Question about brakes

[yolner]

So I'm still working on my deuce and it doesn't get driven much. Before I head out for a cruise around the block I like to pressure bleed the brakes and get a nice firm pedal. Then when the truck sits for a couple of weeks it feels like the pedal goes down further before I start to feel resistance.

I don't have any leaks (fluid level seems to stay constant) and I installed a brand new master and all brand new lines after I got the truck.

Is this a problem or normal?

 

[hndrsonj]

You shouldn't have to bleed the system when you drive it. My pedal is the same every day.

 

[rpollitt01]

I am new also, but from what I hear this is a common problem. Try adding a remote reservior. It is very easy and @ $20!!!....There is a nice thread about it on here. Go to the search option and type in remote reservior...That should give you some peace of mind at leaste....

 

[hndrsonj]

I am new also, but from what I hear this is a common problem. Try adding a remote reservior. It is very easy and @ $20!!!....There is a nice thread about it on here. Go to the search option and type in remote reservior...That should give you some peace of mind at leaste....

A remote resevoir will not fix a pedal getting softer while sitting.

 

[nk14zp]

It might be leaking brake fluid into the airpack.

 

[nk14zp]

Also might have the wrong expander cups in the wheel cylinders.

 

[hndrsonj]

The troubleshooting manuals will take you step by step through the problem.

 

[boondock]

refer to TM's at JATONKA's M35 TM download page.

 

[3rdmdqm]

So I'm still working on my deuce and it doesn't get driven much. Before I head out for a cruise around the block I like to pressure bleed the brakes and get a nice firm pedal. Then when the truck sits for a couple of weeks it feels like the pedal goes down further before I start to feel resistance.

I don't have any leaks (fluid level seems to stay constant) and I installed a brand new master and all brand new lines after I got the truck.

Is this a problem or normal?

Maybe I'm misunderstanding this, but are you saying you bleed your brakes everytime before you drive it if it sits a couple of weeks? This should be completely unnecessary and sounds like an awful lot of work every time you want to drive the truck. If you have no leaks and no fluid loss and if all of the air was bled from the system properly (air pack, all wheels, Master cylinder etc) whenever they were last serviced, this should not be an issue at all.

 

[yolner]

Maybe I'm misunderstanding this, but are you saying you bleed your brakes everytime before you drive it if it sits a couple of weeks? This should be completely unnecessary and sounds like an awful lot of work every time you want to drive the truck. If you have no leaks and no fluid loss and if all of the air was bled from the system properly (air pack, all wheels, Master cylinder etc) whenever they were last serviced, this should not be an issue at all.

The problem is that the pedal gets softer when the truck sits for 1-2 weeks. I can't find any leaks so I'm looking for other potential causes. Bleeding with a pressure bleeder only takes me a couple of minutes.

 

[3rdmdqm]

Are you using DOT5? I couldn't afford to bleed my brakes that often. When you say gets softer after sitting what exactly do you mean? Does the pedal go to the floor? Feel spongy rathern than hard? Is there a change if you pump them up? Are you waiting for the air pressure to build up from the air assist air pack before you notice this? When you bleed them do you notice a definite change? If so I would suspect that either air has not been removed from somewhere (airpack or master cylinder) or some other issue.

 

[rlwm211]

If you do not bleed the brakes do they eventually pump up to a firm pedal, or does the pedal stay soft?

The reason I ask is that if it is getting a soft pedal and it does not pump up firm, then air is getting into the system. Otherwise you could pump the pedal a few times and get your firm pedal back.

I know that you can have a small leak in a wheel cylinder and it can weep out brake fluid but not enough for you to see it on the outside.

Depending on how long you have had your truck, I would highly recommend pulling each wheel hub, and inspecting the brakes, replacing the wheel cylinders, packing the bearings, and doing a primary brake shoe adjustment as per the TM.

Only then will you be sure your truck has good brakes and your bearings are properly lubed with grease. It will take a while to do ( I did two hubs a day but then again, I am 56) but the security you get is worth it.

You have to remember that you have a single circuit system with no real back up if something goes awry. Safe instead of sorry would be the best course of action.

Just my two cents worth.

RL

 

[G-Force]

Yolner,
how is your master cylinder vented on top. Do you have one of those vents like on the rears, trans and transfer case???
If so, take it off. With the temperature expansion and contraction over time those vents will cause the master cylinder reservoir to draw down into a vacuum. This could cause you to pull air into your brake system from your wheel cylinders. not saying this is the problem....but its something to check.

 

[blueeagle79]

On the issue of brakes, I just picked up an A3 form Fort Riley. The brake pedal is very very hard, No telling how long it has set prior to auction. I saw a thread about adding air tool oil to the brake pacs... any thoughts? I have a A2 and its brakes are much easier. Thanks!

 

[yolner]

Yolner,
how is your master cylinder vented on top. Do you have one of those vents like on the rears, trans and transfer case???
If so, take it off. With the temperature expansion and contraction over time those vents will cause the master cylinder reservoir to draw down into a vacuum. This could cause you to pull air into your brake system from your wheel cylinders. not saying this is the problem....but its something to check.

Yes I do have that vent on my mc cap. What can I replace it with?

I will respond to the other advice in this thread when I have a chance to mess with the truck after work tomorrow or friday. Thanks for the good ideas guys.

 

[G-Force]

I would remove the vent and either run a line up to the engine compartment by the air cleaner or install a remote reservoir.

 

[3rdmdqm]

Here is a great link for information about remote reservoirs. Also has a picture of a master cylinder vent.
http://www.steelsoldiers.com/deuce/42401-remote-brake-fluid-reservoir.html

 

[rchalmers3]

Interesting problem. I suggest that as a diagnostic that you bleed one wheel at a time and check results. Also, try a new first wheel position each time you bleed the brakes. The idea is to identify if there is one wheel causing the soft pedal.

Rick

 

[yolner]

Just want to provide an update on my problem. I got rid of the vent on the top of the cap and replaced it with a regular open hose. After two weeks the pedal feels the same as right after bleeding. Looks like problem solved.

 

[goldwing2000]

Good deal. Just be sure you put some sort of filter (or remote reservoir) on that hose so you don't get contaminants into the MC.