This has been sitting around in the garage for some time now begging to be installed. When we rushed to prepare for the EV demo, the brakes weren’t finished – they were hard-pressed to slow down one could say. As most cars have vacuum pumps for power-assisted breaking, it’s a must-have for my car too, especially with the added battery weight (and I’ll get bigger brakes as well while I’m at it, and new tires with good grip for those much torqued-about moments).
This 12v electric pump is a sturdy example from Canada Electric Vehicles – http://www.canev.com – and has fat rubber mounting feet so vibrations won’t be felt when it engages; and it’s pretty quiet too.
Vacuum pump mounting location.
We’ve looked at smaller lighter ones made from impact-resistant plastics which are very good (such as the MES-DEA (link below)), and may use one in the Echo. A one-way valve is fixed to the inlet hose to enforce the vacuum. Unlike repeated cycling on/off to compensate a change in vacuum, some models have a vacuum pressure switch with hysteresis sensor and trim-adjuster to desired pressure – the sensor checks when the pump has enough vacuum and then shuts off, engaging the pump again when the vacuum meets the adjustment setting.
We Extinguished the Reserve Tank Availability Issue, Literally…
While the master brake cylinder can provide a vacuum for regular driving, an additional reservoir could help in heavy demand conditions. I was looking at reservoir tanks online and these can sell up to $90 or more for a good one with a gauge. Some people use tin cans for a reservoir but mine is a solid alternative; a fire extinguisher! This is going to be so cool. Nathan stood over a trash can and fired away to vent the C02/powder etc (hope the neighbors weren’t around to hear the hiss; their cat may have taken a high jump). Anyway, the valve is removed, tank cleaned out and replacement Y-valve added. Now it’s just a matter of getting the right hoses and clamps, connecting it all up and testing (I should get a gauge for the tank perhaps).
Vacuum tank reservoir.
No Vacuum of Stuff Available…
More links for pumps and pump kits here…
- http://www.ev-power.com.au/-EV-Parts-.html
- http://www.evsource.com/tls_braking_system.php
- http://donau.kicms.de/cebi/easyCMS/FileManager/Files/MES-DEA/components/Vacuum_Pump.pdf
Painting the Town – Perhaps Red
Next thing to do is to spray the final coat on all the battery racks and tear my hair out over an expensive item I should not have paid so much for (more on that later). As for the continuity problem in the dash, I sussed out that a 5W load resistor wasn’t grounded; took a while to find in the mess of cables, even with a Fluke and the Starion wiring diagrams were not giving much joy. Ah well, but we’re getting there!
{ 2 comments… read them below or add one }
Oops I forgot to put a check valve in my vacuum system. Funny it still seems to keep the vacuum up OK, although I do get a 1 sec pump burst every 90 seconds. Maybe that residual leak is thru the pump.
I actually used regular (non-pressure) PVC for my vacc tank. I did some asking around and vacuum is actually pretty weak compared to compressed air, it’s equivalent to just -14 psi. So it’s not hard to contain, not much of a pressure vessel is reqd.
Another factoid I found from the CPE who tested my brake system – the booster actually stores enough vac for two braking cycles, and there is a check valve between the ICE and booster for this purpose. So maybe vac pump – check valve – booster is acceptable for many conversions.
Vac pump noise was a big problem for me, I ended mounting the pump on the old air cleaner box on some foam rubber. Quieter pump for me next time.
- David
well written blog. Im glad that I could find more info on this. thanks