Austin-Healey Replica Forum
You are not currently logged in and therefore do not have permission to view the full site. Please log-in or register. Not registered yet? Become a member of the Austin-Healey replica forum to access all of its features and disable advertisements.

Converting power brakes to manual brakes

View previous topic View next topic Go down

Converting power brakes to manual brakes

Post by David V. on Thu Feb 26, 2015 12:46 pm

Is anyone on here running manual brakes (no power assist)? It will soon be impossible for me to draw engine vacuum for the booster and my vacuum signals have been very unequal anyways. I have installed an electric vacuum pump which gives me great brake response, but after about 4 pushes in a row you're out of vacuum reserve until the pump can compensate (usually takes about 20-25 seconds). I will be installing a small tank to increase my vacuum reserve, but that still means that if ever the fuse blows, I'll be out of brakes before I know what hit me.

The other option would be to put a mechanical vacuum pump (belt driven), but that sucks out some horsepower and the kit costs in excess of 1200$ (ouch).

I was wondering if anyone has a manual brake setup that gives good braking power. If so what components are you using and how does it compare?

Cheers

David
avatar
David V.
Admin

Posts : 489
Join date : 2014-05-27

http://healeyreplicas.forumakers.com

Back to top Go down

Re: Converting power brakes to manual brakes

Post by Hotrod on Thu Feb 26, 2015 10:22 pm

David - I'm studying just what you are asking for, but I'm also upgrading the brakes front and rear to larger discs.  I don't know if what I'm planning will help you.  

My plans would be to use a dual master cylinder setup like a race car(literally has 2 separate master cylinders).  These use a balance bar to mechanically adjust front to rear brake bias and don't need a proportioning valve.  It's a more expensive way to go, but has advantages.  I used a similar rig on my T Bucket and liked it.

The engine I'm building should have enough vacuum for PB's, but I think manual would give a better feel.  

The one thing that will be the deciding factor is whether I feel my wife can handle the manual brakes.  They do take more effort.  I've already had to rethink redesigning my front end so that I can add power steering, but I want her to be able to enjoy the car, too.

BTW - I am working on an update for my build thread, but I've been slowed down on the project and wanted to wait until I had something worth reading about. I'm enjoying your thread.

Mike
avatar
Hotrod

Posts : 292
Join date : 2014-06-17

Back to top Go down

Re: Converting power brakes to manual brakes

Post by David V. on Thu Feb 26, 2015 11:12 pm

That sounds very interesting Mike! Had never thought of dual master cylinders. The issue with me is that the new setup i'm installing won't let me get any vacuum at all. So I don't really have a choice, and either have to eventually get a mechanical vacuum pump or get manual brakes. If I could have gotten a bit of vacuum from the engine then I would have been confident in supplementing it with my electric pump, but right now if the pump goes out it'll be little-to-no brakes with no warning.

I've been reading up on it and have also found that swapping the master cylinder for one specifically tailored to manual brakes makes a huge difference. Apparently there are kits available. Also very important is braided brake lines, which I have already, and using a specific pad type. For street use pads that provide really high grip at low temperatures are recommended, and then when you hit the track you swap to pads that have peak grip at higher temperatures and fade less.

Just what I've learned so far. Please let me know if you find anything else. I am really looking forward to seeing some of the work you've done Smile
avatar
David V.
Admin

Posts : 489
Join date : 2014-05-27

http://healeyreplicas.forumakers.com

Back to top Go down

Re: Converting power brakes to manual brakes

Post by Hotrod on Fri Feb 27, 2015 5:32 am

One or two other thoughts.  Manual brake setups usually have more leverage built into the pedal and/or a smaller bore MC.  Both solutions will build pressure with less pedal effort, but require more pedal travel.  

Some diesel cars and trucks have a belt driven vacuum pump for accessories and brakes.  You might look into adapting one of them. Of course the brackets would be custom. I think some 90's era Ford and Chevy trucks used this setup.

Also, I don't know if you're running power steering, but there is the Hydro-boost system if you are.  They put it on some late model Mustangs and some Lincolns (maybe some Caddies, too).  It is also used on 1 ton trucks, but that system is physically larger.  The system uses hydraulic pressure from the PS pump and has an accumulator to store some pressure for emergencies.  Since PS pumps are so easy to adapt to most engines, that might be a solution even if you don't run PS, but it will take some HP.  One warning I can give you about it.  I had a 1 ton truck with the HB system.  The accumulator is pretty small.  You get maybe 1 or 2 good pedal operations and then it losses boost pretty quick.  This was on an older truck, the newer systems may be better.

Mike
avatar
Hotrod

Posts : 292
Join date : 2014-06-17

Back to top Go down

brakes

Post by Loren Tungesvick on Fri Feb 27, 2015 12:03 pm

I have Mustang2 manual brakes, front disk rear drum, and they stop mine with very little foot pressure.
Loren

Loren Tungesvick

Posts : 9
Join date : 2014-06-14

Back to top Go down

Re: Converting power brakes to manual brakes

Post by Jimboquick on Fri Feb 27, 2015 12:14 pm

Converted our "MX" from manual brakes to power brakes about three seasons after we had SSBC {#SSA148-1A} front disc brake kit and braided brake lines installed on the front. Double Diaphragm booster/ master cylinder {Cardone NAPA#54-73201}. Also used a SSBC #A1726 adapter to good effect. Huge braking improvement and much reduced brake force.
Regards,
Jimbo

Jimboquick

Posts : 133
Join date : 2014-06-16

Back to top Go down

Re: Converting power brakes to manual brakes

Post by Sponsored content


Sponsored content


Back to top Go down

View previous topic View next topic Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum