Clutch pedal comes up too high??

[JJorgensen52]

On my new '72 GMC, when you release the clutch, it comes up and stops right next to the brake pedal, the same way my '69 does, but it's not touching the stop. Then if you hit a bump in the road, it will pop the rest of the way up to the stop and it's about 3" higher off the floor than the brake pedal. What's up with this???

I can't see anything that's amiss with the linkage, but there is no load on the pedal until you push it down past the brake pedal. The return spring in this truck is different than my '69 is, so I've got nothing to compare to.

[jocko]

is the return spring installed? the spring should have enough tension to pull the pedal all the way up to the stop. If you do have a spring installed, it would appear that it's too weak perhaps - and that your release bearing is therefore just riding on the pressure plate diaphragm fingers, never fully disengaging. May cause premature release bearing failure. The "load" you refer to is likely just the release bearing fully engaging the pressure plate. Sounds like you need a (or a new) return spring.

[ole dollor]

i would start by looking to see if there is a spring from the peddle to the firewall, and one under the truck on the clutch linkage to the throw out brg. lever. might also see if peddle shaft might be rusty and binding up, may need some grease on the shaft. just a place to start looking. on mine i made a thicker bumper so the clutch peddle would not come up as high as the brake peddle. old knees and hips need all the help they can get...also make sure your clutch is adjusted properly...

[JJorgensen52]

The clutch adjustment feels alright to me, I haven't crawled under it yet to change it (the release point is a little higher than my preference).

Either way, the linkage is all clean and free of corrosion and is properly lubricated. The return spring is installed, but unlike my '69, where the spring is run to the bracket horizontally, the spring on this truck goes straight upwards into the dash. When it is level with the brake pedal, the spring is almost parallel to the pedal - after it comes up the additional distance, the spring is actually pulling the other way. Halfway between the level-with-the-brake-pedal position, and the higher position, there is no spring resistance to the pedal at all.

I wish I had a picture of the spring but I'm traveling this weekend and I can't get one.

[special-K]

In my '71 tow truck the clutch pedal sits higher than the brake pedal,but the clutch pedal returns that high as it should. My problem is the brake pedal isn't returning. The brake lights stay on if I don't pull it up and my brakes drag. I believe it's the plunger on the booster hanging up. You may not have all those symptoms but it may give some perspective. I'd look at the return spring. It sounds like the clutch is functioning ok and it's just the pedal hanging up. How much tow play do you have when the pedal is where it sits low,before it returns to the stop?

[JJorgensen52]

Originally Posted by special-K

In my '71 tow truck the clutch pedal sits higher than the brake pedal,but the clutch pedal returns that high as it should. My problem is the brake pedal isn't returning. The brake lights stay on if I don't pull it up and my brakes drag. I believe it's the plunger on the booster hanging up. You may not have all those symptoms but it may give some perspective. I'd look at the return spring. It sounds like the clutch is functioning ok and it's just the pedal hanging up. How much tow play do you have when the pedal is where it sits low,before it returns to the stop?

My '69 K10 did that (it has a C-20 power brake setup from a '71), it turned out to be the lowest pivot point in the linkage on the firewall was dry and sticking - I soaked everything in oil for a bit and greased it up, no more troubles!

In the lower position there is very little play, it's adjusted to take up as soon as you step on it (I usually try to keep a 1/4" or so of slop)... the upper position, 3" or so. The brake pedal in this truck doesn't come all the way up to the stop bracket, but the firewall linkage is bottomed out and it can't come up any farther.