When I was pulling parts together for my 71 GS restoration I bought a clutch set-up on line. It has the purple colored pressure plate and I think it's a Zoom clutch set-up although I'll have to double check whe paperwork. Question, I adjusted the clutch via the threaded 4" clutch rod and had 2 inches (easy) of travel in the clutch pedal and it's not right. I'm being told I should have 1/2". I tightened the clutch and brake pedal assembly and made sure there was no play or wobble left to right. I took the dust cover off the bottom of the bell housing and when I pushed and pulled on the clutch Z bar (without the spring attached) I watched as there was a lot of tolerance and or slop with the clutch fork moving front and back on the throw out bearing - without the throw out bearing moving. I think this is where the excess slop is coming from although I'm not sure if this is normal. Did I explain this right? Is this normal? Mike NJ Iggycat2004
It could be: 1. You installed the throw out bearing incorrectly to the fork 2. The throw out bearing is wrong. There are different height bearings for different applications 3. The clutch fork is wrong When adjusted, the pedal in the car should depress about 1 inch before the bearing starts to depress the diaphragm.
There are two different bearings depending on if its a small block or a big block. IIRC, the small block one is taller. So if you installed the BB bearing in your 350 by mistake, you would have little to no pedal. Lash at the pedal should be 5/8 to 7/8. There should be a 1/16 to an 1/8 of clearance between the fork and the end of the rod.
Since he has an aftermarket unit all you get is gereric. For example, if you buy a Centerforce Dual friction set up for a Buick 455 and their throw out bearing the height mening the thickness of the bearing is not the same as stock GM. So to fine tune the geometry so it will work correctly, we used a Lakewood adjusable pivot ball.
Zoom pressure plates arent really aftermarket. They're basically stock units painted purple. Its really a Valeo replacement pressure plate in disguise.
Might sound dumb but be sure the throwout bearing is installed the right way. I just seen one break in 4 peices. Ray
Thanks for the response. Background - The entire 4 speed set-up was purchased through Dave Kliener of GS Enterprises with the exception of the clutch, pressure plate and throw out bearing. Everything is virtually brand new with the exception of the bell housing. (The transmission is new out of the box) and the fit and finish is near perfect. I bought all this through Dave to avoid any problems down the road and in hindsight; I should have purchased the clutch assembly from him as well. All this is bolted to fresh 455 rebuilt bored 30 over/ported/staged heads. RG67BEAST - The throw out bearing is installed correctly with the bearing facing towards the pressure plate diaphragm. flynbuick - What would are the benefits installing the Lakewood pivot ball? I don't understand. If I have to pull the tranny to replace the clutch I'll install it - if it helps. PaulGS - everything appears to be installed correctly. I called Dave Kliener today and he suggested I check the two metal flat bearings riveted to the clutch fork and to make sure they are installed properly. I'll look tonight and see if I can see them through the inspection hole. If I'm hearing you correctly the pedal height is 1 inch. I measured mine and it was almost 2 inches. Worst case scenario I'm going to pull the transmission and see what gives. The bad news is the underside is freshly painted and I'll need to be real careful to protect the paint from scratches. Nick from Ivyland Collision did a good job painting this car. What kind of clutch assembly are you 4 speed guys using these days? Thanks, Mike Iggycat2004 NJ
No mention of flywheel in your note. I used the Lakewood adjustable pivot to push my fork towards my many times machined flywheel. As the flywheel gets thinner the clutch gets farther away from the throwout - not a lot but then again it doesn't take much to screw up the geometry. Flywheel 0.125 thinner - extend the pivot 0.125 beyond stock. According to the factory manual you should have approximately 0.75 inches lash (free play) at the pedal. I run a Centerforce Dual Friction with the Centerforce throwout bearing, which is much shorter than the stock throwout. Did NOT have to add more pivot distance to make up for the shorter throwout bearing.
I failed to mention the flywheel is new, never cut. I was under the car tonight and there is something really wrong. There is about 3 inches of play in the pedal when I adjusted the throwout bearing so it would not ride on the presure plate diafram. I was told by a fellow Buick member the clutch disk could be in backwards which could cause this. The first body shop here in Jersey installed the engine and trans combo in the frame with the body off the chassis so I cannot be certain the clutch disk was installed properly. I know I have to take it all apart and I'm really pissed because the paint is flawless and to get the trans and belhousing removed is going to be a real challenge w/o scratching anything. ray: It'll go back to Nick at Ivyland Collision if anything is scratch underneath for redo.. Mike NJ
Mike, Once you get the driveshaft out it might be worth while to use a "padded" floor jack rolling backwards to help get it out. Oh and get Tony to assist in the process. Lift the floor jack against the trans without putting a lot of pressure on it.
gm used 3 different bearings depending on the pressure plate and probably clutch fork(have different ones here). BCA #'s were C-1705, CC-1705 and 1697C. 3 different heights. ou:
We replaced the entire clutch set-up and everything seems to work as it should. We think the ZOOM pressure plate may have been defective but not 100% sure. The same adjustment rod was used on the new clutch and not far off from the old clutch adjustment when installed and quite honestly, I'm baffled.. o No: I have installed many clutch packs in my day and never seen this. Mike Iggycat NJ
There's a lot at play here regarding geometry. I've had six different clutches in my car in the past 4 years. There's only a handful of companies making pressure plates with Valeo making the majority of them. They make McLeod's, Centerforces, and a few others. They might make Zoom's too. AC Delco stock replacements are made in Mexico by by Delco. I too have Kleiner's entire set and it fit perfectly with a Delco clutch kit. What alot of people forget to take into account is the installed height of the PP diaphram once it's torqued on the flywheel. A lot of low pedal effort PP's are shorter from the face of the flywheel to the tips of the diaphrams. People make up the difference with Lakewood adjustable pivot balls. If you choose to go this route, make sure you have more than 2 or 3 threads engaged on the pivot ball into the bellhousing or you could break it off. I've seen it done. Currently I'm running a Hays PP and it's taller by about .750 but then again it's a leg press and I need the clamping power for the track. There is another route one can go, and that's a McLeod adjustable TO bearing. It comes with spacer rings and allows you to set the correct relative height. I forget what the correct travel is of the fork with the PP and TO bearing installed. GS Johnny's right. But then again he's really old. There were 3 different TO bearings with varying heights from GM. The tallest one can be found listed under a Chevy truck from the 60's or 70's. This McLeod piece allows you to select one of the three. It's pricey, but it has a larger bearing face for more positive engagement. http://store.summitracing.com/partdetail.asp?autofilter=1&part=MCL-16505&N=700+115&autoview=sku Summit's expensive but I can get it cheaper through my shop.
