Problem with my brakes, let me know what you think

[benno440]

Hey guys,

got a 68 charger has 4 wheel wilwood discs and 4 piston calipers. has stock style right stuff booster and wilwood tandem master cylinder.

I have always had not the best of brakes due to not getting much vacuum to them from carb never being properly tuned and a big cam (300/305).

i recently had the diff out modifying some things and put it all back together and i was bleeding the brakes. my wife was in the cab pressin gthe pedal for me then bam the pedal went to the floor, i got in and had a look and the I bolt that bolts to the pedal and screws into the booster rod bent in half (yeh i know right, its a 12mm bolt and my wifes not that strong).

So i removed the bolt straightened it and strenghtened it.
so i take it for a drive and like i said i have never really had good brakes but not when i put the brakes on slightly you can feel it starting to pull up but if you need to brake suddenly i have to put neally every bit of strength i have on that pedal and it will start to pull up but will not even lock up, almost like it moves down about an inch then feels like trying to press against a brick wall.

i do not have a very good vac gauge but i know it is really low, but before i start tearing every thing down i.e booster and master cylinder what do you guys think it could be? any help or ideas would be greatly appreciated.

 

[HawkRod]

So I don't know enough to answer the question, but hopefully I can start you in the right direction. I am sure others can chime in too with better help than what I know...

The geometry of brakes is important. You have the travel of the brake pedal and how much that pushes on the brake booster, and how much that in turn pushes on the master cylinder. That could be one place to look if your brake pedal is not creating enough travel of the master cylinder plunger.

Then, the size of the master cylinder (how much volume it pushes per distance the plunger is pushed) is another factor - add to that you have the thickness of your brake lines - if the lines are thicker they need more volume of fluid to move the brakes. This needs to be sized properly based on your calipers too.

Hopefully this might give a couple of things to start checking...

 

[benno440]

supposedly all my gear is correct as per wilwoods specs and there tech line.
i believe it is a 7/8" bore MC. i believe i put 3/16 stainless lines on. pedal rod bolts in stock location approx 1" down from swivel point ( rod lines up straight through firewall)

I remember year or 2 ago when i first installed it the rod that goes from booster to MC was too long as you had to depress MC piston to bolt the MC on and when you went for a drive and the engine bay heated up the brakes would lock on as not letting enough fluid back so i had to trim the rod down as per wilwoods spec.

brakes used to work better but not much

 

[lewtot184]

maybe you need an additional vacuum can or an electric vacuum pump.

 

[benno440]

maybe you need an additional vacuum can or an electric vacuum pump.

could be that simple you think?
is 300/305 cam really a big cam? or is it something else, not keen on stripping it all down if i dont have to.

 

[HawkRod]

Hi Benno,

Many setups are different. The stock power brake booster uses a small "lever" that activates the power brake booster. The bottom hooks to the structure under the dash, while the top hooks to the power booster. The middle connects to the brake pedal. This creates an indirect type of connection that actually increases travel of the master cylinder. Don't know how this helps - as the Wilwood system may not use this at all, but I figured I would attach the picture just in case.

Good Luck!

 

[mopar 3 B]

Or you could just switch it to a manual brake system and not worry about engine vacuum.

 

[benno440]

Or you could just switch it to a manual brake system and not worry about engine vacuum.

well thats pretty much what im running now manual brakes, i would much prefer power brakes, might have to get one of those hydroboost setups.

- - - Updated - - -

Hi Benno,

Many setups are different. The stock power brake booster uses a small "lever" that activates the power brake booster. The bottom hooks to the structure under the dash, while the top hooks to the power booster. The middle connects to the brake pedal. This creates an indirect type of connection that actually increases travel of the master cylinder. Don't know how this helps - as the Wilwood system may not use this at all, but I figured I would attach the picture just in case.

Good Luck!

View attachment 232669

this is the exact booster i have, it sits off the firewall with a bracket and has the offset bracket similiar to that but slightly different.
http://www.summitracing.com/int/parts/rsd-rpb8001/overview/year/1968/make/dodge/model/charger

 

[slepr1]

A shot in the dark here...did you install the 'depth correction plug' in the master cylinder before installing it on the booster?

 

[Propwash]

maybe you need an additional vacuum can or an electric vacuum pump.

could be that simple you think?
is 300/305 cam really a big cam? or is it something else, not keen on stripping it all down if i dont have to.

As a comparison Benno i'm running a 282/292 in my bird and needed to install an electric vacuum pump for the brakes. Made by CVR and it's mounted under the battery tray.

BTW....the below pic is what a stock-like Mopar Bendix disc booster looks like for your car. It has a 1 1/8" bore M/C. It doesn't have the offset bracket like yours. The booster you have is the one "Right Stuff" sell's, and is made for converting manual drum to power disc. It's not intended for converting power drum to power disc, but you won't catch them telling you that.... I found out the hard way and ended up having to track down a bendix booster. Now a couple years later the booster, reinforcement plate and linkage are all easily accessible.

View attachment 232682

 

[benno440]

As a comparison Benno i'm running a 282/292 in my bird and needed to install an electric vacuum pump for the brakes. Made by CVR and it's mounted under the battery tray.

BTW....the below pic is what a stock-like Mopar Bendix disc booster looks like for your car. It has a 1 1/8" bore M/C. It doesn't have the offset bracket like yours. The booster you have is the one "Right Stuff" sell's, and is made for converting manual drum to power disc. It's not intended for converting power drum to power disc, but you won't catch them telling you that.... I found out the hard way and ended up having to track down a bendix booster. Now a couple years later the booster, reinforcement plate and linkage are all easily accessible.

View attachment 232682

mine was originally manual front disc and rear drum, I went power disc all around.

- - - Updated - - -

A shot in the dark here...did you install the 'depth correction plug' in the master cylinder before installing it on the booster?

depth correction plug? if you enlighten me on what this is I can tell if I did or not. I do not remember leaving anything out

 

[Propwash]

mine was originally manual front disc and rear drum, I went power disc all around.

Ahhh. Didn't even realize that was an option for your year of Charger. Either way, an electric vacuum pump would probably do wonders for actually giving you "power brakes". I was struggling to get 11 Hg of vacuum, which doesn't foot the bill to well for the bendix to operate the way it should.

 

[benno440]

I think mine is around 4 lol

 

[Propwash]

4? LOL! Hehehehehe. Yeah, electric vacuum pump or a hydoboost braking system, like you mentioned.

 

[slepr1]

mine was originally manual front disc and rear drum, I went power disc all around.

- - - Updated - - -
Check video at time 1min37sec .

https://www.youtube.com/watch?v=lNtMx_4PBtk


depth correction plug? if you enlighten me on what this is I can tell if I did or not. I do not remember leaving anything out

Check out video below 1min37sec.

https://www.youtube.com/watch?v=lNtMx_4PBtk