# brake vacuum reservoir size and design?



## ElectriCar (Jun 15, 2008)

I have one about that size. Originally I had a vacuum ball about 5" diameter. Adding that much to it changed the operation so that the pump came on instead of nearly every time I hit the brakes to about every third time. I just have to devise something to quieten it down!


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## Woodsmith (Jun 5, 2008)

The size of the reserviour is going to affect how often the pump runs and how long it takes to get full vacuum.
It will depend on the size of the pump. If you have a high capacity pump then you can have a bigger reserviour.

A big reserviour will just take longer to reach full vacuum then a smaller one wth the same pump. However, a larger reserviour will mean the pump may operate less frequently but for longer each time.


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## spdas (Nov 28, 2009)

Aloha, when I got my Yaris that was already EV converted, it had NO reservoir and I was disappointed in the brakes. I though a res. was needed and now you guys confirm it.
Right now, when you hit the brakes, you hear the pump come on and it seems are not very effective for 2 seconds then becomes easier to push and stop better. 

My pump is a MES-DEA 70/6E and seems to have a small relay turning it on and off from action from the brake petal. 

thanks francis


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## DanGT86 (Jan 1, 2011)

The res that I put on mine was a big help but my pump is weak. It only pulls about 15"Hg after 5 minutes. I think most boosters need about 18+"hg. I am trying 3 of those surplus center pumps next. At $15 dollars a piece they were worth trying out. 

Link to the pumps:
https://www.surpluscenter.com/item.asp?item=4-1801&catname=air

I think a pressure switch and reservoir are the best way to go. Without a res of some kind the pump would have to move some serious volume to keep up. 

I hope the surplus center pumps work because I over engineered the mount that I made for them.


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## shoup (Feb 10, 2009)

DanGT86 said:


> The res that I put on mine was a big help but my pump is weak. It only pulls about 15"Hg after 5 minutes. I think most boosters need about 18+"hg. I am trying 3 of those surplus center pumps next. At $15 dollars a piece they were worth trying out.
> 
> Link to the pumps:
> https://www.surpluscenter.com/item.asp?item=4-1801&catname=air
> ...


I ordered a surplus center pump also. How are they working out for you? Nice mount. Mine isn't going to be quite that nice.


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## spdas (Nov 28, 2009)

OK, What size of PVC pipe reservoir would you suggest using this pump MES-DEA 70/6E

thanks
Francis


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## DIYguy (Sep 18, 2008)

Maybe you should try just one first... .?? It says it will do 25" hg.... That should be more than enough.
The price sure is right! lol


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## spdas (Nov 28, 2009)

I already have the MES-DEA 70/6E that came with the car when I bought it. Just wondering if a reservoir would help as it seems the pump needs 1-2 seconds to activate the brake booster and to me is a bit freaky. I see the MES has a pressure regulator built in so it seems the easiest way is to run to Home Depot and fit a 2" x 28" PVC pipe, thread a "tee" in and see if there is any improvement in brake activation.

francis


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## poprock (Apr 29, 2010)

Hi; No-one has mentioned this as yet but PVC will be prone to collapse if it is near a heat source. I discovered this when trying Hydrogen; I let the electrolyte run low and the geny pulled excess amps , generated heat that started a fire in the container, but the container had collapsed under vacuum before this. I know you wont be near a lot of heat, but small trucks have a nice vacuum tank, eg Toyota Dyna.


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## DanGT86 (Jan 1, 2011)

The surplus center pumps work great so far. When I "start" the car it takes 5 seconds to pump down the reservoir. Once its at about 22 inHg they shut off. It takes 2 full presses before they need to come back on which is at about 18 inHg. If I stomp the pedal repeatedly the vac wont go below 15 inHg. Might not even need the res. There is always a good pedal now. 

I'm using 3/8 ID hard plastic line from the hardware store. The white translucent stuff. The pumps run off of the 144v pack through a standard 12v relay triggered by a vac switch.

The pumps are way easier to hook up if you remove the 4 screws in the top and rotate the inlets 180 degrees so they don't point right at the motor body. There is a little locating notch that needs to be cut/filed off to rotate them 

They are a little bit loud but I don't hear them over wind/road noise. Only when stopped.


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