What master cylinder should I use?
09-20-2012, 08:44 PM
#1
What master cylinder should I use? I'm running a Chris Alston chassis with wilwood brakes in front with stock 10 bolt rear end.
I'm looking at purchasing a wilwood master cylinder and not running a power booster.
Should I go with 1 inch.
Also I'm running a t56 what adapter are you using and whatelae is needed for install on fire wall..
Thanka
I'm looking at purchasing a wilwood master cylinder and not running a power booster.
Should I go with 1 inch.
Also I'm running a t56 what adapter are you using and whatelae is needed for install on fire wall..
Thanka
09-20-2012, 10:19 PM
#2
I went with a 3/4 inch clutch master and 1" brake master in mine and haven't had any issues. I've got Wilwood Dynalite 12" brakes in front, stock 10-bolt disc brakes in back, and a wilwood adjustable brake prop valve. The clutch master is connected to a Spec-supplied slave cylinder (Jeremy @ Spec can give you details) via a braided steel line. I'm also using a 18 inch remote bleeder line. The clutch master line is a factory stock hose, with the master cylinder end removed and a 1/8 NPT 90 degree end pressed on by a Carquest machine shop in Chicago Heights (the mod cost only $15 - beats buying a new "conversion line" for crazy $$$)
I'd started out with a Detroit Speed conversion plate and a GM-style adjustable master cylinder made by Ram. Turns out the master was a real piece of crap and started leaking during a shakedown run at Road America. It almost ruined my weekend, and I vowed to not let that happen again. A friend and I did some measuring, and decided the extreme angle at which the master cylinder rod connected to the pedal was likely the underlying issue behind the leak. It was roughly 45 degrees, and the act of pushing the clutch pedal in also placed a lot of side-load on the rod. The rod was slightly bent when we removed it.
Soooo, we devised a setup in which the clutch master rod connected to the pedal at a more direct angle (close to 90 degrees, instead of the 45 degrees of the original setup).
Step 1: The pictures below show a 1981 Trans Am firewall, with the stock power booster and brake master removed, and replaced with Wilwood parts. There are 4 mounting studs where the brake booster connected to the car. The new brake master (green arrow) bolts to the upper two studs, and its push rod connects to the upper hole on the brake pedal.
Step 2: Firebirds and Camaros don't have a whole lot of space in this area to mount the remote reservoir for the clutch master, so we made a mount for it out of scrap angle aluminum (red arrow), which was mounted to the left two studs originally used by the stock brake booster. Washers were placed between the angle-aluminum and the firewall on the left-lower bolt, in order to make things level.
Step 3: To cover the big ugly hole left by the removal of the original T56 master setup, I cut an additional piece of 1/4" aluminum stock. This was mounted to the firewall using existing holes in the firewall (orange arrow, second pic).
Step 4: The Wilwood Clutch master (first pic, blue arrow) is mounted to the right-upper stud originally used by the stock brake booster. A hole was cut in the firewall (second pic) to clear part of the master cylinder body and the pushrod. This hole is over an inch in diameter and centered roughly 3/8 inch "north" of the right-lower mounting stud, which was cut off. I used a stepped drill bit to make the hole.
Step 5: A new right-lower mounting bolt was installed by placing the master into the intended location, bolting the upper flange hand-tight to the right-upper stud, and then marking the location for the bottom flange hole (second pic, purple arrow). The drilled hole penetrated both the 1/4" aluminum plate and the firewall. If you don't need to cover an ugly hole like I did, then you'll likely just need to use a few washers to level the clutch master.
Once assembled, we bled everything out, and haven't had a single issue yet. I've been very happy with the setup. BTW, I'll be selling off the DSE conversion plate, if anyone is interested.
I'd started out with a Detroit Speed conversion plate and a GM-style adjustable master cylinder made by Ram. Turns out the master was a real piece of crap and started leaking during a shakedown run at Road America. It almost ruined my weekend, and I vowed to not let that happen again. A friend and I did some measuring, and decided the extreme angle at which the master cylinder rod connected to the pedal was likely the underlying issue behind the leak. It was roughly 45 degrees, and the act of pushing the clutch pedal in also placed a lot of side-load on the rod. The rod was slightly bent when we removed it.
Soooo, we devised a setup in which the clutch master rod connected to the pedal at a more direct angle (close to 90 degrees, instead of the 45 degrees of the original setup).
Step 1: The pictures below show a 1981 Trans Am firewall, with the stock power booster and brake master removed, and replaced with Wilwood parts. There are 4 mounting studs where the brake booster connected to the car. The new brake master (green arrow) bolts to the upper two studs, and its push rod connects to the upper hole on the brake pedal.
Step 2: Firebirds and Camaros don't have a whole lot of space in this area to mount the remote reservoir for the clutch master, so we made a mount for it out of scrap angle aluminum (red arrow), which was mounted to the left two studs originally used by the stock brake booster. Washers were placed between the angle-aluminum and the firewall on the left-lower bolt, in order to make things level.
Step 3: To cover the big ugly hole left by the removal of the original T56 master setup, I cut an additional piece of 1/4" aluminum stock. This was mounted to the firewall using existing holes in the firewall (orange arrow, second pic).
Step 4: The Wilwood Clutch master (first pic, blue arrow) is mounted to the right-upper stud originally used by the stock brake booster. A hole was cut in the firewall (second pic) to clear part of the master cylinder body and the pushrod. This hole is over an inch in diameter and centered roughly 3/8 inch "north" of the right-lower mounting stud, which was cut off. I used a stepped drill bit to make the hole.
Step 5: A new right-lower mounting bolt was installed by placing the master into the intended location, bolting the upper flange hand-tight to the right-upper stud, and then marking the location for the bottom flange hole (second pic, purple arrow). The drilled hole penetrated both the 1/4" aluminum plate and the firewall. If you don't need to cover an ugly hole like I did, then you'll likely just need to use a few washers to level the clutch master.
Once assembled, we bled everything out, and haven't had a single issue yet. I've been very happy with the setup. BTW, I'll be selling off the DSE conversion plate, if anyone is interested.
Last edited by 1981TA; 09-20-2012 at 11:59 PM.
09-20-2012, 10:25 PM
#3
Disc front, drum rear, no power, would be 1" bore, but Wilwood would be the pople to ask if you are using their master cyl. If you do not use a proportioning valve, you will need a metering valve to "hold off" the front for a split second so the back brakes will hit first, otherwise you will be doing most of your braking with only the front....
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09-21-2012, 07:53 AM
#12
The DSE part is top-notch high quality and made to position a 4th gen master cylinder in the same spot a 2nd gen mechanical linkage would go, so people don't have to do a bunch of fabrication. I have no complaints about the conversion bracket. If you end up using a factory or cheaply made master, however, be prepared for potential leakage. I think the Ram master is cheaply made and would go with a Tick if I had to stick with the factory mount points or didn't want to any fabrication.
