(UPDATE)Anybody that still can't get the Chebby discs to stop?

[Blue71]

OK fellas. I did a little more searching and may have a little light on the subject. Went back to NAPA and referenced the part #'s for the '76 F250 2WD Camper Special M/C. Turns out that there are two part #'s for that year. One is Napa Part # 39014 which is 1 1/4" Bore and the other is Napa part # 36399 which is 1" bore. Can't find my paperwork/reciepts from Napa where I bought the M/C, but I'm betting I got the 1 1/4" M/C which is giving me the hard pedal and won't stop this thing. Can anyone varify the Napa part # that they used before I go out and spend the $$$ on the Napa # 36399 M/C? Was it either of these?

Thanks Much,
Blue71

 

[Skuzzlebutt]

My F250 camper special with dual piston calipers M/C has a 1 1/16" bore and works great. It migh be a '77 or '78 tho.

 

[67EB_in_619]

Try plugging the output to the rears AT the MC... take that entire system out of the mix. Also verify the pushrod to MC clearance... too much gap wastes a lot of pedal.

If it is a problem of too much effort to push the pedal after 1/4 pedal travel.. it very well could be a faulty booster loosing vacuum. Try unplugging the vacuum from the booster and that way you will never have the booster assist and you can see if the pedal effort is linear.

with or without a booster a 1 1/4" MC shouldnt put you in a situation where you cant stop it... just might have to stand on it to move the pedal.. but it should move.


As a side note.. I dont know the year, but many are happy with the corvette MC.

 

[Hazegray]

For the WH Booster "kit", here's the skinny from an e-mail I received from them:

"The bore diameter on the MC for our power brake kit is 1 1/8 inches. We don’t buy them direct, but we do have a Napa part number for it, 4739447."

As stated previously with this setup, I get good pedal response at 1/4 travel, then it's hard to stop past this point. FWIW: This master cylinder has the lines on the passenger side...

 

[American Pride]

the 77 f250 2wd, dual cal. has a mc bore of 1 1/16 and lines on d/s.

 

[67ster]

I used the stock '67 MC , removed the residual check valve , installed a Wilwood adjustable prop. valve in the rear and used a 2lb. residual in the front . I did away with the H valve completely. After some initial hard stops , It felt like the rears were coming in too soon so I dropped the pressure for the rear . After using it for some stop and go driving ( about 100 miles ) it got better and better ,I suppose the pads finally seated ? I will lock up 31s on dry pavement with a firm pedal , no problemo and no booster.

 

[Raskew]

Blue 71,

When I did mine, I bought it from a local parts company called Lordco. The part numer I got was MC36399, and the other model available was a MC39368....looks like the same number as Napa uses.

With the one I bought, I didn't have to take the residual valve out at all. Grinding down the knuckle was trial and error. I ground a whole bunch off and took it for a test drive. It braked OK, but then not well at all. Found out that the caliper was binding again, so I took more off. Now they work great.

Rick

 

[YellowBronc]

Blue,

It's been some time since I did my conversion so I'm not completely positive on the bore size I got. However, if you want to check it with NAPA, here's the part number I bought. It works great with mine. 47-39368 and cost me $35 in July of 2002.

I sure want to say it was a 1 1/16" bore if my memory serves me.