Congrats Au,
I had the same experience removal and installation when I did it the first time. Second and third time you already know... much faster.
Best to have the most flexible extrension for these 4 buggers and a good head lamp.
The running of the motor for the new unit was the same in my case.

I did perform the master cylinder bleeding but did not do the calipers. I did the calipers extensively with no positive outcome for the softness of the brake.

I have the car on the lift now and want to go through all calipers, see if I can see any problems during resealing. I will check if some are stuck or any other issues with them. if I don't find any obvious problem with these calipers I am at a loss what can cause this bad brake performance with a brand new hydro booster unit.
(remember I had squishy brakes weeks before I had the brake incident with the alarm. So I am not surprised that this issue did not go away if it was caused by something else than the hydro booster)

Au, can you report from your bleeding experience with the new scan tool you bought? Did I understand correctly that the scanner is doing all the tricks to bleed brakes without removing the air through cracked lines like during manual bleeding? How the heck does this work? Where is the air going?

Martin

Martin,

No the scanner doesn't bleed the brakes for you, you do have to open the bleeder valves, the scanner is for only bleeding the ABS system by triggering the ABS valves to open to get air out of the valve body and then you do the regular bleeding again to remove the air, the only other way that it is said to get the air out of the ABS system is to do several hard braking sequences on a dirt road, snow or wet road to get the wheels to lock up and trigger the ABS system to activate and thus push the air from the valve body, I don't know if that truly works or not but several members here have reported it worked for them, either way you still have to manually bleed the lines again after to remove any air that may have been in the ABS system, I would think just bleeding the master cylinder again would remove this air, so that how I would proceed, do the ABS bleed, master cylinder bleed and then finally the 4 wheels.

That being said as I mentioned I haven't bled the ABS system yet using the scanner or otherwise, all I did was bleed the master cylinder by loosening the 4 brake lines at the master cylinder while my son worked the brake pedal.

The brake pedal seems to have to travel a tiny bit further than it did before the R&R before any braking action becomes apparent...but when the braking action starts it's much much better than it was before the R&R and the pedal is firm at that point.

Thanks Au,
that makes sense... the air come out the traditional way.
it is hard to trigger the ABS on the lift -I guess- without that magic tool.
So there is another step involved without that tool.

Martin

Update after removal of Right Front caliper.
During removal I already saw the mess on the backside of the disk.
It turned out that one inner side piston was entorely stuck which forced the second piston to compensate.... but this is a mess as we know. One piston did not move any more and the second tries to do the job but of course it has only 1/2 the force of the okay outer side. It is entirely asymmetric to a point when the steel disk is bending in theory... I guess there could be a bigger 'Spring effect' until the brake really bites.... This does the following
A) reduces braking force
B) I might lead to a much bigger fluyid volume to pump until the brake does anything
C) The large amount of fluid moved means that the accumulator is emptied much faster than it should.

I am simply trying to understand my symptoms better...why they occur (remember brake motor running every second time and bad brake performance).
I was guessing this might be my problem for a long time but did not follow up until now.

The stuck piston: I drilled a hole into the housing opposite of the stuck piston and hammered it out with a punch.
You also see that the outer edge of 3 out of 4 pistons has corrosion.
How could that be as this is a rebuilt calipe I bought from Napa 3 years ago, maybe 3.5 years?
The paint or powder of the caliper is entirly failing... My guess is that the flaking off powder at the seals let water and moisture inside and thus the pistons were starting to corrode.
It would be so much better if they did a proper paint job, or imply do nothing.
In the last 2 pictures you see the outside of the disk (looking good) and the last picture is the poor inside of the disk (looking bad). I'll probably not change the disk.

What am I doing now?
I think I will buy a set of rebuilt calipers to get some traction... buy time and then I could rebuild the old calipers over winter.

Best, Martin

Attached Images

       

I just bought a set of caliper from amazon- A-Premium Brand.... Yeah right....premium. LOL. It will be cheap China stuff but I guess it can't be worse than the Napa caliper which stared failing after 2.5 years.
Anyhow I will keep the old castings and rebuild the old set over winter. Is there a reasonable source for our front pistons -8 pieces needed ?

Martin

I just changed out a NAPA caliper after 7.5 years and almost 50K miles, right rear, as it had seized and took out pads and rotor. Not too disappointed here. I put new NAPA caliper/pads and rotors back on.

rd: Yours were better then with 7years... I always liked the original casting of the NAPA rebuilds but I decided to take the risk of ordering cheap replacements (don't need to return my cores) but can keep the old casts and rebuild them over time myself.
I guess the cheap new calipers will be good for a couple if years... I hope at least. Then I have a rebuilt set on the shelf, if need be.

I guess the calipers are a weak part in these cars, unfortunately.

On new or rebuilt calipers for those people in the "rust/snow belt" or anywhere else for that matter, I would pull back the piston boots and and fill it with the same lube/grease used on the moving parts of the caliper to help keep water from penetrating in there next to the piston to avoid the piston from rusting as in Martin's photo, just make sure the lube is rubber safe.

@AuSeeker , probably a good idea, similar to keeping the slider pins lubed.

Let's hope replacing those parts will end you brake saga for awhile. Looks like a smoking gun to me.

Finally Success!

I changed all the calipers and the brakes are just great....as it should be on a Toyo.
Its not as crisp as with a Mercedes or Porsche but so much better than everything I had before.

Looking back I had two main issues and the two coincided unfortunately and got me confused big time.

Issue #1: seized brake caliper pistons (on these crap 3 year old NAPA remanufatured calipers with heavy corrosion underneath the boots which led to hard to no piston movement. 2 of the 8 front pistons where entirely frozen... and all the rest of the pistons were at least hard moving with a thick layer of corrosion.

The frozen calipers not only made the brake almost unusable with a super soft brake pedal but also this lead to unusually short intervals for the brake motor to come on (every second time).

[It was NOT the master brake cylinder leaking as some people thought.]

Issue #2 ABS/TRC brake alarm

This alarm drove me nuts and to this day I don't know what this was about.... how it started. With the new hydro booster at least this alarm went away.
It might be some contamination inside the ABS block but who knows.


I have a smile now braking.....again

Thanks for all you help and suggestions.

Martin

That's great news. I don't recall seeing any report of uneven rotor and pad wear. I do recall calipers being rebuilt. Most of the thread focused on the booster module and alarm. We did correctly deduce that it was more than that. In either case, this repair took way longer than it should have.

Good to hear you have solid brakes now. This goes to show that the calipers on these are the first thing to look at even if only a few years old.