GMC CCKW352 Hydrovac type 1

[the dodger]

Hi can anyone assist the brake pedel has gone hard and im told its the hydrovac. Has anyone fitted a kit to one and if so how difficult and what are the pitfalls. any assistance would be appreciated. thanks

[Degsy]

Never had to do the the one on the jimmy I used to own but if you go on the CCKW forum I'm sure you will find the info you require.

CCKW.org

[Chris Warne]

If you get a rebuild kit, it should have full instructions in it. Not done a GMC Hvac, but my Half-track kit wasn't too nasty a job, but the kit had full, period, instructions in it.

[Rex]

If you disconect the Vac pipe from the mainfold, see what the pedal is like then,

if it's ok you have a servo fault, I keep the seals in stock for all types

Are you sure its a type one? Vac control unit at one end and Hyds at the other.

Rex Ward

[R Cubed]

Select from this.

[Gordon_M]

Most likely the first series tandem in the image above.

 

Eminently rebuildable and no real problem. Only had to do one, for somebody else, 20 years ago, and it worked first time. Never had to pull or rebuild one on my GMC or DUKW.

 

Original rebuild kits aren't that easy to get, however the special bits aren't the bits that normally go. You can rebuild one and just replace the ordinary seal bits (as you would in a master cylinder) and it should work.

 

(The special bits are cylinder seals, felt, and rear piston pushrod seals that are like master cylinder piston seals but have a hole up the middle for the power assist rod.)