Spongy brakes

I have a 99 Tahoe that I really like and plan on towing a small travel trailer. It has the tow option and everything, but I am concerned about the brakes. We had the brakes checked at the Ford dealership that we bought this at and then again at the local Chevy dealer (to the tune of $58.00) and everybody has said the brakes are fine but to me they feel spongy and sometimes they have to go almost to the floor to stop. I am not at all comfortable with them. I have looked at some of the aftermarket kits for rear disc conversion..but thats over $1200 not including labor. Any sugestions?

Any brake lights on?
Will brakes slide all 4 wheels?

First test is engine off pump brakes a few times to remove vacuum from booster.
Then step on brake and see if you have a good full pedal.
Post back on that.

Rear disk brake will not help much.
Most breaking is on front wheels.

No lights on and the vehicle has ABS so I didn't try to lock up the wheels. I did pump up the brakes with the engine off and the pedal got nice and firm. Thanks

OK if firm pedal up to the top with engine off says front and rear brake hydraulic system and adjustment OK.
In first post on pedal going almost to floor does it do that all of the time or part time?
Can you feel any pedal drop or seep down with light brake pedal apply light sitting at stop sign with in gear?
Any brake fluid lose?

I have a 99 Tahoe that I really like and plan on towing a small travel trailer. It has the tow option and everything, but I am concerned about the brakes. We had the brakes checked at the Ford dealership that we bought this at and then again at the local Chevy dealer (to the tune of $58.00) and everybody has said the brakes are fine but to me they feel spongy and sometimes they have to go almost to the floor to stop. I am not at all comfortable with them. I have looked at some of the aftermarket kits for rear disc conversion..but thats over $1200 not including labor. Any sugestions?

your vehicle has rear drum brakes ?

If so this problem is quite common. the pro's that are experts at these brake systems for some reason don't get it with why this occurs.


the drums made in todays world are of much softer metal[this wears down faster]. the use of brake shoes not using the ASBESTOS lining material , but a highly abrasive mix , adds to the problem.

replace the rear drums. since you towing a trailer , you will need to replace these drums at every time the shoes are worn.

when the drums are removed look at the top radius of the shoes. If this is worn but the bottom radius not worn much ,this is the drums worn or bell shaped from overheating..............

NEVER EVER CUT DRUMS !

No loss of fluid..and the brakes seem to go to the floor only part of the time. It will hold the pedal with light pressure at a full stop in gear. I'm beginning to think who ever did the brake job last took the cheapest way possible and bought junk pads and shoes.

Cheap wil not stop good but should not lower pedal.
As J cat said rear shoe or drum wear may lower pedal.
But that part of time is not right.
Part of time with no fluid lose could be in master cylinder or air in system.
Has the brake system and ABS system been bleed good?

No loss of fluid..and the brakes seem to go to the floor only part of the time. It will hold the pedal with light pressure at a full stop in gear. I'm beginning to think who ever did the brake job last took the cheapest way possible and bought junk pads and shoes.

the pedal going to the floor would indicate the master cylinder is failing since you have not lost any fluid.

spongy brakes mean air in the brake system.

when braking normally if the brake effort is lacking , replace the rear drums if as I mentioned , the top of the shoes are only worn.


since you had this inspected and paid for this inspection something is very wrong here...............



shoe/pad quality is not a factor with you complaints............

Thanks to all that gave me their advice...I know when the brakes were looked at at the ford dealer, they said the shoes were at a 4 and they replace them at a 3...I doubt if anybody miked the rear drums to see if they were still in spec so if I put new drums and shoes on the rear is it worth the extra dollars to put performance parts here? I will also have the brakes and ABS bled at the same time. Any recommendations for parts ? I have been pretty much out of the loop for a while so I am looking for some good feedback. Thanks

Thanks to all that gave me their advice...I know when the brakes were looked at at the ford dealer, they said the shoes were at a 4 and they replace them at a 3...I doubt if anybody miked the rear drums to see if they were still in spec so if I put new drums and shoes on the rear is it worth the extra dollars to put performance parts here? I will also have the brakes and ABS bled at the same time. Any recommendations for parts ? I have been pretty much out of the loop for a while so I am looking for some good feedback. Thanks

I have been using the advance auto brake parts with the lifetime warrantee. so far with a good number of vehicles It has worked out.

Spongy brakes are a common problem with this truck chassis. From what I've read and from limited experience, you can bleed them till the cows come home and still have spongy brakes.

To be 100% sure, the ABS system needs to be cycled using what's called a Tech II scanner to remove all air from the unit by cycling all the ABS solenoids to dislodge any air bubbles.

Second, do the old, two-man brake bleed or the one man with the hose bubbling into a jar of fresh fluid. I've found that I can't get a good tight seal around the bleed screw to do a good vacuum bleed, but other setups may vary. DO NOT LET THE RESERVOIR GO DRY!

Three, adjust the rear brakes properly. Even though the rears don't provide the majority of the stopping power, they do engage first to give stability to the vehicle, the proportioning/combination valve then works to adjust the front/rear pressures. If these engage late due to them being too loose, then it can feel like braking is delayed.

Hope this helps!

This should help you out quite a bit...invest in a good set of new pads!!

Pads - Check out Hawk LTS - they are "thicker", therefore the brake pedal travels less before the pad touches the disc.

Discs - you can also invest in slotted rotors - don't go Chinese and no need for cross-drilled.

Stainless Steel Brake Lines - some people have noticed firmer pedals going this route, but i personally can't see how a set of Stainless lines would be better then a new set of rubber (the whole expansion theory).

Net Net - new pads should give you the best bang for your buck.

Check out this link:
http://www.tahoeyukonforum.com/forum/showthread.php?t=19820&highlight=hawk

They also discuss the upgraded 3/4 ton caliper.

Hope this helps.

This should help you out quite a bit...invest in a good set of new pads!!

Pads - Check out Hawk LTS - they are "thicker", therefore the brake pedal travels less before the pad touches the disc.

Discs - you can also invest in slotted rotors - don't go Chinese and no need for cross-drilled.

Stainless Steel Brake Lines - some people have noticed firmer pedals going this route, but i personally can't see how a set of Stainless lines would be better then a new set of rubber (the whole expansion theory).

Net Net - new pads should give you the best bang for your buck.

Check out this link:
http://www.tahoeyukonforum.com/forum/showthread.php?t=19820&highlight=hawk

They also discuss the upgraded 3/4 ton caliper.

Hope this helps.



So when my brakes pads wear down, my pedal travels more? I don't think so.

Then add your insight as to why premium pads require less pedal travel then cheaper pads.

So when my brakes pads wear down, my pedal travels more? I don't think so.

when pads/and or rotor/drums are excessively worn the amount of brake fluid in the pistons is much larger in volume...this now creates a softer pedal as the fluid needs to be compressed more to create the braking pressure.

when I had to brake very large transportation vehicles I used a pressure supplied bleed machine. the guages told this story quite well.

these toy trucks/vehicles weigh 5,ooolbs..when you bleed brakes for 50,000lbs you must not make stupid mistakes and ignore worn braking componets.

So when my brakes pads wear down, my pedal travels more? I don't think so.

Right on track there Laxman21.

To add a little info.

Worn rear shoes out of adjustment can lower pedal travel.

The original post said spongy brakes.
And little lower than he thought they should.
{Which is sometimes normal with a lot of power brakes.}

But full solid with engine off which would point to just brake booster soft and causing more travel .

If a pedal is more spongy than normal the ABS unit and complete with brake system.
If pedal is lower than normal or not full pedal with engine off check andadjust up rear brake shoes.
Many require a ABS scanner to bleedthe ABS system.

when pads/and or rotor/drums are excessively worn the amount of brake fluid in the pistons is much larger in volume...this now creates a softer pedal as the fluid needs to be compressed more to create the braking pressure.

when I had to brake very large transportation vehicles I used a pressure supplied bleed machine. the guages told this story quite well.

these toy trucks/vehicles weigh 5,ooolbs..when you bleed brakes for 50,000lbs you must not make stupid mistakes and ignore worn braking componets.


Brake fluid compresses about 1-2% at the most and it is greater at high temperatures, so in all reality you won't notice much at the pedal. Maybe 1/2" to 3/4 at high temperatures.


Don't those very large transportation vehicles use air brakes?

Brake fluid compresses about 1-2% at the most and it is greater at high temperatures, so in all reality you won't notice much at the pedal. Maybe 1/2" to 3/4 at high temperatures.


Don't those very large transportation vehicles use air brakes?

the large transportation equipment will have , on different manufacturers , air brakes as well. however the hydraulic brakes are superior...very much so ! air brakes suffer from mositure . this then causes braking issues especially in cold weather..

also air does compress very well , compared to hydraulic brake fluid .

when you replace the worn brake componets the brake fluid in the lines and pistons is reduced. this then causes a much harder pedal..

air in the system will also do this ..when bleeding it is important to slowly press down on the brake pedal.. pumping quickly causes air bubbles to form...

with the pressure bleeder I used , we always filled the system with the pressure very low on filling...instead of filling the brake reservior we filled thru the brake calipers this pushed back all the air out the system ...

the large transportation equipment will have , on different manufacturers , air brakes as well. however the hydraulic brakes are superior...very much so ! air brakes suffer from mositure . this then causes braking issues especially in cold weather..

also air does not compress very well compared to hydraulic brake fluid .

when you replace the worn brake componets the brake fluid in the lines and pistons is reduced. this then causes a much harder pedal..

air in the system will also do this ..when bleeding it is important to slowly press down on the brake pedal.. pumping quickly causes air bubbles to form...

with the pressure bleeder I used , we always filled the system with the pressure very low on filling...instead of filling the brake reservior we filled thru the brake calipers this pushed back all the air out the system ...


Air compresses much better than liquids. But I understand what you are getting at.

Air compresses much better than liquids. But I understand what you are getting at.

that is true I did not correctly explain that fact.

because brake fluid does not compress as easy as air this is why brake fluids work better with braking systems , than air....also to create a large enough force / volume to get the braking forces required you always get a delay with air brakes..