Hugh B

12 hours ago, john1950 said:

You could try Bygone Bedford, P.A.Blanchard. or Green Machine Surplus. They are in the U.K. 

Thank you very much cheers

On 4/18/2016 at 4:31 AM, Tamber said:

Don't worry, I'm definitely going to be keeping the yellow paint job. DBG is nice, but I just can't see my truck in it. (Though it most definitely was in it. Underneath all that yellow; the inside of the roof -- where it was covered by the roof lining; etc.)

 

Update of the Day

 

I've pulled the brake servo and master cylinder apart... well, the master cylinder off the servo, and dismangled the servo. Rusty brake fluid puked out of back of the master cylinder, so the seals are clearly well and truly shot. m/c was set aside for now while I focussed on the servo.

 

 

 

Mmmmh, schmoo.

 

To start with, the linkage to the brake pedal was just flopping about uselessly, and the rod to push on the back of the master cylinder wasn't going anywhere in a hurry; so I pulled off the cylindrical bit on the front, that runs parallel to the master cylinder.

 

Caution: It contains a spring-a-mathing, and it sprung-a-mathung, even though I was expecting it and was bracing. I did manage to keep hold of all the pieces, though.

 

 

Next move was to remove the other big daft chamber thing; again I braced for spring-a-mathinging, but there wasn't any this time.

 

Plenty of crud, though. :-X

 

But this let me peer into the mechanism.

 

Nothing too complex; but that fixed pin on the right was definitely unhappy. Plenty of corrosion around one end of it; probably where it's been steeped in gunge for the last however-long.

 

Over my lunch break, I dragged the mechanism-y bit and the Big Daft Chamber over to the pressure washer and gave it a good blasting down; which made it easier to handle. Then I used my 3 pm break to wire-brush the rust off -- 4" grinder and a wire cup brush FTW! Just be really careful that it doesn't snag an edge and kick back, or you lose fingerprints and sizeable chunks of flesh before you can say "Ow" --, and paint, the outside of the pneumatic assist piston's cylinder; looks rather nice, now, in satin black.

 

Anyway, then I had to get the mechanism working again. I broke out the hot air-gun and gave it some warmth, and a lot of penetrating oil. After three or four goes around with this routine -- eyes watering heavily in the fumes of vapourising Double TT -- I eventually got it to start moving!

 

With this wind in my sails, I broke out the air-gun, and started applying pressure to the assist piston. Whereupon it went to the end of its travel, and stuck there. Damn.

Cue levering on the mechanism to reset it, and a few more cycles of heat & oil, and behold!

 

 

 

The port I first applied pressure to, the wrong one, is the outlet of a little valve that's acted upon by the underside of the linkage to feed controlled air pressure to the assist ram.

 

I still need to get a fitting or two out of the BDC, such as the main air feed pipe to it, which I have managed to snap the top off... without budging it even slightly in the threaded boss. (I tried heat & penetrating oil, put the right size spanner on it -- the ring end, even! -- and all I did was round the top of it off. So then I broke out the stilsons, and broke the top right off it. Ah well, these things are sent to try us.)

 

Since there's no mechanical linkage between the BDC and the servo, the only purpose I can think that it serves is as an accumulator or other reservoir of air for the brake assist; so, in the worst case, I can cannibalise the chamber to turn it into a cover for the rear of the mechanism, and use another small air receiver -- with appropriate valving, etc. -- to replace it.

 

And more wire-brushing uncovered...

 

 

Cast in "AP 7374" and stamped "APGA5183 1971 REV4". A quick search has revealed nothing enlightening about those markings. Perhaps enlightenment shall be found on the master cylinder; underneath its total skin of rust.

Hi Tamber, great job u have done here.

Im just getting my brakes back together on a 77 TK Bedford which has the same servo/master cylinder( being a Clayton Delwandre i presume) but i need a new diaphragm/ rubber thing seal between m/c and servo? Like the one in your pic. Could u direct me to somewhere i could get one possibly? Cheers from Australia