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10 in. of vacuum at idle. what's the cure for my dead brakes


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My car has a long duration cam and I think it killed my power brakes ! Does anyone know of an easy fix? The pedal is rock hard but the effort is extreme to stop the car. The system is stock 74'. Is there a manual system out there so that I could eliminate the booster completly? The car is drag raced and street driven on weekends. Any input would be great....

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Guest Anonymous

That link didn't display for me this morning, but if its what I think it is, it would be a vacuum reservoir canister. It stores vacuum and is used quite often for this problem. And yeah at 10" of vac you probably aren't supplying enough vacuum for the booster.

 

You might be able to find one BTW in a wrecking yard, look for a old land yaht Ford (like a earlier Tbird) as they used a TON of vacuum accessories and often put them on the car to run all of them successfully. It'll look like a coffee can basically with a few hose fittings and a check valve on it. Good luck.

 

Regards,

 

Lone

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The vacuum canister that Datsun used can be doubled or tripled up to add more volume, which allows the vaccum to hold up longer with each cycle of use. The second alternative I can suggest is a slightly smaller master cylinder, or larger caliper pistons (or larger total piston area if you go with multi-piston calipers) which entails a brake upgrade. If you have already installed a larger master cylinder (like many of us already have), you may want to return to the smaller OEM version. Decreasing the MC/brake piston ratio will improve the pressure or leverage against the rotor, but will proportionally increase the pedal travel to do so (which will make your pedal less "rock hard").

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I'd recommend the electric vacuum pump. I used the canister on an 88 Monte Carlo SS and there were times i got stuck in stop and go traffic and there wasnt enough reserves to step on it a few seconds later :eek: . The electric pump solved my problems, but it does cost a lot more. flamedevil.gif

 

I think its this one, im not sure though

http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=24728&prmenbr=76

 

http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=7761&prmenbr=76

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Im running a crane cams vacuum canister and it has helped a whole lot. I need the resavoir as I have a rather lumpy cam. Extreme energy roller cam..234/242..530/540...110 lobe. It solved my problems!

 

zfan..Mike 2thumbs.gif

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Sorry about the delay in response time guys. I do thank all of you for the input and have thought about trying the reservoir for more volume but at 10in. of vacuum I dont think volume will totally solve my problem.Has anyone tried going to a Dodge style manual brake MC ? This is common on many drag cars with monster cams. My cam specs.out at 246/246 at.050 with a 108deg. lobe separation angle.Where can you buy a electric vacuum pump?

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