[Andree]

Hi,
Thank you so much for your quick response. It would be really helpful if you can give some kind of type designation for this spare part.

Thanks and have a great day,

 

[carrera79]

Hi,

planning to rebuild (perhaps) or change for new bosch units my 2 boosters on my US 1750 69 spider.

where to buy them in Europe ?
(quality, price) ?

thanks

 

[verrilli]

Hi,

planning to rebuild (perhaps) or change for new bosch units my 2 boosters on my US 1750 69 spider.

where to buy them in Europe ?
(quality, price) ?

I just purchased a complete Bendix/Benditalia unit from Alfaholics. Quick service.
Classic Alfa was a little cheaper, but out of stock.
Highwood was more expensive.

I just got the new unit installed last night. Next step is to bleed the system. I hope that it solves my "sticky brake" problem.

 

[carrera79]

Please let us know

 

[Ranz]

My sticky brake fix. 1600 RHD standing pedals. Single remote booster.

After:
(A) suffering a sticking brake problem for some time, all 4 wheels, best I could tell,
(B) determining it was the booster by removing the vacuum line (brakes stopped sticking). This was disappointing because I had just paid for a rebuild. "New sleeves everywhere".
(C) figuring it was that little bullet valve sticking/ not releasing (fluid pressure must be depressing it ok, coz I got brake boost assistance when I pressed the pedal, but it probably wasn't releasing coz brakes stayed on sometimes).

I did 2 things:
(1) Removed booster, removed air valve assembly, removed bullet valve (dreaded that bit after reading posts, but was able to get adequate purchase on the inside of the conical bullet valve using some external circlip pliers - squeeze pliers, pliers noses forced out against sides of bullet, wiggle, pull). Lubricated bullet with rubber grease and reassembled. Result - no change. Drat.

(2) Figuring that maybe a new/stronger return spring in the pentagonal valve help might solve the problem, I removed pentagonal valve only (fiddly, 5 screws releases the valve, but you're working upside-down, but no bleeding required afterwards, as booster body stays on the car).
Removed circular cap/hat (process described in earlier posts. Pretty simple). I saw that the conical spring is pretty flimsy. Found in the useful box a narrower, shorter, stronger, conical spring from the base of the inside of a dead small torch. Slipped small spring under existing. Reassembled. No more brake sticking.

Huge relief. HUGE.

What do I think my problem was?
Definitely bullet valve was sticking. Rebuilder probably just made the new insert/sleeve a little snug.if I saw the problem again, I would do both the above things.
Picture shows relevant bits, and relative size of springs. Regret not measuring for posterity.

 

[1750GT]

Your solution may unfortunately be a temporary one I fear. The bore into which that bullet is sliding in has begun to deteriorate due to either corrosion of the Aluminum ...or due to breaking down of the rubber of the little piston seal causing rubber to be deposited on the walls of the bore. Either one will reduce the clearances between the piston and the bore...hence the sticking. The heavier spring allows the piston counter this increased friction but eventually this too will not be sufficient. If it were me...I would remove the unit and clean out the bore that the valve resides in immediately before it's too late. I have taken apart a few of these units already and on some...I could not remove the bullet valve no matter what I did. If the bullet still slides...now would be the time to do this...M2CW.

 

[Ranz]

Thanks 1750GT, but I hope not....
In the booster rebuild I described, the rebuilder said he had to resleeve "everything".
I did also describe removing and lubricating the bullet. In doing so, I checked and cleaned the bore.
Anyhow...fingers crossed.

 

[Del]

Out of curiosity, just what is the market for these? I've got a couple of used ones from the very old days of the mid 60's GTVs and the Austin Cooper S Minis in my spares storage. I do have a rebuild kit for one, but it is likely a tired kit by now.

 

[Ranz]

Sticky Bonaldi booster solved

Ok, so the air valve still isn't doing what it should do....What to do?
Thought #1: Bypass booster (just remove and block off vacuum hose for now), order and install a 20mm M/cyl. Old M/cyl leaking anyway. Tick. Done. Brakes not as good as before, but NO STICKING.
Thought #2: How about a left-field fix for the booster of replacing the air valve with an auxiliary, electrically-powered valve to let the fresh air in, to keep the booster working. It could be run off the brake light switch. Nope - if I disconnect the existing line from the air valve to the booster, I can't restore vacuum to the rear half to create pressure equilibrium when I am not braking.
Thought #3: How about creating a secondary air inlet to the rear of the booster? Nope, that would still leave the pesky air valve in play...and it's not working properly now to restore said vacuum.
Thought #4: How about reversing things and putting the electric valve in-line with the vacuum supply line? That is, turning the vacuum on-and-off, not the fresh air. Why not give it a try. Not sure if the air valve wouldn't still find a way to interfere, but...
Bought one, bodged up a test loop of pipes, and...
BINGO
- Stronger brakes thanks to the 20mm M/cyl, with minimum increase in pedal travel,
- still have boost,
- no apparent side effects from switching vacuum on and off instead, including brake modulation.
Here is a pic of the unit and as installed. I needed to buy 10mm barbs to suit the vacuum hose, plus a piggy-back spade connector to go onto the brake pressure switch.
Not textbook, but I am stoked.
Valve cost $17, with postage. Barb's $5.

 

[1750GT]

...thanks 1750GT, but I hope not....In the booster rebuild I described, the rebuilder said he had to resleeve "everything". I did also describe removing and lubricating the bullet. In doing so, I checked and cleaned the bore. Anyhow...fingers crossed.

Out of curiosity...who re-sleeved the cylinder for you? I ask because of the half dozen or so rebuilders I contacted only 1 was willing to re sleeve the 3/8" bore for the bullet piston....the one that said could do it gave a quote of $450.00 per unit to "re-sleeve" everything...a bit much.

 

[Ranz]

Rebuild conducted in Qld, OZ.
Approx AUD350 all up.
Found them thru an eBay ad for rebuilt boosters. Flat rate quoted, and he wasn’t too thrilled because mine needed ‘everything’ done....and they obviously didn’t get the air valve operating perfectly.
Int’l postage to/from OZ would probably hurt.

 

[1750GT]

..I removed a stuck bullet piston using a grease gun connected to the booster inlet connection

Just to add a bit more to this one.....I also have found that by injecting grease into the main bore cavity.... the little piston valve easily comes out. I even went back to one cylinder that in no way was I able to remove the little fellow with repeated heat and hammering cycles....but with the grease it came out with very little effort. The key is to block all the outlet port with blanking plugs or even by simply blocking them with rubber clamped over them.....I fabricated an end plate drilled and tapped a hole to accept a grease nipple..here's a photo of the set-up...

 

[BaselJ]

I know this is a very old thread. I found it to be very helpful. I'm hoping to get some advice on reassembly.
I took the Bonaldi booster for my 67 GT Junior apart years ago and am trying to put it all back together. Its been so long that I dont remember how I got the circlip out. Assembly seems pretty straightforward, except that I'm concerned that I might score the cylinder bore when installing the circlip (#6 in the diagram in post #19). Although the circlip is near the end of the bore, there is a seal (#3) that works in this area, so damage should be avoided.

Here are two ideas:
1. Its not that deep into the casting, so maybe I could do it very carefully with long nose pliers... maybe not?
2. Or, perhaps cut a piece of plastic, form it into a tube and slide it into the bore, with the end just shy of where the circlip goes. Then insert the circlip, slide it down the bore with the plastic preventing contact with the bore until it snaps in place and remove the plastic.

Any advice or experience is appreciated,
John Basel

 

[1750GT]

The cir-clip has 2 tangs that can re readily grabbed with a needle nose pliers....so it should be dead easy to avoid scoring the bore.

 

[BaselJ]

Yes, it looks like long nose pliers fit easily. Also, the bore is larger just past the groove for the circlip, so even if it did get loose, there would be no damage.
Plan to assemble today. Lots of parts to get right!

 

[BaselJ]

While rebuiilding the air valve, I wanted to make sure that I got everything assembled correctly, but couldnt find a photo of those parts here. So, I opened up a spare to see how they go. I took this photo showing the way the parts go together. Hope it is helpful to someone else.

 

[BaselJ]

Also, I noticed that the tapered springs in the air valves were different in the 2 boosters I have apart. The one in the booster from my 67, marked 7H is made of much finer wire and is much weaker than the one I found in a spare booster marked 9I. Comparing the spring strengths, I estimate that the 9I is about 3 times stronger than 7H.
All the other parts in the air valve look identical. Wonder what a stronger spring would do? More or less boost?
Also, wondering what the markings mean. Maybe 7H is 67 production and 9I is 69 production??
John Basel

 

[1750GT]

I'm guessing that the boosters are of different manufacture? Regardless...without a test rig set up....it would be guesswork to determine if the spring stiffness affects the operation in any noticable way.

 

[kengta]

Guessing: 7H = 1967 August and 9I = 1969 September?

Guessing: 69 heavier car, heavier spring?

K

 

[BaselJ]

I'm guessing that the boosters are of different manufacture?

Both look identical on exterior and have Bonaldi cast in. So I think just different lots.