The Stovebolt Site Forums The Parking Lot Big Bolts 1956 LCF 5700 gas tank and master cylinder

Now that i got it running on a gas can through the mechanical fuel pump I removed tank from behind seat.
Major pinholes and 2 inches of rust/varnish!
I need a new tank. I have 3 for my 54 but they look wrong.
Is the lcf tank the same as the 1/2 ton pickup?
Also I have a very stiff brake pedal, went down about an inch and got real stuck.
Hoping lubing linkage may help.
If necessary to replace master cylinder, where would I find the correct one?
Note - it has been sitting for 5-6 years and also has a hydro vac.
Thanks! Mike

I have been doing some searching this morning and found a thread about using a spectra gm55b tank in a 1959 2 ton.
I think i am going to order one up and get it on the way unless someone says, no that won't work.
Looks identical to the one I have.
Were they originally painted on the outside?
Mike

The Task Force tanks all fit the LCF, cab is the same as the small trucks. I was able to rebuild my master cylinder and all six wheel cylinders, good high peddle and no leaks.

ALL of the 5000 Series LCF's used the 17.5 gallon tank, just like the pickups. The 7000 & 9000 Series LCF's had a 21.5 gallon tank with a different filler neck.

Mike B

Great info! This helps a lot.
Buckshot, very cool truck. I may need some brake info on fixing/rebuilding.
Mike b, i only see an 18 gal tank for sale,
Is this correct? Amazon has a spectra premium gm55b tank.
Looks right but does say capacity. That was the one i was going to order as soon as i find out if i also need the sending unit.
Advice?
My current tank is baby blue, truck is omaha orange! Lol. What's up with that? Weren't they just plain metal?
Thanks, Mike

You won't find the 21.5 gallon tank being reproduced as most suppliers are not even aware of these larger tanks being installed in the larger trucks.

The original TF small tank is listed at 17.5 gallon. The new tank 18 gallon GM55B looks right to me.

They were natural metal when new...

Mike B

Thanks for all the info! I ordered a gm55b tank and a new sending unit.
I happen to have 2 additional tanks on the frame rails. I will clean them at local radiator shop and have some extra capacity. There is a 4 way valve under seat. 3 tanks so I am hoping 1 position is off, i need to decipher and label.
I will post a follow up with pics when done installing.
Thanks! Mike

Hey 78 buckshot,
How long ago did you rebuild your brakes?
Where did you source your parts?
When the old owner tells you truck sat for 3-4 yrs I figure I will double that and assume 8 and go through the brakes. Lol
Thanks, Mike

Ok. So master cylinder cap finally came off. Inside was pretty clean but dry.
I put in some fluid and then greased the entire chassis and sprayed pb blaster on all non greasable moving points.
When I was done brake fluid was gone so i added more and it is now staying full.
I pump the pedal( moves free now but i have to pull it up with my toe) and bubbles come up in master. I was able to loosen all wheel cylinder bleeders (strange bleeders, like a nut with a hole, no hose nipple). Brake fluid runs out with gravity.
I have searched and read hundreds of past posts and still need advice.
Question.
Where are the sources for parts for these brake systems.
My Napa locally is not great.
Can I attach a nipple to those wheel bleeders? For tubing?
My hydro- vac only has one bleeder I can find. It can be seen in 1st post.
Am I missing something?
Thanks! Mike

Mike, I removed all six wheel cylinders and the master, casting numbers on the wheel cylinders will get you the kits. Be aware that past repairs may have used different cylinders so you need the casting # from each. I was able to save all of the pistons, soaked the bare cylinder in muriatic acid, washed with hot water and detergent, honed them and new guts and new bleeders. Master cylinder same process. I replaced every inch of hard line with cupro-nickel and all new rubber hoses. I have bypassed the hydro-vac with hard line due to internal leak in the chamber, so for now I have manual brakes that work very well, no leaks, firm high peddle. I had 92 bales of hay on it and braking was fine - you just have to anticipate stopping but that is normal driving for big trucks. I am lucky enough to have an independent parts store in town that the guys aren't afraid to break out the old catalogs when needed. I did all the brake work in 2018.

Thanks!
I am going to try to bleed it to get it home.
But, I want it to be 110% before driving on roads.
I really don't like the current bleeders.
I just had surgery and hope to get back on it next week.
Was there a plug in the bleeders originally?
Can I put a nipple in there?
I work on a lot of cars and will be buying a pressure bleeder.
Probably the basic Motive kit, and make adapters i need for different MCs if anyone has an opinion.
Mike

Looks like something is missing? Are all 4 the same as that? Perhaps broken off? Did you get the cylinder(s) off? Bleeders normally have a nipple with a hole in it surrounded by a hex to turn it. New bleeders are available to fit old cylinders, however, if old cylinders have rusty bleeder threads, likely, then bleeding might be more difficult.

Ed

Mike,

I have a '54 GMC 630(same cab as '54.1) that has a replaced pickup tank(16) gal. So do mean that it probably came with a 21.5 gal. tank? There is lots or room behind the seat. So I might be able to find a 21.5 gal tank(original) in a larger truck? That would of course need to be cleaned out? Hate to spend more money, but 503's really suck fuel.

Thanks,

Ed

I can't say what GMC did, but Chevrolet had the big tank in the big trucks...assume GMC did as well.

Yes, you'll need to find one used as the are not being reproduce...make sure you get the filler neck with it as they are different than the small tank necks ...

Mike B

Ed, all 4 are the same at the wheels.
Rears have one (wheel cylinder)opposite of the one in the picture in post above and the line goes into those. See pic
Fronts the line goes into the cylinder with the bleeder.
I assume 2 cylinders each wheel in rear and single cylinders in rear.
Nothing broken just a bad picture. If I turn the small nut in the center (7/16) brake fluid comes out of hole in center.
Mike
Ps. Had to include last pic of exhaust! While running i brushed out with long wire brush, and I was covered in red dirt! Lol. Exhast tone sounds great now too!

Arghh! Sorry, I meant to say, I assume 6 wheel cyl total. 4 rear 2 front.
Mike

Lightningtruck,

I mistook your picture with the bleeder removed, sorry; do you have everything worked out?

Mike B, thanks, I will look for a big truck fuel tank.

Ed

Ed, i need to try to bleed brakes. Currently pedal goes to floor and stays. Do i have a missing spring?
I can only find one bleeder on the hydro-vac. Plus a can't get that bleeder to loosen.
I may take hydro vac off and examine on bench.
Bypass it for now.
Mike

There is usually a return spring, hole in pedal bracket, usually long spring hooked to a crossmember.

Many have two bleeders, supposed to do front one first. Gentle heat, 6 point wrench, try both directions after cooling, RH only nudge(technical word?) carefully. New bleeders readily available.

Ed

The picture of the "bleeder" looks like someone put in a flare nut in place of bleeders. I did not use a pressure bleeder, just the old fashioned way with help from a peddle pusher.

Hehe,
I am going to enlist a peddle pusher. The piece left in the wheel cylinder is hollow and threaded on inside, I have seen a picture before I think on stovebolt. Normally a small bolt in hole. You remove bolt, turn hollow piece that is left in wheel cylinder to bleed, then re install plug/bolt. Maybe for dirt? I thought that was orig.?
Anyway, I am going to make efforts to bleed and report back.
I got my new fuel sender and just waiting on tank.
Check out old sender!
Mike

Mike B,

Could you measure height of 21 gal tank for me so I can identify one if separate of truck?

Thanks,

Ed

I use Aero Kroil for penetrating oil. Works better than PB or liquid wrench. But it may not be up to the task of rusted brake bleeders. It's worth some trouble to avoid breaking them off (far too easy to do). I would assume you need to overhaul the wheel cylinders and just take them off the truck and put them in the bench vise then you can get them as hot as you need to with a torch to get the bleed screws out. If you do break one off there exist reverse-twist drills (Snap-on, among others) so you can drill it out and hopefully the bleed screw will begin to turn with the drill before you hit bottom.

On my hydro-vac there is a large hex cap at the end of the cylinder with a bleed screw in it. Un-screw that, heat it and remove the bleed screw. I would not heat it in situ. Otherwise I'd put the hydro-vac on the bench and go from there. Cardone sells remans for a coupel hundred bucks exchange. You can also buy parts but I haven't researched where lately.

A pressure bleeder will make bleeding the hydro-vac much easier otherwise your pedal person will get bored and testy and claim to have pressing things to do.

Not home this weekend, will take a picture with measurements of the one on the wall next week...

Mike B.

Thanks,

Ed

Ok, so it has been unbearably hot and i just got stiches out from my surgery on ankle.
But progress has been made.
I have never tried the kroil. I am a pb blaster believer but i will get some. As for the left handed bits I have used those and I agree they work well.
I got the tank and it looks great. I installed the sender unit and turned tank upside down and not a sound like float moving. So I took it apart and bent the float arm and now it moves freely. I put heavy canvas where the missing anti squeak pads were and hooked it up. Replaced all rubber lines and added a fuel filter. Put 5 gal gas in it and fired it up! It is now self contained! I purchased the tank from Amazon and sender from e-bay. All is good!
Mike
Note, when you drop the 9/16 wrench behind tank it is a bear to get out! Lol

Now for the brakes. I crawled under truck and wire brushed the whole hydro-vac.
And what did I find? Another bleeder. I heated both bleeders just a bit and cooled with Pb. Tapped them tight then loose and they both broke free. So my son was the pedal pusher and fluid started to come from bleeder closest to front of truck, then other h-vac bleeder. So we moved to back wheels and they bled and we now had quite a bit of pedal. But ran out of day light. I need to un stick front drivers bleeder and bleed both fronts, but I have good pedal and brake pedal now returns. Before it was bled it just stayed on the floor. I hope to drive home this weekend!
I want to find another master cylinder cap and build a power bleeder. I hope to flush system a few times and start driving. After I check trans and rear end gear oil.
I will power wash truck and post some pictures asap.
Mike

I'd be concerned that the canvas would wick moisture over time and cause the new tank to rust...the original anti squeak was rubber.

If you haven't already done so, you should take this time to replace ALL of the steel and rubber brake lines. They may look fine on the outside, but they fail from the inside out!

Mike B

Too funny, i told my son the same thing about moisture. I am an AZ native, still dont get this humidity!
Where would one get the brake lines? I have all the brake flaring tools. And about 1/2 a roll of line because I assume rigid lines are nla. I wonder what size our trucks use, stuff i have is from a 13 horse trailer brake job. Can you get rubber lines?
I will order an anti squeak kit and swap out the canvas.
Thanks! Mike

Mike, I used almost all of a 25' roll of cupro-nickel line. I replaced every inch of hard line with the 1/4" x 25ft. I took the old rubber hose to my local independent parts store and the matched them.

As 78buckshot said, you can buy copper-nickel alloy brake lines from you local auto parts store. Just make sure you match the existing line size so the replacement line fits the wheel cylinders and frame fittings. 3/16" and 1/4" are the most common size used on our trucks and it's easy to bend.

https://www.napaonline.com/en/p/BK_8131318

Mike B

Thanks buckshot. Did you replace the small lines that connect the wheel cylinders inside the drums?
When you say matched, were they pre-made rubber lines?
Or did they make up custom?
I drove it home tonite, gearing is hard to get used to. 5sp with 2sp rear. I did not shift rear. Ran great and drove well.
Had good brakes for only bleeding the hydro-vac and rear wheels!
I feel like if well maintained the stock brakes will be just fine. But I agree lines should be replaced.
Mike

Mike B. You and I were typing response at same time.
Thanks for the great info! Any pitfalls to look out for?
Mike

Mike lightingtruck, I can't remember if I had to replace one of the inter-cylinder lines. The rubber hoses were a stock item, just need thread info and length. All of the steel lines on my truck are 1/4 inch - from the MC to hydro, from hydro to the first tee, and from there to all of the wheels.

Thanks 78buckshot.
I am gonna start gathering parts, I can't wait to get a plate and pick up some stuff at the lumber yard!
Mike

I have a matched set of 1957 Michigan plates on mine, however I am not going to register it as historic due to very strict limits on use. I drive it on the gravel roads in a 15 - 20 mile radius from my house and haul hay for our horses. Today I took some equipment to a friends house 6 miles away on gravel roads. I just like to drive trucks.

The steel line that connects the two wheel cylinders together MAY have a unique thread pitch that is no longer available, so you MAY have to reuse the old flair nuts. My advise would DON"T THROW ANYTHING OUT TIL YOU"RE DONE!

You want to replace every inch of brake line...don't leave ANY old lines in the system, you only have one circuit and if you blow a line your without brakes!

Be safe!

Mike B

10-4 Mike B
You give solid advice and I agree. I never throw anything away! Lol
Reason 1-100. When I put the canvas strips on tank straps because I didn't want to damage new tank it was because about 2 weeks before I cleaned out under one side of my work bench.
I said to my self "I don't need all these old inner tubes I haven't used in 5 years" and threw them out. Now I have to loosen straps and replace canvas. Lol
Thanks, Mike

Plastic web belts and tiedown straps, frequently found along side the road, do not retain as much moisture as cotton belts/straps.

Ed

Well I was able to buy some of the regular style bleeders and connect a harbor freight vacuum style brake bleeder to the hydra-vac and the wheel cylinders.
It pulled a lot of fluid through the system and I have great pedal now.
I have driven it around the last few days and brakes work great. I am going to start replacing lines one by one.
Ed, the strap idea is great, super durable material!
I found some shower liner from a recent job too. It is a grey rubber like material. Between those 2 I should be able to insulate straps for free.
Mike
Pic of original bleeder and new replacement.