# hydroboost master cylinders



## coulombKid (Jan 10, 2009)

I've seen brake boosters that use power steering fluid in an accumulator to achieve power assisted braking. On several EVs presented here, I've seen both vacuum pumps and Toyota electric power steering pumps installed. Would it be possible to drive a hydro-boost master cylinder from the same demand pump used for the power rack and steering box?


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## piotrsko (Dec 9, 2007)

That is how it is done on my F-250 truck. pretty much everything domestic over 3/4 ton rating has one. you can tell your power steering pump is going bad because the steering gets "jumpy" when you apply brake.


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## coulombKid (Jan 10, 2009)

I found this pump package that could be run from an on-board inverter. I'm not sure how big an accumulator (with pressure switch) would be needed to run both a power rack and pinion box and a hydro-boost master cylinder from it.

http://www.hyjacks.net/PT501pgs40-41.pdf

I believe the P105 might fill the bill.


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## piotrsko (Dec 9, 2007)

well the hydroboost has a built in 6 oz reservoir that ford says is good for 3 stops, but I barely got one, and figure about another 8 oz per application for the steering.


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## coulombKid (Jan 10, 2009)

Would it be possible to charge an accumulator with ATF and use it for a power steering box and a hydro-boost master cylinder? Having multiple hydraulic systems with differing fluids just doesn't make a lot of sense. The EV adapted Power Glide has an auxiliary pump for the controller set-ups that were available before the Solitron1 came out with its PID idle function.


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## Rational (Nov 26, 2011)

coulombKid said:


> Would it be possible to charge an accumulator with ATF and use it for a power steering box and a hydro-boost master cylinder? Having multiple hydraulic systems with differing fluids just doesn't make a lot of sense. The EV adapted Power Glide has an auxiliary pump for the controller set-ups that were available before the Solitron1 came out with its PID idle function.


ATF probably has a lower boiling point than brake fluid and so it may let you down during hard braking.


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## coulombKid (Jan 10, 2009)

Rational said:


> ATF probably has a lower boiling point than brake fluid and so it may let you down during hard braking.


I thought the hydro-boost systems were hydraulic over hydraulic. In other words I'd expect valve controlled power steering fluid to develop force on a piston mechanically connected to the piston in the master cylinder.


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## Rational (Nov 26, 2011)

coulombKid said:


> I thought the hydro-boost systems were hydraulic over hydraulic. In other words I'd expect valve controlled power steering fluid to develop force on a piston mechanically connected to the piston in the master cylinder.


So then it might work.


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## piotrsko (Dec 9, 2007)

pre-1985 PS pumps from ford/dodge used ATF. they are still available as with 2000 ps pumps for the f-250. ATF isn't a problem but #'s of pressure requirements might be. Not sure if the transmissions have high enough pressure as I'm pretty sure the ps pump outputs 300 psi.


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## toddshotrods (Feb 10, 2009)

This has also been popular in hot rodding for years. It solves the problem of not having enough vacuum for the brakes with the more radical engines. Here's the most popular hot rod-oriented company. In the FAQs it says, _"You should not use any type of ATF as it may foam excessively when it gets warm."_


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## piotrsko (Dec 9, 2007)

Bet you they sell an expensive proprietary fluid! and that looks to be a chromed version of what is sitting on my F-250, ATF an all


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## toddshotrods (Feb 10, 2009)

piotrsko said:


> Bet you they sell an expensive proprietary fluid! and that looks to be a chromed version of what is sitting on my F-250, ATF an all


No, they recommend using whatever power steering fluid your vehicle uses, so probably if ATF was specified you can use it. Their kit uses whatever power steering pump you have on the vehicle and whatever fluid it requires. The FAQ was probably directed towards their most popular customers, and whatever they typically have.

Anyway, I wasn't specifically recommending that system - just posting it for reference. Their systems are indeed based on factory Bosch units, they just package it to make it easy for average bolt-on types to use. Chrome because they sell to car show types. Give the customer what they want...


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## donx03 (Nov 19, 2011)

*GM Hydroboost for brakes USING MR2 Power Steering EHPS pump* 

Hello Group I am starting my conversion, and I was wondering since the Gen3 MR2 pump is the best for Power Steering, is it safe to run the brakes off it using a GM hyrdoboost kit?

I'd like to know that this is safe. Here is some information about Hydroboost, this you can find on a 2001 Silverado, most Diesels use hydroboost, because the engine has little or no vacuum.

Hydroboost uses 800-1200 psi
MR2 P/S pump 2000 psi, however turns off when steering is not detected.

*Hydroboost braking systems have been around for a long time. They have been used on many GM truck models and have been used on race cars for years. How does a hydroboost system work? Before I answer that question let me explain how the conventional power brake systems work. Most power brake systems employ a vacuum booster to provide pedal assistance when braking. That large drum attached to your brake cylinder in your engine compartment uses vacuum produced by your engine to help push the plunger in the brake cylinder when you apply pressure on the pedal.​ A hydroboost system uses hydraulic pressure to assist in pushing the plunger in the brake cylinder when you step on the pedal. The hydroboost unit simply replaces the vacuum booster and fits between the firewall and the brake master cylinder. Most hydroboost systems piggy-back on the power steering system for the hydraulic pressure.​ What are the advantages to the hydroboost system? The most noticeable difference is in the braking response and reduced pedal effort. A typical vacuum system depends on your engine for the vacuum source. Once engines are modified, they often do not produce sufficient vacuum to provide the assist necessary and therefore, stopping your car requires more pedal effort on the part of the driver. The hydroboost system is much smaller and frees up space in the engine compartment for things like deeper valve pan covers, etc.​* 

http://corvettec3.ca/hydro.htm]


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## Rational (Nov 26, 2011)

Regarding safety: 
from my book on decision theory by the Brit DV Lindley, it is recommended to list all possible outcomes, both good and bad, from combining or separating automotive functional blocks/modules. 
Making an exhaustive list will not be easy.

Then figure failure likelihoods and possible consequences of those failures.
http://www.google.com/imgres?q=deci...6&tbnw=129&start=0&ndsp=25&ved=1t:429,r:3,s:0
Then pick the best outcome. 

Right or wrong, at least you showed Due Diligence in making an important decision. It's the Reasonable Person standard.

You say you never done this? 
Yes, you have - every time you walk out to your car in a thunderstorm you have made a judgement about your desire to go somewhere vs. a small [~60 fatalities/yr out of 330M people in the US] risk of losing your life.

Cars and smoking cigarettes are dangerous but people do those things anyway. For your background level of risk for cars, see
http://www-fars.nhtsa.dot.gov/Main/index.aspx


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## coulombKid (Jan 10, 2009)

I like the purpose built Powerglide for EV use put out by a vendor in Kansas. I'd like to make the seals in a hydroboost power brake booster and the seals in a power rack and pinion system compatible with the Powerglide transmission fluid so that one properly sized electrically driven hydraulic pump and accumulator could service the needs of the transmission when the traction motor has not turned yet as well as the needs of the brakes and steering. I'd like to drive that pump with a blue flash inverter so that I also would have the 120 VAC on board to drive the 5000 BTU hermetic AC compressor and condenser I've set aside.


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## piotrsko (Dec 9, 2007)

Fords and chevies use ATF / mercon 4/5/6 for pump fluid, same as the powerslide. one suitable pump ought to suffice for P/S and Power brakes with leftover for trans.


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## epyon (Mar 20, 2008)

Use a electric oil pump . The power steering pump is at 160 psi to "1500 psi" !! Your trany is from 30psi to 59psi .


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## tinkeringgreg (Mar 27, 2008)

coulombKid said:


> I like the purpose built Powerglide for EV use put out by a vendor in Kansas. I'd like to make the seals in a hydroboost power brake booster and the seals in a power rack and pinion system compatible with the Powerglide transmission fluid so that one properly sized electrically driven hydraulic pump and accumulator could service the needs of the transmission when the traction motor has not turned yet as well as the needs of the brakes and steering. I'd like to drive that pump with a blue flash inverter so that I also would have the 120 VAC on board to drive the 5000 BTU hermetic AC compressor and condenser I've set aside.


The powerglide and hydroboost systems will both use ATF but the powerglide cant produce enough pressure (125 psi max) to operate the hydroboost and the hydroboost operating pressure is way too high (1400 psi max) for the powerglide. You will have to reduce the pressure going to the trans and still use a motor driven PS pump for steering and braking.
I hope this helps
Tinkeringgreg


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## coulombKid (Jan 10, 2009)

tinkeringgreg said:


> The powerglide and hydroboost systems will both use ATF but the powerglide cant produce enough pressure (125 psi max) to operate the hydroboost and the hydroboost operating pressure is way too high (1400 psi max) for the powerglide. You will have to reduce the pressure going to the trans and still use a motor driven PS pump for steering and braking.
> I hope this helps
> Tinkeringgreg


 Ah, so to pull this off I have to put a pressure regulator between the hydraulic main/accumulator and the transmission. Also may want a solenoid valve down stream of the regulator that opens when I take it out of park.


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## tinkeringgreg (Mar 27, 2008)

coulombKid said:


> Ah, so to pull this off I have to put a pressure regulator between the hydraulic main/accumulator and the transmission. Also may want a solenoid valve down stream of the regulator that opens when I take it out of park.


Yes that would be a good idea. any automatic transmission will leak fluid internally back into the sump which is not a problem with an idling ICE but this leakage could be enough to drain an accumulator if it is too small. You may want to connect the solenoid valve so it opens as soon as you touch the accelerator which would apply the clutches in the trans before the motor gets power.


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## toddshotrods (Feb 10, 2009)

If you have budget for it, you can skip all the vacuum and hydraulic plumbing issues and run one of the new electric systems. The hot rod guys are using them now, with big cam ICE engines (low vacuum at idle), and giving pretty good feedback on them.

http://www.speedwaymotors.com/electric-master-cylinder-brake-th.html

http://www.mustangmonthly.com/techarticles/mump_0905_electric_high_power_master_cylinder/index.html


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## piotrsko (Dec 9, 2007)

nice, but if I had a grand to spend, i wouldn't be discussing this.......


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## epyon (Mar 20, 2008)

ABS Power Brakes will rebiuld a electric factory brake system for $450.00 . Still high but gettable after a mounth or two .

www.abspowerbrake.com


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