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Default Brake Upgrade Options

The combination of an increase in weight in an EV coupled with the lack of the plentiful vacuum that ICE provide means that in most cases some efforts must be taken to upgrade the brakes (this may even be required to register your vehicle). There are several options but the stopping power of your new EV should be as effective or better than the old car to maintain the safety of you and the car you have spent so much time and effort building. Below are possible options for upgrading your EV's brakes:
  • Install a Vacuum Pump: If your donor car had power assisted brakes then this is generally considered a must for your conversion. This process involves buying a small 12V vacuum pump and a reservoir (either a tank or some use PVC tubing) to connect to the existing power braking system. Sometimes some noise dampening may be desirable as the pumps tend to make a lot of noise.
  • Increase the diameter of your brake rotors: Every inch of rotor diameter increases the brakes leverage to stop the vehicle. Many models of car/truck have larger brake discs available for sporting models. For some more pedestrian models look to bigger cars/trucks from the same manufacture. For example the Chevy s-10 has rather small rotors. I noticed while walking through the wrecking yard that the Chevy Astro van has big rotors, that appear to be able to be made to fit.
  • Install a smaller master cylinder: This obviously has limits to how far you can go, but a small change in the bore of the master cylinder will increase the power at the brakes, while using the same pedal effort (with a proportional increase in pedal travel)
  • Install stainless steel braided brake lines: These will not increase the power of the brakes, but they will reduce excess pedal travel, by not expanding with the pressure of pressing on the brake. This can help reduce excess pedal travel from the install of the smaller master cylinder.
  • Buy high performance brake pads: High performance brake pads can have significantly more friction. This can be quite dramatic, although it comes at the expense of brake longevity, a small price to pay, in my opinion. (Buy performance street pads, and not racing pads. Pads designed for track use require being "up to temperature" before developing full stopping power.
  • Install a Hydrobooster: Hydrobooster is like a vacuum booster except it uses your power steering pump to provide power, instead of a vacuum source. You can find these on most 3/4ton and 1 ton trucks. Best/Cheapest place to locate them is in a junkyard. If you get one from a junk yard, you need to get the power steering pump with it as well, as it is a bigger pump and you will need the extra fluid flow to power your brakes. Some adjustment of pedal throw or master cylinder bore size may be needed after installing one of these.
  • Vent Brakes: Venting brakes is a trick used by street rodders to increase braking capacity. Drilling holes in surface areas of Drums/Rotors where Pads/Shoes contact. This allows the gasses and pressures of brake dust and heat to easilly escape the mating surfaces, increasing the contact area thus better braking performance. with a 1/4 inch drill bit, Drill three to five holes diagonally across the contact surface of the Drum/Rotor. This should be repeated four times in a version of a clock face 12, 3, 6, and 9 O'clock positions. YOU MUST TURN DISKS/DRUMS AFTER DRILLING. This is to remove any burrs left from drilling. Best scenario is to start with new Disks/Drums. Venting brakes is easy to do and will increase braking ability by aproximately 25%. You will notice it immedeately. For many vehicles, you can also purchase cross drilled rotors from any number of parts suppliers (or try ebay).


Created by mattW, 12-14-2007 at 09:45 PM
Last edited by jlsawell, 09-22-2008 at 05:52 AM
11 Comments , 20226 Views
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  #2  
Old 05-27-2008, 01:40 PM
antonis antonis is offline
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Exclamation Re: Brake Upgrade Options

hi i was reading your ideas here and i must say that are not correct all of them. the one and right conversion is to put a motor with a vaccum pump.first a question. have you ever lost the servo/vaccum while driving?after couple of depressing the pedal it goes so hard to press that you think you going to cash and probably will. not larger discs not smaller master cyl. not drilling will help. my job is a mechanic and all i like to do is modifing my car and i wouldnt do any of that. only if u try larger discs with the servo u will have more stopping force. my idea is using a vaccum pump , maybe from a diesel engine (diesel engines dont produse vaccum) with a motor. if u dont want to spend any energy connect the motor with the brake light switch. that will only work when u press the pedal.thats my idea of making the brakes work the same way as with the engine. plus saving money is the main idea...
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Old 05-27-2008, 08:39 PM
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Default Re: Brake Upgrade Options

You mean something like this (already there)?;
"Install a Vacuum Pump: If your donor car had power assisted brakes then this is generally considered a must for your conversion. This process involves buying a small 12V vacuum pump and a reservoir (either a tank or some use PVC tubing) to connect to the existing power braking system. Sometimes some noise dampening may be desirable as the pumps tend to make a lot of noise."

If you want to add the diesel suggestion then go for it, anyone can edit the wiki. But most of those suggestions were assuming you also would include a vacuum pump except you may need more stopping power due to the additional weight of some Lead Acid battery packs.
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Old 05-28-2008, 09:06 AM
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Default Re: Brake Upgrade Options

dear mattw
i was not trying to show the way but to prevent maybe some mistake made from some people which have no the required knoledge about mechanics. not reading something which is a 'must' maybe will make some to follow the wrong path. ( maybe when i was reading it my mind was elsewhere) anyway, thanks and keep up the good work. and i apologise if i missunderstud something...

chears
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Old 01-21-2011, 11:28 AM
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Default Re: Brake Upgrade Options

Quote:
Originally Posted by antonis View Post
if u dont want to spend any energy connect the motor with the brake light switch. that will only work when u press the pedal.thats my idea of making the brakes work the same way as with the engine. plus saving money is the main idea...
Not to pick on the commentor, but for the sake of others, please do not try this particular idea. The point of brakes is not to save money or energy, it is for SAFETY.

The last thing you want is any extra delay from when you hit your brakes to when they engage. Not only is a motor going to take at least hundreds of milliseconds to start up when you hit the brakes, but it takes TIME to create a vacuum in your brakes. Your brakes won't work for probably more than a second.

When you're going 60mph, a few milliseconds is a car length. A second or more is suicide and endangering others. Please nobody consider doing this and just take the energy losses from running that motor CONSTANTLY as part of your battery pack energy calculations.
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Old 01-22-2011, 11:57 PM
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Default Re: Brake Upgrade Options

of course the idea is safety and i did not forget that. just for the record the idea is to have ALL the time vaccum in the servo mechanism. yes what you said is correct about the delay of the motor BUT the servo keeps the vaccum even if the pump/motor are not working ,with a one way valve. SO, even if the pump makes couple of minutes to work, the servo has the vaccum needed for depressing the pedal hard 2-3 times. by the time you do that the pump will allready be in ,and pumping..NO delay , you allready have the vaccum needed...correct me if i am wrong..maybe i wasnt that clear...
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Old 05-15-2012, 01:21 PM
64jeep 64jeep is offline
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Default Re: Brake Upgrade Options

I would be extremely careful of a master cylinder swap.

A modern vehicle is designed to have different amounts of braking power for the front and rear. Typically the front will have more braking power than the rears so that if the brakes lock up, the fronts will lock up first and keep you going straight. If the rears lock up first, you may spin out. The amount of braking power is a function of brake rotor/drum diameter and master cylinder piston size.

The next thing to consider is the plumbing. Different cars have different routing for the brake lines. On my 77 porsche 924, the master cylinder has two piston, one serving the front PS and rear DS brakes, and the other serving the other two. This is done to reduce the risk of a spinout in the event of failure of one of the lines. If you swap master cylinders, you could unintentionally reroute the plumbing and mess up this safety feature.

Just be aware of what you're doing and be safe!
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Old 03-05-2013, 01:43 AM
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Question Re: Brake Upgrade Options

After reading through the posts , as an ex mechanic , the safest and simplest option would appear to be a vacuum pump with reservoir . With the key on, pressing the brake pedal activates the pump before moving which cuts out when set vacuum is reached. This gives a constant vacuum which is maintained by usage. It may have changed but the standard here was enough vacuum to be available for three pedal actions. As a side note, I had an Isuzu NPR 450 7 ton truck. While descending a hill with the exhaust brake engaged the fan belt snapped. With the combination Alternator/Vacuum pump/Oil pump being belt driven it required some quick down shifting and leaving the engine running without oil pressure to use the exhaust brake.. I do have a 12v electric fuel pump. If the internal valves were reversed would this become a vacuum pump?
I would like to hear some budget solutions from members, please.
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Old 03-05-2013, 07:53 AM
64jeep 64jeep is offline
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Default Re: Brake Upgrade Options

I'm finishing up my car and used a rotary vane pump and electric motor for vacuum. I got the parts from www.surpluscenter.com. Here are the parts:

Rotary Vane Pump
Electric Motor
Jaw Coupling

There's also a muffler on there but I don't have the link. If you put a little paper towel in the muffler it's much quieter. You just have to make sure the pump is not hard mounted or it vibrates the car pretty good. It works pretty well for me. Here's a picture in my blog, though this is before I realized it shouldn't be hard mounted. I don't have a pic yet of how I remounted it.

http://electricporsche924.blogspot.c...challenge.html
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Old 04-09-2017, 02:05 PM
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Default Re: Brake Upgrade Options

Quote:
Originally Posted by 64jeep View Post
I would be extremely careful of a master cylinder swap.

A modern vehicle is designed to have different amounts of braking power for the front and rear. Typically the front will have more braking power than the rears so that if the brakes lock up, the fronts will lock up first and keep you going straight. If the rears lock up first, you may spin out. The amount of braking power is a function of brake rotor/drum diameter and master cylinder piston size.
Yes, but assuming that you are using a normal dual master cylinder (not a racing setup with separate front and rear master cylinders and a balance bar), there is only one piston in one bore so the diameter for the front and rear circuits is identical... and will still be identical to each other with a different master cylinder.

The difference between front and rear is made in the cylinders at the wheels (calipers for disks or slave cylinders for drums), as well as disk or drum diameter, and with a proportioning valve.
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