Brake booster

[MD]

The Bonaldi twin servo boosters on the Berlinas is a sore point with me. Contrary to the theory that you could never have a complete brake failure as each controlled one front and one rear caliper, the theory is all bolony. I had total brake failure with this set up. I mean brake pedal straight to the floor with absolutely not effect on the calipers.

One fatal flaw in the booster design is that it has "o" rings in the cylinders instead of cups. With "O" rings you can get blow by if they compress enough which must have happened to me.

Anyhow provided the VH44 have cups and not "o" rings they would be fine for the job. It is possible to buy new ones still but you may be looking at $750 + for each one...xee.

Somewhere in the back of my head, I seem to remember that you could get a pair of Datsun 180B brake booster assemblies to do this job. Worth looking into if bucks is important as well as safety.

I should point out that if others are to benefit from this information on brakes instead of oil catch cans, perhaps it should be moved to an appropriate topic set..

[mickl]

I have received quotes to refurbish my existing lockheed vac assists and quotes are for about $450 each. Refurbished VH 40 or 44 units can be bought for about $300 each so this is a better option for me based on cost.....and this project is certainly starting to mount up costwise!
I think the VH 40 units are bigger diameter than the vh44. My existing lockhheed units look like the same size as the vh40 howeverI would prefer smaller ones like the vh44 which would be easier in the engine bay provided they do an adequate job. fitting also seems a bit different with the Vh as they have only one mounting bolt in the centre of the large end whereas my lockheeds have two mounting bolts at this end.
Can anyone advise me on the suitability of the Vh units and which one of the 40 or 44 units would be best. Also, if it is easy to fabricate another bracket for the vh mounting.
Thanks
Mickl

[berlinaman]

Hi Mickl

I have recently fitted 2 new boosters to my 1750 berlina. They are lockheed reproduction ones bought through the Classic Alfa website (UK). They cost 135 pounds each and I had them shipped here for about $510 total.

I have since had them fitted but am still having problems with my brakes sticking on. I was expecting this to be cleared up with the new boosters so was a bit dissapointed. Ihad previously had my rear calipers rebuilt so it must be the front calipers. The whole system is also being let down by pads that make horrible scratchy noises. The pedal feel is a bit different from the originals (lockheeds - not sure what model) - a bit softer and more travel to get them to start working. They also seem to 'bite' a second or so after the inital application.

I am going to attend to the calipers and pads next. if that fails to give me the as new feel I want then it can only be the master cylinder and lines/pipes.

I have kept the originals and may try to rebuild them myself one day.

cheers

Tony

[giulia_veloce]

Hi Berlinaman

Remove the 2 front + 1 rear flexible brake lines and see if you can blow through them.
Or maybe you can jack the car up,wheels off the ground,start the engine,push the brake pedal,release it and see if any wheels wont turn freely.
Probably time for caliper overhauls also.
The above is always a good place to start.
Then have a look at the boosters.

Robert

[mickl]

Hello Tony
I checked the UK  Classic Alfa website and the BR001 lockheed like units are 225 pounds plus 24 pounds post which converts to Aus $383 each. How long ago did you buy them? Am I looking at the wrong item?   

you seem to be having some of the same troubles I have experienced. I have renewed the master and all four calipers so far and fully bled the system and checked the flex hoses so these boosters seem the only problem now. I was going to send them to a guy in Eunaway bay QLD to repair but if new ones can be had for  what you paid then that is more economical

[pancho]

Is it a vicroads or RTA requirement that cars run a booster? I would think that as long as the required pedal pressure is exerted there is no definite requirement for a booster but I'm hoping to find someone who has a definite answer on this.

Do cars such as Lotus Exige/Elise and similar run boosters ?

[aggie57]

Pancho - I'm pretty sure the only requirement is twin circuits on later cars.  I doubt it's a VicRoads requirement, more likely ADR's.

[Sportscar Nut]

Pancho

Not sure about the ADR/ Vicroads rules on booster requirements but the Exige runs a tandem master cylinder with a vacuum servo. Fairly standard brake setup on the Elise/ Exige's - it's the weight!

Paul

[pancho]

Thanks for the info guys, I note that the early gta's ran no booster - I'll need to do some further ADR and/or Vicroads reesearch on this. I don't want to run a single mc/circuit.

[berlinaman]

Hi Mickl,

Sorry about the slow reply, I got stuck in Tassie.

Re the repro lockheed boosters, sorry I made a mistake about the supplier. It was not Calssic alfa but Highhwood Alfa. I bought them 5 weeks ago. They were here in a week and the guy's name is Chris. Hope that helps.

And thanks to the others re remedies for my sticking brakes. I will, when I get the time, check them out bit by bit.

cheers

Tony

[mickl]

Thanks Berlinaman, I have emailed Chris at Highwood and the brake boosters and a new waterpump will be on their way soon.
Mickl

[berlinaman]

Good oh Mickl,

Hope you finally get the brakes you paid for.

cheers

Tony

[mickl]

The two new boosters have been installed, brakes bled umpteen times as well as the master cyl (which has a screw rather than a bleed nipple) which had a small amt of air. I have now had the master and all calipers done up at a brake specialists, replaced both boosters and still the brakes do not work!
This is what happens....after bleeding all calipers, i pump up the brake pedal about 10 pumps and it gets very hard. The back brakes are locked on and the front wheels are freewheeling....no brakes at all. The back will only come off by bleeding out the pressure at one of the back calipers.
It seems that the only thing I have not replaced or done up is the pressure proportioning valve just in front of the back axle. Could this be the culprit? How can you test to see if it is working correctly? I was going to remove it and pull apart but the owners manual says it should not be tampered with. Help!
Mickl

[Colin Byrne]

When you are bleeding the brakes, do you get a good stream of fluid out of both front calipers?

[mickl]

Hi Colin. Yes, each caliper is bleeding fairly equally.
Mickl