The Stovebolt Site Forums The Parking Lot Big Bolts Bleeding brakes on 2 ton

Good evening everyone!

Well, I am going to have to replace the master cylinder on my 1952, 6400 Loadmaster. I have done a lot of brake bleeding on the old pickups but never on one of these 2 tons and according to the manual, they used to do pressure bleeding with a tank, and they call for backing the top shoes all the way off, etc.

Anyone here ever bled the brakes on one of these 6400 Loadmasters, and how exactly did you do it?

Thanks in advance!

Kevin

Kevin,

After trying to bleed the original brakes (with hydro-vac assist) on my 54/55 2-ton GMC COE by "coventional" technique, and failing to get a good pedal, I bought this pressure bleeder:

https://www.ebay.com/p/Motive-Products-0102-Power-Bleeder/1337282658?iid=312131547093&chn=ps

Following the procedure for pressure bleeding described in the Shop Manual (including the order of bleeding), I got very good braking system performance. Of course, I should have believed that the Shop Manual technique for this type of brake system.

http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm0531.htm

Tim,

Thank you, I really appreciate that!

It seemed a but complicated so I thought I had better seek expert help!!

Kevin

[quote=tclederman]

Since this work is in my near term future I'm going to order one of those. Thanks for saving me hours of frustrating work!

Speed Bleeders were the answer for me! Here is a link to a brake bleeding discusion on my '48 LoadMaster 4400.

I rebuilt the master cylinder and all six wheel cylinders on mine, replaced every bit of line and hoses, bypassed the hydrovac until I rebuild or replace it. I had no problem bleeding with no use of power bleeder, just the old fashioned way. I have very good peddle and no leaks. 1957 2 ton

What type of "power brakes" are on your 1957 truck?

I see that an Air-Pak compressed-air/hydraulic brake unit used on 1956 trucks (it might have been an option). It was bled differently from earlier big trucks that had a hydro-vac "booster".

My truck is rated at 16000 lb. GVW, has what I think is the original Hydro-vac booster mounted on the outside of the frame rail under the driver seat. Brake line runs from the master to the Hydro-vac, out of the Hydro to a tee then on to front and rear. 1/2 inch steel tubing runs from the engine compartment down to the booster to feed vacuum. At this time I have bypassed the booster due to internal leaking, it did supply some boost when it was still plumbed into the system but I couldn't keep the master full. From what I have seen on the forum it looks like a Bendix booster but I have not tackled that project yet.

Sorry about bot seeing your first post with:

" . . . bypassed the hydrovac until I rebuild or replace it. I had no problem bleeding with no use of power bleeder . . . "

No power bleeding would be needed in your set up.

http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm0508.htm

I bought a weed sprayer from Lowes and made a pressure bleeder out of it. (take the nozzle off the sprayer end and attached it to an old master cyl cap). You can put a gallon of brake fluid in it and pump it up and bleed to your heart's content!

I think I bought one similar to this one: https://www.lowes.com/pd/Chapin-2-Gallon-Plastic-Tank-Sprayer/1000176197

Greetings all and Merry Christmas !!

I realize this is an older thread but would love to get some info especially from 78 Buckshot who did exactly what i intend to do. I also have a 57 5700 and looking for possible part numbers for the rear wheel cylinders or the rebuild kits for them. I rebuilt the fronts but so far only the passenger side is holding guna take another shot at the drivers side. The rebuild kit I got for the fronts are Dorman #11303 would like to know if that is the same as the ones you used ?

any info is greatly appreciated !!!!

Mike

Welcome to the forum Mike. I'll dig around in my receipts and the boxes that the kits came in and try to give you some numbers. I think all of my kits were Wagner/non-Dorrman but I'm not 100% sure. I did the master and all six wheel cylinders the same way, took them apart, soaked the iron castings in muriatic acid, washed in HOT water and detergent, honed, new kits in all. Of course all new rubber lines and copper/nickle hard lines. It's been about three years and no leaks and good brakes.

for my 58 Viking 60, I used the following: UP = Napa part #, the other is Raybestos from Rock Auto.
rear wheel cylinder kits, (1 1/2" ring type) UP 147, WK147
master cyl kit (1 1/4") UP33 , MK33
front wheel cyl kits (7/8 diameter) UP 129, WK129
rear brake hose, UP4000, DH4000
front brake hose UP25664, BH25664

Thanks for your quick reply had a hard time finding this thread (new to this site) I was able to source new rear cylinders from local old school parts house called “Mars” which still has the original sign from opening in 1948 !!! The cylinders are Dorman part number W81803 Sup and W 81802 Sup upper and lower not sure which is which sorry !! So now I’m off to the fronts which are both leaking after rebuild. I’m gunna give them one more shot at honing unless someone has a source for replacement cylinders ?? Thanks again for your replies and knowledge

Btw I sent my hydrovac out for rebuild to REI just waiting for them to send it back. While I wait for that I’m going to replace all steel lines with the nickel/copper type. The short ones inside the drums had a leak and figured might as well replace them all like “78buckshot” did !! Peace of mind will go a long way !!!

Thanks again to all

Good brakes on a big rig are cheap life insurance, not only for yourself, but for the folks who share the road with you. If you aren't able to find replacement cylinders, it's possible to reline the old ones with stainless steel sleeves that will outlive a couple more owners of the truck. Don't discard a leaky cylinder- - - -someone here will be able to recommend a shop that specializes in relining them.
Jerry

White post restorations in VA.

Ed

Make sure you save the old flare nuts for the line that connects the two cylinders at each wheel. The thread pitch on them could be different than the rest of the system, if so they are not available and will need to be reused.

Mike B

I bought one master cylinder from Chevs of the 40s several years ago, then later when I replaced all the wheel cylinders, I got them from Rock Auto. Bled them the conventional way and had a helper. Took some time but did work. Brakes work excellent, and no more leaks.

Thank you all for that info had to take some time away᠁these are great tips will update ASAP ᠁
Got the Hydro back from REI took 2 months they had to re-sleeve it and man did they make it look brand new !!
The cost was $495. + shipping one way !! I really wanted to get the true pedal so I spent the xtra cash

235 Kidd᠁any chance u have the rock auto part numbers for the fronts or at least the manufacturer?

kthomas On those vertical cylinders,If you can get a .001or.002 feeler gaugedown past your cup,be sure it's burr free,you might vent that air. Just wait till it slobbers out,not real fast but can work.

I am working on the brakes for my '54 6100. Again. If the truck sits for a couple of months without use which can happen in the winter time for me, the brake fluid goes somewhere. Last week the MC was dry. I can pump the brakes to get a good pedal so I have been working on bleeding them. I know I read somewhere that someone was using Speed Bleeders but in my search for these I am having a difficult time finding the correct part. Is anyone else using these and can you tell me a good part # for Russell brand?

For those of you with Brake Boosters, I sent mine off to White Post in VA to restore since cores couldn't be found at the time to get one from the Auto Parts Store. They did a great job and has a lifetime warranty on it.

If you see no brake fluid dripping from fittings it's either going in a brake drum or in the Hydrovac can. I'd pull the drums before it does more damage.

Double check that booster, even if it's been rebuilt. That's where my fluid had been secretly going until discovered. REI did a great job on mine.