99 Yukon brake pedal becomes hard to press when braking suddenly. Power assist prob?

[MarkD51]

ok I think im going to go with a cardone remanufactured booster $89 on amazon and a new cardone master cylinder $35. There is an AC delco (made by durrastop) for $54 but I don't think it will make much difference. Any thoughts guys? Also for the brake switch clip is it just one of those c looking clips or is it something else? Thanks.

As for the Brake Switch Clip, all big auto parts stores like AZone, Oreillys, Advancedm NAPA should carry the clip kit, which will come with a number of different types. One of them will be the correct one.

Mine, and probably yours too, was a round washer type outer clip, with a central C-Shaped spring clip which will pop on-click onto the Brake Pedal Stud after the Brake switch is reiinstalled first.

The clip is the most frustrating of the entire job IMO. Getting it off.
Putting the new one on is a breeze.

With the steering shaft in the way to clear access to the four power booster's stud's nuts, as sunlit has said, you'll need yourself a good assortment of 3/8" drive extensions, universal swivel to remove-re-install them. While the new Booster won't come with a firewall gasket, the original should be fine.

When installing the new booster, you'll need to install the booster slightly canted with the plunger rod going more to the passenger side of the vehicle.

This will then insure the plunger rod will be on the correct side of the brake pedal (right) You'll get the plunger rod eye back onto the brake pedal stud before buttoning up the booster's 4 nuts. Not really a hard job but is a tight squeeze under there, and it takes time, and some patience, and a few rests as you go. A good flouro shop light is an aid as well, seeing is important.
Mark

 

[MrSpicy]

Thanks for the advice Mark, it will come in handy- looks like I will likely start it next weekend when I get more time. Ill order the parts today and then stop by a parts store on the way home from work to get that kit.

What are your guys' thoughts on a one person brake bleeder? I have never used one and am not even sure how it works. There is multiple models available and wouldn't even know which one. Any Recommendations ?

 

[MarkD51]

Thanks for the advice Mark, it will come in handy- looks like I will likely start it next weekend when I get more time. Ill order the parts today and then stop by a parts store on the way home from work to get that kit.

What are your guys' thoughts on a one person brake bleeder? I have never used one and am not even sure how it works. There is multiple models available and wouldn't even know which one. Any Recommendations ?

I've tried a few one man brake bleeders over the years. One, the little cheapo plastic bottle with the little round magnet on the side, you clip the unit somewhere, open bleeder valve and pump the brakes. While in theory this should work, it is IMO not the very best way to bleed.

Then there's the type which is a vacuum pistol type with gauge and bottle, various hoses for hookup, usually more money, something like $35 or in that whereabouts. This type is IMO better, the hose attaches the the bleeder screw and you "suck" the fluid, and any possible air through each brake line via vacuum.

Then there's the pressure type, with a small canister that you pressurize, akin to like a weed sprayer, and a cap or an adapter is fitted upon the Master Cylinder's Resevoir. With the type of Resevoir we have on these Hoes, it meant ordering with it the large rectangular adapter plate that "chains" around the entire Master Cylinder. Thus in effect clamped to the top of the Resevoir and sends pressure through the entire system.

You fill the tank with clean brake fluid, pump till 7-10psi is achieved, then go to each corner and crack open the bleeders.

This I personally had trouble with, couldn't get good pressurization, and wound up sending the Unit back for refund.

While I know our model of vehicle has that ABS Unit which can easily be screwed up in no time with improper bleeding procedures, I may be wrong about this, but I would still say the least expensive, and perhaps most reliable method for us shadetree mechanics doing such service will still be "the two man bleed".

One person in the cab to pump up the brakes, hold, and the other cracking open the bleeder valve with a short length of hose running into a small glass jar.

Others might disagree, and I know many say our vehicles are a bear to bleed, to say that one good bleed will clear all air, some will say bleed bleed bleed, that once may not be enough?

The goal is of course to bleed till one sees nice clean fluid exiting, and no evidence of air bubbles. And of course to always start at the furthest wheels from the MC (RR-LR-RF-LF)

Hopefully others here will add, and comment to what I've written-said.
Mark

 

[SunlitComet]

there is no delco made by durastop and i would find that part suspicious.

 

[MrSpicy]

Thanks Mark really appreciate the info. I think I will just print out your posts and use them as a guide. I will be doing the job tomorrow so I can let you all know how it goes.

Yeah I didn't like the sound of the Delco MC so I just went with the Cardone, cheaper anyway.

 

[SunlitComet]

ac delco or delphi is preferred but raybestos or bendix are good as well. when it comes to mc, never buy remanned units. new only.

 

[MrSpicy]

Hey guys so I got job done..well some what. Got the booster and mc replaced. Who ever had and worked on the car last had messed with the booster before and the brake switch clip was missing and was only on with a rubber boot thing. Went to the local oriley and the ass-hats working there could hardly figure out what looking for- kept trying to give me a kit for the drum brakes. After i finally suggested to the kid at the counter to try searching for it they found it but its special order.
Never went to another store because while my dad was helping me with it he some how broke the brake switch and now the column shifter park brake lock keeps locking and i cant shift out of park but if i jiggle the brake switch it starts working.

Question is does any one know the part number for the switch, I want to make sure ive got the right one. Also can it be changed without removing much of the dash?

 

[SunlitComet]

brake light switch gm 93801734 about $15 at local dealer.

 

[MrSpicy]

Thanks thats the one I was gonna order so looks like I've got the right one. Found a Delco one for about $11 on the interweb. Hopefully it swaps out fairly easily.

 

[SunlitComet]

ha, good luck with that.