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Author Topic:   Clutch problems
dode
Member
posted April 06, 2003 01:08 PM
Ok, yet another giant headache dealing with a 86+ block. I have the engine entirely assembled and ready to go, and went to hook the clutch stuff up last night and again ran into problems. I am running a lightweight flywheel from an 88 Corvette, with a 10.5" clutch. All is fine and dandy. Then, I installed our McCleod steel bellhousing. Again, everything was good. Then, I measured from the back of the bellhousing where the trans bolts on to the fingers of the pressure plate. I measured 2 7/16". Ok...so then I have our Saginaw 3 speed there with the stock clutch type hydraulic throwout bearing on the shaft with no shims and I measure from the mounting ear on the trans to the end of the throwout bearing (I am trying to estimate how much I need for shims) and the dimension is 2 3/4". Anyone know how this can be? I thought there was a problem with the throwout bearing, but it is fully compressed. So, I took that throw out bearing and compared it to a stock fork type throwout bearing and they are the same size. Anyone got any clue as to what to do? Do the newer style transmissions have longer input shafts or what? I am at a loss. The only thing I can think of is to take the front bearing retainer off of the tranny to gain some more space, and replace it with like a flat piece of 1/4" aluminum or something. Would this be ok to do? All I know is I need a clutch and I need it in a hurry. I mean the stock throwout bearing won't even fit. Does anyone know? I need help in a hurry. Racing is a week away and we already missed play day. Thanks.

John

jnewman44
Member
posted April 06, 2003 11:06 PM
I run a 87' block, light weight flywheel,ram 3 finger 10.5" clutch, stock alum. bellhousing(60's- early 70's), 4speed sag., stock clutch fork, stock release bearing. Every thing seemed to work for me. Check the application of your bellhousing, You shouldnt need the late model one unless you are using the T-5 tranny or the stock hydralic slave cylinder. Also when you tighten the pressure plate you can watch the fingers depress(quite a bit actully), so make sure your disc is the correct thickness and the plate is torqued to spec. Remember the only difference in the 86' & up block is the flywheel

[This message has been edited by jnewman44 (edited April 06, 2003).]

dode
Member
posted April 06, 2003 11:26 PM
The disk and pressure plate are both brand new and are from a 75 Corvette. I am at a total loss as to what is going on. Yes, the fingers depress correctly. The disk specs out to the correct thickness. I can do without quite a few things, but not without a clutch. The bellhousing is the same one we used with the old style block last year with the same transmission. Any other ideas?????

John

c21
Member
posted April 07, 2003 12:04 PM
.3125 is the thickness of the clutch disk. I don't have the measurement of the throwout bearing right now, but I do know that it is within a few thousandths of the dimension on my brand new stock throwout bearing. The pressure plate is standard 1675 used on just about everything 10.5" I believe. I just called the parts store and they are sending in a pressure plate for an 88 corvette to see if it is different. I hope that it is, even though it costs a little more. I need to get this fixed ASAP. Sheesh this can be really frustrating sometimes.

John

c21
Member
posted April 07, 2003 01:32 PM
I looked at it, and no I would not do that. If I had a mill, I could to it, but I don't right now. It is a little more complex than I first thought. I suppose I could do that but I really don't want to. Heck I just put a new pilot bearing in. That would also move the tranny back, making the driveshaft too long (it is really longer than I like now, but it works). I REALLY hope this pressure plate works. Thanks a bunch.

John

Eljojo
Member
posted April 07, 2003 08:37 PM
I ran into a problem this year similar to yurs...but going the ther way. I needed a longer throw-out bearing. (stock mechanical) Could your pressure plate be set to use a short throw-out bearing and you've got a long one? Luckily there is a clutch repair shop here in town. He builds a lot of clutches for tractors and trucks, but there isn't a lot about friction clutches that is really different. You might look in your phone book for a specialist. He saved my bacon. He built a clutch for me using a Chevy center and a tractor four blade clutch. Then he installed metallic pads on it and I really like it. It works like a triple disc, making you want to load the trailer with a winch!


jnewman44
Member
posted April 07, 2003 11:36 PM
A new disc will measure about .320, ram, oem, whatever. An 88 pressure plate is probably for a T-56 6 speed tranny. Try something that came with a 4 speed, like a 79 camaro or vette. Some newer stuff like 88 might have a resesed flywheel.


dode
Member
posted April 08, 2003 08:13 AM
Well after playing around with it some more, I still have no answer. I have found a smaller stock throwout bearing that will fit though. I really don't want to run a slave cylinder, but I don't have much choice I guess. I do have another problem though. The first time I thought it was a fluke, but it has happened twice now. I bolted the clutch assembly together with the flywheel on the engine, going around several times to tighten down the bolts evenly. Then, when I go to take it off, one time I had one bolt seize up so hard that I twisted the head off (brand new grade 8 bolt). Well, I finally got that one removed, but then proceded to do it again, this time with two bolts. It happens when the bolts are about halfway out. They just stick like they are welded in place. I have run a tap through all of the holes, so I know the threads are good. I really can't risk messing up this flywheel as these are next to impossible to find. I am guessing it has something to do with the pressure from the pressure plate, but I don't know where I am going wrong. I am installing and uninstalling the pressure plate just like I always had. Anyone have any ideas? Thanks.

John

jnewman44
Member
posted April 09, 2003 11:00 PM
I think (not that I'm payed to)that pressure plate bolts should be lubed with oil or locktite and torqued to 35 ft/lbs. Flywheels are easy to find. Flatlander racing has a 15lb or 16lb lightweight for a one piece rear for about $140. Thats what I have. After this engine I dont think I will build another one peice rear main racing engine, To much hassle. Kevko builds a good pan for cheap though.


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