled. I pulled out a 65 support and tested it (without bushings) and got less help on the way up, but almost 16 pounds on the way down. So the early car is not as 50/50 over-centered as the later cars. Looks more like 1/4 spring to the top (or less) and 3/4 help on the way down.

[Brian Conway]

Thanks Bill for the spring function description.  Simple and understandable.  Picture is of the assembly for my 65 and shows the spring is under tension even in the ' at rest ' position.  Brian

[Bossbill]

Good pic Brian.
I did take two more pics so that it's understood just how far forward the pedal has to be in order to install the spring. First pic shows this with the spring completely relaxed.

The second pic shows why you have to pull the pedal out -- interference with the pedal support at the firewall "L" and if you don't remove the bump stop it will also hit there.

[Brian Conway]

About removing the clutch pedal bump stop...  In Bill's photo's showing the bump stop and, I believe, the carriage bolt head attaching it to the pedal support ?  In this configuration the bolt head nut is on the inside of the pedal support.  Making it absolutely impossible to get a wrench on for removal.   That was my experience.  Brian

[jwc66k]

In Bill's photo's showing the bump stop and, I believe, the carriage bolt head attaching it to the pedal support ?  In this configuration the bolt head nut is on the inside of the pedal support.  Making it absolutely impossible to get a wrench on for removal.   

The brake pedal support came as a complete assembly to the line. For service, usually to replace the two plastic "U" pieces, it was always easier on the bench (master cylinder disconnected). With the support installed, it's tight but doable with the instrument cluster and seats removed.
Jim