Please explain how the vacuum tank on 3B works? (1 Viewer)

[45Dougal]

It can't overpressurise.... you are pumping air out of the reservoir to make a vacuum. The maximum vacuum is zero bar, vs ambient air pressure at around 1 bar.

The broken tab is on the switch which tells when the vacuum is weakened too much by using the brakes, and needs pumping down again.

Yes, connect the pump to the existing line so it can suck the air out. There should also be a non return valve somewhere to stop air leaking back in through the pump when the pump is off - might be inside the pump.

If you can't solder a wire into the tab, then you can order a switch something like this... https://www.aliexpress.com/item/100...IJL5nVT9kXQITL7cscN9NIjngDT3_SSQaApY8EALw_wcB

 

[Wayneraintree]

much appreciated! I ordered the switch and will get it installed.

 

[Wayneraintree]

I’m wrapping my head around wiring the switch up and thought I would ask for feedback on this potential set-up. I’ll include the switch plug info and my attempt at the wiring logic, any feedback is welcome! I’m not excited about trial and error with brake booster vacuum so I want to get it right and possibly help others in the future looking to go electric vacuum pump. I’m not clear on what position 86 needs to be and maybe I’m off on others but here’s what I’m thinking:

 

[45Dougal]

The grey plug feeds the relay coil.
Red to 86
Black to 85
When you connect it, the relay should click 'on'. If you suck hard on the vacuum port it will click 'off'.

Connect your fused +12v supply to "87" - this will power the pump when the relay switches on.
Pin 30 goes to the red wire on the pump.
Black wire on the pump goes to ground.

 

[Wayneraintree]

Is the black plug on the vacuum switch used for anything?

 

[45Dougal]

The black plug is power to the vacuum switch as shown on their diagram

 

[Wayneraintree]

I hooked the black plug up as shown in the picture as 45Dougal mentioned and I have vacuum! Test drive tomorrow after I clean up wiring and I’m hoping this the final round of work. Thanks for all the help.

 

[45Dougal]

Good to hear - presumably it's running up for a few seconds and then stops when you reach full vacuum, until you push the pedal and it starts over?

 

[Wayneraintree]

Good to hear - presumably it's running up for a few seconds and then stops when you reach full vacuum, until you push the pedal and it starts over?

I just had a chance to test drive it and it’s hanging around 20 on the vacuum gauge. It runs up for a few seconds to 20 when it starts up and then as I depress the peddle while driving, it seems to maintain that level. The noise from the vacuum pump is barely noticeable really.

 

[45Dougal]

I just had a chance to test drive it and it’s hanging around 20 on the vacuum gauge. It runs up for a few seconds to 20 when it starts up and then as I depress the peddle while driving, it seems to maintain that level. The noise from the vacuum pump is barely noticeable really.

Sounds like it's working fine
Depends where you're pump is I guess, but I can't hear anything over the roar of the H once it's running tbh!

Did you get any photos of your install?

 

[Wayneraintree]

The vacuum pump is double isolated mounted on the inner fender under the booster. I ended up doing dual batteries with a split charging system in this round of work. The old 45 is a bit unique as the original harness burned up at the EDIC as a PO made their own relay with series of diodes that failed. I rewired the whole rig with an aftermarket American auto harness that needs minimum 100 amp hence the GM 1-wire alternator 160 amp and the need for an electric vacuum pump. You’ve really helped me out immensely and I appreciate it!

 

[Wayneraintree]

Meant to add this pic:

 

[45Dougal]

I thought about adding a light just to let me know that the pump is running from time to time... the gauge is a nice solution

 

[Wayneraintree]

agreed, on this rig I've got everything set up manually since the original harness wasn't salvageable although I do have the glow plugs on the toyota ignition key. I run an FJ60 hood cable to shut the engine down and mechanical guages and so on. Orginally the 45 was a cab and chassis complete knock down state from New Zealand so my refurbishment has given it new life. The boost on the electric pump seems a little quicker and stronger than the previous set up so I am pleased with how it turned out.