Gonna replace my MC and brake hoses, A couple of questions.

[toms68cst]

I'm getting ready to change out the Master Cylinder and brake hoses on my '68. Everything is stock.

Does it matter which I do first? Should I just bleed the whole works when I'm done?

I see that you need to bench-bleed the MC. Some Youtube videos show bleeding the proportioning valve after MC replacement. I don't see a bleed port on my prop valve. Is this necessary?

Bleeding the brakes otherwise seems pretty straightforward. Sounds like only DOT 3 Synthetic is available these days but should be OK to use.

Any other tips?

[PbFut]

Bleed at the end. I saw a lot on bench bleeding the MC when I was looking at tips while doing my cleanup. I am not convinced it matters but I did so as it was easy. I had some old tubing and fittings laying around. I cut and installed two short tubes on the MC and cycled fluid back up the reservoir as suggested. I did this while the MC was in place on the truck. Then placed the bleeder tool on the combo valve to lock the safety ram. Hooked up the MC to combo valve and vacuum bled furthest to closest corner. As long as the Proportion Valve section of the Combo valve is working correctly, it’s a snap to do. The proportion valve on my combo unit was faulty and it took me a couple days of questioning my technique before I realized the valve was bad. Inline had a replacement to me in two days and I was good to go. As a side note. The bleeder tool for the combo valve is not required if everything is in working order and you bleed slowly. The tool is < 10 bucks on Amazon and eliminates lots questions if things are not working correctly. It saved me with the faulty proportion section. Buy the plastic one. Less chance of damaging the ram you are locking in place.
Just realized yours is a 68. I don't think you have a combo valve unless someone added front discs. You will have one less component to deal with and bleeding will be a snap.

[don t. - 72gmc]

I have a 70 GMC...4 drums.

I bought 4 quarts of DOT3. Like you said, synthetic is all thats available. I used 3 quarts.

I bench bled master as I still had the connectors from years gone by. All I needed was the plastic tubes.

Bled the system after all was installed, ready to go. As stated, farthest to nearest.

Good luck...Don.

[BigTopGT]

I'm in a similar boat, in that I just replaced the MC, but I'm not getting anything to the rear brakes.

The shop taking care of it while I'm out of town (or I'd have done it myself) wants to replace he rear brake hoses.

Tom, is there any chance you've got part numbers you can share for those rear hoses, so I don't buy the wrong ones 15 times.? 😁

Mine is a 67 with coils and 8 lugs

Thanks!

[72c20customcamper]

Originally Posted by BigTopGT

I'm in a similar boat, in that I just replaced the MC, but I'm not getting anything to the rear brakes.

The shop taking care of it while I'm out of town (or I'd have done it myself) wants to replace he rear brake hoses.

Tom, is there any chance you've got part numbers you can share for those rear hoses, so I don't buy the wrong ones 15 times.? ��

Mine is a 67 with coils and 8 lugs

Thanks!

Only one rear hose . Mine I used a Napa part 36592 there are two hoses listed one is 13 inches the other I believe was 18 mine in the truck was 13 so I’m assuming the 18 is for 4 wheel drive

[BigTopGT]

Originally Posted by 72c20customcamper

Only one rear hose . Mine I used a Napa part 36592 there are two hoses listed one is 13 inches the other I believe was 18 mine in the truck was 13 so I’m assuming the 18 is for 4 wheel drive

Here's what NAPA says.

Never easy, is it? 😁

[BigTopGT]

Originally Posted by 72c20customcamper

Only one rear hose . Mine I used a Napa part 36592 there are two hoses listed one is 13 inches the other I believe was 18 mine in the truck was 13 so I’m assuming the 18 is for 4 wheel drive

Thankfully, we got the rear brake line sorted, but I'm still not getting the brakes to come on the way they should.

. So frustrating.

So, you guys are thinking it's a bleed issue?

[72c20customcamper]

Originally Posted by PbFut

Bleed at the end. I saw a lot on bench bleeding the MC when I was looking at tips while doing my cleanup. I am not convinced it matters but I did so as it was easy. I had some old tubing and fittings laying around. I cut and installed two short tubes on the MC and cycled fluid back up the reservoir as suggested. I did this while the MC was in place on the truck. Then placed the bleeder tool on the combo valve to lock the safety ram. Hooked up the MC to combo valve and vacuum bled furthest to closest corner. As long as the Proportion Valve section of the Combo valve is working correctly, it’s a snap to do. The proportion valve on my combo unit was faulty and it took me a couple days of questioning my technique before I realized the valve was bad. Inline had a replacement to me in two days and I was good to go. As a side note. The bleeder tool for the combo valve is not required if everything is in working order and you bleed slowly. The tool is < 10 bucks on Amazon and eliminates lots questions if things are not working correctly. It saved me with the faulty proportion section. Buy the plastic one. Less chance of damaging the ram you are locking in place.
Just realized yours is a 68. I don't think you have a combo valve unless someone added front discs. You will have one less component to deal with and bleeding will be a snap.

68 has a combo valve I had a hell of a time bleeding the brakes I had to use the bleeding tool

[Wrenchbender Ret]

Do the master cyl. first before anything else. Bench bleed the MC & install it. Pump the brakes a few times till the pedal gets firm. You can bleed a little at the tubes connecting at the MC. Then bleed at the wheels. You will not waist a lot of fluid this way.

George

[toms68cst]

Thanks for all the input everyone. I ordered up a Delco M.C. and Delco hoses from Rockauto. I have not checked the hoses yet, but the M.C. looks to be a perfect fit and resembles the original one pretty well.

[BigTopGT]

Originally Posted by toms68cst

Thanks for all the input everyone. I ordered up a Delco M.C. and Delco hoses from Rockauto. I have not checked the hoses yet, but the M.C. looks to be a perfect fit and resembles the original one pretty well.

Awesome sauce!

Any chance you've got a link or part number?

[toms68cst]

I'll post up the part numbers once I am sure they are all right.

I got some pre-work done this afternoon. Will probably tackle it tomorrow.

Do I need to put anything on the threads of the fittings into the master cylinder?

[72c20customcamper]

Originally Posted by toms68cst

I'll post up the part numbers once I am sure they are all right.

I got some pre-work done this afternoon. Will probably tackle it tomorrow.

Do I need to put anything on the threads of the fittings into the master cylinder?

Nothing on the threads . Seal is done by the flare on the tube

[Steeveedee]

In fact, don't put anything on the threads. Brake fluid can be degraded by many things. As an aside, I've seen where people put Teflon tape on fuel lines, which are also double flared. They also do not need thread sealer.

[Rust_never_sleeps]

Where those old-a$$ hoses connect to the hard lines you'll want to start marinating them in penetrating oil, PB, etc as early as possible.
Particularly in the back, if the nut rotates but doesn't turn separately from the tubing, it'll kink like your creepy Uncle

[BigTopGT]

Originally Posted by Rust_never_sleeps

Where those old-a$$ hoses connect to the hard lines you'll want to start marinating them in penetrating oil, PB, etc as early as possible.
Particularly in the back, if the nut rotates but doesn't turn separately from the tubing, it'll kink like your creepy Uncle

Like Creepy Dave? 😁 😁 😁

https://www.tiktok.com/t/ZT867UsJF/

[71CHEVYSHORTBED402]

Originally Posted by Rust_never_sleeps

Where those old-a$$ hoses connect to the hard lines you'll want to start marinating them in penetrating oil, PB, etc as early as possible.
Particularly in the back, if the nut rotates but doesn't turn separately from the tubing, it'll kink like your creepy Uncle

[toms68cst]

Love the creepy uncle comments!

I got the MC changed out and bled yesterday. It went pretty well. It's a lot firmer and sure than the old one.

Now I'm working on the hoses. Got them soaking overnight. Hopefully the fittings break loose. I've invested in a set of brake line wrenches.

[toms68cst]

Thanks for all the help everyone. I managed to get the front lines off and replaced with no problems. The rear fitting did not budge so I gave up on it for now. I think I may have to replace the whole brake line from the cab to the back of the truck.

I got everything bled out with some assistance from the wife.

Here's a copy of my order.

[BigTopGT]

Hey gang,

Still trying to find the center line and it looks like the thing that I'm missing is the actual brass distribution block.

When you're ordering the hose, does it come with that distribution block or do I need to go to Home Depot and pick one up?

[Steeveedee]

There should already be one attached at the pumpkin.

[BigTopGT]

Originally Posted by Steeveedee

There should already be one attached at the pumpkin.

Ah, gotcha.

I assumed it was all one piece to be replaced.

[Steeveedee]

As long as it has been on there, it may get destroyed when you remove the lines.