Fix for those that have the Mcleod Master Cylinder
03-03-2008, 07:54 AM
#21
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Well I rebored/honed my McLeod smooth and installed a brand new McLeod rebuild kit and it still has the same problem. So I dont think it is the cylinder bore smoothness.
03-03-2008, 09:20 PM
#23
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This is a really good post. Thanks! I am having the same issues ever since I replaced my clutch and master. I researched through McLeod and their super moderator sent me this link http://www.mcleodind.com/forum/showthread.php?t=84 I'm not sure which of the two will fix the problem but it's worth doing both mods to make sure you won't have to end up taking the m/c back out.
Last edited by 99SilverZ; 03-03-2008 at 10:29 PM.
03-12-2008, 12:00 PM
#26
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The reason for boring the housing is to get rid of any metal shavings that were in the housing from CNC, shavings tend to tear seals. The reason there is a pressure fluctuation is in the design of the CNC piston versus the Wilwood piston. The CNC piston has a O-Ring to keep fluid in the cylinder which is a half *** design where as the wilwood piston is machined to cup the fluid against the inner wall of the cylinder. You may need to slightly grind down the ball end of the Master cylinder rod that connects to the pedals. The seat on the CNC piston is deeper than the seat on the wilwood piston so the ball end does not seat flush against the wilwood piston. A smaller I.D. retainer washer would also be beneficial.
03-12-2008, 12:07 PM
#27
The reason for boring the housing is to get rid of any metal shavings that were in the housing from CNC, shavings tend to tear seals. The reason there is a pressure fluctuation is in the design of the CNC piston versus the Wilwood piston. The CNC piston has a O-Ring to keep fluid in the cylinder which is a half *** design where as the wilwood piston is machined to cup the fluid against the inner wall of the cylinder. You may need to slightly grind down the ball end of the Master cylinder rod that connects to the pedals. The seat on the CNC piston is deeper than the seat on the wilwood piston so the ball end does not seat flush against the wilwood piston. A smaller I.D. retainer washer would also be beneficial.
Thanks for the update and advice.
03-16-2008, 10:43 PM
#28
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hmmm, so if i have never had this issue should i bother tearing the master down? i have had it on the car for at least 4 years without a single issue. the stiff pedal feel i have found to be contributed to the fact that I am running a street twin, and the lt1 style i was running felt even firmer than an ls1 clutch setup, guess i will find out how soft it is in a day or two 
03-17-2008, 06:48 AM
#29
Well, I just ordered the rebuild kit from Jegs but they are backordered till 04/01/08, Summit is backordered till 04/04/08. I'll add this to my list of things to do when I pull the trans and throw on a new flywheel. I'm going to be putting in a remote bleeder at the same time so I figured I'd try this rebuild kit as well.
03-17-2008, 12:07 PM
#30
Well, I just ordered the rebuild kit from Jegs but they are backordered till 04/01/08, Summit is backordered till 04/04/08. I'll add this to my list of things to do when I pull the trans and throw on a new flywheel. I'm going to be putting in a remote bleeder at the same time so I figured I'd try this rebuild kit as well.
03-17-2008, 06:07 PM
#31
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Here another cheap fix http://www.mcleodind.com/forum/showthread.php?t=164 It's alot cheaper than a $30 kit thats on back order. Just in case you missed it, it's napa part#12400. And yes it works, as I have tried it.
03-17-2008, 09:06 PM
#32
Can somebody take a picture of the issue for me? I'm in the middle of doing some tuning this week, but next week I plan on pulling the trans and the Master/Slave cylinders and would like to fix the issues with my clutch setup. So having a picture of what to look for would be helpful.
Thanks.
Thanks.
03-17-2008, 09:41 PM
#33
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hmmm, so if i have never had this issue should i bother tearing the master down? i have had it on the car for at least 4 years without a single issue. the stiff pedal feel i have found to be contributed to the fact that I am running a street twin, and the lt1 style i was running felt even firmer than an ls1 clutch setup, guess i will find out how soft it is in a day or two
03-19-2008, 09:37 AM
#34
I ordered my Wilwood rebuild kit this past week... when it comes in (and I install it) I will post the results. I hope this works as I've been dealing with this for way too long. Thanks for all of the information... too bad I didn't see the NAPA part number a couple of days ago...
04-01-2008, 10:22 AM
#35
My kit should be here today or tomorrow. I'm going to guess that my master cylinder o-rings are leaking as I don't have an issue with air in the line or old fluid, but after a couple high rpm (6500+) shifts, or even a prolonged WOT run, say in 3rd gear from 2000-6500 rpm, the peddle feels normal, but I have issues shifting. The trans was completely rebuilt by Sixspeeds inc and the clutch and pressure plate seemed to be fine.
Does anyone have a rebuilt diagram for the Mcleod master? I'm sure it's pretty self explanatory, but having an expanded parts diagram is always helpful.
I'll snap some pics when I pull it apart.
Does anyone have a rebuilt diagram for the Mcleod master? I'm sure it's pretty self explanatory, but having an expanded parts diagram is always helpful.
I'll snap some pics when I pull it apart.
04-01-2008, 09:27 PM
#36
Big problem. I got the Wilwood rebuild kit today, pulled the master cylinder, pulled it apart, went to replace the piston and the wilwood one won't go in much more than 1/2".
I measured the diameters of the Mcleod one and the Wilwood and the Mcleod is 0.807" and the Wilwood is 0.810", granted, it doesn't sound like a lot, 3 thousands, but trust me, it's not going to go in.
The cylinder bore is supposed to be 13/16 which works out to be 0.8125 and I measured the opening to be 0.8115, but it must get tighter as it progresses down.
I'm ready to call it quits and just buy a factory master cylinder and call it a day.
Does anyone have a diagram for the Mcleod master cylinder?
I measured the diameters of the Mcleod one and the Wilwood and the Mcleod is 0.807" and the Wilwood is 0.810", granted, it doesn't sound like a lot, 3 thousands, but trust me, it's not going to go in.
The cylinder bore is supposed to be 13/16 which works out to be 0.8125 and I measured the opening to be 0.8115, but it must get tighter as it progresses down.
I'm ready to call it quits and just buy a factory master cylinder and call it a day.
Does anyone have a diagram for the Mcleod master cylinder?
04-01-2008, 10:14 PM
#37
I got this from their tech support last year:
"Put the M/C on end with the rod facing up. put the spring in first with the metal cup attached facing upward. Then put the rubber cup in next with the hollow side downward. Then put the piston on top of the rubber cup (flatend down) and then the pushrod with washer and snap ring last. Lastly the rubber boot."
No diagram, they don't have one.
"Put the M/C on end with the rod facing up. put the spring in first with the metal cup attached facing upward. Then put the rubber cup in next with the hollow side downward. Then put the piston on top of the rubber cup (flatend down) and then the pushrod with washer and snap ring last. Lastly the rubber boot."
No diagram, they don't have one.
04-01-2008, 10:55 PM
#38
Thanks for the reply viper. I figured it out when I looked at the wilwood site. But still, the wilwood piston is too large in diameter to work. So I'm back to the drawing board. I'm still going to try and use the wilwood spring and put a new cup on the end of the piston. It will give a slightly softer peddle pressure. I definitely needed to clean out the master cylinder. It was filled with crap and the spring was a mess. We'll see if this makes a difference.
04-02-2008, 06:31 PM
#39
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I'am the one that started the origanal post. If you look at the cup you pull out it syas it's 13/16 inch. That's why I orderd that size from Wilwood. Just shows the maching is off on some of these master cylinder compaired to others. Sounds like yours was simular to mine. Bore was tighter at the top and bigger at the bottom. I had the most problem when it was cold; piston would hang the most then. After it warmed up it would start working better. But still cold or hot if I pumped it real quick several times pedal would start dropping closer to floor and pedal wouldn't come back up like piston was sticking. I did use a small two stone wheel cylinder hone and honed out master cylinder before installing the Wilwood kit. Remember you don't want a mirror polished surface inside. The small scratches the hone leaves on the cylinder walls holds a film of brake fluid that helps lubricate the piston and seals. I would hone at the top more until the Wilwood piston goes in. Mine is still working great.
04-02-2008, 07:42 PM
#40
I'am the one that started the origanal post. If you look at the cup you pull out it syas it's 13/16 inch. That's why I orderd that size from Wilwood. Just shows the maching is off on some of these master cylinder compaired to others. Sounds like yours was simular to mine. Bore was tighter at the top and bigger at the bottom. I had the most problem when it was cold; piston would hang the most then. After it warmed up it would start working better. But still cold or hot if I pumped it real quick several times pedal would start dropping closer to floor and pedal wouldn't come back up like piston was sticking. I did use a small two stone wheel cylinder hone and honed out master cylinder before installing the Wilwood kit. Remember you don't want a mirror polished surface inside. The small scratches the hone leaves on the cylinder walls holds a film of brake fluid that helps lubricate the piston and seals. I would hone at the top more until the Wilwood piston goes in. Mine is still working great.
Thanks for the reply. My problem is that it is tighter as it progresses into the cylinder bore. I can get the wilwood seated but there is no way it's going to move in the cylinder. Unfortunately, I have no way of accurately opening up the cylinder bore myself. I guess I could take it to a machine shop, but how much is that going to cost me.
At least I got it cleaned out as it was a mess inside there as you can by the spring. Worst case scenario is I pick up a new '02 GM master cylinder and hope the engagement is good.