Hello all. Some tricks and tips. 40 years in the hobby. My 1969 Innocenti Mini Cooper has the same booster. Here's what I did. Always use spirit only to flush or clean hydraulic brake parts. Disassemble the parts. No force. Bathing will loosen a lot. Here are the delicate steps. Guideline: a little is good, too much is disastrous. Clean and derust the entire brake booster in a bath of citric acid. 10 quarts of warm to hot crane water, ~100 to 200 grams of citric acid, 1 tablespoon of salt, 1 squirt of regular dishwashing detergent. Let it sit overnight. Disassemble the cylinder further. Take out the internals, i.e., the rubber seals, etc. The air valve screws are difficult to loosen. Therefore, place the cylinder in an oven, ~120 °C, 1/2 hour. When it is hot, the screws are very easy to loosen. Place the aluminum cylinder in dilute hydrochloric acid. I use a professional dishwashing detergent from the restaurant. Important: read the instructions ;-). First try duration and dilution. Maybe with an old carburetor. If you do it right, the aluminum will be like new! Immediately after removing the aluminum, passivate it. That is, protect it from oxygen. Rinse it off and apply water displacing oil like WD40, camellia oil or white oil. Immediately really means immediately. Be prepared. Treat the cylinder carefully with a honing brush. E.g. Gunsons honing brush set. ;-) As a student, some decades ago, I repaired the diaphragm with a bicycle repair kit ;-) It still holds. In general, old Italian rubber is of outstanding quality. Order a suitable set of spare parts. If you need a new filter, use and adopt a damper from compressed air technology. E.g. a filter made of sintered bronze. In the meantime, have the steel parts galvanized. Or paint them with a decent acid primer. An acid primer for aircraft gives a yellowish, opaque appearance similar to galvanizing. Never galvanize safety-critical nuts and bolts. They would otherwise become brittle. Use brake paste for assembly. E.G. www.ate-info.de/en/details/produkte/ate-bremszylinder-paste-180-ml_spanisch When storing brake boosters, first flush them out with benzine. Then fill them up with brake fluid. "Shorten" the connections with a brake line. Alternatively, you can leave them open. Spray some mild silicone oil on them. Cheers & greetings from Germany, Lake Constance, Detlef

No funky background music, no constant talking, just pure engineering, you dont need much else do you, just the right amount of narration to explain things then let the viewer enjoy, brilliant episode again 👍

All I can say is, I'm impressed by your videos. My 69 Berlina has two boosters (South Africa)

ridiculous that this channel is only 42k subs considering how incredibly well produced it is. amazing work

Bravo, nice video. You removed the mystery of these things.

Hello, I have a Hillman Hunter 77 with this brake system and with this video I just understood how the remote brake works. Thank you very much and greetings from Perú

i love the jazz background! Really suits the car

I added some tipps & tricks. 40 Years in the hobby. See below. Great video, great work. Cheers.

You have a really lovely Duetto Spider. I owned a 1600 GT Junior back in 1986 so I know how special these cars are... 👍

You’re either born engineer or a born producer, I’m not sure which, but your videos are always educational, soothing and make me want to restore cars to the end of my days. 👍

One year on from this episode release it’s now my turn to overhaul my rear booster. What an episode and so thankful that you created this one. Top job Jethro

Just a quick note to say hi, and feed the algorithm. Excellent video as always!

i swear you are the only guy on this planet that can make me watch brake booster repair

I feel like..I should drink coffee while watching ..

Thanks again for your great videos

Brake fluid being drawn into an engine (in small quantities) isn't a horrible thing. Many, many moons ago, my high school physics teacher owned a car repair shop. I was having trouble with carbon build-up on the valves, so he showed me how to mix up a 50/50 mixture of brake fluid and auto transmission fluid and poured down the carbs- it really cleaned up the cylinders!

Excellent video, like the rest of them. Great to see the passion you also share for these amazing pieces of mobile art.🤟🏻😎

Really nice.... Some things strangely falls into a category of "unserviceable"... I really like it when that is proven wrong.. :)

This is the most enjoyable channel i've ever seen. The calmness, precision and good tips relax me like no other. Amazing work, keep cool ! best regards from Hungary :)

Someone in Italy did just that 50-ish years ago when the unit was first assembled. Good viewing, thanks.

Jethro great job.I did this brake booster bonaldi on gt junior few years ago.buon lavoro bests regards from slovakia👌

Good Job: Clear explanation and good photography. Thank you!

Maybe alfa part supplier's should sponsor you for instruction video's, well done.

nice, they look similar to the VH44 brake booster

Jethro that was a master class on rebuilding and restoring a brake booster. I doubt I could keep all the parts in order, but I'm glad that you can! Always a pleasure to stop by and see what you are up to!

@23:57 - It was not mention but I feel I should state it here for everyone's benefit. There is a difference between a vacuum hose and a regular PCV hose. A vacuum hose is designed and reinforced in such a manner that the hose stays rigid and does not collapse under a vacuum. Although, the performance of the PCV hose might be satisfactory now. You may want to reconsider your choice for long term reliability and safety. Think about the condition and environment the hose will have to endure. The prolong exposure of high temperature will make the hose soft and supple and under the right circumstances the hose may collapse, leading to unsafe brake operation.

Great video, would love to see your cleaning and plating process.

the perfect instructional video!! thank you I m about to rebuild the 2 boosters in my Lotus Europa (Lockheed brand but very similar I guess)

Just got around to watching this one. It appears to be what we in America call a "hydrovac" booster, actuated by hydraulic pressure instead of just a pushrod from the pedal. There is one on my 1962 Ford F-600 truck project! I sent mine out to be restored. it was worth $400 to save me time hunting for parts! I made a video on the history and basic operation of the unit over on my other channel Duluth Junction Workshop. Over here they were most common on medium duty commercial trucks as well as luxury cars, so it's very interesting to see the same setup on a sports car! I have to imagine they had to use a hydrovac due to space limitations. Cheers!

Just watched a '67 Duetto Spider auctioned off online. It went for AU56,000 which, considering it was in fairly average condition, was a bit of an eye-opener. Oh, and you've inspired this old Alfa fanatic to re-enter the fray. Later this week I'll be taking delivery of a 2003 147 Ti 5-speed. It's not as cool as a Duetto but I'm a pensioner, so have to work with what I can afford. It has 88,600km on the clock and needs a crank sensor, an alternator, a cambelt set (7 years!) and some serious clearcoat correction. But at AU$2,200 I just couldn't pass it up.

Whooo Hooo! Made my day Jethro!

Thanks so much for making this video. I’ve just watched it for a second time and used it as a guide while rebuilding both the boosters on my ‘73 Super. One of the little air valves was really stuck but I read online that if you blanked off the end of the cylinder you could pump it full of grease to push the piston out. It worked a treat!

Lovely video, as always!

Only perfection is good enough for Jethro, another piece of art! Good luck with your business, and remember we all watch the other cartubers too, so a little less perfection is good enough for is 2. Not that i don't appreciate your hard work, but you gotta watch yourself sometimes. Best of luck

Excellent

Hey Jethro, that was superb and so relaxing to watch. I love rebuilding parts on old cars and bikes, so satisfying. Top work Sir!. 👍

9:25 - I had to re-watch the explanation of how a vacuum booster works - not because it wasn't clear, but because I was distracted by wondering "Is that a Montblanc 145 in burgundy?"...

Great information and filming.

Fantastic Jethro! Thank you.

Fantastic ep, J. Demystifying but in a real easy to follow way. Much appreciated.

Easy to see why no one wants to touch these. Another area of expertise you've tackled, Jethro. Kudos!

I’m always amazed at all the parts that you manage to rebuild. Great work as usual 👍

Whow, amazing again! My Julia needs some help at the same breakpart. Your video took away my fear of being overtaken a bit. Thank you for that!

I can’t add anything that hasn’t already been said. Great work as usual. Thanks!

If only things still were made to be this serviceable. I had never given much though before on how a booster really works, but I think I understand it now. Quite interesting and well put together!

Wow what great blog 👌👍🏼

Always enjoyable to watch your “clean” video..

Nicely done Jethro. At least its serviceable, most brake boosters are a sealed unserviceable unit and I would imagine that a replacement unit for this car would be unobtanium.

Thanks

Nice job! Nice result!

Fascinating content as always 👍🇿🇦

Just rewatched this as I reassembled the first of my two boosters. So useful to double check the order and orientation of all of the parts. Such an informative video. Thanks so much Jethro!

I've always looked at brake boosters as a monolithic unserviceable lump, and in some cars they are. This was quite educational, I've never seen one with a removeable band.

Great video, thanks so much

After my 5th or 6th booster on my '65 it was nice to see just how simple of a part has given me so many headaches! Great video, Jethro.

Great video

fantastic episode and like others comments i love the fact you dont have rave music playing all the way through. its so relaxing watching you and i love that you can hear your spanners clanking as you work .. awesome cant wait for the next .. respect from the uk

Immensely satisfying. Not only that: no copper grease on my hands! Great video. :)

Great video Jethro!

Very nice and detailed video, thx!

Perfect job , bravo !

Jethro.... good to see you today.. this booster tutorial was excellent. I learned a few thing today... Not sure the Alfa hand book went to that extent on the subject....very nice..

Excellent video, highest quality technical content and taking the angst-loaden mystery out of the brake-black-box. I really enjoy Your calm, music-, fake-suspension- and drama-free tech vids very much. I gotta learn how to metal-plate like You do it - that quality surface is way over any three layer paint "restoration" I ever tried with the outsides of crumbly-brownish booster housings. Thanks for sharing!

Thanks a million for the non-stop detail your videos convey.

JB, the hottest auto vlogger on KZfaq by far!!!!!!

Thank you very much for your video, I've been waiting for it for a long time. It's the only video on the internet that explains how to reconstruct a bonaldi, fantastic!

Much awaited and appreciated, fine filming and engineering as always. Thanks 👌

you could probably manufacture a somewhat decent filter from an air silencer for pneumatic cylinders, by the lloks of it a 1/4'' cylinder silencer would do

I'd rather not smell that fluid, but thanks for the offer.

Fantastic work as always! Reassembly of the main unit rubber seal looked like a tedious task with a spring constantly fighting against you and a a shaft to line up...and a clamp to try slip on 😬

Clear and professional work as usual, I really enjoyed watching your video, useful tips and extreme precision in the cleaning and reassembling parts. I will wait for the next episode to learn something new. Thanks for your videos.

Precision work as usual. Meticulous. I really enjoy your attention to detail.

a great video like always :-)

During my college days in the mid 1970’s I bought a used 1969 Duetto Spyder. Correct me if I am wrong but I believe it had 2 Bonaldi boosters. Both leaked, constant spongy pedal and no one could repair it. Ended up removing the boosters and the pedal was finally firm but needed muscular legs to stop. Very dangerous. ATE calipers all around. Too bad I didn’t have access to your knowledge. The zinc plating looks very good, should have given it a dichromate dip for corrosion protection.

Just fabulous craftsmanship brilliant content Jethro 🥳👍

Jethro .. that’s a perfect rendition of how it’s done.. well executed.! The best bit was the leopard scarf rag.. too good to use , I would have been wearing it hehe.. Love to see your plating process...

Electro plating instruction would be a very interesting video.

Perfect timing Jethro, I have just stripped both of the boosters for my 1973 2000 GTV and am about to clean and reassemble them. Thanks for the video! I have the rebuild kits from Classic Alfa - when I bought those in 2019 they were also available from Highwood and Alfastop. They include the diaphragm, seals, gaskets, bolt lock plates and the 90 deg hose. 15+ years ago I had both sleeved in stainless but one diaphragm had now split and both boosters were leaking slightly into the vacuum chamber. There was quite a lot of crystalized brake fluid in the air valve. I have also just rebuilt the double circuit master cylinder, honed with a new set of seals. My fingers will be well crossed when I put it all back together again :) Early in my ownership of the car I had trouble with the rear brakes being slow to release, which turned out to be the small 90 degree rubber hose collapsing under vacuum. Took a while to find!

Alfas are the only cars I've ever heard of to have problems with vacuum brake boosters, at least as catastrophic as sucking brake fluid into cylinders :D

Perhaps a it of lapping, on the end of the rod that fits into the high pressure piston? Just an idea...

Top quality content, enjoyed every second of this video!

Quality content done with style! Nice work JB!

Wow you have know idea how much this helps me 😀 Thank you very much for a great tutorial, and yes you explained it perfectly

😎👍

If you need a new filter, use a damper of air-pressure equipment. E.g. sintered bronze filter.

I think my ‘73 Porsche 911 used the same brake calipers. Do not remember if they had a booster they called them “A” caliper’s the A from Alfa.

It's great that they are user serviceable. ATE in my Saab 96 is factory sealed

Excellent, thorough workmanship and very satisfying to watch and listen to. Would it be possible ti take a 5 minute time out to show us your watches?

Such peerless work, and I always celebrate when you release a new video! Spectacular filming, and great voice-over. Thanks for this!

Important: I told you wrong. It's an ALKALINE professional dishwasher detergent. "ECOLAB Topmat". Use very carefully.

I wonder if I'm right in thinking these are a "remote" type of booster? That is to say it is not physically connected to the brake master cylinder actuated by the driver. You normally see the booster located on the same side of the car as the driver adjacent to the bulkhead but not in this case. The early Ford Escort Mexicos and RS1600's had a remote brake booster made by Girling which were a nightmare to rebuild even in the 80's when parts were available off the shelf. Instead of being physically actuated by the brake pedal they are actuated by vacuum which adds a another bunch of seals and pipes and valve which can go wrong.

My '67 Duetto did not have the booster. The big problem I ran into is the calipers were aluminum with chrome plated piston bores, and could not be just simply re-built if corroded. Once I got good calipers, the brakes were very good.

Hi Jethro, I find your movies both entertaining and informative, thank you. However there is one area that I can't find anywhere and that is a repair of a 116 rear caliper. I know you specialise in 105's however can you give this a thought as no one else seems to want to cover this topic. Regards. Jim

I enjoyed that, although the lack of a kit of new parts always makes me very uneasy. I guess if the Cubans can manage, so can we! A couple of things I wonder about, though. It's been my understanding that brake fluid protects rubber rather than harming it. Also, if that was red Loctite, why? Last I bought it, it was labeled permanent, although very high heat could burn it away and allow bolts to be loosened but that's not the intended use. Blue is guaranteed to lock parts until you take a wrench to the fastener.

Hi Jethro, it’s been a while, any more content in the pipeline? I’ve missed your top quality videos

Hey Jethro you say very simple 🤣 but where did you find the explanation about how this booster works ? so good video again ... for a little bit more i would think i could do it myself 🤣🤣🤣

Hello Jethro, really nice job on your Duetto. Your videos are so helpful for my restoration. As i watched this video I mentioned that on mine air valve the small spring is missing😢... obviously someone disabled in the past and lost this spring 😢. Could you give me some information of this particular spring? Greetings from Austria. Fabio

On top of all right comments: did everyone notice the good taste "touch" of using a fontain pen to mark the lines of all those small parts, certainly a "Montblanc"? Justy amazing how Jethro is able to turns engineering into art!

Whoa.... Do you have the brakes wrapped up and driving it ? We sure would like to hear about that 😎

You mentioned electroplating the parts. Can you please say if it was a zinc plate with a blue passivate? The finish was lovely and even.