The GMC CCKW

Got a really dumb question... I got a set of rebuilt wheel cylinders from VoV and installed them some time back. Well, went to bleed the system yesterday and had an issue. 5 out of 6 bleeders are weeping. We checked them for being tight, etc... when we pulled the "bad" ones you can see how the bleeder screw seats - you see the mark on it but do see that it isn't sitting just right - allowing the weap. Have any of you seen this before? I will be contacting Bob to see what he thinks...

Thanks,
Rob

Rob,

I have not seen that ever on new wheel cylinders for any type of car or truck. Granted...It could happen to one as a true manufacturing defect but should not be more than the odd one.

Please let me know either here or in a PM as I have 6 of VOV's rebuilt wheel cylinders waiting on the shelf to go on my CCKW in the spring.

Happy New Year.

Bill

Will do... I have done many brake jobs and changed mine out since I was rebuilding the axles and such. I am looking into the matter and will post my results. Since I work on the truck during my spare time, the next posting might be a few weeks.

Good luck on that situation.

Update.... talked with Bob and he is willing to send me new ones to replace these - nice to see a dealer stand behind his products even though it has been over a year. I was slow in getting them in and so I am happy to see this. I am first going to try new bleeder screws before I pull each wheel apart again since it is not fun at all and time consuming!!

I will post updates.

I have also been getting assistance from Joel on this so I am very thankful this board helps connects me with resident experts on CCKWs.

Thanks

Thanks for the update Rob.

Please keep us/me informed of your successes.

From a selfish point of view this certainly is disturbing. Did Bob say what it was that was and the cause? You know how long it takes to do brakes on six wheels only to have to redo them.

I am not looking forward to this potential "comeback" situation.

Bill

Bob has only come across one two problem bleeders with the many pairs he has sold. I got new bleeders today and will fit them this coming weekend. I am just not sure and he is working with me like mad so kudos to him.

I had done a complete tear down of each axle so we replaced all bearings, seals, brake parts, etc.... a complete overhaul per the TM. I can't even recall how long it took but everything was cleaned, gone over, etc. A few weekends to say the least.

Rob

Update.... I replaced 5 out of the 6 bleeders and all looks good. I was able to get NOS banjo bolts and washers from Joel for my hydrovac so things are looking real nice. We had so much success that the engine, trans and clutch assembly are back in the truck. A great weekend to say the least!!

Hi Rob, sounds like you had a very rewarding weekend! Did you use your original Hydrovac or a newer replacement? Speaking of Joel where has he been lately I know he wasn't feeling well a few weeks ago and kinda dissappeared for awhile hope everything is okay with him. He is a great source of information on these trucks. The sites not the same without him!

nwmv wrote:Speaking of Joel where has he been lately I know he wasn't feeling well a few weeks ago and kinda dissappeared for awhile hope everything is okay with him. He is a great source of information on these trucks. The sites not the same without him!

Joel is hanging around another site these days. He contacted me a little while back, and said that he was taking a break from this site for a while.

Gee I hope we didn't drive him away with silly questions

I have a 3rd Series Hydrovac that I had rebuilt. Was not cheap but at this weight, I wanted to do everything right.
Do it right the first time and don't cut any corners is what some old wise sage said.... make sense to me

Yup.... He said the same thing to me



506

I have been watching this thread since I was told before I bought my shop van that at least two of the wheel cylinders leak. I am of the opinion since most of the work is getting to them, it is best thing to do is to redo the whole assembly but replace or at least check all the seals and re-grease it all. (wheel bearings and the like) Is there a one stop shopping to get all that is needed at one spot? I am assuming that it all needs to be replaced from the metal brake line forward into the wheel.

I am told my van will arrive at the end of February. I have to wait for a piggy back ride to afford the shipping. It seems it is coming with a stuart tank. The tank belongs to someone moving to Houston and my shop van then comes to me. This is my first duce so I am pretty excited but the wait is killing me.
Denny

I only wish!!! I replaced everything - brake shoes, springs, wheel cylinders, brake hoses, seals, bearings, races, etc. Basically, they were rebuilt from top to bottom. I figured while I was doing the job, I should do it right. I got stuff from Frank V, Joel, a bearing supply place and Bob M.

Hi

Ive made a start today with a large brake maintenance after 3years.

A few months ago I bought new brakecilinders and a mastercilinder.
And this week silicone oil.

I learned in the last years that the brakecilinders wont last forever
after a overhaul. Now I had discovered 2 small leaks in a very short peroid thats why it was time to do a large brake maintenance.

The truck had not moved since september last year, Iam pretty
sure thats the reason it started to leak, hopefully the new silicone oil
prevents this.

All parts are taken off today and i discovered all axleseals need to be replaced inner and outer. And one wheelbearing is pitted.
Everything is being cleaned and primed, the brakelines are flushed.

Tommorow I start with the built up and I hope that I will never have to change the brakecilinders again. Because I now will be using the
silicone oil, instead of the normal dot4 brake oils.

Greets,

Corné

Corne,
What is the difference in Silicone oil at lets say Dot 3? Thicker? I guess I am asking why will it be better?
Denny

I dont know the difference in thickness, but all M35a2 truck from the
US Army use silicone oil. Normal brakeoil seems to produce water in
the system and water makes the brakecilinder to rust.
Thats the reason why normal brakeoil needs to be changed in every 4
years or so. Silicone oil does not, that why all M35a2 use it, because
they are never used and had to be standby at all times..

A friend of mine uses silicone oil for his Ford GPW for about 25 years and
never had any leaks or other problems.

I just want to give it a try and hope it works, but it will never work
against mud.

Corné

Corne,
I did not know that. It sounds like a decision I will need to make in the near future. I hope others will give their opinion on the pros and con's of using it. I know I will be due for a break job with my CCKW, if it will ever get here. I expect it with in a week but it could be delayed somewhat due to a piggy back I am using to keep the cost of shipping down. So I have to wait till he is ready to come this far south.

anyway I hope others will voice their opinion of the silicon break fluid sense I know nothing about it. What is the brand you use?

Here is my 2 cents
Silicone brake fluid ( DOT 5 ) has a tendency to NOT absorb moisture (water) like the DOT 3 or 4 fluids do.
so where does the moisture collect ? on top of the silicone fluid in your master cyl.and /or wheel cyl. and it will eventually cause pitting at the fluid line. So it is reccomended to flush and change the silicone fluid also.
I use it 1 vehicle with no leaks to date (and it is not as tuff on fresh paint as the regular fluids are.)but I have changed it every 2/3 years.
On my M20 (hyd. clutch, brakes, and throttle systems ) I needed to sleeve all my cyls both master and slave Billy at White Post did the job ,he offers a life time warrenty on his work BUT ONLY if you use DOT 4 and he is specific about not using SILICONE ,He claims it will turn the rubber parts to jelly.So... I used dot 4 for the M20, but...I still have silicone in the Chevy with NO problems and no "jelly"
White post also reccomends a fluid flush and change every 2 years.
I have noticed that the Dot 4 is easier to bleed ( in that air bubbles come thru quicker ) than with the silicone.
I use a pressure bleeder and it is currently full of Dot 4 so the next project will probably get Dot 4
I guess this was more like a dollars worth
John