SUPERCHARGE

Hi peeps. Need some advice on my next step here. Since I've bought the truck 2 years ago, my brakes have been very spongy and always believed the cause to be due to air in the lines. Problem was that all bleeding screws were rounded and one was snapped so never bothered to do it.

Last week, I decided to get new discs, pads, and other necessary components to make my braking system shine again. Ironically on the way to the store to pick these items, a brake line blew. The line that goes from the (ABS block) to the Y join in the rear axle had to be replaced. So all is done now.

At this point I bled from all calipers, starting from longest to shortest line. I bled all the old fluid out, at this point bubbles and air were long gone. I bled approx 2.5 liters of brake fluis to clean the lines properly.

Now, although my brakes have much more friction, the brake pedal is still very spongy and bottoms out failry easy. I'd say it's about 20% less spongy than before which is not a big change.

Other than bleeding at all four calipers, should I of bled from somehwere else like the master cylinder? I clearly have another problem somewhere, just trying to figure out where.


thanks

Parke10

iTrader: (5)

im no brake expert,but maybe the master cylinder?

SUPERCHARGE

This would tend to be my first guess as well but the thing is, it's been evenly spongy for the 2 years I've owned it. With a bad master cylinder, wouldn't the sponginess get worse and worse until it hardly exerts any pressure to the brakes?

The rubber lines around the wheels are good and the calipers are superb. Guess Im waiting for someone to tell me I forgot to do this or that which would be causing the problem.

KySilverado

iTrader: (7)

I never liked the feel of the original brakes on mine. It could be the master cylinder. If you get air bubbles in the anti-lock unit its nearly impossible to get out from what I've read. You'd also be amazed at what replacing the rubber lines at the calipers with stainless units will do for pedal feel.

You mentioned that they sometimes will bottom out. If it were air you should be able to replicate it always. If intermittent I'd lean toward master cylinder.

SUPERCHARGE

Hmm... so the stock brakes aren't that great to begin with? Well, first off, it's not intermittent... they work steadily the same every time. The brakes do start grabbing 1/5th or a quarter of the way down and will stop the truck rapidly enough going halfway down. They never HAVE to bottom out, but forcing the pedal to the metal doesn't require much force and the truck will never stop that quickly even when pedal is fully depleted. Let's put it this way. My 1993 Saturn's brakes require approx 3-4 times the force to purposely bottom out the brakes and the car with old pads/rotors stops incredibly faster.

Let's put it this way, the truck will never brake hard enough on for the ABS to turn on dry road. In order to see the ABS turn on, I need very wet road or snowy conditions.

I don't know, maybe I'm being picky and these trucks simply have spongy-*** brakes with not-so great stopping power to begin with?

KySilverado

iTrader: (7)

Yours sounds normal to me.

My factory setup would never activate the anti-lock on dry pavement. The brakes on these things adequate for the average guy but are severely lacking with any go performance mods.

I had too many "oh ****" moments in mine and decided to upgrade. Magnified more so when I went bigger tires and wheels. SSBC Kit on all 4 corners. 14" rotors, calipers, ss braided lines and hydro boost. It stops much better now. I can even get the anti lock to come in at will.

1slow01Z71

iTrader: (36)

You need a tech II to actuate the ABS motor to do an auto bleed so you can make sure all the air is out of the system and add some stainless lines wll firm up the pedal feel a lot more.

SUPERCHARGE

Wow... interesting, so maybe my truck's all good after all. Problem with upgrading is that I do bring this truck into some pretty severe off-road conditions, so I need more rubber than more rims. I'm going to give the truck a lift soon and get bigger rubbers than a bigger rim.

Considering most of you tell me to put stainless steel brake lines to replace the rubber lines, I'll keep that in mind and will most likely do that before I decide to start re-using my truck for towing heavy stuff.

1slow01Z71, I'm assuming a tech2 is an expensive piece of equipment only found in GM or specialty shops?

Guess I'll be happy for now and when the opportunity comes, try a same model truck/suv and see if I really do have a prob. If so... we'll see about this tech2 thing. Weather buying one makes more sense than going to a GM shop.

Thanks a lot for your info guys! As usual, you've been a big help.

viciousknid

iTrader: (8)

If you have a cam or low vacuum pressure then your brakes will be softer than normal. However they are spongy in stock form because they run off vacuum.
I'd recommend a Hydroboost swap.

Just do a search on here for Hydroboost if you don't know what it is.

Mrgoodwrench3

It sounds like the internal bypass is leaking in the Master Cylinder causing the low pedal. A new unit can be installed and bled without using the Tech 2.