clutch master ideas for 70 k20 nv4500 swap w/internal slave?

[rickcdewitt]

i'm tentatively looking at a .700 bore wilwood master since stock is something like .690(i think). anyone care to share clutch mc woe's or triumphs?

[LockDoc]

Originally Posted by rickcdewitt

i'm tentatively looking at a .700 bore wilwood master since stock is something like .690(i think). anyone care to share clutch mc woe's or triumphs?

I can't help with the clutch master/slave but here is how I did my NV4500....

http://67-72chevytrucks.com/vboard/s...d.php?t=673588

It depends on what style of NV4500 you have though.

LockDoc

[rickcdewitt]

too late now for me to do that but thanks for the interesting read. i do miss not being able to run the 12" clutch anymore. all crickets on clutch masters?

[LockDoc]

Originally Posted by rickcdewitt

too late now for me to do that but thanks for the interesting read. i do miss not being able to run the 12" clutch anymore. all crickets on clutch masters?

If you type "hydraulic master cyl" into the Google box above, click on the circle in front of "67-72chevytrucks.com" and click on the google button you will find more info on it. Just check on what year the thread covers....

LockDoc

[Taibo]

Originally Posted by rickcdewitt

too late now for me to do that but thanks for the interesting read. i do miss not being able to run the 12" clutch anymore. all crickets on clutch masters?

Not sure why you can't run a 12 in clutch BUT the master you have picked might be a bit small. Wilwood has a 1 in diameter master which is what I use in a 1991 miata I race in SCCA V8 Miata. The clutch is a Spec Stage 4 multi disc clutch and the throw out bearing requires just a bit more fluid than a 0.7 in master will supply to disengage it with a short throw. Fluid volume is what moves the bearing and the larger diameter the master (within reason) the easier the clutch will engage and dis-engage. Pedal throw is determined by where the master fulcrum is placed, not master volume.

[rickcdewitt]

Originally Posted by Taibo

Not sure why you can't run a 12 in clutch BUT the master you have picked might be a bit small. Wilwood has a 1 in diameter master which is what I use in a 1991 miata I race in SCCA V8 Miata. The clutch is a Spec Stage 4 multi disc clutch and the throw out bearing requires just a bit more fluid than a 0.7 in master will supply to disengage it with a short throw. Fluid volume is what moves the bearing and the larger diameter the master (within reason) the easier the clutch will engage and dis-engage. Pedal throw is determined by where the master fulcrum is placed, not master volume.

thanks for the reply, 6.0l has a different crank pattern than an old 350 for the flywheel as far as the 12" clutch.i looked up the bore size of a stock internal slave master cylinder and had a friend measure the pedal length,distance of pushrod from pivot and stroke for a 2002 2500hd w/nv4500.almost ready to buy stuff and start hacking but would really like to have a dialogue with peeps who are running this combo in a 67-72.

your car sounds like a blast!are you running a chevy motor rather than the smaller ford small block?i know a guy who fit a 5.0l in an rx-7 in tech school. do you need that much clutch for such a light car?

Originally Posted by LockDoc

If you type "hydraulic master cyl" into the Google box above, click on the circle in front of "67-72chevytrucks.com" and click on the google button you will find more info on it. Just check on what year the thread covers....

LockDoc

golden advise for sure. my truck would still have an edeljunk on it and dump truck trans without it!

[rickcdewitt]

pasted this here from my build thread to spur some more discussion!

did some pedal ratio and throw measurements on the stock clutch pedal with a bare floor and a 3/4" thick spacer under the pedal to compensate for sound deadener and floor mat in future.

pedal is 14" long from center of pad to pivot

6 to 1 ratio is 2-1/3" down from the pivot and gives 1-3/8" throw

5 to 1 ratio is 2-4/5" down ,1-5/8" throw

3.5 to 1 ratio is 4" down, 2-1/4" throw

had a friend measure his stock 2002 2500hd setup for me but he's lazy so i take these numbers with a grain of salt

24" pedal length

6.4 to 1 pedal ratio, rod is 3-3/4" down from the pivot,3-1/4" stroke.

looking under the dash theres room to move the pivot up a bit above the hanger and extend the pedal by the same amount if i need to for extra leverage.

also i think the stock internal slave master is 18mm from doing more looking on parts sites.

i'm no expert but it seems a 6 to 1 pedal ratio is optimum?

if my friends measurements are right i think i'll need a larger than stock master to move enough fluid?i ought to double check the throw.

[Ugly71C20]

I run a 13/16th" willwood with my external slave nv4500 and it has a ton of pedal travel. I would go with a 1" if you can find one

[rickcdewitt]

Originally Posted by Ugly71C20

I run a 13/16th" willwood with my external slave nv4500 and it has a ton of pedal travel. I would go with a 1" if you can find one

how's your pedal effort?
Also how far down do you have to push the pedal for it to disengage?
One last question,how far down from the pivot is the pushrod attached?

Thanks for the reply,rick
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[Ugly71C20]

The pedal is effortless, its just a long throw.

Pushrod is 2" below the pivot and the the pedal moves 7.5". Thats from about 1" from the furthest it will come up to about 3/4" off the floor. I hope that helps

[DWilbur]

I installed NV4500 in my 1971 I used the 1995 bell housing that came with the 4500. using the hydro parts from 1995 truck it is external set up. my engine is 2004 5.3 L

[rickcdewitt]

Originally Posted by Ugly71C20

The pedal is effortless, its just a long throw.

Pushrod is 2" below the pivot and the the pedal moves 7.5". Thats from about 1" from the furthest it will come up to about 3/4" off the floor. I hope that helps

so i'm guessing the pushrod moves about 1 to 1-1/8"?easier pedal than factory linkage? i like that you set it up so the pedal isn't as high as factory.

your trucks not that ugly,you should have seen the factory puke yellow w/silver rattle can top on mine before i painted it! i wish i had some before pics to show.

what intake setup did you run? i still haven't decided whether to try to keep the 2000 enclosed box or try something else?

[Ugly71C20]

Originally Posted by rickcdewitt

so i'm guessing the pushrod moves about 1 to 1-1/8"?easier pedal than factory linkage? i like that you set it up so the pedal isn't as high as factory.

your trucks not that ugly,you should have seen the factory puke yellow w/silver rattle can top on mine before i painted it! i wish i had some before pics to show.

what intake setup did you run? i still haven't decided whether to try to keep the 2000 enclosed box or try something else?

Maxed out is 1.4" I have a stop set before it bottoms out so maybe 1.25" or so. I actually put a return spring on my pedal to add a little more resistance. I am 6'3" so with the pedal all the way up my knee is up by my chest.

I am running a bone stock 2003 5.3. Just bolted on some headers and rigged up an air filter. It's a pretty fun setup, enough power to get in trouble
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[rickcdewitt]

Originally Posted by DWilbur

I installed NV4500 in my 1971 I used the 1995 bell housing that came with the 4500. using the hydro parts from 1995 truck it is external set up. my engine is 2004 5.3 L

i've had a stock 95 master coming for a week that was 30$ on fleabay,18mm bore i think.figured i'd make a shop floor/cab floor mount jig to test masters/disengagment before i hole saw the cab since i have a spare 4 foot -3an clutch line and another pedal setup to set it wherever i need to.i'm not sure what bore i'll need so i'll slice and dice on the jig untill i'm happy.

how far down the pedal did you mount the pushrod?

i've been checking on your build now and then since i thought about a crew cab when i started my build, nice man!

[rickcdewitt]

copied from my build thread for you guys following this-

so i took a gamble and bought a clutch master gm#19183066 off ebay supposedly for 94-95 c2500 trucks(going off the ebay fitment guide) 18mm bore and 1.5" stroke. also 2 bolt flange for easier mounting than the 2000 master.its not plastic or aluminum either and being a gm part might allow easier replacement in the future. also the line points down where i want it and uses the russell adapter to the 4ft long -3an line that i have without another adapter stacked on that.i think a 3ft or slightly shorter clutch line will be perfect once the inner fenders are in and i can route it perfectly.

i wound up mounting the pushrod 2.5" down from the pivot on the pedal since it gave me around 1-1/2" stroke of the pushrod and drilled the corresponding holes in the firewall to mount the master with the pushrod level. also cut and extended the pushrod 1.5" so the pedal would be up against the rubber stop.

after getting it shoehorned in and bled by myself pretty good but not great i did the scientific test of pulling my truck to a hill and pushing down the pedal until it rolled. it started to disengage with the top of the pedal pad 4" from the floor and was free at 3" and had 2 more inches until the master bottoms out 1" from the bare floor.
i'm hoping it will be enough to let it shift freely whenever i finally get it running! with help bleeding it the pedal disengagement should be a little higher and i'll shorten the pushrod so the pedal hits the floor right before the master bottoms out.
also with power applied to the disk it will engage/disengage over more than the 1" of pedal throw it takes to roll or stop it on a shallow hill. even though it sounds touchy it actually felt pretty good.

as far as pedal effort it might be very slightly more than stock setup with a 12" clutch with freshly greased up linkage.

i put a spacer under the flange to tilt it up for bleeding that will come out when done


the booster brace wound up in the way so i had to bend,cut and weld it to fit behind the resevoir.

don't laugh at the linkage,its temporary until i buy a little heim joint and thread the pushrod for it. i figure its all temporary until it runs and is proven to work as desired.i plan on welding short pieces of pipe into the holes i cut in the firwall ribbing to stiffen them back up.i also might run a strap from one of the bolts to the brake pedal bracket under the dash as well to make sure it never flex fatigues and cracks.

[DWilbur]

Originally Posted by rickcdewitt

i've had a stock 95 master coming for a week that was 30$ on fleabay,18mm bore i think.figured i'd make a shop floor/cab floor mount jig to test masters/disengagment before i hole saw the cab since i have a spare 4 foot -3an clutch line and another pedal setup to set it wherever i need to.i'm not sure what bore i'll need so i'll slice and dice on the jig untill i'm happy.

how far down the pedal did you mount the pushrod?

i've been checking on your build now and then since i thought about a crew cab when i started my build, nice man!

I have not set up the master in the cab yet my cab is still at the body shop getting final priming and blocking done. I hope to have the cab back in about 2 weeks so I can set up the clutch peddle.