Wow Granny, that looks significantly worse than mine. Is that one pit on the vacuum port a rusted hole completely through? I wouldn't have paid for mine if I had seen it beforehand, and if I were to see yours beforehand, I might have thrown up right there on the counter in the parts store. Woof.

So I put a couple miles on the car and it works. Doesn't hold vacuum for long after you shut off the motor, but I'm supposed to be headed to a car show this Saturday and it should get me there and back. I'll mess with taking my old one apart and swapping the seals into it some time after the pressure is off.

Charles, I'm not sure the lathe will come in handy in building a device to take the clamshell apart, but the lathe will certainly be the perfect machine to reproduce one of these in stainless:

Making a new one of those that won't rust and pit like the original is certainly on my list while I've got the patient on the table!

 

 

Edited September 16, 20168 yr by Captain Obvious

Zedhead, I spent a couple cycles looking for an alternate booster from a different car that I could adapt to the Z, but I was pressed for time and didn't spend a lot of effort on it. The first big hurdle I encountered was that the booster for the Z does not have the input shaft location centered between the mounting stud locations. It's closer to the bottom than the top and seems to be unusual due to that.

Things like the size and location of the vacuum port is no problem, but the mounting to the firewall is more difficult to deal with.

Edited September 16, 20168 yr by Captain Obvious
Had my directions swapped

Capt. O

What about the 10" booster option from a 79-81 ZX?   Did you consider that, Zcar Depot has it available.

I know originality is not a huge concern on your car.  Looking at the cardone boosters, I would want a better option.

2 hours ago, Captain Obvious said:

 The first big hurdle I encountered was that the booster for the Z does not have the input shaft location centered between the mounting stud locations. It's closer to the top than the bottom and seems to be unusual due to that.

I see.  Some of the Rockauto pictures seem to be true to the part, where you can see the offset.  Here's the Prior brand image. Out of Stock, of course.  Edit - one more picture.

Edited September 16, 20168 yr by Zed Head

CO, yes that rust hole goes all the way through, it would have cost me more to ship back then throw it out so I mounted it and it works but I have to have the hose clamp snug up against the face of the booster.  I would install modern brake booster at the drop of a hat, wishing you guys luck on your hunt.

 

I didn't consider the 81ZX booster as I didn't see much of an advantage replacing one difficult to find booster with another difficult to find similar priced booster. The real trick, as Zedhead suggested, is to find a booster with the same firewall bolt pattern and the rest can probably be made to work. That's what I spent a little time on, but didn't turn up anything.

I don't even think it needs to be the same diameter. The stock booster on my 280 was the 8 1/2 inch version and I think an inch or two smaller would be fine. I might actually even prefer it. An inch or two larger (as evidenced by the ZX booster "upgrades") works as well. Just a softer pedal I assume.

I'm pretty much positive that there is a good alternative out there, but finding it without dimensioned drawings from the manufacturers is hunt and peck.

I'd be happy to be part of the team that does the investigative work into an alternative and so far, the asymmetric input shaft compared to the mounting holes has been a non-starter for me.

4 hours ago, grannyknot said:

yes that rust hole goes all the way through, I have to have the hose clamp snug up against the face of the booster.

Woof. And I thought mine was ugly.

How can they sell that with a straight face???

I just took a quick look at my booster, and the input shaft is actually closer to the bottom than the top. Had the direction of the offset wrong.

Doesn't really matter since the clamshell can be assembled in many different positions, but I did edit and fix that above.

So another project during this off season was to do something better with my brake booster. I took both the newly purchased "rebuilt" unit, and my old failed original boosters apart and reassembled one unit using the best parts from the two, plus a couple new parts I made to replace some rusty bits. Here's the final unit. Reassembled, painted, and ready to put back in the car:

Some of the internal parts were really crappy, so I made some stainless replacements. I used stainless steel for everything with the exception of the threaded output shaft tip. I reused the original tip because it's hardened and I didn't feel like dealing with the heat treating. Besides, it doesn't ride against the vacuum seal, so even if it's not perfect, it doesn't affect operation. Here's what I made:

Here's a pic of the smooth stainless output shaft sticking through the vacuum seal. This has GOT to seal better than the rusty crusty versions I had from both the boosters. My idle will thank me:

As a bonus... My PO had painted the booster that came with the car, and I found the original sticker hiding under a thick coat of paint. Thankfully the paint didn't stick too well to the plastic sticker, and I was able to chip most of it off. It's not perfect, but it looks "appropriate" for the rest of the car. I haven't put it back on yet. Anyone have a good reference pic showing the location of where the sticker should go?

Good job as usual Capt O! here is a reference for you.

Thanks for the pic. So it looks like the sticker is just centered on the top of the booster. I can do that!

Really looking forward to this coming spring after all the salt is off the roads. I've made a couple improvements and customizations this off season that I'm anxious to test!

 

 

Providing closure to this project. My power brakes work again, and the booster holds vacuum overnight, so I know it's leak-tight.

I put my sticker on, and I'm calling the project officially "done". Even though I'm getting pretty good at it, here's to hoping I don't have to open one of these things up ever again:

I sure wish I had a source for the internal rubber parts that wasn't simply to buy a "rebuilt" unit. I know they're putting new rubber parts in the rebuilds, so I know they're available. Just not available to me without buying a whole unit!