full brake job

[isaac_alaska]

need to do a full brake job on my civvy, looks like it's all real similar to the M37 though. wondering where the best place to order parts from is. i ordered a windshield gasket from vintage and they were very easy to work with so i'll probably just order from them, unless there's a better or cheaper option. but my main questions is if there is a dual circuit master cylinder that's easy to bolt up. i figure since i'm replacing it anyway i should probably install a dual circuit while i'm at it.
thanks for the help!
-Isaac

[w30bob]

Isaac,

We just had a pretty long discussion on the subject a month or two ago. Turns out there is no direct replacement dual chamber master cylinder with the 3 bolt mounting pattern of the stock master cylinder. You're going to have to make a simple adapter plate that goes from the 3 bolt to a 2 bolt pattern of most dual chamber MCs. The issue becomes how to vent it. If you want to locate the MC in the same place as the stock one (under the running board)..........and you intend to do some frequent off roading where its wet you'll have to figure that out. Most modern dual chamber MCs use a rubber diaphragm under the top cover, so water won't mix with the brake fluid, but it will fill up the reservoir between the cap and the gasket and start corroding things. I'm still searching for a dual chamber MC with the 3 bolt mounting pattern.....its possible Avanti or International actually used one for a short period of time.......I just haven't found one yet. Search for the posts under "dual chamber" and you can see what we discussed.

regards,
bob

[isaac_alaska]

thanks bob, i guess if that's the case i can just make an adapter plate, probably not too difficult, or even build a whole new bracket out of plate steel. as for venting, the holes in the cap of modern dual circuit could be drilled and tapped and nipples threaded in.

[Cal_Gary]

I completed my brake overhaul last year and the toughest part was finding a shop that could turn the drums. Charles at M-Series supplied my special-order oversized shoes; the usual vendors have most everything else you might need.
Gary

[isaac_alaska]

vintage powerwagons lists having .030" oversized shoes as well, but they cost extra.

i'm trying to get my master cylinder functioning enough to be able to drive the truck around in the yard, and see if there's any leaks in the brake line system. it was pretty siezed up but i got it apart, tomorrow i'm polishing the inside with steel wool and putting it back together.

i want to take the drums off and look at the wheel cylinders, drum linings, and shoes, but i'm stuck at the three flat-head slotted bolts that retain the drum to the hub. i tried using an impact driver (the kind you hammer on the back of, looks like a heavy duty screwdriver) but that didn't work. is it pretty typical to have to drill them out and replace them with new bolts?

[Cal_Gary]

Yep, very typical; mine were already rusted away, and I need to clean out those threads and add the new bolts myself so you added a reminder without knowing it!
Thanks,
Gary

[Kaegi]

yes those screws get real stuck. sometime can get them to turn with a pointed punch. or drill head off then pull drum by pulling the bearings and then you can grab the threads that stick through the back side with vise grips and screw it all the way through. if you rebuild the master cylinder the napa part number for the kit is Number 1

[w30bob]

Isaac,

Kaegi is right, but if you walk into a NAPA and ask for part number 1 the freckle faced 18 year old parts kid is going to think you're nuts. And if there isn't a seasoned parts guy there you ain't getting the master cylinder rebuild kit. Ask for part number "UP-1".......junior can actually find that in this computer. It runs about $18 here in Maryland, but price does vary by location.....and I think Alaska and Hawaii are always more expensive for EVERYTHING. Let us know how you make out.

regards,
bob

[isaac_alaska]

i bought a handful of 1/4-20 phillips head stainless steel screws today to replace the bolts i'm about to drill out (i'm guessing they are 1/4-20 but i haven't actually checked yet) but then i was thinking that if they ever DO get stuck again, it will be very hard to drill the stainless screws out. so i might find something else to use instead.

as for the master cylinder, i got it apart, and the parts inside it actually looked in very good shape, aside from quite a bit of rust on the cylinder itself, and inside. everything was siezed up. We dont' have a Napa here anymore (i helped tear the store down about 15 years go, so they could build Carquest) but the rubber parts inside didn't look worn or cracked, so i cleaned them all up and re-used them. for the cylinder, i soaked it for a few hours in a solution of about 1/2 gallon water to 1/2 cup muriatic acid, and then scrubbed it with a wire brush. for inside, a 1 1/4" plumbers wire brush works really well, just take the plastic piece out of the handle, twist the wire handle up a bit more, and chuck it in a drill. takes ALL the rust out. then i used steel wool on all the brass parts and shined them up like new. putting my finger over the exit hole and pushing the plunger with a socket extension, it makes good air pressure, so i think it's gonna be good enough for driving around the yard. Wish i had taken pictures, but it's hard to remember everything when working with acid and Brake fluid. can't stand the smell/feel/taste of brake fluid.....
eventually i'll re-do it better, but since i'm leaving town in a week i can't afford the two weeks the post office takes for parts.

i also got parts to make a reservoir extension, so now i'll have a reservoir mounted on the firewall, connected by a piece of 3/8 copper line to the original. that will make it MUCH easier to refill without needing a funnel.

a couple of the bleeder valves from the wheel cylinders were broken, but carquest actually had a whole bag of them in stock!
also got parts to make a vacuum bleeder, if all goes well and i get off work early tomorrow i'll be bleeding the brakes and testing them out!

thanks for all the input

[Kaegi]

the drum screws are 3/8 NC. I would use regular steel and antisieze. stainless galls easily. I only use it where strength doesn't matter and there is a nut on one side. the small stainless bolts are not high quality in most cases. unmarked Chinese stuff is all I see in the stores.

[isaac_alaska]

haven't tackled the bolts yet, maybe tomorrow. more likely next year, since i'm running out of time and i'd rather spend what time i do have buttoning it up for the winter so it will stay a bit more dry and out of the elements. before i go and buy bolts, what length should i get? by the looks of it, 3/4" are probably long enough, but for some reason the factory ones seem to stick out the back quite a ways.

i did get the brakes bled, vacuum bleeder didn't want to work, maybe cause i had air leaks in my lines, or maybe cause the wheel cylinders were leaking under vacuum. i havent' seen any fluid at them yet though. i did put teflon tape on all the cylinder bleed screw threads but maybe not enough. the buddy system worked though!

now instead of the pedal falling to the floor, it goes about 1/2 way and then gets totally solid. no pumping required! i'll attribute the 1/2 travel to probably worn brake shoes.

also, because the stock master cylinder is a total pain to add fluid to, i added a little modification.

that's a 1 1/4" x 4" pipe nipple with bell reduces on both ends, the bottom feeds through a 3/8" copper line to the original fill location, and the stock fill cap has been moved to the top of the bell reducer, so it can still vent. easier brake fluid checking plus extra reservoir size!


eventually i will get that hub off


honing the master cylinder with a wad of steel wool woven into a piece of rope. real high tech stuff here!







*edited* let me know if my photos show up this time, hate to resort to facebook hosting but sometimes it works

[52 M-42]

Isaac,

That sounds like a great mod/improvement. I've often muttered about the poor design of the brake fluid filler hole.

Your pictures didn't make through the ether; is it possible to re-post them, or send them to the mods for posting if you can't? I would really like to see what you did.

If that doesn't work, could you PM me and I'll send you my email and I'll post them for you.

Thanks, Isaac!

[Kaegi]

you didn't like getting bruised ribs adding brake fluid? ;/) if you attach the extension to the fender or body it should have some flex or the line will crack form frame flex and vibration. you can put a couple coils in the copper line or and a short flex hose.

[isaac_alaska]

maybe they will come through this time? i edited my previous post.
as for line flex, i used about 18" of soft copper tubing, with 3 bends in it, so it should be able to flex fairly well. it may eventually break, but a break just means a bit of fluid loss, and i'll be able to replace the line with something longer with a couple coils in it.
got the exhaust welded up and bolted in today, it idles very quietly now! Pretty sure i need to rebuild the carb though, accelerator pump seems lacking

[Kaegi]

great looking truck! are those DC3 tires? seen lots of Alaska pics from the old days with those tires. FYI Dodge was the first vehicle to make it up the alcan. Also a friends' father was a surveyor on multiple legs of the construction and he used only Dodge 4x4s to go shoot it all before the heavy equipment came through.