Posted By: rattler
Master Cylinder Size? - 03/13/13 12:40 AM
What bore size Master cylinder are you guys running with a front disc, rear drum manual break set-up?
Master Cylinder Size?
Posted By: RapidRobert
Re: Master Cylinder Size? - 03/13/13 01:29 AM
65 dart DD. 74 A discs/10" drums. 1&1/8 dual alum M/C. On paper the bore is too big but just me putting around town the pedal effort needed ain't excessive (& I'm not that strong). It will lock em up in the rear if I brake too hard but that rarely happens
Posted By: rattler
Re: Master Cylinder Size? - 03/13/13 02:43 AM
THanks. I had an 1 1/8 bore dual aluminum on my green truck. It never would stop very well with 88 dak front brake set up and 70 b-body 11" rear drums.I am thinking it may be the weight sensing proportioning valve deal on the dak. I am replacing that stuff with a b-boby proportioning valve in front and only the single line to the rear like normal.I am trying to improve the breaks before I go down the track this year. Doctor Diff is building me a 1350 drive shaft now.
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Posted By: RapidRobert
Re: Master Cylinder Size? - 03/13/13 03:09 AM
Quote:Funny you mention that as I used the OE drum splitter when I put this together as I needed transportation fast & I figured to put around town I could get by with it for awhile but it'd been over 6 years & zero issues from the supposedly mismatched brake components
It never would stop very well with 88 dak front brake set up and 70 b-body 11" rear drums.I am thinking it may be the weight sensing proportioning valve deal on the dak.
Posted By: Cab_Burge
Re: Master Cylinder Size? - 03/13/13 06:38 PM
I had a 15/16, one of the new alumimum Mopar stock OEM, on my Duster with fenderwell headers, the heat from the headers got to it after 6 yrs so I bought another one from Summit that I thought was the same size, it wasn't 
It was a 1.0 inch diameter, I hadn't measure the original one until it went bad 
The new one is harder to stop the car, it takes more pedal pressure I did the same thing on another drag car that I drove for another racer, the car had sat for five + years between being raced so the M.C. took a dive at the Winternationals during time trials, it was not good but I survived it, same thing on not measuring before replacing 
Take yours out now and measure it 
It was a 1.0 inch diameter, I hadn't measure the original one until it went bad The new one is harder to stop the car, it takes more pedal pressure I did the same thing on another drag car that I drove for another racer, the car had sat for five + years between being raced so the M.C. took a dive at the Winternationals during time trials, it was not good but I survived it, same thing on not measuring before replacing Take yours out now and measure it
Posted By: radar
Re: Master Cylinder Size? - 03/13/13 06:51 PM
I wouldnt buy another manual brake m/c that was more than 1" for chrysler disc/drum.
Posted By: 70Duster440
Re: Master Cylinder Size? - 03/13/13 08:00 PM
I ran a 1-1/8" truck MC and didn't care for it. A panic stop would be a chore. Bought a 1-1/32" aluminum unit from Dr. Diff and it was a big improvement. 15/16" would probably be even better but I can live with it.
(And when I added the blower, exhaust temps boiled the fluid so I had to add a heat shield).
(And when I added the blower, exhaust temps boiled the fluid so I had to add a heat shield).
Posted By: rattler
Re: Master Cylinder Size? - 03/14/13 12:22 AM
I have asked Dr. Diff for a suggestion on Master size. One thing that may be an issue is my pedal ratio, it is 8 to 1. He said I should have about 6.25 to 1. I'll wait and see what he suggests.
Posted By: rattler
Re: Master Cylinder Size? - 03/14/13 06:17 PM
What would be the stock Dodge application for a 1 inch bore aluminum 2 bolt master.If I am going to change bore size, now would be the time while I have the 1 1/8 off.
Posted By: RapidRobert
Re: Master Cylinder Size? - 03/14/13 08:02 PM
Quote:89 dakota -15/16". 85 diplomat- 1&1/32". Couldn't find a 1" listing & do check the 2 I posted to confirm that the bore dimentions are correct
What would be the stock Dodge application for a 1 inch bore aluminum 2 bolt master.
Posted By: BDW
Re: Master Cylinder Size? - 03/14/13 11:33 PM
Posted By: rattler
Re: Master Cylinder Size? - 03/15/13 12:20 AM
Thanks, I'll probaly put the Diplomat master in. That will be about 17% difference im piston area. I have an 8 to 1 pedal ratio, so I don't want to go too small on bore.
Posted By: cruzin
Re: Master Cylinder Size? - 03/15/13 03:12 AM
Just curious, where/how did you achieve an 8:1 pedal ratio?
Like many others, through trial and error, I'm using a 15/16" on my manual disc/drum e-body.
I've recently been switching out and and trying different diameter rear wheel cylinders. I've learned this also will significantly affected braking performance, especially if you are experiencing rear wheel lockup.
Like many others, through trial and error, I'm using a 15/16" on my manual disc/drum e-body.
I've recently been switching out and and trying different diameter rear wheel cylinders. I've learned this also will significantly affected braking performance, especially if you are experiencing rear wheel lockup.
Posted By: rattler
Re: Master Cylinder Size? - 03/16/13 01:29 PM
I had to hang a set of pedals under the dash of my truck( they originally came up threw the floor). To get the pedal down to where it needs to be, it ended up being 16 inches from pivot to pad. The break rod is 2 inches from pivot to rod bolt hole in pedal. I should finish the breaks up today with the F body master and switching to B body proportioning valve. I can't drive it yet, waiting for my new drive shaft to arrive.
Posted By: Cab_Burge
Re: Master Cylinder Size? - 03/17/13 04:44 AM
Quote:Is that a 1957 Dodge cab? It looks really good from the rear
THanks. I had an 1 1/8 bore dual aluminum on my green truck. It never would stop very well with 88 dak front brake set up and 70 b-body 11" rear drums.I am thinking it may be the weight sensing proportioning valve deal on the dak. I am replacing that stuff with a b-boby proportioning valve in front and only the single line to the rear like normal.I am trying to improve the breaks before I go down the track this year. Doctor Diff is building me a 1350 drive shaft now.
I had a 1957 Dodge one ton(small back window) car hauler that had a bunch of miles on it when I bought it, I ended up replacing the motor,clutch, radaitor, rear end and cab It ended up with a 1959 or 1960 cab on it, CRS disease 
Posted By: babarracuda
Re: Master Cylinder Size? - 03/17/13 02:35 PM
I have 73 Duster front disks and pedal effort was terrible. I bought a MC form DR Diff which I believe is 15/16. Much easier pedal effort and stops great. A little more pedal travel but I am used to it now.
Posted By: rattler
Re: Master Cylinder Size? - 03/17/13 03:05 PM
Yep Cab, it's a 57 Dodge cab and bed with a little 512 in it.This year it going down the track. I hope.