New brakes are a bit weak

HDTony · Aug 18, 2011

Ok granted it's a manual break system in a 45 year old car. I get that, but I just upgraded the front drums to disc and the new rear end has a much larger drum setup. I did the front with the kit from discbrakeswap, excellent customer service by the way and a very nicely assembled kit.

I've bled the living crap out of the system, adjusted the proportioning valve per specs. But it just doesn't seem like that much more braking than my original setup. I vacuum bled the system, then had the wife jump in and do the pump pump hold method till the fluid was clear as a bell and noo bubbles. Pedal is firm but it comes in rather late in the pedal stroke. I have the pedal adjusted all the back so the bump stop is barely touching the dash.

Is there anything else I should be checking?

golf4283 · Aug 18, 2011

Did you change the master cylinder? The pushrod may need to be adjusted.

horseballz · Aug 18, 2011

What master did you use and does it have a residual vale in it for the rear brakes?
Gene

HDTony · Aug 18, 2011

golf4283 said:
Did you change the master cylinder? The pushrod may need to be adjusted.

The pushrod from the pedal to the master? I have it adjusted out so the pedals bump stop is just touching the dash

HDTony · Aug 18, 2011

horseballz said:
What master did you use and does it have a residual vale in it for the rear brakes?
Gene

Yes, I adjusted it so the rears juuuust almost lock up under hard braking

iskwezm · Aug 18, 2011

my manual disc are NOT usefull in a emergency stop. They work, but but im not comfortable with them at all.

chris66dad · Aug 18, 2011

Have you called Dennis @ CSRP?

He should be the go to guy for this.
My 2 cents...

HDTony · Aug 18, 2011

chris66dad said:
Have you called Dennis @ CSRP?

He should be the go to guy for this.
My 2 cents...

Didn't want to bother Dennis, as he is a busy man, but I will give him a shout.

chris66dad · Aug 18, 2011

He is great at customer service and helping with questions or problems. I am certain he will not consider it a bother!

Rusty67 · Aug 18, 2011

When you changed to the new MC did you bench bleed it before it went into the car ? If you don't bench bleed the MC it can be nearly impossible to get the air bubble out of the MC. The entire system will seem free of air but it may not be.

Also, did you get an MC with a residual pressure valve ? If not do you have a residual pressure valve in line for the rear circuit ?

Did you adjust the rear drum shoes out so that they almost meet the drum ?

HDTony · Aug 18, 2011

Yup, bench bled it.

My kit has the adjustable proportioning valve, not the residual. Is adjusted.

Just talked to Dennis, he thinks there's air in the system, I am going to bleed it again and see what happens.

Rusty67 · Aug 18, 2011

The residual pressure valve and the proportioning valve server 2 different functions. Check with Dennis to make sure you got a disc/drum MC that has a rear residual pressure valve in the MC. If you don't have one, your rear drums will never work right.

Double check your rear brakes and make sure that you adjusted them out properly as this can cause a weak pedal.

I agree with Dennis that there is provably still air in the system. Another thing to check is to see if air is getting into the system. There may be a loose fitting somewhere. Did you put in new wheel cylinders ? If not, make sure the old ones aren't leaking at the rear.

2+2GT · Aug 18, 2011

Ok granted it's a manual brake system in a 45 year old car. I get that, but I just upgraded the front drums to disc and the new rear end has a much larger drum setup. I did the front with the kit from discbrakeswap, excellent customer service by the way and a very nicely assembled kit.
I think so, too.

I've bled the living crap out of the system, adjusted the proportioning valve per specs. But it just doesn't seem like that much more braking than my original setup. I vacuum bled the system, then had the wife jump in and do the pump pump hold method till the fluid was clear as a bell and noo bubbles. Pedal is firm but it comes in rather late in the pedal stroke. I have the pedal adjusted all the back so the bump stop is barely touching the dash.
OK, here's the deal. If you switched to disc brakes thinking they would be easier than drums, you wasted your time. Disc brakes work better than drums, in that they don't fade as quickly, and recover quicker when they do. However, disc brakes require higher hydraulic pressure, and while variables such as cylinder diameter can affect results, manual discs typically require more pedal effort than manual drums.
If you use the car for performance driving, or just drive it hard, you should have the discs.
If it's just a fun car, cruise night, etc., and you wanted an easier pedal, adding power boost to your drums would have been enough.

HDTony · Aug 18, 2011

I'd be fine with more pedal pressure, I work out I can handle it. My concern was I'm not feeling much resistance in the pedal till it's about half way through it's travel, and not getting any significant stoppage on the car till about 3/4 travel.

HDTony · Aug 18, 2011

Rusty67 said:
The residual pressure valve and the proportioning valve server 2 different functions. Check with Dennis to make sure you got a disc/drum MC that has a rear residual pressure valve in the MC. If you don't have one, your rear drums will never work right.

Double check your rear brakes and make sure that you adjusted them out properly as this can cause a weak pedal.

I agree with Dennis that there is provably still air in the system. Another thing to check is to see if air is getting into the system. There may be a loose fitting somewhere. Did you put in new wheel cylinders ? If not, make sure the old ones aren't leaking at the rear.

Is there a way to tell by looking at the master, to see if it has one? Part number maybe? I hate to keep bothering Dennis.

degins · Aug 18, 2011

HDTony said:
Is there a way to tell by looking at the master, to see if it has one? Part number maybe? I hate to keep bothering Dennis.

It has one. There is either a red residual pressure valve attached inline after the proportioning valve or attached at the rear outlet of the master cylinder (our new MC are configured this way).

BTW, I'd prefer that you bother me, give me a call anytime. I don't believe that the forum is the best place to perform customer service. Not that I don't appreciate everyone's opinions, but diagnosing the hydraulics must be approached systematically, and I'd prefer to control the message. It's less confusing that way.

dennis112 · Aug 19, 2011

2+2GT said:
OK, here's the deal. If you switched to disc brakes thinking they would be easier than drums, you wasted your time. Disc brakes work better than drums, in that they don't fade as quickly, and recover quicker when they do. However, disc brakes require higher hydraulic pressure, and while variables such as cylinder diameter can affect results, manual discs typically require more pedal effort than manual drums.
If you use the car for performance driving, or just drive it hard, you should have the discs.
If it's just a fun car, cruise night, etc., and you wanted an easier pedal, adding power boost to your drums would have been enough.

This advice is spot on and mirrors my experiences with both disc and drum brakes.

Even with the increased pedal effort, I am very happy with the stock 65' K/H Mustang discs at the strip as they do slow me down and never fade.

As to if there is a problem with the OP's installation, well I am sure that he is in good hands working with the parts supplier.

PoppyMod · Aug 19, 2011

HDTony said:
Is there a way to tell by looking at the master, to see if it has one? Part number maybe? I hate to keep bothering Dennis.

Hi,
I won't say it's the "cure all", but, I made an improvement in my manual disc/drum (2.5") system by adding a residual valve (<$20) at the "T" connection on the rear axle. It was super easy to install. You simply disconnect the the front line, install the small cylindrical valve into the "T" followed by the front line into it. Re-bleed the rear system. This valve will retain a slight pressure in the rear system to keep the rear shoes from backing off the drums as far as they do. This may be some of your noted prolonged pedal travel.
As 22GT mentioned, it won't reduce the pedal effort, it will help to maximize what your have. I felt the difference.
Good Luck!

Rusty67 · Aug 19, 2011

Dennis, I get what you are saying and I really kind of agree but it is also good to see that everyone here on the forums universally supports your product and wants to try to help. Its almost good publicity =)

On the other hand, you are right, a systematic troubleshooting approach is what will solve this problem.

My last suggestion on this issue which I haven't heard a response to is, have you adjusted the rear drum brakes out properly. If you don't have the rear adjusted properly it will cause excessive pedal travel before the car starts to brake.

degins · Aug 19, 2011

Rusty67 said:
Dennis, I get what you are saying and I really kind of agree but it is also good to see that everyone here on the forums universally supports your product and wants to try to help. Its almost good publicity =)

On the other hand, you are right, a systematic troubleshooting approach is what will solve this problem.

My last suggestion on this issue which I haven't heard a response to is, have you adjusted the rear drum brakes out properly. If you don't have the rear adjusted properly it will cause excessive pedal travel before the car starts to brake.

Rusty, Agreed. The forums are here for people to discuss their common interest and it is natural that folks will seek out or offer opinions.

I did speak to the OP. Adjustment of the rear brakes is always the first suggestion when excessive (soft) pedal travel is experienced. If a soft pedal persist after that, I suggested that there is likely air in the system.

New brakes are a bit weak

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