Brakes/ Radiator

[90GMCJim]

I have been paying attention to my master cylinder and noticed it was low the other day. Found signs of a leak somewhere.

After doing research I seen the c3500 1 ton swap pop up a lot.

No longer available. At this point I have no problem replacing the booster and master cylinder. Any recommendations.

I do have the el dorado rear disc brake setup and 3/4 ton wilwoods in front. Rear semi float and 8 lug swap in front.

On to the radiator I see signs of a big leak around the reservoir. What could be causing this? I added half a gallon of distilled water and today there is nothing inside.

Any help or suggestions would be highly appreciated appreciated. Driving this rig a lot more and the kids like going to local

 

[nvrenuf]

The plastic reservoirs are known to crack.

 

[Wes Harden]

For the brake booster, stock for your truck is fine. The master you could go with the Cadillac eldo, or a gmt800 3/4 ton with disc/disc

 

[90GMCJim]

For the brake booster, stock for your truck is fine. The master you could go with the Cadillac eldo, or a gmt800 3/4 ton with disc/disc

Thank you. Does the year make a difference?

 

[Wes Harden]

shouldn't matter on year, but for the gmt800 early 2000's. Any GM master should fit your booster, the important part is the diameter of the piston bore and that it is for disc disc config

 

[90GMCJim]

shouldn't matter on year, but for the gmt800 early 2000's. Any GM master should fit your booster, the important part is the diameter of the piston bore and that it is for disc disc config

Those 2 distribution blocks below the master. Any chance that those go bad? Is that 1 wire on top for the brake light in the dash? I never did the prop valve when doing the rear disc brakes. The brakes bleed fine and the rig stopped good. I do have it. Should I use that? Prop valve for the rear?

 

[imiceman44]

Those 2 distribution blocks below the master. Any chance that those go bad? Is that 1 wire on top for the brake light in the dash? I never did the prop valve when doing the rear disc brakes. The brakes bleed fine and the rig stopped good. I do have it. Should I use that? Prop valve for the rear?

A lot of people ditch the prop valve when they go disc rear.
It's not the best thing to do but it's been working good for 50% of those who do it.
If your happy with it then it's all good

 

[Wes Harden]

That valve is also reffered to as combo valve as it has 2 jobs. 1st as a saftey valve, if 1 half of the brake hydraulics looses pressure a shuttle valve will move to block the line/s with a leak. The 2nd is to provide the proper amount of flow for balanced braking.

I would keep it. The other porportioning valve you mentioned is probably to balance a modified brake system, if needed.

Disc calibers use more fluid to actuate over wheel cylinders. Wheel cylinder master cylinders also incorporate a residual pressure valve to maintain enough fluid in the line for quick activation.

 

[nvrenuf]

Iirc, that vertical black box is part of the Rear Wheel Antilock Brakes. It’s very likely that the RWAL components quit working a long time ago plus having rear disc brakes now changes everything. If you’re going to open the system for a master cylinder I’d delete the dead weight.

 

[tarussell]

Iirc, that vertical black box is part of the Rear Wheel Antilock Brakes. It’s very likely that the RWAL components quit working a long time ago plus having rear disc brakes now changes everything. If you’re going to open the system for a master cylinder I’d delete the dead weight.

The old RWAL system - it was troublesome when it was new !

Keep the hydraulic safety valving equipment and adjust as needed but say goodbye to the electrical system.

 

[90GMCJim]

I just ordered a new coolant reservoir. Looked up the master cylinder for a gmt 800 around 2002. Rockauto does not list disc/disc setups on their description. So I just go with the larger master cylinder? Bigger piston?
I believe there are 2-3 sizes.

 

[tarussell]

You could also just verify if the year chosen offered rear disc brakes by looking up the individual parts for the rear brakes and go from there on selecting the largest M/C bore diameter.
GMT-400 HD3500’s ( medium-duty not just a 1-Ton ) had rear discs and large bore cylinder diameter as well as the regular 3500 GMT-800 stuff to go along with a rear disc application.

 

[nvrenuf]

If I remember correctly, my master cylinder is for a 99 C3500HD.

 

[90GMCJim]

If I remember correctly, my master cylinder is for a 99 C3500HD.

The 99 3500 on rockauto all have the same bore size. On the 2002 gmt 800 they are slightly larger.

Also is both threads 1/2-20?

 

[nvrenuf]

I doubt rockauto is show a true “HD” series truck.