How hard is your brake pedal?

[PDPerry]

Over time, the brake pedal on Mr Bubbles has softened considerably.

Braking seems ok, but the pedal softness is disconcerting.

He currently has a bit over 225,000 miles under his belt. Been well-cared for by his original owner (me).

Not to be too personal, but how hard is your pedal on a similarly-aged Hundy?

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[AimCOtaco]

Your truck, OK, Mr. Bubbles.. He needs a master cylinder re-build.

 

[marshotel]

I have a 1998 LC w 190k miles.

My brake pedal is also pretty soft, especially on the first stroke.
It feels firmer once you pump it once.

The truck stops fine, but the brake pedal feels mushy, and you have to step down on the brake pedal pretty hard compared to my 2009 Tacoma.

Also, the electric brake booster pump seems to run a lot; -- it runs for about 45 seconds after the truck is started from being cold, and then the little booster pump comes on for 5-10 seconds everytime I hit the brakes.


Like I said, the truck stops fine-

Apart from the mushy pedal feel and the frequent cycling of the booster pump, I have no problems with the brakes.

Because everything is working okay at the moment, I am not too interested in tearing into the master cylinder-

It is a critical system, and I think the rebuild requires taking the whole dashboard apart.

If it ain't broke, I ain't gonna fix it, but would appreciate opinions from others here.

 

[2003lx470]

Engine running and foot on the break pedal and if the pedal goes down little by little toward the floor, he need to either rebuild the master or a replace.

 

[2000UZJ]

Mine is firm on the first press, rock hard on second. MC never touched.

 

[duggy]

Mine is firm on the first press, rock hard on second. MC never touched.

Is that normal? Mine is the same way and it feels weird.

 

[Bismarck]

Has Mr. Bubbles had a recent brake fluid replacement? Made a big difference.

 

[APKhaos]

^+1 on fluid flush. Sounds like you may have entrained air in the system.

 

[PDPerry]

My thoughts as well...

 

[2000UZJ]

Firm means the system holds pressure and doesn't leak.

Firm brake pedal to me means a good solid system.

 

[marshotel]

My thoughts as well...

let me know if the flush and bleed fixes it.

my fluid looks nice and pretty clear (translucent), in the reservoir anyways.

Does anybody know if the electrical brake pump cycling is normal?
sometimes for 45 seconds when starting from cold.

 

[duggy]

I'm not sure how the electric booster works but I imagine some type of reservoir holds pressure until it reaches below a certain threshold. Even with the truck turned off, it should hold pressure, I'd assume. If you have some type of leak and the truck is sitting, this may explain why your pump is running for 45 seconds on a cold start.

 

[spressomon]

Pre-Stoptech BBK: Brakes always sucked from when I bought it with 69k miles (less suck with the ART set-up); always took 2 strokes to get somewhat firm pedal; on steep off-road down slopes brake pedal would go to the floor sometimes (slow crawl downs). Bleeding and fluid refresh had no effect; did gravel road ABS flush; never had the dealer flush and bleed; original MC plunger.

Post-Stoptech BBK: Brakes are incredible with similar peak power to the ART & Porterfield set-up I was running but with significantly better modulation and overall brake effectiveness; ~ 1/2-1" free play with very firm pedal after that. After I installed the BBK I did my typical brake fluid flush and bleed and then had the dealer do a bleed with their SST just for grins (didn't notice any significant difference in brake performance after the dealer bleed...FWIW); I installed a new plunger at the time of install. No more double pumping, no more disappearing pedal on steep down slopes, no more wanting for more brake in any situation.

Summary: I suspect the two pump syndrome found on some 100-Series, based upon Skidoo's experience, is probably related to the MC plunger and possibly air in the ABS circuit. Given how easy and relatively inexpensive the MC plunger is to swap I recommend doing this R&R for baseline if double pump is present. The pedal stroke, I believe, is related to the calipers.

 

[cboyd]

I had the two pump thing going and after several re-bleeds with no improvement, I had the dealer inspect everything on the calipers. They found a sticky guide in one of the rear calipers. Rebuild with new guides and haven't had the two-pump since. I was getting ready to do the MC rebuild if that didn't work.

I'm at 205k.

I've talked to all the dudes on this thread about the same issue!

 

[cboyd]

I had the two pump thing going and after several re-bleeds with no improvement, I had the dealer inspect everything on the calipers. They found a sticky guide in one of the rear calipers. Rebuild with new guides and haven't had the two-pump since. I was getting ready to do the MC rebuild if that didn't work. I'm at 205k. I've talked to all the dudes on this thread about the same issue!

Ok, revisiting this thread. Had good success with the brakes all the way to California and back to Utah. First trip into sticky mud and water and the two pump pedal situation came back. Cleaned everything out suspecting storm thing in the caliper. Not any better. Had it up for an oil change and asked them to look at rear calipers. The found sticking guises on both sides. This time I dint make the pedal any better. I was prepared to jump for reman rear calipers, but they said they looked good and wouldn't recommend. I had them also check from wheel bearing nuts and retorque.

Now I really want this fixed because my new-to-me 2006 100 duly driver has killer brakes! In fact, grabby by contrast! Now I know what can be, though acknowledge the 06 system is different to some extent.

So time for the MC plunger fix? I only question this because, for a time after they rebuilt the right rear caliper, it felt good.

 

[RobRed]

Calipers have major influence on the brake feel. OE calipers are cheap enough I'd replace the rears.

 

[bigredmachine]

a siezed caliper can cause a low pedal as can sticking slider pins, you may have one pistion on a front caliper thats siezed. best way to check is to take a big pair of channel locks and compress the caliper pistons and see that they move freely. its a good place to start before doing a mc rebuild or replacement.

 

[2000UZJ]

a siezed caliper can cause a low pedal as can sticking slider pins, you may have one pistion on a front caliper thats siezed. best way to check is to take a big pair of channel locks and compress the caliper pistons and see that they move freely. its a good place to start before doing a mc rebuild or replacement.

That is a great way to check. Easier and quicker way is to remove the wheel and inspect both inner and outer pads through the caliper. Both inner and outer should have similar wear.

Another way, is to take a IR temp gun. Cruise for .5-1 mile at 40MPH. COAST to a complete stop. Put the vehicle in park and use the IR temp gun to take readings of all the rotors. If a caliper is in fact sticking that rotor will be much hotter than the others. I would not use this method to "officially" rule it out, but it can help you determine if the caliper is sticking. That is how I discovered my frozen caliper. All 3 rotors were ambient temp (90*F). The sticking caliper (driver rear) was 240*F.

 

[SALTY METHODS]

85K on my '98 and my brakes are bit spongy also. Not bad but not what I suspect how it came from the factory. Stops fine though.

 

[cboyd]

Calipers have major influence on the brake feel. OE calipers are cheap enough I'd replace the rears.

RobRed- what do you think about the brake lines? Obviously if I am going to pop for new reman rear calipers, I'm guessing I should also do the lines? Stainless or new factory? Then a good bleed all around...

Not sure if should work with the dealer or find a local expert. I really want to jump in and do this myself but have no experience with brake work and bleeding. I know that if I do it, I'll understand the system better and can maintain it better.