Need advice on Brakes

[Aussiedeza]

Got my 70 challenger getting its brakes looked at last few days as they wont let it get registered with it the way the rear is locking up at the moment.

It has front discs and rear drums and i got a new master cylinder and booster installed a few weeks ago also new lines and fit up kits for rear drums, i only been driving the car for one day before this so it was hard to tell if the brakes felt any better.

The guy looking at it now says the brakes are really hard and don't travel far and believed it was because my 318 isn't making enough vacuum and hooked my booster up to another cars vacuum but it still wasn't much better.

I Called up the previous shop that installed the booster and they said that is how they performed from the factory and these engines never really make that much vacuum also my cam may be another reason i have low vacuum. not sure if my cam is not standard it is a bit rough to cruise at low rpm.

the current mechanic is going to keep looking at it tonight and get back to me tomorrow but to me it would seem silly to install a electric vacuum pump if the booster still doesn't do much when it has enough vacuum.. anyone else had similar issues?

Sucks i thought i was just bringing it in just to get a adjustable proportioning valve put in to stop the rear locking up may be in for serious money now. but if i have too i might as well do it right, should i even stay with this current booster system or go something different?

i am having a few issues with timing and backfiring atm too because i recently pressure washed my engine bay maybe my vacuum is a little lower then normal because of that?

Cheers

[dfrazz]

Check for vacuum leaks first because your motor should make enough vacuum for power brakes unless you have a radical set up.  A vacuum pump sucks and makes too much noise that will drive you crazy, ask me how I know.  If you are going to ditch the vacuum, I would suggest a hydraulic set up but it is pricey!   

[Aussiedeza]

yea think i might just see if i get away with a adjustable portioning valve to stop the rears locking up and look into what a hydraulic set up will cost me

[Aussiedeza]

can i get away with installing something like this
http://www.ebay.com.au/itm/Wilwood-Adjustable-Proportioning-Bias-Valve-Distribution-Block-Brake-Switch-/280845940737?pt=LH_DefaultDomain_15&hash=item4163b8f801
and just get rid of the old proportioning valve all together?

or do i need to keep the stock mopar one in and just add one of these guys for the rear? http://www.ebay.com.au/itm/WILWOOD-BRAKE-PROPORTIONING-VALVE-ADJUSTABLE-BIAS-FRONT-TO-REAR-WB260-8419-/400881766329?pt=LH_DefaultDomain_15&hash=item5d566a4fb9

I ask because the brake mechanic i had look wanted to recondition the stock one for $300 seems silly when you can buy new ones for less.

[brads70]

The rod in the booster that goes into the M/C is adjustable , make sure it's not into the M/C too much. Also when I had drum brakes I used the truck wheel cylinders . They are bigger and help with the rears locking up before the fronts.
Try using the truck wheel cylinders. Stock bore is 15/16" and the trucks is 7/8" (Raybestos WC37236, DORMAN  W37236). 
http://www.cuda-challenger.com/cc/index.php?topic=66387.30
http://www.cuda-challenger.com/cc/index.php?topic=85620.0;nowap

[roadman5312]

   Easy way to see if a booster is working.  Sit in car, engine off. Apply a good amount of pressure to brake pedal. Holding the pedal down,start the engine. If the booster is working the pedal will sink 1 1/2 to 2 inches.

[lifesatrip1111]

Dan, I have a 71 challenger with a 340. My issue is that I use it as much as I can, and I like driving at speeds between 60-80mph. I needed real stopping power and had discs on the front and drums on the back... I also have a mild cam in my car and the vacuum was okay but not great. The real solution to stopping is having full discs. The other part of the solution is buying a hydraboost system for the braking. It works off the power steering and eliminates the use of vacuum altogether,,,,It is not cheap, but it's not expensive either. I also changed my steering because I wanted more control, and now I don't have to make a three point turn to make a u turn. Stopping power is equal to a modern car. The car stops on a dime.  Safety is my prime concern and now I don't worry that I can't stop. Other Challenger owners have driven my car, and they are amazed on how well it stops and how responsive my steering is...