well I have been thinking of putting vacuum breaks on my ev. now, I have been driving it with out vacuum breaks since the conversion, It just wasent that big of a deal to me. I find myself in need of a weeked project so now its vacuum breaks for my ev. you all know by now that im a cheapskate so, YES here they are vacuum breaks on a budget.
if you want power breaks and dont want to kill your wallet here's how to do it.
1. 12v vacuum pump, on ebay 64.99 + free shipping, how ever i dont like to wait for anything so
vacuum pump from your local napa auto parts store part # bk6002973 $84.99 + tax and walk out with it.
2. pvc pipe and end caps and plastic barbed fittings from home depot $20.00
3 inline fuse block from auto zone $5.00
this pump is pretty quit with the hood closed, and gives 15 inches of vacuum. Now I know, I know, most cars require 25 inches of vacuum for the breaks. well at 15 inches this pump stops my 96 nEon with ease, so if your car is around the same size/weight it will work well for you too. but if you feel that you need more vacuum simply add another in parallel. the pump is almost plug and play, just wire it to the keyed 12v on the car and attach the hoses and cylinder. it has an auto shut-off at 15 inches of vacuum so you dont even need a pressure switch. make your cylinder and hook it up, and then..... power breaks, and it pulls about 2 amps of 12v power.
even if you needed 2 pumps and bought them both from napa, it still would not cost more than $200.00 so you cant get the pump for that price anywhere.
pump from napa $93.00 out the door
2" pvc pipe $4.00
2 2" end caps $8.00 all bought at home depot
3/8 barbed fitting $3.00
1/8 barbed fitting $2.00 all bought at ace hardware ( home depot dident have the elbow fittings)
1' of 3/8 vacuum line $2.00
3' of 1/8 vacuum line $2.00 all from autozone
pvc glue and epoxy for the fitting I had at home
3 hours of install time
total is: $114.00
and it works great
now in some cases you might need to make the cylinder shorter and fatter, just use bigger diameter pipe.
Actually, 15 inches of vacuum is plenty to operate a PB system. I haven't seen an ICE that pulls 25 inches of vacuum, except maybe for a moment in high-rpm drop-throttle condition, but I guess they do exist.
Most modern cars are 18-22 inches at idle, my older ones are a little lower, 16-20 inches. Add a hot performance camshaft, and that can easily drop by a third, even in half. Most of those cars can still pull power brakes and the other vacuum systems in the car without trouble.
In my experience, power brakes are good down to around 12 or 13 inches of vacuum, but the systems are all different and no doubt have their own quirks at low vacuum. 15 inches should be OK with any of them, though, particularly with an accumulator so the vacuum doesn't drop.
WOW great job. I would be concerned about running your circuit NOT through a relay, if yiu get funky accesory preformance you may want to consider it. I haven't built my system yet but my parts are a 135v dc pump (20-25 mmhg) (surplus center) for $25 dollars, pressure switch, $23 (cloud) and relay cheep. I will run off of my pack voltage. I'm running a little truck which stops pretty well without it but i plan on putting the power on the breakes. thanks again.
I'm planning to use the mechanical pump from a diesel ice engine. Just run it off a cam built onto the end of the drive motor. To me, this would be cheaper, more efficient and reliable... I think...... I hope!!!
I'm about to try this and have bought 2 of the Ebay pumps, just in case 1 isn't enough (my car is quite large). It's an ingenious idea to use a small low-power quiet pump and simply size the chamber large enough for the maximum number of brake applications required. So I have a few questions based on your experience. How long is the PVC chamber? How many times can you pump the brakes before the chamber empties and the assistance becomes ineffective? Can the pressure switch in the pump be adjusted so it pulls more vacuum?
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