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Old 04-18-2017, 09:07 AM   #1
coolfool_2
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Join Date: Aug 2016
Location: Kitts Hill Ohio
Posts: 23
Clutch Master Cylinder/Slave Cylinder Question

I recently swapped my 61 front crossmember with a 1986 c10. As a result, i had to come up with a new setup for the clutch/brake system. I bought a Wilwood 260-1304 clutch master cylinder, thinking it would work as I have seen other members using this setup. I got it installed but it doesnt seem to be throwing the slave far enough. To get the clutch to engage, i had to adjust the clutch fork so far out that while it will fall into gear, the clutch slips so bad that its undrivable. Am i missing something in tuning this setup to work with my 61 or am i going to have to find another master cylinder with a larger bore? Really confused on what I am missing as i thought this was a recommended combination for the hydraulic clutch.
Thanks in advance.
Josh
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Old 04-18-2017, 11:02 AM   #2
padresag
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Join Date: Feb 2008
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Re: Clutch Master Cylinder/Slave Cylinder Question

show us what set-up that you used. I take it that you are using the same slave and that you have not changed the clutch assembly. are you utilizing the full throw of the master. you may be just short stroking.
ron
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Old 04-18-2017, 11:17 AM   #3
coolfool_2
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Re: Clutch Master Cylinder/Slave Cylinder Question

Quote:
Originally Posted by padresag View Post
show us what set-up that you used. I take it that you are using the same slave and that you have not changed the clutch assembly. are you utilizing the full throw of the master. you may be just short stroking.
ron
Correct, i am using the factory clutch assembly, didnt change it or the slave cylinder. System worked correctly before changing over. Also verified and the master cylinder stroke is the 1.4 inches as advertised.
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Old 04-18-2017, 11:32 AM   #4
padresag
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Re: Clutch Master Cylinder/Slave Cylinder Question

are you sure that you are utilizingvthr full stroke of the cluych master( not that you may need it all). your problem may lie between the clutch pedal pedal and the clutch master.
you may find some info in here.
http://www.67-72chevytrucks.com/vboa...d.php?t=362375
ron
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Old 04-18-2017, 12:07 PM   #5
sweepleader
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Join Date: Apr 2017
Location: Long Lake
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Re: Clutch Master Cylinder/Slave Cylinder Question

I am guessing that you changed the master because of the disc brakes from the '86. So, does that part work the way it is supposed to?

The new master for the clutch must be the same bore size as the old master was. I am thinking it was 1 1/8". That is pretty big compared to modern stuff. If that is correct and the new clutch master is smaller, you will have to increase the fluid displacement some way. One way is to put in a larger bore master. The other way would be to change the leverage of the pedal on the master or the throwout lever on the slave. The pedal is easier to mess with, you would need to move the pushrod hole toward the pedal and away from the pedal pivot. This might also require moving the master on the firewall to keep the pushrod lined up with the master bore. None of this is easy.

The best way, even though it might be expensive is to get the right bore master. It might be possible to use a single cylinder master from the old truck or car line and bolt things together. I never tried that, but it could work.

Hopefully someone here will have a direct, inexpensive, solution for you.
Best of luck,
Happy trucking.
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Old 04-18-2017, 08:59 PM   #6
StepSide1965
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Join Date: Aug 2013
Location: Muskegon Michigan
Posts: 29
Re: Clutch Master Cylinder/Slave Cylinder Question

Quote:
Originally Posted by sweepleader View Post
I am guessing that you changed the master because of the disc brakes from the '86. So, does that part work the way it is supposed to?

The new master for the clutch must be the same bore size as the old master was. I am thinking it was 1 1/8". That is pretty big compared to modern stuff. If that is correct and the new clutch master is smaller, you will have to increase the fluid displacement some way. One way is to put in a larger bore master. The other way would be to change the leverage of the pedal on the master or the throwout lever on the slave. The pedal is easier to mess with, you would need to move the pushrod hole toward the pedal and away from the pedal pivot. This might also require moving the master on the firewall to keep the pushrod lined up with the master bore. None of this is easy.

The best way, even though it might be expensive is to get the right bore master. It might be possible to use a single cylinder master from the old truck or car line and bolt things together. I never tried that, but it could work.

Hopefully someone here will have a direct, inexpensive, solution for you.
Best of luck,
Happy trucking.
Talk to Captain Cab, I bought his setup. For my 65 with the NV 3500 works great..
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Old 04-19-2017, 12:12 AM   #7
Captainfab
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Join Date: Mar 2007
Location: Coeur d'Alene, Idaho
Posts: 19,864
Re: Clutch Master Cylinder/Slave Cylinder Question

That Wilwood clutch master has a .750" bore. With an original slave cylinder you need a 1" bore clutch master. That is what I would supply in my booster bracket for the '60-'62's with the hydraulic clutch.

Quote:
Originally Posted by coolfool_2 View Post
I recently swapped my 61 front crossmember with a 1986 c10. As a result, i had to come up with a new setup for the clutch/brake system. I bought a Wilwood 260-1304 clutch master cylinder, thinking it would work as I have seen other members using this setup. I got it installed but it doesnt seem to be throwing the slave far enough. To get the clutch to engage, i had to adjust the clutch fork so far out that while it will fall into gear, the clutch slips so bad that its undrivable. Am i missing something in tuning this setup to work with my 61 or am i going to have to find another master cylinder with a larger bore? Really confused on what I am missing as i thought this was a recommended combination for the hydraulic clutch.
Thanks in advance.
Josh
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