i swaped in a 454, sm465, 14b, d60, np205, into my jeep wagoneer. i used the novak hydralic clutch kit to convert over from manual clutch pedal. the problem is that these kits were designed to deliver about an inch of hydralic clutch pedal engagement. they told me (after i bought it), that these kits really dont work well with some one ton 12 inch clutches because these require a little more pedal travel (about an inch and quarter) to fully relase the plate and let the gear go in. guess which one my truck has? yess the 12 inch clutch. currently i can drive the truck a little but not for long becuase the throwout bearing rides on the pressure plate a little. throwout bearings wear out fast like this.

after talking and arguing with novak for a while now, i still have not solved the problem.

novak told me that my only solution was to have centerforce custom build me a 12 inch pressure plate that will require only an inch of travel to fully disengage the plate. this is an astronomical price.

my solution. is it possible to install a 10.5 or 11 inch clutch in this tranny from like a big corvette? will i need to have my flywheel redrilled to do this? will this work? i think that if these stock clutches survived under the high horse power big block covettes it can totally survive under my truck. what do you guys think i should do? any other solutions?

My buddy ran into the same problem when he swapped a 350 in his CJ8.

He was already running the 465. But he ended up getting a different throwout bearing that would engage the pressure plate and make it release fully. Ill have to ask him what (if he even remembers) what PN of throwout bearing he used.

since your drive train is all chevy id just find yourself a stock hyd clutch set up and run that.

When I did my Cummins conversion I had the same problem. What size master cylinder are you using and what size slave did they sell you?? I also used a longer throwout bearing that I got from Jegs http://www.jegs.com/i/Centerforce/183/N-1086/10002/-1?parentProductId=750605

My conversion used a 3/4" master and they sold me a 7/8". I have since changed it to a 3/4" and the long throwout bearing and problem fixed..

if i use a smaller shorter throwout bearing wont the pressure plate still require the same distance to release the plate?

i'm using the wilwood 3/4 inch bore slave cylinder, the novak slave also has a 3/4 inch bore. according to novak, the slave cylinder rod should be going up and down about an inch, which my is currently doing.

I've read on Pirate that Center-force says the clutch fingers need to be depressed 3/8 to 9/16 to get complete release (11 inch Chevy clutch). You have to work backwards to determine how much clutch arm movement it takes to get the required release bearing movement. And, no, a longer release bearing has nothing to do with how far you're moving the release levers of the clutch plate.
My Chevy clutch arm results in good release if it's moved 1 inch. I figure the clutch arm has a 3:1 ratio; Therefore, my slave cylinder must have a minimum travel of 1 inch. That means my clutch master cylinder must have at least 1 inches of travel, also, if it's the same bore size as my slave cylinder. If the MC has a smaller bore, or the clutch pedal will not give 1 inch of MC compression, then you won't get the required 1 inch movement in the slave cylinder; air in the system will also reduce the slaves extension.
So, if your using a 3/4" MC bore and a 3/4" slave bore, your slave extension will be equal to your pedal throw--as measured where the MC's push rod is attached to the clutch pedal arm.
I'm using a 7/8" bore MC and a 7/8" bore slave cylinder. My clutch arm moves 1.250", as does my slave cylinder. Consequently, my clutch release arm also moves 1.250 inches. Before I upgraded to a 7/8 bore MC, from a 11/16 bore MC, I was getting 3/4 inches of slave extension, and was barely releasing my clutch, with the pedal hard in the carpet. Now I have a little too much movement, and a way stiffer clutch. I'm seriously considering changing a 3/4 bore MC to relieve the leg stress.

. And, no, a longer release bearing has nothing to do with how far you're moving the release levers of the clutch plate.


Need to brush up on your simple physics and geometry.

For example, if you took a bottle jack with an 10 inch lift, stack a 4 inch block on top, its going to lift a total of 14 inches. Put a 5 inch block on, it will lift 15 inches.

In this case, the longer throwout bearing is the block on top of the theoretical jack.

And it works, because that is how we solved (on the recommendations of Novak) the clutch release issues on my buddys CJ.

Need to brush up on your simple physics and geometry.

For example, if you took a bottle jack with an 10 inch lift, stack a 4 inch block on top, its going to lift a total of 14 inches. Put a 5 inch block on, it will lift 15 inches.

In this case, the longer throwout bearing is the block on top of the theoretical jack.

And it works, because that is how we solved (on the recommendations of Novak) the clutch release issues on my buddys CJ.Um not really. If at rest, your bottle jack is say 12 inces top to bottom with a 10 inch stroke. You then put a 4 inch block on top of it. The top of the block still only moves 10 inches.

Need to brush up on your simple physics and geometry.

For example, if you took a bottle jack with an 10 inch lift, stack a 4 inch block on top, its going to lift a total of 14 inches. Put a 5 inch block on, it will lift 15 inches.

In this case, the longer throwout bearing is the block on top of the theoretical jack.

And it works, because that is how we solved (on the recommendations of Novak) the clutch release issues on my buddys CJ.

Extending the length of the release bearing is the same as extending the length of the slave cylinder push rod--that would just reduce the free space between the bearing and the clutch--not affect the amount of travel of the slave cylinder, other than to reduce the distance it must travel before the bearing contacts the clutch. If the release bearing was too short for the application (Chevy bearings come in "short" and "long" configurations), then you'd have excessive clearance between the clutch release fingers and the bearing, requiring excessive movement of the slave cylinder to make up for it, with no stroke left to actually depress the release fingers. Your clearance between the release bearing and the clutch fingers should be ~.060, with the release bearing in the retracted position, and the slave cylinder completely retracted.

It's all about leverage. You need to find a clutch arm with the proper ratio, and possibly a different throwout bearing.

Is the ball pivot in your bellhousing in good shape?

What clutch arm arm you using?

Novak website has a good writeup on selecting proper clutch arm and throwout bearing:
It even has a chart and part numbers for different throwout bearings.

http://www.novak-adapt.com/knowledge/clutches_etc.htm

the pivot ball is new. the fork i'm using is the one included in the kit, which was designed to have the correct ratio.

and yes, i read the novak link. i have read it a thousand times already. you noticed in the link that they say nothing about using the 12 inch one ton clutches having a longer throw to release the clutch. i read the entire link before i bought the kit as well.

has anybody ever redrilled thier flywheel? what kind of shop can do this?

the pivot ball is new. the fork i'm using is the one included in the kit, which was designed to have the correct ratio.

and yes, i read the novak link. i have read it a thousand times already. you noticed in the link that they say nothing about using the 12 inch one ton clutches having a longer throw to release the clutch. i read the entire link before i bought the kit as well.

has anybody ever redrilled thier flywheel? what kind of shop can do this?

12 inch clutches came in sbc's and half tons to, and also are you using the full efective stroke of your slave cylinder? if not go to the larger master cylinder, all the clutch components are off the shelf gm parts, also could just go buy the master and slave for a gm hyd clutch and should work just fine, the pics on the novak site look to be using a gm slave.

From Chevypower: "---the pics on the novak site look to be using a gm slave."

Got a clue as to what year and model Chevy has a slave cylinder that looks" like Novak unit? I'd be interested. It looks higher quality than the old "Iron Duke" slave I've been using.

Um not really. If at rest, your bottle jack is say 12 inces top to bottom with a 10 inch stroke. You then put a 4 inch block on top of it. The top of the block still only moves 10 inches.

True, and I see what you are saying, a 10 inch stroke is still a 10 inch stroke. But stack a 5 inch block ON TOP of the jack, (or underneath for safety sake) the jack will achieve a 1 inch of overall height compared to using a 4 inch block. This was the analogy of what I was trying to show by using a thicker throwout bearing.

From Chevypower: "---the pics on the novak site look to be using a gm slave."

Got a clue as to what year and model Chevy has a slave cylinder that looks" like Novak unit? I'd be interested. It looks higher quality than the old "Iron Duke" slave I've been using.

there is one pic of a machined aluminum one but all the pics with the bellhousing, bracket and slave asembled look like a gm slave cylinder, 85 to 91 gms used that set up, the only difference is the slave bracket was cast as part of the bellhousing where the novak kit is just a bolt on bracket.