Talk to me about clutch master cylinder size...

Time2Dune

Time2Dune

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I currently have a 4.3 chevy with an 091, the clutch pedal is pretty hard to push (always has been). Everythinh works well trany was just rebuilt and clutch and pressure plate are good.

I have never really thought much of it, just is what it is, until I tried my buddy's car ( honda with a mendiola) his was super easy.

I currently have a 7/8 master cylinder, I have read that the lager the size = shorter push but harder pedal. Is this true? 

What size is everyone running? 

Thanks

 
I would think that a lighter pressure plate would solve this problem.

 
AlpineFunco said:
I would think that a lighter pressure plate would solve this problem.
Click to expand...
If a smaller master cylinder doesn't fix it ill have to pull it back out this summer, just hoping not to.

Thanks

 
On your 091 trans, is the arm that the slave cyl moves stock height or did you buy the taller one from weddle? There are also different bore slave cylinders. Not sure what pedal set your running but in wildwood, they offer different ratio pedals as in 5:1 and 7:1 for example. I had a 3.8 series II in a rail with a built 091. That had a stage 3 -9" clutch and it made my knee hurt for 3 days after pushing that clutch for a week. Thats when I went with the taller external clutch throw arm and smaller sized master with wildwoods higher ratio clutch pedal. Night and day difference.

 
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5/8 bore will give relatively the same feel and stroke as if you were using a stock set of VW pedals. 3/4 will be less throw but slightly firmer pedal. 7/8 I bet would feel like an on/off switch for the clutch. I run 3/4 w/ a wilwood slave cylinder and I like the feel of it. 091 with the Weddle clevis arm that uses a heim instead of the nut and bolt. 091-141-701-K-4

 
I have a ¾ on my clutch and 7/8 on the Brakes.  I am going to go to a 11/16 on the clutch. What is everyone one running in the brake master? 

 
Smaller master = lighter pedal, longer pedal throw.

Larger master = stiffer pedal, shorter throw.

Common master sizes used are 5/8" and 3/4" for 8" and 9" clutches.

7/8" is good for big Chevy bell housing and 10.4"/11" clutches.

 
I run a stage 3 9" on my Subaru, I just changed to a 5/8" Jamar last year and the pedal is OK. Not super light, but not straining either.

The newer Jamar doesn't seem to work like the old CNC, there is more dead throw in the beginning that I'm trying to fix now. Seems like the first hole in the piston is farther inward than what CNC did.

But like the others said, clutches should be 5/8" not 3/4".

 
Thanks everyone, picking up a new 5/8 tomorrow at kar tek, ill keep you updated. 

 
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