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Tech Spam thread - because 1/4" BSP gets 5 hand spans to the jiggawatt


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On 30/07/2022 at 17:30, Nominal said:

It's a journey.

I blew a rear slave cylinder out back in late Feb, and since I was having to work on the rear brakes I thought it was time to get the booster/MC rebuilt, it's just over 50 years old and never been off the car (I'm pretty sure). The front calipers were rebuilt last year.

I took the lot into the brake shop (ABC). They supplied new rear shoes and the slave cylinders easily enough but then took ages to get the booster done. They told me that the were having trouble getting the booster to hold vacuum when reassembled. Eventually they got it to work after replacing (one, both?) diaphragm. (I dunno I thought I was paying them to do that anyway). Instead of rebuilding the original big nut M/C they supplied a new pattern part with an alloy body. They also stripped down the brake warning switch/slider part and put new seals in it.

When I put it all back together initially I couldn't get the warning switch slider to reset properly. Later on I've worked out that the pin on the end of the switch is too short so the warning light never actually goes out no matter where the piston is.

I took it for a drive up the road but the brakes weren't right, quite grabby at the front (discs) and still felt like the rears weren't working (too much pedal travel). I wasn't even sure that the replaced M/C had the same pipe arrangement, in the stock setup the rear part of the M/C goes to the rear brakes.

So I sent the original M/C down to the place in Christchurch who rebuilt it. Thought I'd be sweet, but no. I couldn't get the rear brakes to bleed properly. Eventually I disconnected everything from the rear and just put a return pipe from the rear port back into the M/C, when pushing the brake pedal almost no fluid was coming out the rear port. So I sent the M/C back to Chch to be checked. They sent it back with no notes so I don't know if there was an issue or not.

I've made a rig to bench test the M/C and it seemed to be working OK, but when I put it back on the booster the pedal travel was massive so pulled it off again.

So after that I had a measure up and worked out that there is about a 15mm gap between the end of the pushrod out of the booster and the push point inside the M/C. Looking into the booster I couldn't really see if the reaction disc was in there (I've done a bit more googling of how boosters work) There didn't seem to be anything loose inside the booster.

So, I took the booster and the M/C back to ABC on Monday for them to have a look. I showed them the issue but I haven't heard anything from them. There must be something wrong inside the booster but I don't know what. I did have a go at splitting it, but gave up as the force I was applying seemed excessive. 

 

 

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LOL, I have to confess I haven’t had one of those in bits for a long, long time. Even when all the internal parts were available new they were pricks of things to work on. The two piece Bakelite valve body had a habit of breaking when you unscrewed them and it was often a mission to get them to hold a vacuum when reassembled. As a rule of thumb if an earlier style tandem PBR Mastervac is is working and most importantly dry inside all I would do is replace the output shaft seal & lubricate, replace the foam air filter and lubricate the input seal. In their defence they were reliable as long as the master cylinder didn’t dump brake fluid into them.

Yes the cans are hard to separate, even with a jig it’s quite easy to bend the studs or even rip them out. The trick is to work your way around the lip with a small pry bar to break the seal, even then the diaphragm rubber sticks to the steel can like s*** to a blanket!

Another option is to bite the bullet and spend around $500 AU on ebay and buy a new aftermarket booster/master cylinder assembly.

https://www.ebay.com/itm/222137052973

I think Flash bought something similar for his Mustang, could be worth contacting him re the supplier.

With rear brakes I never trust the self-adjusters, a little extra effort when assembling often avoids excessive pedal travel issues. It’s also important to radius the shoes to fit the drums.

Feel free to PM me if there’s anything I can do to help.

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2 minutes ago, sr2 said:

 

LOL, I have to confess I haven’t had one of those in bits for a long, long time. Even when all the internal parts were available new they were pricks of things to work on. The two piece Bakelite valve body had a habit of breaking when you unscrewed them and it was often a mission to get them to hold a vacuum when reassembled. As a rule of thumb if an earlier style tandem PBR Mastervac is is working and most importantly dry inside all I would do is replace the output shaft seal & lubricate, replace the foam air filter and lubricate the input seal. In their defence they were reliable as long as the master cylinder didn’t dump brake fluid into them.

Yes the cans are hard to separate, even with a jig it’s quite easy to bend the studs or even rip them out. The trick is to work your way around the lip with a small pry bar to break the seal, even then the diaphragm rubber sticks to the steel can like s*** to a blanket!

Another option is to bite the bullet and spend around $500 AU on ebay and buy a new aftermarket booster/master cylinder assembly.

https://www.ebay.com/itm/222137052973

I think Flash bought something similar for his Mustang, could be worth contacting him re the supplier.

With rear brakes I never trust the self-adjusters, a little extra effort when assembling often avoids excessive pedal travel issues. It’s also important to radius the shoes to fit the drums.

Feel free to PM me if there’s anything I can do to help.

The shop told me they had an old fart come in to consult on it and he said they were a pain. I want to keep the car original if at all possible, a new system would require a cert too. Will ping you if I need advice.

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10 hours ago, Nominal said:

The shop told me they had an old fart come in to consult on it and he said they were a pain. I want to keep the car original if at all possible, a new system would require a cert too. Will ping you if I need advice.

LOL, I suspect I might be classified as being an "old fart"!

Nothing wrong with keeping things original, tidy HG's are getting thin on the ground theses days. I've never seen a new booster install from that era needing a cert, the aussie stuff was pretty generic.

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There are about 50ish of these going in the skip this week, ex stadium leds, however quite a few of the drivers have blown but the leds are mint, are they worth salvaging? The new drivers are over $300 on Ali. Each big panel has two lights and two drivers at a total of 600w. They go hard for what they are, will sling a few up around the shed 

F201D13A-A527-4365-9E5C-A172FC675230.jpeg

F5857A91-1DA3-4701-B5A6-CEB68B47CABA.jpeg

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1 hour ago, MaxPower said:

There are about 50ish of these going in the skip this week, ex stadium leds, however quite a few of the drivers have blown but the leds are mint, are they worth salvaging? The new drivers are over $300 on Ali. Each big panel has two lights and two drivers at a total of 600w. They go hard for what they are, will sling a few up around the shed 

F201D13A-A527-4365-9E5C-A172FC675230.jpeg

F5857A91-1DA3-4701-B5A6-CEB68B47CABA.jpeg

What volts amps? Might be cheap/dirty psu options we can suggest.

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Just bookmarked that site funnily enough. Looks like you can pay with CC so not too much risk really. I'd lean towards legit till proven otherwise. Can ship a bit for $10 if using the right company. 

What are you after?

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17 hours ago, Nominal said:

No, but have seen the ads. Last time I mail ordered metal from the www.themetalcompany.co.nz, shipping was $70. It was 1m long though.

Was it wide or something? I get up to 2m sent here for less than 15

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