MC Rebuild

[Seth_O]

Before the flames come out: I searched through half a dozen TM's and on the site, however at this point I am ready to accept defeat.

Can someone lend a brother a hand and point me to the TM I need to rebuild the MC in my '68 deuce?

I assume once I get the soft parts out I am ok to hot tank the shell?

 

[Pooch1128]

http://www.jatonkam35s.com/DeuceTechnicalManuals/TM9-2320-361-20.pdf

chapter 8-10

 

[Seth_O]

Tks Pooch. Chpt 8 appears to have instructions on removing and reinstalling, but nothing on rebuilding it?

 

[Pooch1128]

I did search on this site for rebuild and all I found was info on the kits, if there is any rebuild info out there, not sure where....

 

[Seth_O]

Yep, that's the same result I had. Bit frustrating, although I am by no means a search expert on the search function on here......

 

[Pooch1128]

this as a little info....http://www.steelsoldiers.com/deuce/...-exploded-view.html?highlight=master+cylinder

and maybe this.....http://www.steelsoldiers.com/deuce/51117-how-remove-brake-master.html?highlight=master+cylinder

 

[hndrsonj]

I'd look in the 1965 or older TM's. I'm guessing it's not in the newer ones. They'd just replace it. By the way they are on ebay for $45 new...

 

[rlwm211]

On Jatonka, in the Deuce TM section, there is TM 9-1827C which is a "Lockheed/Wagner" Hydraulic Brakes manual explaining the hydraulic brake system with illustrations of the components within the MC and other portions of the system. While I have not found a specific manual for rebuilding the master in the TMs This manual should give you more than enough information to rebuild your master cylinder. The hardest part is getting things back together correctly and to me a picture is worth a trhousand words. This is a pretty simple project as far as actually rebuilding the master goes. Bleeding the brakes will take longer, and is as important as the rebuilding of the master because if there is air in the system, you will have marginal or unreliable brakes.

In order to rebuild the master you will need a hone to properly clean the main bore of the master so it is suitable for use. You can get a hone at your local autoparts store. The diameter is 1.5 inches approximately. You will need a rebuild kit which you can obtain from several sources. MV parts dealers, or ebay may be a good place to start. You will also need DOT5 brake fluid to bleed the system after you reinstall the master. It will take about 2 quarts of fluid to bleed the system. DOT 5 is pricey and you will want to find it from an MV parts dealer as it can be very priciey bought in small quantities. I read recently that JC Whitney has it fairly cheap.

You will want to turn the hone slowly and do an area, then move along a bit further, and do another area inside. You do not want to create a cross hatched pattern when you hone your master. I use a light spray lubricant to cool the stones and remove the material removed. Hone the bore until it is shiny and smooth and prelubricate the parts as you put them together with DOT5.

I hope this helps and please feel free to post any further questions in this thread and I will do my best to help you as I can.

RL
​

here is the link to the site I mentioned: www.jatonkam35s.com ​

 

[Seth_O]

Pooch: tks for the link to the exploded pic, that was helpful.

RL: great TM, it has a wealth of info on the MC and should allow me to rebuild it w/o trouble.

I took a look at ebay, starting prices were $65. I can get a rebuild kit for $25 so that's still a cheaper route (even by the time I get the cylinder tanked and I hone it.)

Tks for the feedback guys, really appreciate the help.

 

[rlwm211]

Seth, if it is possible, I would pull the master and inspect it first. If the corrosion on the bottom of the bore is bad enough you may be better off replacing it. It is a question of how much honing is required.

I initially rebuilt my master but found that the rear seal (not the one under high pressure) weeped because I had to hone the bore as much as I did to get to smooth metal. I had gone outside of what was within the abilities of the seal. There is not any specs I know of, but if it takes more than 15 minutes to get the bore in good condition, I would probably replace it. The longer you run the hone, the more metal you are removing.

I just wanted you to consider this as an option. As far as cleaning and honing, I would use brake cleaner to clean the master. Better to know what you have before making a firm plan.

RL

 

[Seth_O]

I am on the fence on rebuilding it vs replacing it. Initially I pulled it because I was servicing my airpack and the MC is so easy to get to with the airpack out, I figured I might as well. I did find a significant amount of crud in my airpack hydraulic piston. It seemed to hone just fine and was in good shape, but there was a lot of debris, rust, and sludge in there - I figure it migrated it's way down there from the MC.

When I examined the MC on the bench, there was significant debris and rust in the main chamber. I scrubbed it with a wire brush and the metal underneath seems to be solid and good, which is what put me on the trail of a hot tank and rebuild.

However, with a NIB MC on ebay right now for $65, that looks like an appealing route as it removes the guesswork and the labor.

 

[hndrsonj]

MILITARY NEW MASTER CLYINDER,FOR M35A2 , DUECE, - eBay (item 330515635113 end time Mar-05-11 19:48:22 PST)

$45 plus shipping

 

[Seth_O]

Pulled the trigger on a new one last night. Now if I can just get my airpack issue sorted out I can get the truck back on the road!

Tks to all for your help on this.

 

[rlwm211]

What is your airpack issue?

RL

 

[Seth_O]

The brass bushing which attaches the j-pipe to the rear plate on the airpack (covering the piston) sheared off. Liberal application of heat, PB blaster, and force did not get the remains removed from the cover. I drilled it out, but have not been able to get it clean of the threads. Currently looking for a replacement cover plate, I have a WTB posted in the classifieds, I am hoping someone has a trashed airpack they replaced and are willing to sell just that one piece off it. I am not in a position to purchase an entire airpack - other than that one issue the airpack is in good shape and serviceable.

I've never seen brass do this before, it behaved as it if were very brittle. I suppose being 45yrs old will do that.

 

[rlwm211]

Is your airpack the old style, as I have one that cannot be rebuilt and have the parts if need be.

RL

 

[Seth_O]

It is the old style (long.) PM me with price with shipping, it would be awesome if you have a useable end piece I could use.

Tks RL.