Clutch master cylinder not big enough?

We are about through with installing the "93 5.9 Cummins into the "94 Chevy dually. We have run into a problem that we did not anticipate. We can
shift the NV4500 tranny when the motor is not running but not with the engine cranked. We have bled all the air out of the fluid line. The good ol
boys at Advance Adapters agree with us that the stock "94 Chevy clutch master cylinder with a 3/4" diameter bore is not pushing enough fluid to the
Dodge slave cylinder, the "94 Dodge clutch master cylinder having a 7/8" diameter bore. We have as yet been unable to find a clutch master cylinder
with a longer stroke or larger bore diameter that will bolt up to the "94 Chevy firewall. Would any of you guys know where we might find such an
animal?
 
Just move the one from the dodge you took the engine out of. Or just skip the clutch when driving. I drove my old F-250 diesel without clutching for over a 100,000.
 
No can do. Shifter won't go into any gear while motor is running. Plus you cannot mount a Dodge clutch master cylinder on a Chevy firewall. Chevys bolt on. Dodge's screw on.
 
sometimes bleeding out a hydraulic clutch can be very hard to do. if you can get the slave cylinder vertical and pushing it by hand is needed
 
Make sure you have 1/8" gap/freeplay between your "clutch-pedal-push-rod" and the piston in the mastercylinder Your master cylinder may not be returning for enough so you won't get a full stroke out of the master cylinder if you don't have this freeplay. Same goes for brake master cylinders.
 
(quoted from post at 20:19:26 05/11/17) We are about through with installing the "93 5.9 Cummins into the "94 Chevy dually. We have run into a problem that we did not anticipate. We can
shift the NV4500 tranny when the motor is not running but not with the engine cranked. We have bled all the air out of the fluid line. The good ol
boys at Advance Adapters agree with us that the stock "94 Chevy clutch master cylinder with a 3/4" diameter bore is not pushing enough fluid to the
Dodge slave cylinder, the "94 Dodge clutch master cylinder having a 7/8" diameter bore. We have as yet been unable to find a clutch master cylinder
with a longer stroke or larger bore diameter that will bolt up to the "94 Chevy firewall. Would any of you guys know where we might find such an
animal?

So do you have a dodge NV4500 hooked to it?

The only suggestion I have is to swap the rear engine plate, and find a GM NV4500 and get everything transmission related back to GM specs.

Keep in mind P chassis bread trucks in the late 80s and early 90s offered a 4BT Cummins, so that is where the GM to B series plate will come from.
 
The NV4500 came off of a "98 Chevy 3500. The tech guy at Speedway Motors told me that the ideal arrangement is a 3/4 I.D. clutch master cylinder and a
7/8 I.D. slave cylinder. When I told him the I.D. on our slave cylinder is 1" while the I.D. on our slave cylinder is 3/4, he said we are not pushing
enough fluid to adequately move the clutch away from the pressure plate. He said we either need a bigger master or a smaller slave. I found a .93 I.D.
for a "96 Chevy with the same type of flange and ctc bolt holes as ours so I ordered it. I'll let you know if it solved the problem. Thanks for the
interest.
 
I was told by someone to call Southbend Clutch. They said they overcome this problem by installing a slave cylinder for a "94-"97 Jeep Wrangler. Did so. Problem solved. Shifts fine now.
 
Solved the problem. Contacted Southbend Clutch. They said to install a slave cylinder for a "94-"97 Jeep Wrangler. Did so. Shifts perfect now.
 

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