Hello Cor, I had the same problem with my vacuum brake booster after was 20 years old. The push rod that goes between the master cylinder and booster was wearing out and grapping. If you can still find a auto parts store that carries repair kits to replace that one part.
In my case, the rubber diaphragm was leaking, so instead of replacing it with another brake booster, I install a Hydro Brake Booster. No vacuum is needed. I got my hydro brake booster from my Auto Parts Store which I have been going to since the 60's. The hydro brake booster cost about the same as a vacuum brake booster. At the time I got a factory re-manufacturer one for about $250.00. The problem was that I need some of the old parts from a old one and a set of hoses and hose connections that only a hydro booster uses. So I went to a junk yard and took any year hydro booster and all the hoses of a vehicle which I paid $50.00 for. I got $50.00 core for it for the new one I got. The hydraulic power comes from the electric power steering pump that I got from EV Source which is use normally for power steering but it can also at the same time be use for the hydro brake booster. A lot of new vehicles are using this same system using the power steering pump. On how to install the oil lines to the hydro boost and to the power steering rack, there is information from this web site call: Hydro Boost Brake Conversion -/- Stu Off Road He use all new parts from a auto dealer and also use a higher pressure system where had to replace his power steering pump to a high pressure one using special DOT brake oil. My EV is a 77 year and the hydro boost unit came out of a 86 jeep which uses the same DOT brake oil as my vehicle. You can use a different DOT brake oil, but this requires to flush out all your brake lines and replace the slave cylinders at each brake. The power steering oil does not mix with the brake oil. The power steering high pressure outlet line that comes from the electric power steering pump passes through a drive pump that is in the hydro boost unit. Then it exits out and goes to the high pressure inlet in the power steering hydraulic rack. The the oil line that comes from the power steering rack is call the low pressure side and goes back to the power steering pump. To fill the power steering unit with Power Steering Oil, you tap in to the low pressure return line with a tee. You than connect a line to a small fill tank which is about a pint size of fluid. I got this small tank from my auto parts store. The hydro brake booster has a master cylinder connected to it, just like it did to the vacuum booster. There is a push rod and a rod guild that is retain out of the old vacuum booster that was use as a core trade in. Put only Brake Fluid in the Master cylinder. My vehicle weighs 7030 lbs and the 1000 psi electric pump works great. Unlike the vacuum brake booster where you may push the brake peddle a little bit hard and may lock up the brakes. I can give the hydro brake booster the same amount of brake peddle, and it becomes smoother. Roland Today, no one wants to repair it, just replace the whole unit. ----- Original Message ----- From: Cor van de Water via EV<mailto:ev@lists.evdl.org> To: Electric Vehicle Discussion List<mailto:ev@lists.evdl.org> Sent: Tuesday, August 12, 2014 2:17 PM Subject: Re: [EVDL] Regen : Conversion advice I do have a brake vacuum pump with a sizeable reservoir (holding vacuum) and my truck can stop pretty well, though I often use the brakes so little and so gentle that from time to time I have to force myself to make a harder stop, just to keep the brakes from getting stuck. On my previous EV truck, the vacuum pump was drawing so much current on 12V and my battery so weak (the DC/DC went out) that I disabled the vacuum pump and simply pushed harder on the pedal. I could still make an emergency stop, I just had to *stand* on the pedal, but it still worked and I never had a collision in that vehicle. The problem the vacuum pump in that vehicle had was that there was no reservoir and the pump was not entirely up to keeping the brakes fully powered, so when braking with the vacuum pump the brakes first engaged too forceful, but then lost pressure and slowly faded so you had to keep pushing harder during the stop, while the start was too grabby. I noticed that in one incident where it had just freshly rained, I was driving on city streets doing maybe 35 and the light turned red close before me. I started to brake, but all I got was locked up wheels from the grabby brakes and I floated through the intersection, aquaplaning with locked brakes. Luckily it was empty. After that I disabled the pump and had no more "incidents". I like the Prius braking and it is very similar to the Leaf - it gives you plenty of stopping power when planning ahead and only if a light unexpectedly changes or another surprise happens, do you need the friction brakes. Since regen can typically only give you around 50% back, it is better to anticipate with your speed long before even using the brakes. Regards, Cor van de Water Chief Scientist Proxim Wireless Corporation http://www.proxim.com<http://www.proxim.com/> Email: cwa...@proxim.com<mailto:cwa...@proxim.com> Private: http://www.cvandewater.info<http://www.cvandewater.info/> Skype: cor_van_de_water Tel: +1 408 383 7626 -----Original Message----- From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of Willie2 via EV Sent: Tuesday, August 12, 2014 10:29 AM To: Electric Vehicle Discussion List Subject: Re: [EVDL] Regen : Conversion advice On 08/12/2014 09:12 AM, brucedp5 via EV wrote: > Regen is much more to me than just regaining some range. It is a safety item > that I would use for dynamic braking. Since my physical size is large, I > physically fit better in a larger heavier vehicle (why I chose to have a > S-10 Blazer converted). So, regen would be quite useful to me in a heavier > EV. After driving my regenless conversion quite a distance, then driving a Leaf (with relatively poor regen) and then the Tesla (with really great regen), I can say that I MUCH prefer regen. Regen makes it easier and more convenient to drive. Aside from putting a little energy back in the battery. I doubt that the Tesla will ever need any brake work. That's amusing because the Tesla has these enormous brakes visible through the wheels. In my experience, one of the most common failures on conversions is the brake vacuum pump; my conversion spent perhaps 30% of it's life being driven without power for brakes. My wife refused to drive it in that condition. Reasonably so; it was quite exciting never knowing for sure that you could make an emergency stop. Though I did mange to avoid rear end collisions. _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub<http://www.evdl.org/help/index.html#usub> http://lists.evdl.org/listinfo.cgi/ev-evdl.org<http://lists.evdl.org/listinfo.cgi/ev-evdl.org> For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA<http://groups.yahoo.com/group/NEDRA>) _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub<http://www.evdl.org/help/index.html#usub> http://lists.evdl.org/listinfo.cgi/ev-evdl.org<http://lists.evdl.org/listinfo.cgi/ev-evdl.org> For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA<http://groups.yahoo.com/group/NEDRA>) -------------- next part -------------- An HTML attachment was scrubbed... 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