[1750GT]

That little valve is the reason a lot of these units no longer function properly. Corrosion/grunge deposits seem to build up around the seal and the bore thereby seizing the little valve in position. I applied heat to the housing using a propane torch and then firmly slammed the body against a block of wood (however you need to take the entire unit apart in order to do this). Sometimes I needed to do this three or four times....applying penetrating oil might help provide some lubrication as well. Again, this may or may not work for you...out of four units I was able to get only three to budge.

Also, if you find any of the plastic bits broken, they don't come in the rebuild kit.....I have a few extras if you need.

 

[105GTV]

thanks rossano for the input and will give it a try with some heat cheers mate

 

[BlpltGTV]

Time to revive an old thread here. I got on the brakes hard on Sunday heard and felt an audible "pop" and my pedal got hard, and the car was far less inclined to stop. The booster is one of the newer Bosh types, I installed it Nov of '06.

When I apply the brakes, the idle gets rough and I can hear the booster hissing from some place. I checked the valve in the intake, the bottom diaphragm (I had this assembly work loose in the past) checked the gaskets and I haven't found anything. The booster is trying to work but loosing vacuum from someplace. Is this likely a failed seal inside (its not leaking any brake fluid nor is it sucking any fluid into the intake.) or where should I start looking? I think I still have some of a rebuild kit around here.

Thanks,
Will

 

[105GTV]

If the idle runs rough when brakes applied sounds a typical symptom of losing vacuum somewhere. Given its a pretty new booster I would track down all external components like non-return valve, vacuum hose and all connections for culprit.

 

[BlpltGTV]

Its something in the booster. If I squeeze the vacuum hose at the booster it settles out nicely. I've checked everything short of pulling the booster out and fully taking that apart. I have a feeling I will be doing that this weekend.

Will

 

[valvo0]

White exhaust smoke

Hi,

My 1969 single Bendix servo is leaking and giving me white exhaust smoke.

Any idea which part of the servo i need to fix.

The whole servo was bought only 3 years ago but only used for 3 months until full restoration which is just completed; but completely no brakes now !

Guidance much appreciated.

 

[105GTV]

Pull the vaccuum hose at both ends to look for signs of fluid leaking. If positive most likely the fluid leaks thru the little air valve where there is no short cut but disassemble the whole unit for repair. There is also chance the leak may appear at diaphram push rod when pump seal gives up. Don't drive without fixing this and in either case it is not difficult to fix.

 

[valvo0]

Thanks for info;
I will pass info to my mechanic.
The vaccum hose was wet with hydraulic fluid and also the servo unit.
Where is the little air valve where there is no short cut.

I have presently puled out the servo and connect the hydraulic lines so I can use the car without the servo for now.

There are 2 types of repair kits available; which one do I need; the one with the diaphram ?


Robert

 

[105GTV]

The repair kit with the diapharm and seals is the one you are looking for. The kit should come with the little air valve seal. You unscrew the pentagon shape flange and detach from the pump body then you see that llittle valve seal hidding there.

 

[1750GT]

Woah....so you bought this servo new only 3 years ago and it's now leaking? You might want to first disassemble the unit before committing yourself to buying the kits.....there might be an outside chance that the bore is scored and that you might just want to replace the unit instead. Also, the pentagonal valve is not usually a problematic component and the seal for the little piston that actuates the pentagonal valve diaphragm comes with the basic repair kit anyways.

 

[Graham Hilder]

I know this is kind of an old thread but I thought I would post what I learned this weekend. I have been rebuilding the boosters on my '69 Spider and didn't see any way to remove the air valve piston. While fooling around I found that if you run the booster plunger back and forth in the right sequence the air valve piston will pop out. It's easier to describe with pictures: ...

Many thanks Rich - great to see the photo of what it looks like. I'm trying to get this valve out of a booster that's already been dismantled, apart from this vavle. This means the hydraulic cylinder is all stripped out and empty, so I can't use your neat method. The valve is stuck pretty tight - I can tap it down a bit deeper but can't move it upwards and outwards at all. The metal is as hard as anything so I can't drill and tap it to draw it out. Knocking the casting down on to a hard surface doesn't jolt the valve out either. Heat hasn't helped. Anyone got any other ideas please?
I guess I could re-assemble the hydraulic cylinder and then try Rich's trick. But I suspect the valve's too tightly stuck for that to work in this case....

Thanks all,
Graham H, N.Z., 1750GTV.

 

[gprocket]

Hi Graham:
I must admit that I wrote that post in my idealistic youth. The battle scars of age has taught me there are many a valve that need far more than a little pumping. In fact I have a bucket full of boosters with stuck valves. I've tried everything I can think of to no avail.

 

[Graham Hilder]

Well I had two other boosters lying around and for these the air valve pistons came out quite easily. Lucky eh! For the remaining one, the stuck one, I might close off all the exits and try a little compressed air into the cylinder barrel to blow the little blighter out.
Best regards,
Graham H

 

[Graham Hilder]

G'day from New Zealand,

I'm completely refurbishing the brakes on my 1971 1750 GTV (Euro, carbs, standing pedals, dual boosters), and I don't see any vacuum check valve anywhere. The banjos on the boosters are all small and look equally-sized, and the outlet at the rear of the inlet manifold is just a straight-through stub with nothing inside it. Anywhere else the valve might be hiding?

Thanks all,
Graham H.

 

[jamesm]

I've been following the BB for some time now and gleaning lots of very useful infomation for my 1972 S2 Spider which is currently in boxes having had the metalwork repaired and painted. I'm currently ankle deep in dismantled brake booster (4 of them!) and like many of you before am having a problem with the small piston that drives the air relief valve. I have tried GPRockets trick of covering the input port and drawing the piston, I have also tried the logical extension of covering the ports and pumping 150 psi compressed air - result no movement what so ever. My final attempt to shift this is to use the same trick I used on the calipers - pump them full of grease.

So, please can anyone tell me where I should find the other end of the passage connecting the piston that drives the air relief valve and the main body of the server - i.e. one end will be under the piston - so where is the other end. My thinking is that if it's all gunged up them my grease plan may not work either.

Many thanks
JamesM
1972 S2 Spider 2L
1974 GTV 2L

 

[kengta]

Well, I might want to pursue this further....

Mini Spares - Product......and at 133 BP (about $266 each )...cheaper than what I've seen so far and they sure look like Benditalia's or the new Bosch units. Also,

Mini Spares - Product..... I wonder if those rebuild kits includes these hard to find plastic pieces. If so, will they fit the Bonaldi's? I guess a few phone calls will be required in order to find out.

Has any one used this or other Mini/BMC suppliers to buy the boosters or kits. They may be slightly less expensive than the UK Alfa Suppliers.

Still can't get mine fully apart. One Brass bush issue and second one the inner piston.

Ciao

Ken

 

[101/105guy]

I had a brake shop rebuild the booster on my Super and they got a new valve from the BMC supplier. I supplied the basic Alfa kit.
Works a treat !

 

[AlfistaChris]

Over the years I have seen the booster in many cars and they all could be interchanged, as I did with some.
Cars I can remember are Fiat, including Spider, 127, 128, BLMC Mini, Innocenti Mini, Volvo and Alfa of course. It may be of help for someone seeking a part.
Some South Africa RHD conversions used them too.
Prices for the same part had huge differences, I used to buy Fiat, as they were the cheapest.
If you have to fit two of them maybe better take identical ones.
The non return valve to the intake manifold was often placed as separate part in the hose.
Chris

PS had a quick look and found one selling 1989 Mini booster for 138 Euros.
It´s in Germany, sorry.

http://www.mini-kestel.de/kestel/katalog/web_mini.pdf

 

[wenpri]

After attempting 3 rebuilds of boosters for my 69 spider, finally gave up. They just would not work properly. Interior leaks and/or improper function. These were done in an alfa repair/restoration shop with proper equipment and a knowlegable mechanic. Ran into many of the disassembly and assembly problems reported above. When new units were installed, everything worked well. Do you know that Road and Track's reveiw of the 69 found the dual booster brakes to be so good that their deaccelerator device could not measure the stopping power. Interesting. Also that issue had a Ferrari 250 GTO for sale at 8 or 9 thousand dollars. Love to be able to pay today the capital gains on 15 to 20 million dollars.

 

[kengta]

New BOSCH booster

Well I gave up on the BOOSTER rebuild idea and ordered a BOSCH unit from Classic Alfa UK.

So will make some of comparisons to the original Bonaldi units I have.

1- Marked BOSCH as noted by others. BOSCH 14-060870 13 2 07 where the 13 AND 07 are more or less inverted.
2- has an additional cast in blank boss for a different inlet port location at 90 deg to the Alfa location
3- Has a foam filter instead of porous metal.
4- uses 5 threaded screws vs the 5 sheet metal screws on original
5- uses a M6 clamp hex head bolt and nut that is longer than original M5 screw
6- large diaphragm house is yellow zinc plate vs the silver zinc of original
7- mounting studs are same thread as original, 5/16-24 and a bit longer
8-the outlet end of cylinder is lathe cut vs as cast in original.

other observations-

one of my Bonaldi units is stepped as cast at outlet.

Classic Alfa also had as original units, more expensive and rebuilt units, with a core charge. They recommended the BOSCH unit. They were not interested in purchasing my used units for rebuild stock but suggested they may have some value down the road when the BOSCH units are NLA.

I intend to wipe the unit down with lacquer thinner, mask off the hose and filter ports and spray with clear lacquer from a rattle can before installation..

FWIW

Ken