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Discussion Starter · #1 ·
Can someone tell me what master and what it took to install in a 70 Chevelle with manual disk/drum setup? I see the Wilwoods, and stock replacements, but I am worried about messing up a working brake system. I have a stock manual drum/drum master in the car and I generally have no problem getting it stopped. I plan on getting into the high 8's soon at probably 152 and the car is almost 3200 lbs. I have been putting it off for fear of not getting pedal ratio or bore size right and winding up with a setup that doesn't stop. It has a stock firewall and pedal assembly if that matters. I don't have the tools to do much fabricating so I need kind of a bolt in setup. Thanks.
 

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I would say a 7/8 bore master would give you the best pedal feel.
 

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I did this swap on my nova and have been trying to get it to work correctly for over a year. It will stop, but not great. I used a M/C off of a D150 dodge pickup, similar to strange but cheaper. I can get you the part number, but I am thinking my problems is the bore is too large on this one, it is 1-1/8. You will need a 7/8 like stated or 1" bore and I think you will be better off than I am.

There is an article on Dragstuff that lists all of the part numbers and their bore sizes. I can find it if you need them.

James
 

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I used the stock master on a disc/drum setup and worked fine,just make sure to get the right proportioning valve like one off a camaro. I now run a wilwood with a 1" bore and cant really tell a diff stops just fine.
 

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Just learned myself last week that a Stock Replacement Master for an 89 Caravan has a 7/8 Bore and has the same bolt pattern as a Wilwood for under $50
 

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Discussion Starter · #7 · (Edited)
I forgot to mention the car has a Wilwood disk brake kit on it, and was never a disk/drum car. It also has an adjustable proportioning valve on it now. As far as I can tell, the stock master is a 1" bore size. And I am seeing that a smaller bore means more pressure. But when I bought the Wilwood Kit, they recommended a 1 1/8" master. I think I tried the 67-68 camaro master that was that bore size but with manual disk/drum and a new GM prop valve and the back brakes to me seemed weak. I was only going 125 at the time and didn't have a problem getting stopped.
 

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I forgot to mention the car has a Wilwood disk brake kit on it, and was never a disk/drum car. It also has an adjustable proportioning valve on it now. As far as I can tell, the stock master is a 1" bore size. And I am seeing that a smaller bore means more pressure. But when I bought the Wilwood Kit, they recommended a 1 1/8" master. I think I tried the 67-68 camaro master that was that bore size but with manual disk/drum and a new GM prop valve and the back brakes to me seemed weak. I was only going 125 at the time and didn't have a problem getting stopped.
Yeppers this changes my comment!LOL! I'm still running the stock front disc brks and when we narrowed the rear end I went with big ford bearing ends and used drum brakes off of a 83 f-150.
 

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i used a mc98895 ( 1 1/8'' bore) on my 71' Chevelle, car is still sitting stands so who knows if it stops :eek: but i had to blow out the two mounting holes to fit over factory studs. its was $35 off amazon, and the 24mm bore version is $38

 

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Discussion Starter · #11 ·
I finally got a call back from Wilwood, and they told me that it's a toss up between a 7/8 and 1". They said the 1" is more linear, and you should feel it as soon as you step on it. 7/8" may have more of a dead spot and increase much more quickly meaning it can be touchy if you get on them too hard. Has anyone else heard of this?
 
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