105 sticking brakes

[Mr Frog]

This is a follow-up to a topic posted by Craig H in September last year. My 69 105 brakes are sticking on (but not locking). They clear after a moment or two. I am wondering whether this might be a problem with the booster, or with a faulty valve somewhere in the system. I have checked the system and there are no leaks - and there shouldn't be because it was rebuilt in 2003. Apparently 105 models had two booster versions; one that could be refurbished, and one that could not. Does anyone know for sure if this is correct. The only identifying marks I can see on my booster are Lockheed and the number 0287 (as near as I can tell - the marks are very indistinct). I am not even sure if this is the original booster. Is it possible to isolate such a problem either to the booster or to something else in the system? Can anyone tell me which  booster version can be refurbished, or whether new boosters are available. many thanks in anticipation.

[1750GTV]

Hi Mark,
As far as I know, the early model 105s had a single servo system which was replaced by a tandem system on later models. I think the Lockheed servos were used on the earlier models with Bonaldi/Bendix ones on the later models, though I'm not sure when any of the transitions occurred - someone else may be able to help.
According to the various spare part dealers, kits are available for both, though through personal experience I know that the Bendix kit is incomplete. By the time you mess around it's easier and cheaper to buy a new servo but get ready for a shock - they aren't cheap.
Is your car a single or tandem system? Post some photos if you can.
The easiest thing to do to attempt to diagnose the problem is to disconnect the vacuum lines and plug the proximal bit from the manifold. The car will still stop, though with more pedal pressure required, so don't go too quickly. If the problem persists it's likely to be a master cylinder issue. The tandem m/cs can be fiddly to bleed sometimes - in fact the entire RHD system can be a real pain because air gets trapped in all of the loops as the brakes lines ascend and descend from m/c to servo to caliper.
I've attached a couple of comparative photos plus a circuit diagram of the tandem RHD hydraulics.
Good luck and keep us posted,
Chris

[Mr Frog]

thanks chris- the pix are helpful: mine is definitely the lockheed system.  I will try to locate a new one. I followed most of the directions in the old craig h post and I'm pretty sure the problem is the booster. (will post pix of car when the rain stops - we're almost under water here).