HYDROVACS

[joel gopan]

I am sort of curious how many collectors keep their Brake System in top operating condition. The CCKW is a large vehicle and needs good operating brakes in order to stop. I have been helping owners by making up the Late Conversion Kit that uses the Bendix 374750 Third Series Hydrovac. I borrowed a NOS Kit from a friend, and had exact copies of the required brackets and brake tubing fabricated. I bought a quantity of the late hydrovac that was stored for 50 years by a surplus dealer, and these are sent to a professional Factory Remanufacturer . The 3/4" vacuum hose is unique to brake systems, and is expensive, the wholesale is over $10.00/ft and comes in 20' rolls. My present Hydrovac is a 1st Series, and was manufactured in France by Bendix in 1968, it was installed new in 1986, and at first sign of leaking or malfunction, it will be upgraded to the Later system. The 3rd Series is larger in OD, and does not clear the Propeller Shafts by much, and that is why I have gone through the effort to duplicate the original mounting brackets.The 3rd Series Kit is Post war, and shows up in the 1951 SNLs. TheWWII NOS kits for the 1st and 2nd Series Hydrovacs are way too old to be safely used, and there are no present day kits being manufactured for the early Hydrovacs.
I am a firm believer of safety first, and using an installation that is factory engineered for the CCKW.
I am just curios what other owners do.
Joel

[dr deuce]

I have a more modern Bendix 2510296 booster on two of my CCKWs. They are a diaphram type and I have had it on one CCKW for over 6 years now with no problems. It is a bit tricky to install as it is slightly larger in diameter than the newest CCKW booster. It would have gone a bit easier making adapter brackets had I removed the original ones. I decided to make adapter brackets that mounted off of the original ones in case I ever wanted to go back.

Even with Annie the CCKW-Schield-Bantam crane truck, this booster stops the truck almost unbelieveably well! And Annie is one heavy truck...

I still would like to have a dual system with two smaller, maybe Chevy boosters, but trying to split 6 wheels between the two and not separating the fronts and not having one axle doo all the work... I could see balancing as a problem.

Steve AKA Dr Deuce

[Corne Lauwerijssen]

Hi

How I maintain my brakes

Well last year I rebuild all wheelcilinders and cleaned the system
with new liquid DOT4. I check all hoses and lines regulary and
the mastercilinder ofcourse.

I also have a French Bendix Hydrovac Joel and to be honest Ive
never done anything to maintain it. It works perfect, but can you
give my some advise. I know it needs some lubrication, but where and
how much.

Thanks,

Corné

[Matt]

I'm hoping somone can help me out.

The Hydrovac on my CCKW Compressor truck is a post war Bendix unit,I'm not sure which model.I will be replacing the whole brake system with new and recon parts and would like to refit the original 1st series Hydrovac (Bendix model H-76-4,part#372428) but I am missing some parts,the air cleaner (GM Part#2131682)
The elbow from the top of the cylinder(GM part#244540) and the mounting studs which run the lenghth of the Hydrovac body.

I would also like to hear from anyone who has had any luck in finding a rebuild kit for a 1st series Hydrovac that is usable.

As always I'm greatful for any suggestions.

Matt.

[dr deuce]

The booster in my cargo truck was becoming intermittent in that it would boost sometimes and sometimes not at random. Not good.... There is a valve in it that lets brake fluid pass the boost piston so that even if you have the engine off you will still have something. I think it was sticking as I could hear the engine react to the vacume change, but no boost.

I removed it and took it to the local (good) truck/autoparts store. They had an exact rebuilt one in stock for $132 exchange! It is $232.90 with no core.

This is the newer Midland diaphram type pn RV2512140X


Steve AKA Dr Deuce

[bobc]

After reading this posting I went out to check what I had,the two 43 trucks I parted out and my 45 open cab all have the same type of booster,a one piece cylinder type,niether of my manuals 43/44 show this type of booster.When was this type used or is it a post war modification?

[dr deuce]

There are number of different types:

1. Mechanical booster acting on box type master cyl (ACKWX-CCKWX)
2. twin cylinder, valve on one end, piston on the other (1st type hydrovac)
3. twin cylinder, valve and piston on same end (2nd type hydrovac)
4. larger single cylinder, valve and piston on same end (post war I think)
5. The one I use which is a diaphram type which is larger than #3 (steve)
6. Some DUKW owners use an M-series air-pak as they have an air compressor for the tire inflation system


Steve AKA Dr Deuce

[retro-roco]

Old, OLD, post, but wanted to add an illustration of the different types, to help people identify what they have, or what they need...

Credit to Paul and TM9-801.com

vacid.jpg