C10 master cylinder plumbing

[ga-stepside]

Which master cylinder port is the front brakes on a 1967 C10 with power disc/drum conversion? I have read that on a standard C10 the port closest to the firewall is for the front brakes, is that true. If that is true the PO plumbed this thing wrong. Also note the small size of that front line.

[72SB]

FWIW my CPP MC/Booster for a disc drum 72 (was a non power brake disc/drum truck) my front brakes are forward reservoir and rear drums the rear reservoir. Also the front lines are thinner than rear brake hard line....just like your set up

Not sure what donor or kit you have but suspect it would be the same.

[ga-stepside]

Originally Posted by 72SB

FWIW my CPP MC/Booster for a disc drum 72 (was a non power brake disc/drum truck) my front brakes are forward reservoir and rear drums the rear reservoir. Also the front lines are thinner than rear brake hard line....just like your set up

Not sure what donor or kit you have but suspect it would be the same.

I have no idea where mc and pv came from. From what I have been reading the K10 and the C10 plumbing is backwards, K10 has it they way we are plumbed. Could be the CPP MC is different than the standard GM ones.

[A1971Blazer]

I have 2 K/5 Blazers and 2 C10s...the front port (bottom) is for the front brakes, the rear port is for the rear brakes on all of them. they all have disc/drum

[ga-stepside]

Originally Posted by A1971Blazer

I have 2 K/5 Blazers and 2 C10s...the front port (bottom) is for the front brakes, the rear port is for the rear brakes on all of them. they all have disc/drum

All those posts I read about k10 and c10 being backwards came off this site. I am so confused!!!!!!!!! Makes sense since every picture I see of the PV plumbed to the MS has them plumbed that way.

[HotWheelsFan]

Front disc brakes use more fluid than drum brakes...

As the brake pads wear, more fluid is found in the calipers. As drum brake wheel cylinders operate, springs collapse the wheel cylinders and push the fluid back to the master cylinder. Thus you should find the larger reservoir going to the front.

Bob

[dmjlambert]

I believe it is C20's that have the front reservoir going to rear brakes, and on C10's the front reservoir goes to the front brakes. It is the C20's with the swapped plumbing that causes confusion in my opinion.

The disc brake reservoir should be larger than the drum brake reservoir. For C10's the bore size is 1-1/8 inch for manual or power brakes. Manual brake master cylinders have a deep pushrod hole, while power brake master cylinders have a shallow pushrod hole. Here is a thread with the master cylinder technical info and other good info, including some example C20 info and pictures mixed in. https://67-72chevytrucks.com/vboard/...30#post8909230
But I don't know if there is a right and wrong for the arrangement on a truck that has been converted to disc brakes. If there was a right or wrong, I think your truck is right in my opinion.

I have a C10 71-72 pre-bent tubing set from Inline Tube on my 1969 C10 that has spindles and brakes from a 1971 donor truck, and a manual brake master cylinder. Here's what it looks like, very similar to yours.
-

[Ironangel]

Originally Posted by ga-stepside

Which master cylinder port is the front brakes on a 1967 C10 with power disc/drum conversion? I have read that on a standard C10 the port closest to the firewall is for the front brakes, is that true. If that is true the PO plumbed this thing wrong. Also note the small size of that front line.

Your brakes are plumbed correctly! Only the 20 and 30 series does the front reservoir control the rear brakes and rear reservoir control the front brakes. This is copied from a 72 service manual... The smaller 3/16" line is as per the factory fittings in the MC and the Combination Valve. Your good!

[ga-stepside]

Thanks guys I feel confident mine is plumbed correctly now.

[MikeB]

My 69 has a 71-72 booster and master. Front reservoir is for front brakes. For the type of master cylinder you have, the rule of thumb is the larger reservoir is for front discs.

For whatever reason, GM used 1/4" brake lines on the rear.