Converting power brakes to manual
Converting power brakes to manual Ok, here's the deal. I've got a hankerin to start building an ITB intake manifold for my GTO, as a welder/fabricator for a living this is a decent but welcome challenge to me. My main concerns with vacuum operated controls is really the lack of vaccum with an ITB intake manifold. I can take care of the MAP sensor with a vacuum accumulator/manifold and I guess have a 2nd vacuum accumulator/manifold with a vacuum tank to operate my a/c duct controls. My issues arise when I start to think of the power assisted brake system on the car, I realize they displace a large volume and require decent vaccum to work correctly, requiring a larger vacuum tank than I want to deal with.
I realize that if I just remove the booster and redo some of the linkage it will be quite hard to press the brake pedal, not too much of an issue since I only deal with traffic maybe 5min a week at most. What can be done to keep this from happening? Can I rework the motion ratios in the brake pedal assembly to lessen the force required without loosing too much brake pressure or making the excursion length insanely long? I plan on upgrading to Brembo F50 calipers in the front and OEM mitsu evo 2 piston rears, that alone should decrease my brake pedal pressure, but I don't know if it will be enough.
Ok, if you made it this far I'm done rambling.
Any opinions?
I realize that if I just remove the booster and redo some of the linkage it will be quite hard to press the brake pedal, not too much of an issue since I only deal with traffic maybe 5min a week at most. What can be done to keep this from happening? Can I rework the motion ratios in the brake pedal assembly to lessen the force required without loosing too much brake pressure or making the excursion length insanely long? I plan on upgrading to Brembo F50 calipers in the front and OEM mitsu evo 2 piston rears, that alone should decrease my brake pedal pressure, but I don't know if it will be enough.
Ok, if you made it this far I'm done rambling.
Any opinions?
Teching In
Joined: Mar 2004
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How about a vacuum pump? If not that route, I'm sure someone makes a decent manual brake setup. Look around, especially with speed/race equipment brake companies. Someone else will probably know more about it, but these would be my first two guesses for solutions.
You could try changing to a manual master cylinder. I have thought of that.
Only thing is most kits are made for aftermarket big brakes so they are smaller. Meaning a bigger ratio from pedal to wheels. Which I think means that it will require more pressure to stop.
Maybe a OEM manual master cylinder...
Only thing is most kits are made for aftermarket big brakes so they are smaller. Meaning a bigger ratio from pedal to wheels. Which I think means that it will require more pressure to stop.
Maybe a OEM manual master cylinder...
Last edited by 2002_Z28_Six_Speed; Dec 13, 2007 at 08:31 PM.
Don't think there's any OEM manual master cylinders for a GTO, might be something aussie market. Guess I'll give tilton a ring tomorrow. I've thought about a vacuum pump but I'm fairly opposed to any belt driven or electric vacuum pump, plus space is at somewhat of a premium. Most of what is considered "spare" room on the sides of a motor in a GTO will be taken up by intake plenum.
No. I meant something that was OEM from another car. Maybe something from an older GM car. If the spacing of the studs was right you could adapt it. It wouldn't be a 5 second job but even the aftermarket jobs use adapters.
I am with you on the vacumn pump. Something else to have in the way plus it puts even more strain on your timing set as well as continously reducing your fuel efficiency.
Here is the manual aftermarket kit for the F body.
Just as an example. Personally, I think it looks bulky in that photo.
Maybe the answer is to get a small MC from an old GM car and adapt it.
I am with you on the vacumn pump. Something else to have in the way plus it puts even more strain on your timing set as well as continously reducing your fuel efficiency.
Here is the manual aftermarket kit for the F body.
Just as an example. Personally, I think it looks bulky in that photo.
Maybe the answer is to get a small MC from an old GM car and adapt it.
Last edited by 2002_Z28_Six_Speed; Dec 13, 2007 at 09:02 PM.
Perhaps a hydraboost sort of setup like what is used in late model Escalades would work? It uses the power steering pump to pressurize a hydraulic brake booster. You might still be screwed on the HVAC, however.
Wow, that setup from Burkhart looks fairly nice. I'm quite skilled on the lathe/mill at work, I'm willing to bet I can just replace that plate where it bolts onto the firewall, might actually have enough room for that vacuum pump over behind the passanger side strut tower. Hydroboost is beyond out of the question, takes much more power to pump ATF than it does to pump air. Does anyone have any idea on horsepower requirements and CFM pumping capacity on belt driven vaccum pumps like the moroso unit? I guess I could afford to loose ~10hp to have something belt driven and take advantage of crankcase scavenging at the same time.
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The Burkhart unit does look pretty good. But the idea of it is even better. You could go to O'Reiley's and pick up a reman 1970 chevelle two well MC for ~30.00. Then draw up the plate and longer pin you would need. Send it off to be made and be done with it. Cheaper, smaller, and better looking than the Burkhart.
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I don't have an f-bod, but I just finished doing the conversion from power (vacuum) assist to manual. I have 13" Wilwood 6-pistons calipers on the front and 12.5" Wilwood 4-pistons on the rear. I had to change the master cylinder to a 1" bore, tandem reservoir Wilwood setup, and also change the GM combo valve to a 4-disc setup. To deal with the need for increased pedal power, I had to re-drill the brake pedal arm farther up the shaft for increased mechanical leverage.
Bottom line, I removed ~17 lbs. of booster/MC stuff (the new MC is aluminum instead of pig iron) and now have brakes that are very progressive and powerful, but require quite a bit more legpower to stop. I never liked the non-progressive American-style on/off power brake setup.
Jim
Bottom line, I removed ~17 lbs. of booster/MC stuff (the new MC is aluminum instead of pig iron) and now have brakes that are very progressive and powerful, but require quite a bit more legpower to stop. I never liked the non-progressive American-style on/off power brake setup.
Jim
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Joined: Mar 2004
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From: Laguna Niguel, CA
I don't have an f-bod, but I just finished doing the conversion from power (vacuum) assist to manual. I have 13" Wilwood 6-pistons calipers on the front and 12.5" Wilwood 4-pistons on the rear. I had to change the master cylinder to a 1" bore, tandem reservoir Wilwood setup, and also change the GM combo valve to a 4-disc setup. To deal with the need for increased pedal power, I had to re-drill the brake pedal arm farther up the shaft for increased mechanical leverage.
Bottom line, I removed ~17 lbs. of booster/MC stuff (the new MC is aluminum instead of pig iron) and now have brakes that are very progressive and powerful, but require quite a bit more legpower to stop. I never liked the non-progressive American-style on/off power brake setup.
Jim
Bottom line, I removed ~17 lbs. of booster/MC stuff (the new MC is aluminum instead of pig iron) and now have brakes that are very progressive and powerful, but require quite a bit more legpower to stop. I never liked the non-progressive American-style on/off power brake setup.
Jim
