New member 2003 Z71 with brake issue

[MOZ2121]

Hey guys new member here just wanted to say hello and pick your brains on something.
I picked up this tahoe a few years ago and the brakes were horrible, I tow very frequently and under load the brakes are down right scary. Now I've read up on the hydroboost upgrade and the 07+ front caliper upgrade, but I'm wondering, why can't the old vacuum system be repaired or diagnosed? I've been to about 4 mechanics and all say everything looks good, but I know how these cars are supposed to performed I've owned one since 2004. I was going to throw some money at a new booster and master cylinder but I've also read that some get no improvement after the replacement. Let me know what you fellas think.

 

[Bill 1960]

Welcome. You’re going to have to tell us as much as you can since we can’t see it or take a test drive.

What symptoms specifically are you having? Soft pedal, lack of booster assist & hard pedal?

Is the braking proportional front and rear as far as you can tell, or is one end not contributing?

Can you get ABS engagement with an emergency stop?

Have the brake pads and calipers been inspected for wear and contamination? Have they been changed?

 

[Big Mama]

Welcome to the forum from Virginia. Lots of knowledgeable folks here that’ll help with your brakes.

 

[George B]

I owned an 03 Suburban Z71 for 5 years that had crappy brakes. They just felt spongy and didn’t inspire confidence. They stopped it but not as good as I liked. I did end up with a new master cylinder that didn’t help and bled about a gallon through the system. Some have had good luck with the NNBS brake upgrade and I have read about a larger bore master cylinder too.

Try a couple stops in gravel that get the ABS to actuate and see if the brakes get better.

 

[MOZ2121]

Welcome. You’re going to have to tell us as much as you can since we can’t see it or take a test drive.

What symptoms specifically are you having? Soft pedal, lack of booster assist & hard pedal?

Is the braking proportional front and rear as far as you can tell, or is one end not contributing?

Can you get ABS engagement with an emergency stop?

Have the brake pads and calipers been inspected for wear and contamination? Have they been changed?

very soft and spongy, going down a mountain pass once was scary as hell , wouldn't stop for beans luckily I made it out ok. I've had other tahoes with vacuum assist and their brakes were perfect, even my dads 2001 tahoe with 250k miles brakes 1000 times better.
I've never had the ABS engage at any speed , if I slam the brakes at any speed they will not lock just eventually comes to a stop .

the braking seems proportional as far as I can tell, although sometimes when I really slam on them I can feel a slight throbbing on the pedal.

the calipers, rotors and pads are new and were installed about 3 years ago by previous owner.

system was bled twice.

 

[OR VietVet]

Welcome to the forum from Oregon. Fortunately my 05 Z71 has the hydro boost brakes. They work great. If the brakes are that bad and you likely have heated them up a few times just trying to stop. The pads may be baked enough that they should be replaced. How much vacuum are you making with the engine? Air bleed at booster?

Upgraded brake system, options at RA. There are a few threads here about the hydro boost changeover that has been done here.

 

[Dantheman1540]

I feel the trucks with the vacuum booster come with very poor brakes from the factory. The hydro-boost upgrade is the single best upgrade I've done to brakes on anything I've ever owned. It's actually a significant difference where SS lines and new pads/rotors have never made much difference to me. If you are considering dumping money into replacing the vacuum booster I'd recommend just getting the hydro-boost. I don't think the money difference would be much if any and the improvement will be drastic.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

You are already receiving sage advice from the knowledgeable folks on this Forum.

 

[Tonyrodz]

I feel the trucks with the vacuum booster come with very poor brakes from the factory. The hydro-boost upgrade is the single best upgrade I've done to brakes on anything I've ever owned. It's actually a significant difference where SS lines and new pads/rotors have never made much difference to me. If you are considering dumping money into replacing the vacuum booster I'd recommend just getting the hydro-boost. I don't think the money difference would be much if any and the improvement will be drastic.

The pwr steering pump needs to be changed for hydroboost?

 

[MOZ2121]

The pwr steering pump needs to be changed for hydroboost?

I've read that you should , to one that has two outlets , new hydraulic booster ,new master cylinder , 3 new lines , and new brake pedal. at least from the quick research I've done