The time consuming details....
 

Hi Alex

I will share my experience based on the C15a which has some application...others can chip in with more C* specific experience.

-The front section of brake line is probably about the same for all Chev CMPs. Is this section of brake line only held by the two clips just under the radiator?

**** Your set up on the dront corss memebr is correct and probably the only section simialr to a C15a

-The holes in the side of the frame where the above brake line meets the brake hoses....were these holes originally fitted with grommets?

****On the the early C15a the steel line stops at the hole in the frame. That hole is filled by the end of the flexible brake line and held in place by a U shape spring clip. The steel brake line is flared and screws in to the end of the flex line. On the outside of the frame, the flex line goes directly to the wheel cylinder..... that means finding a rubber flex line about 18 inches long.... Wagner/Raybestos still makes them and I can dig up the number for you.

-The rear brake line going from the master cylinder to the right rear section of the frame.

*** correct brake lines and wiring are all on the RH side. The line should go to the rear frame and stop about even with the rear axle. The end of the line connects to a strap steel bracket coming form the frake and extending about 8 inches towards the gear housing of the rear axle. To that bracket a simialr but shorter flex line is held in place with a U shape clip. So the steel flared line screws into the end of the rubber line and the flex line reaches down to a 3 way block on the rear axle....brass block usually held in place by a bolt for the rear axle cover. The you have solid steel lines snaking on top of the axle housing to each wheel cylinders.

Now for the clipping or wiring and lines. Phil Waterman will chip in here with his near fire due to loose wiring.

Regardless pf where or how many clips they had to hold the wiring and brake lines in place ***** make sure you instal as many as is requried on your truck to keep everything from rubbing, wearing and potentially start a fire or cause you to loose all braking capacity.

On the C15a the brake lines are runned inside and through cross members and is it, to me anyways, impossible to run one solid line from the master cylinder to the rear axle... you need to have a union joint mid way. I was able to obtain NOS felt gromlets from Brian Ashbury.... my stainless steel brake lines have rubber hose cladding over any area that might rub on a cross member. Now is the time to fiddle with these parts...once the body goes down it becomes a nightmare.

My brake line was cut just behind the cab and one clip remained, which is positioned on the inside of the rear cab support (see picture). Does anyone have a pic of the original rooting of this section of brake line? Is it just a straight line from this clip to just in front of the rear shock absorber...than curving to the bracket which secures it to the rear brake hose....all without clips?.... Yes I think so but we nwo better now!!!

Hope you are still enjoying your project.

Bob

PS looking for some pictures for you

Pictures....
 

First of all the front lines going through the frame..... the new ones have clips the original ones had "jam nuts" which may be hard to find or make your own by cuttinga suitable nut in half the thickness.

The long rubber flex line in front were held out of harms way by a spring attached to a clip on the line and the spring was attached to one of the inside fender panel screws.....a primitive design soon replaced on later cab 13.

Spring is about 4 inches long half in. diametre similar to spring used for CMP seat back rest.

Notice the angled brass block on the wheel cylinders....they are items hard to find these days.

Cheers

Brake hose support springs
 

For what use it is Bob, the GMC 6x6 CCKW used a similar brake hose set-up on all of its six wheels. The hoses ran direct from chassis to wheel cylinders with a support spring to hold them up.
The springs were produced specifically for that purpose and may possibly be the same item as used on your truck. They are quite easily stretched and were of an unusual construction having the hook at each end made from heavier wire and loosely retained by means of the spring ends being wound in a cone shape.
The captive end of the hook was bent back on itself and could not come out through the hole in the conical end
CCKW parts vendors may still have them.

David

Bob,

It's fascinating to see the detail differences between the different models in de CMP family, even the ones produced during the same period!

I have added a few pics which show the configuration of the C8 brake lines....well, least on mine ;-)

Fitting the brake hoses directly to the frame rails makes sence, but somehow the Chev guys choose to do it different with the C8 (at least have seen this on 3 different C8's). The C8 has a bracket which holds the brake hose.

At the rear the configuration is also slightly different from the C15A....on the C8 a bracket is welded to the rear exle, which holds the brass brake tee and secures to the brake hose. The other end of the brake hose secures to a bracket riveted to the right hand frame rails.

I also added a piece of a picture from Clive's factory photos CD showing a similar rear brake line layout on a MCP Chev. Last but not least is a picture of the (front) brake tee secured to the frame with a clip.

Thanks for the advice Bob. I was kind of thinking of adding a few extra clips here and there to keep everything in the right spot....I even have a few holes available in the frame which don't seem to be used for anything else. "seem" as I am not sure if they ought to be used for the wiring loom(?). Anyhow, I will probably secure the bake line on a few extra locations, but that does mean adding a few extra bends in the brake lines to get to all the existing holes, as all the "spare" holes are not in line with the orginal (?) routing of the brake lines.


Definately! But, I have lost a bit of momentum in the project as the budget jar is about empty for now and I need to sort a few details first before I can continue. I know if's part of the fun....but I always try to do the "detective work" during the weekdays and the labout during the weekends!

Alex

Quote:
an unusual construction having the hook at each end made from heavier wire and loosely retained by means of the spring ends being wound in a cone shape.

David; your description on the springs sounds a lot like the springs used inside the Chevy brake drums to hold the brake shoes.....No idea if the C8 used springs on the brake hoses at all....on mine there is no sign of them, but I guess the hoses could have easily been replaced during it's lifetime.



oh..the C8 brake hoses up front are the same as the one at the rear, # 476719. Luckily these are available at most Chev parts suppliers! Thanks for the offer Bob, but I guess for once it's a benifit that the C8 is largely based on civvy components ;-)

Alex

Dirk at LWD was able to help me with an alternative brake junction block. We had a few to choose from and I decided to go for this one as it uses the same thread size as on the original block and also the same thread on all three holes. Basically it means I can swap the block easily if I ever find the original one.
There was only one problem....it's Ford.....but, as you can see in one of the is the manufacturer for these blocks seem to be the same, "W". :thup2:

The block has a hole in it to secure it to the frame with a bolt, in stead of the clip as used on the original.
I modified two thick washers to fill up the hole and to get the new bolthole off-centre, so the block would sit a close to the original location as possible.

Next step is making new brake lines. After reading several stories about making brake lines, I decided to use Cunifer, a Copper-Nickel-Iron alloy. I bought this and a tool to make double flares a few weeks ago, but the trouble was finding the correct fittings and that brass brake block. Now all material was present, I was able to start making the lines.
Allthough the actual work is not too difficult, you need lots of time to measure and bend the lines....testfit, bend a bit more....testfit again.....bend some more etc.
I am not completely happy with the front line yet, but I will have another go next weekend.

Alex

"A" plus pass mark......
 

Nice job Alex ......good looking flares .......

I particualrly like how you shaped a washer to fit the hole in the frame....nobody else will ever see it but you know it was done right.

Brake line layout looks good.

Bob C

I was in a truck supply place last winter and they had pre made brake lines in 3" increments from about a foot long to 8 feet long. The long ones were only about $4 each. They even had the protective wire wrapped around them.

Thanks guys! Not all flares came out that good, so I had to scrap a few lines as they were too short to be used again, after cutting off the bad flare.

You can also buy straight section of pre-made brake line here at some shops, but in my case the trouble was finding ones with the correct thread fittings.

Alex

Looking good Alex, I look forward to the day we both drive our monkey-faces!!

Groet,

Stefan

Same here Stefan!! Would be lovely to see these opposites together on the road....big F60H vs small C8....Ford vs Chev.

More brake lines. This is what I decided on the long line to the back.....armed with the MLU comments I decided to make a small detour in the line to reach an existing hole I could use for a clip. The Clips are also shown (3 planning in stead of 1 as on original)...all mocked up as I intend to spray the inside of the frame one more time before I fix the brake lines. The brake hoses also came in ;they are also loosely attached to mock everything up. Rear axle also received new lines.

I was planning on showing how I made the brake lines and which tools used, when my brand new tool broke! Or actually the threads stripped from the spindel so I had to use an old fashioned flaring tool to make the last two lines!

I also took the master cylinder apart...what a "surprise".....pitting! I am looking at having it sleeved here in Holland, but might end up shipping it over the pond and back for rebuild!

Alex

It's about time for an update. I had the master cylinder sleeved in Stainless by the Fillins station in the US. Sleeving seems to be a lost art out here in Holland and even with import tax and postage it was cheaper to have it sleeved in the US. You can see the difference in the first two shots. Than it was a matter of assembling it again with some brake grease and a rebuild kit.
Finding the big copper washer for the plug at the rear was a challenge again, but in the end I found it at a tractor parts supplier here close at home.
The last pics shows the master cylinder fitted on the truck and I was almost fully satisfied.....

The thing that had been bugging me from the beginning was that one of the studs in the master cylinder casting was not really screwed in far enough.....So, took the master cylinder off again and with help of two nuts and a spanner I tried to screw it in further. I didn't even put the thing in a vice, but than it was "snap".....cracked the casting! I unscrewed the stud and found the lower half of the hole was filled with black crud....maybe even from the factory??

Not a happy ending this weekend, I'm afraid....and really don't know if this thing can be saved or not.

Alex

Bad luck.....
 

What a bit of bad luck Alex......

The casting maybe welded but how high is the risk of the brakes failing later....

Can you clean out the crude at the bottom and will that leave you enough thread to set a stud then have it welded to the casting..

At the barn we have been in the habit a running a tap in every bolt holes to clean the threads and a die over old bolts.

Bob

Bob is on the right track but braze don't weld. if the threads are shiny clean then you should be able to get the brass to run down at least half the thread, that will bind it all back together. You will need a heated tin of sand to bury most of the cylinder in to prevent distortion and cracking from cooling to quickly.

Alex, in my opinion you have to scrap it. Just too risky. How do you explain after an accident, that you thought you had done a good job of welding it?
You only have a single circuit system. It has to be right.
Sorry Alex. Just one blokes honest opinion.

Bad luck with the master cylinder, always a good way to ruin a productive weekend of work. For what it is worth and being a mechanic myself I was always taught and practiced that you never apply heat to brake parts or steering components as it fatigues the metal/cast and it will fail over time. My advice would be to source another component and run a tap through every thread, blow it out with compressed air prior to assembly. I even run a die nut over every stud and bolt thread.
Cheers,
Dave.

Two options
 

I agree with the other fella's Alex. Im afraid you'll have to get another one.

This is bloody frustrating and I would be very upset myself having just had it resleeved.

There may be one other option.

If you were to take it to a professional repairer and he was to say he can and will fix it, then I think you would be OK to proceed with a repair job - providing the professional does the work.

I suppose then it is a matter of cost - if the repair is as much or nearly as much as replacement - well then, go with replacement.

I think it could be repaired. It's been sleeved so there's no danger of it leaking pressure. You'd have to use a zip disc to cut the crack wider then thread the bolt in and braze it up.

Guys,

Thanks for all your comments. It was a mix of bad luck and stupidity. I thought I had partly unscrewed the stud myself when removing the master cylinder from the truck, so I never thought that screwing it back would cause this result. An expensive lesson. On checking my pics from before removing the thing I noticed the stud was already sticking out too far, so either it came from the factory like that or it happened somewhere during it's career. Anyway, there was some black sludge in the hole....a bit mud-like. As I say....next time I will definately take the time to clean the hole and thread.

I agree with all you guys.....can it be fixed?....I think so, but I would definately ask a professional shop in stead of trying myself. Is there a risk?....I think so, even though the sleeve is pretty much a closed chamber as Dave noted. The risk of it cracking again or warping during the treatment is present, so even if it can be properly welded, it could prove more expensive to get everything sorted again than to have another cylinder sleeved...
Most of all, even if It was fixed properly, I wouldn't be sitting comfortably on my way to Normandy!

So, the only sensible thing seems to be to cut my losses, look for another Master cylinder, or at least the casting, have it sleeved in Stainless again and do the same procedure again......well, without the cracking hopefully.

thanks for the feedback guys, much appreciated!
Alex

Alex, it is a good lesson for us all. The gunk in the hole develops a high pressure (just like a hydraulic ram)when the stud is screwed in against it. It was probably thick enough to seal, rather than exiting down the thread.
Some guys would never say anything. We learn the fastest, when we make mistakes. When we see the mistakes of others, sometimes the warning can penetrate our own skulls. (me included)

Guys, The reach of MLU is amazing. I was offered a replacement master cylinder from a fellow C8 owner. The funny thing is that he is not on MLU as far as I know, but he did read about my master cylinder disaster. The replacement cylinder is now on it's way to get sleeved. Thanks Guido!

It's about time to update the log. Attached are some pics of the rear cab supports. One needed some work as the steel suffered a lot from the contact moist held by the wooden spacer which is sandwiched between these supports and the cab floor itself.

Alex

Some more pics of the supports and a sneak preview of the new wooden spacers.

Alex

Wood = Rust
 

Hi Alex

What ever hard wood you use as replacement make sure that the wood has been soaked in a oil base paint for the first one ro two coats than full strenght paint for a top coat...... takecare to insure that paint has soaked into every bolt holes.

I have literally encapsulated my wood using POR 15...... the finished product is very resistant to abrasion ) rubbing of floor and bracket).

In the original design as the wood got wet it decays and generates tanic acid that will other wise rust a bolt shaft to a perfect hour glass shape.

Keep up the good work.

Bob C

Just out of curiosity, couldnt hard rubber be used instead of wood, solves a lot of problems and as so thin and only a packer wouldnt go noticed!
I know it goes against originality, which im all for, but why have to strip it all again in 10 years to re-do!
Im now waiting for the purists with pitchforks and burning torches at my door!!!! :fry:

Bob,

Thanks for the additional tips. I used Oak for the wooden spacers and treated this with a product called Owatrol. I did a test-piece first to see if the Owatrol, primer and paint would work together. The actual spacers received their first coat of Owatrol yesterday, which does indeed soak into the grain. I will post some pics in the next few days, to show which
procedure I followed.

Paul,

Well, for these floor-spacers rubber would probably work just as good. However, the cab 11/12 also uses a wooden frame in the roof section. Using rubber there would not be a good idea, as in this case the wood is not used as spacer, but as an actual structural part.

Alex

Wood versus rubber....
 

Hi Paul

I see nothing wrong with using a "modern" material particularly in hard to see areas. Hard rubber or the polyurethane used in modern car suspension would certainly insure long life and would have no detriment on the resoration quality.

After all I am coating my sandblasted parts with POR 15 and everyone knows that witches' brew did not exist back then.

As pointed out by Alex, wood is needed to redo the roof frame BUT I will increase the corner stress areas with thicker metal reinforcement behind the wood.

I am also running a Pertronix ignition system as it is more dependable and unnoticeable.

But I have kept a supply of old CMP tires with thick side walls to cut out rubber spacers such as for the T case, etc.

'Tis a strange thing restoration...... we work on a vehicle design to last minutes in battle and they have survived for over 70 years...... can you imagine how long they will survive after we are finished rebuilding them....?

Bob C

About time for an update!

Time for the wooden spacers; Phil Waterman uploaded some excellent pictures and measurements of the woodwork onto his website. I copied the measurements onto some new Oak, but of course I should have known better....the C8 wooden spacers differ from the C60S ones, as the chassis rails are quite different! So, in the end I combined Phil's pictures with the info and measurements that I was able to retrieve from my rotten C8 spacers and made the new ones.

I treated the spacers with a coat of Owatrol (a wood preserver) and made sure it soaked into all grain and holes. This was followed by a coat of black primer mixed with Owatrol, a coat of Khaki green with Owatrol and finally pure Khaki green. Only the last coat was done with the spraygun, the other coats done with a brush.
Soon afterwards I realised the long spacers were in fact too short! My original spacers were so rotten that I hadn't noticed that the straight edge at one end was not the actual end of the wood, but in fact the remains of a cut made to clear the steel cab floor supports. The spacers were about 20cm too short, so I took some more oak and fixed the issue.

The spacers are now waiting till I have the floor done.

Alex



Next update in two years :D