Clutch pedal won't return

[Gregsenne]

Hi everyone
I am in the process of building a 1986 GMC Sierra. The engine is a 1989 350. The truck used to be an automatic, but i'm converting it to a manual. Transmission is a Muncie SM465 from a 1979 1 ton. The clutch pedal is all manual linkage. I know the 86 trucks might have come with the hydraulic setup, but I don't have the money for it, and have all the manual linkage stuff.

I have the clutch fork pushrod extended all the way out, and the pedal grabs at about halfway through. Then, it doesn't retract the rest of the way. It's like the pedal stops when the pressure plate springs are all the way out, and the pedal doesn't come the rest of the way up. From halfway through to all the way to the floor, it feels like it should, and retracts properly.

I have a small spring between the clutch fork and the Z bar. I also have a long spring between the bottom of the clutch fork and the frame, just ahead of the shock mount. Both springs have tension on them.

The Z bar mounts in a ball screwed into the side of the bellhousing, and the other side I had a bracket made by a friend at a machine shop that I bolted the other ball into (because I didn't have the factory bracket).

There is a heavy spring on the pedal itself, that goes from the pedal arm to the pedal bracket. Honestly, I couldn't see how it would work, because it never seemed to pull the clutch back up. Maybe I have that installed wrong? Before I had the linkage hooked up (with the heavy spring on the pedal), the clutch would stay all the way up, but if you pressed it 1/4 way down, it would spring down to the floorboard.


Thanks for any help. I have included a few pictures the best I could.

[76stepsidechevy]

Sounds like your springs are setup right. I think my 76 only has the one going to the frame under the truck and the one under the dash. I read somewhere that the one under the dash is supposed to make the clutch easier to push in. I always feel like my pedal should return more than it does too but its been like that since i got it a year and a half ago. I figure the clutch would've burned up by now if it wasn't fully engaged.

[Gregsenne]

I've drove several of these trucks though and the clutch usually returns most of the way up. Also, I wish there was a way to make it engage higher on the pedal, but the pushrod is extended all the way out. My car's clutch has about an inch of freeplay from fully up before it starts to engage, I'd like my truck to be like that too. Right now, the clutch pedal has about 6 inches of freeplay before it feels like the throwout bearing hits the pressure plate
Any ideas on extending the pushrod? Or do I have something else wrong? I thought the purpose of the long spring from the clutch fork to the frame was to return the pedal through the freeplay range. But it really doesn't seem to make a difference in the way the clutch feels if I have the spring in or don't have it in.

Originally Posted by 76stepsidechevy

I think my 76 only has the one going to the frame under the truck and the one under the dash.

I think the smaller spring from the clutch fork to the Z bar is just to keep the pushrod held tight against the clutch fork, so it doesn't fall out.


Thanks.

[76stepsidechevy]

Could very well be, I had a habit of picking up on the clutch pedal for a while and the pushrod did pop out on me once. Theres a kit to replace the rods with new ones with heim joints at the ends. It really improved pedal feel quite a bit. Have you checked out the condition of your rods at all the pivot points? mine were a lot worse than I expected.

[Gregsenne]

Ok Ill check into a different rod, maybe if I just get a longer one the clutch will come back out all the way and I wont have to worry about the pedal not returning. Everything looked good on all pivot points. I cleaned everything up good before I put it back on and regreased the Z bar.

[MalibuSSwagon]

http://cmc.speeddirect.com/itemdesc....50-125&eq=&Tp=

Speed Direct push rods

[Gregsenne]

Thanks for the link. I think if I was going to spend $100 on a pushrod, I'd just upgrade it to hydraulic. I already have a hydraulic bellhousing and the hydraulic pedal set.
Thanks for the help. i'm going to try to find or make a longer rod. Don't see why I can't just unscrew the pushrod and put a longer bolt or allthread in it (with the end that hits the clutch fork ground down to a rounded point). Any thoughts?

[Gregsenne]

I am still confused on why I'm having the issue though... Even though that truck didn't come with a manual linkage clutch, it had all bolt holes in the right spot, and marks on the floorboard for where the rod should go through, too. So If I put everything in exactly where it should go, why is my pushrod too short? Or maybe my pushrod isn't the problem, it might be something else! I really don't know...

Also, does anyone know if that truck was supposed to have a hydraulic or manual clutch? It's an 86 so I'd say hydraulic, but it's a GMC, and I know GMCs were a year or so behind the Chevys. Reason I ask is because there are factory holes for a manual clutch setup, but no holes for a master cylinder.....

[thomas_a_reed]

I had a simular problem, but mine was caused by putting the shorter throw out bearing intead of the longer throw out bearing.. Made a new rod from a couple of nuts and piece of all thread and that fixed the problem for me.. worked just fine for as long as a drove the truck..

[Gregsenne]

I have the short style throw out bearing, and I've heard mixed feedback as to which one I need. I have been reassured by every clutch shop that the short one is the only correct one for that transmission.
I've also been told that on manual linkage clutches, it's supposed to grab close to the floor, whereas hydraulic clutches grab close to the top.
So if it is supposed to grab at half way or closer to the floor, then I guess I'm fine.
If I have a problem I think i'll just put in a piece of allthread.
Thanks

[76stepsidechevy]

It would be really easy to make a longer rod actually, I would give that a try and see what you come up with. I guess you're better off with it catching low then too high though, at least you know the clutch is fully engaged.

[cjlinkster]

My 1984 C20 clutch pedal does the same in regards to engaging close to the floor and then only returning about 1/2 way up when released. It feels like it is fully disengaging properly. I usually lift the peddle the rest of the way with my foot.

[liftlawssuck]

It does sound and look like your springs are on correctly. I don't even run the heavy one inside. I don't like the way it makes the pedal feel. Once my pedal starts to have some play. Like not returning all the way or the clutch engages too low you just have to adjust the adjuster rod. You can make the pedal engage anywhere you want. I like mine nice and high. Anyways just mess around with the adjuster rod. Also grease in the bellcrank always helps too.