Wanted: C15A Brake servo linkage

[eddy8men]

Hi folks

i need a linkage like the one pictured, i have a ford linkage but it's not correct for the chev and i don't fancy adapting it to fit.
any help would be appreciated. cheers

rick

[Grant Bowker]

Although there's nothing to stop you adding the linkage and booster to a C15A, they weren't delivered in that configuration - only the heavier trucks were judged to need the booster. Adding the power brake equipment was part of the process for "Converting a 30 cwt Canadian Military Pattern vehicle into a 3 ton vehicle" described in the service bulletins.

[eddy8men]

thanks grant that's good news and has just made my life a bit easier. cheers

rick

[Hanno Spoelstra]

Originally Posted by Grant Bowker

the process for "Converting a 30 cwt Canadian Military Pattern vehicle into a 3 ton vehicle" described in the service bulletins.

Grant,

That's interesting! What else needed to be done to complete the process?

Thanks,
Hanno

[Phil Waterman]

Hi Rick

Having a HUP no booster, C60S Pattern 13 large drums, and C60L Pattern 12 small drums I'd like to add a few comments on brake boosters, it is the equivalent of being able to push on the brake peddle with an added couple of hundred pounds of force. Having that in mind the brake system really needs to be up to snuff.

CMPs when the brakes are properly adjusted have better brakes than many if not most trucks of the time period. You can lock the wheels on a HUP at 30 MPH in a panic stop if the brakes are properly adjusted. We are spoiled these days by self adjusting brakes and the result is that we forget that even a little excess peddle travel means it is time to adjust the brakes. Yes you can really tell the difference when the booster is functioning or not. All you have to do to prove that is stop the truck on a hill, kill the engine step on the brakes a couple of time to use up the stored vacuum and you will really know what the booster is doing. I have a hill on the road into the house where I do this little test on a regular basis, just to check the health of the braking system.

Now to the brake booster take the time to bench test and set up the booster before it is installed on the truck. Making sure you have no vacuum leaks is critical, even a few inches loss of vacuum will really impair the operation of the booster. Being sure that you have the booster and linkage adjusted per the manual will make a big difference in the function of the brake unit. The manual tells you to make a little test bushing and gives the dimensions this little bit is critical to getting the booster and linkage to work correctly.

Brake booster on C60S with big brake drums works much better than Brake Booster on C60L with small brake drums. The small drums of the 16" wheels trucks just don't have the same braking force.

I've often wondered if there were C15As fitted with brake boosters and winches in the field particularly in Italy to meet the need for short wheel base trucks in the mountains to tow guns. I've always wondered if this was the origin of idea of putting winches on C15As after the war.

Brake booster on C15A would surely improve its ability to tow heavier loads, at low speeds in steep terrain.

Will look forward to hearing about you progress.

One last tip the boosters need to be serviced yearly with the adding of oil and rotating if the leather seal dries out not much boost.

Cheers Phil

[eddy8men]

thanks phil, lot of info there and i must admit if i had the chev and not the ford linkage then i would go ahead and fit the booster but unfortunately i don't so i will leave it off and put it back to original spec but thanks for taking the time to enlighten me.
i plan on getting the truck ready in time for summer. it will be the first green vehicle i can take out on the road and just enjoy driving it
cheers

rick

[Private_collector]

I have the vacuum booster on my 2wd Ford CMP, and as Phil has stated, it really makes a difference. The chap I bought the truck from demonstrated it's stopping ability by locking up all 4 wheels at about 40km/h. Hell of a noise, and very dramatic effect. Luckily it was on an isolated road in the country, so only a handful of cows got upset. The booster assembly was totally rebuilt before I bought it, so I didn't have the drama of sourcing the right parts. I was able to use my fellows sources to get right parts ordered to rebuild the one on my restoration vehicle. Alas, that infirmation was lost when my previous computer went west without warning, or I could point you in the right direction for the seals and felt lubricating ring.