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Race Car Brake Assistance, no vacuum available


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With multiple separate throttle bodies there is no way to use the usual booster setup without a vacuum pump arrangement, as far as I know. Simple question, is there a suitable alternative brake boost system available?

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Most throttle bodies have some sort of vacuum fitting on them.  If you connect them all together you may be able to run a vacuum booster off it that is what many OEM individual throttle body setups use.  If you are running hydraulic power steering, a hydoboost setup could be used.

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If you just delete the booster and go to the appropriately sized (smaller) manual master you should be able to get decent brake feel. If you drove my car and I didn't tell you the brakes were manual I doubt you'd say anything about the pedal feel at all.

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Like John M,  I also used a Non-Booster equipped Road Race 240Z back in the Day. You have to eliminate the Booster. Make a Custom length Pushrod. Depending  on you Pedal effort, you may want to relocate the Clevis Pin hole in the Brake pedal upwards a bit to change the Pedal ratio. About 0.750" to 1.0" is enough. We used a standard 7/8" Master on our ICSCC  D-Prod Z  . Worked out very well. Good modulation with proper setup. 

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It's for the race 350Z I bought, it has two Tilton MC's and no booster. I've always used a booster because it gives a light sensitive pedal feel which for me avoids brake lock up, anyway It's going to get it's first track test soon so we'll see. 

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On 7/6/2019 at 3:22 AM, 260DET said:

It's for the race 350Z I bought, it has two Tilton MC's and no booster. I've always used a booster because it gives a light sensitive pedal feel which for me avoids brake lock up, anyway It's going to get it's first track test soon so we'll see. 

I've have good luck using the electric vacuum pump from a diesel VW/Audi - they are readily available on ebay - search "VW electric vacuum pump".  Harder to find is an adjustable Hobbs (or similar) normally closed vaccum switch (i.e., opens when vacuum exceeds a reset threshold)...

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Thanks Tim, will check that option out.

 

My past experience. To get good pedal feel when using a vacuum booster it has to be set up right, bit of a black art. Anyway one booster was not set up right, the brakes were light switch on/off but boy did it stop, better than anything before or after. Hence my preference for power brakes, it's just part of getting the car to perform as close to the edge as possible without using driver aids.

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On 7/5/2019 at 2:51 AM, 260DET said:

With multiple separate throttle bodies there is no way to use the usual booster setup without a vacuum pump arrangement, as far as I know. Simple question, is there a suitable alternative brake boost system available?

 You could also put in a electric vacuum pump, Volvo uses them a lot, used ones are cheap.

https://www.ebay.com/itm/01-11-VOLVO-V50-C30-C70-S40-SEDAN-ABS-SERVO-VACUUM-PUMP-BRAKE-BOOSTER-MOTOR-OEM/223224522343?fits=Make%3AVolvo&epid=1711309953&hash=item33f937e667:g:3wUAAOSwKCZb5fuc

Edited by grannyknot
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Still need space for the booster though. I think GM's Hydroboost solution would work, not sure, but I keep coming back to wondering why you don't just tweak the manual brakes? Smaller masters will give a lighter pedal, larger will give a stiffer pedal that needs more pressure. It's not that hard to get it right.

Here's a youtube video on replacing a broken Hydroboost setup: 

 

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LOL, very bad. Track test coming up soon so we'll see. If extra vacuum is required for a power brake setup a vacuum switch controlled electric pump seems to be the best option, if needed a vacuum tank can be added for extra capacity so its not going to be, bugger, this is not working so throw it away and try again. I hate that.

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So what's happening is that a Z31 turbo vacuum pump is going to be used although before I found out about that a Hella UP28 pump was ordered, duh. Would not touch the aftermarket ones given the ridiculous prices they want and they are as noisy as hell. Apparently. Just need a switch now to keep the vacuum up and then off when max is reached.

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