Master Cylinder Rebuild - DIY (1 Viewer)

[Skidoo]

Firstly, great knowledgeable post! Thanks!

Do I really have to remove all those internal panels to remove the 4 nuts on the mounting bolt? I just start to do this...don't know where to start and end, thanks!

Isn't that hard to remove them. I couldn't find a position where I could see what I was doing under there until I removed them. Maybe you are really flexible.

 

[flintknapper]

Isn't that hard to remove them. I couldn't find a position where I could see what I was doing under there until I removed them. Maybe you are really flexible.

That was my experience as well. Simply couldn't see them well enough without the panels removed.

 

[zhloea]

That was my experience as well. Simply couldn't see them well enough without the panels removed.

Finally got this guy out, I am glad I pulled the trigger, just as my guess before, the old one obviously bought form junk yard and eventually throw the pump issue to me....

So I found it impossible to use a torque wrench for the brake line connector on the MC, how do you guys know it tight enough?

Thanks to you guys. You guys give me ideas and courage to do this!!!

 

[flintknapper]

Nice work.

Brake line connections, just snug them up good. If they don't leak you are fine. Don't tighten them so much that you feel them 'chatter'....you'll be good.

Good job Sir!

 

[2001LC]

I lightly oil hard pipe and threads of flare nut. Start threading on and snug by hand, making sure flare of pipe seat squarly. Sung nut with flare wrench. Then I use a flare nut crows foot socket on extension. Just like when doing the fuel filter flare nut. I torque to 10ft-lbf. Which since home made SST spec is 11ft-lbf, reduced 20% (to 8.8ft-lbf) for oiled threads, plus add a 1.2 ft-lbf for luck.

 

[Eyedaho]

I lightly oil hard pipe and threads of flare nut. Start threading on and snug by hand, making sure flare of pipe seat squarly. Sung nut with flare wrench. Then I use a flare nut crows foot socket on extension. Just like when doing the fuel filter flare nut. I torque to 10ft-lbf. Which since home made SST spec is 11ft-lbf, reduced 20% (to 8.8ft-lbf) for oiled threads, plus add a 1.2 ft-lbf for luck.

View attachment 2697066

If you spin that crow's foot 90° you will get a more accurate torque.

How to Use a Torque Wrench with a Crowfoot Wrench | TEKTON

Learn how to accurately use a torque wrench with a crowfoot wrench to measure torque. Use the included Torque Conversion Calculator.

www.tekton.com

 

[zhloea]

Have a question about the bleeder screw on the calipers. As I said I changed the bleeder screws before refill the brake fluid to the newly replaced MC.
After I installed the new bleeder screws, I torqued them to 11lb, and I use brake cleaner to clean the remnant brake fluid on it and calipers, then these area becomes nice and dry after the cleaning.
Then I just let the truck seating in the garage without the wheel installed and back check this afternoon, there is small wetness around all four new bleeder screws, but no drips.

So is this small wetness after replacement normal? what to do If it becomes real leaking from the bleeder screw? Teflon?

( I checked this online, somebody said there is a small leftover in the hole of the screws or on the threads, it will leak out slowly after the replacement..., but I am not sure it is right or not. )

 

[flintknapper]

Have a question about the bleeder screw on the calipers. As I said I changed the bleeder screws before refill the brake fluid to the newly replaced MC.
After I installed the new bleeder screws, I torqued them to 11lb, and I use brake cleaner to clean the remnant brake fluid on it and calipers, then these area becomes nice and dry after the cleaning.
Then I just let the truck seating in the garage without the wheel installed and back check this afternoon, there is small wetness around all four new bleeder screws, but no drips.

So is this small wetness after replacement normal? what to do If it becomes real leaking from the bleeder screw? Teflon?

( I checked this online, somebody said there is a small leftover in the hole of the screws or on the threads, it will leak out slowly after the replacement..., but I am not sure it is right or not. )

Typically there is a small amount of residual fluid around the bleeder threads that will migrate out after bleeding the system.

I would spray them again with brake cleaner and check back after a few days of driving. IF after that time you find more brake fluid then tighten them a bit more. But yes, a small amount of wetness is normal around the threads right after bleeding.

 

[Layonnn]

Recently started having the brake booster motor make some occasional whining noises. No lights, no change in brake feel, fluid is slightly dark but level is fine. 100 series has 225K miles. Will probably be replacing the brake boost pump (47070-60010). Should I go ahead and rebuild the master cylinder as well while I'm in there if no other issues present? Terminals on the abs unit and at motor look pristine.

 

[flintknapper]

Recently started having the brake booster motor make some occasional whining noises. No lights, no change in brake feel, fluid is slightly dark but level is fine. 100 series has 225K miles. Will probably be replacing the brake boost pump (47070-60010). Should I go ahead and rebuild the master cylinder as well while I'm in there if no other issues present? Terminals on the abs unit and at motor look pristine.

It would be a good idea. It is very easy to do. Mine looked to be in good shape still (MC piston) but I wanted to have a new one on hand when I pulled the unit....just in case. The replacement part is not expensive and the job just takes minutes.

 

[krice118]

Time until accumulator charged. 28 seconds new (new booster assembly with good seal and lines throughout system, including caliper pistons) 30 to 34 second average good system 13 to 20 years old with good voltage from battery. 36 sec -1, 38 sec -2, 40 sec -3.

So I pumped my brakes 40 times (pressure left around 28/30 push) while engine off / key out then turned key on and it only too 28 seconds of run time for the booster to fill the system - this is good? Asking because yesterday morning the ABS light came on and so did the audible warning.

 

[2001LC]

Recently started having the brake booster motor make some occasional whining noises. No lights, no change in brake feel, fluid is slightly dark but level is fine. 100 series has 225K miles. Will probably be replacing the brake boost pump (47070-60010). Should I go ahead and rebuild the master cylinder as well while I'm in there if no other issues present? Terminals on the abs unit and at motor look pristine.

Not sure what "occasional whining noises" is. Sometime we hear alternator, drive belt or pulley bearings whine!

BUT if brake fluid dark and staining present in reservoir, these are bad signs. If at same time you hear the "sound", some call screaming banshee. You also see bubble coming up front of reservoir. Than you'll need a new master.

So I pumped my brakes 40 times (pressure left around 28/30 push) while engine off / key out then turned key on and it only too 28 seconds of run time for the booster to fill the system - this is good? Asking because yesterday morning the ABS light came on and so did the audible warning.

28/30 seconds is excellent. I get that with new booster assembly and a strong battery (12.4v or better)

 

[zhloea]

Not sure why your replacing master. I'd be digging more to see if "long test time" is other components first.

But in the end if replacing master. It's not hard for me, but then I've R&R a lot of them. I've bleed about 12 system already this year. I've been buying Toyota brake fluid by the case. In fact going to pick up a 1/2 case now,. Second time in a week Dealership did have a full case for me.

Few tips:
Pre-prime master with brake fluid. By just adding a can of fluid, and work plunger until fluid flows out brake line ports.
During assembly, I clean and lightly oil pipe and threads of flare nuts. I than thread on each all the way by hand. Working hard line so I'am sure to seat flare of pipe squarely in port. I torque them each to 7ft=lbf, after master mounted completely.

Sometimes to get pedal to firm up during bleed is a pain. In those I use my hand vacuum pump, drawing fluid to each caliper/bleeder.

I always test time of booster charging 5 times, and check for leak before driving. Pedal must feel good and firm on every press. I then drive on dirt road and slam on brakes. I do this at least 3 times. I must hear ABS kick in.

I still a little confused about that "Pre-prime master with brake fluid." what is the purpose of this particularly for the new MC? Assuming we will do the full flush, because we eventually need to push fluid through the MC to brake lines then to calipers out for bleeding, then why this pre-prime still necessary?

 

[krice118]

28/30 seconds is excellent. I get that with new booster assembly and a strong battery (12.4v or better)

Thanks @2001LC. Any idea why my ABS and BRAKE lights would come on as well as the audible warning? Went away fairly quickly though and only has happened twice in the last 2 years. This is my DD.

 

[2001LC]

If you sneeze on engine, ABS will shut down. But usually requiters clearing DTC.

With alarm & self clearing. It's likely brake fluid level or brake system pressure issue. Cold OAT can effect seal (shrink), than we may get alarm on cold morning as we first start driving. Level dropping below minimum can trigger also.

 

[Layonnn]

Not sure what "occasional whining noises" is. Sometime we hear alternator, drive belt or pulley bearings whine!

BUT if brake fluid dark and staining present in reservoir, these are bad signs. If at same time you hear the "sound", some call screaming banshee. You also see bubble coming up front of reservoir. Than you'll need a new master.

Sound is similar to that in the video and is definitely coming from the motor of the brake booster assembly. Color of fluid is a medium brown-ish. Zero bubbles coming from reservoir, I let the pump prime and watched it for a few minutes.

Parts I have arriving today and plan to install are:
Brake Booster 47070-60010 ($778)
Master cylinder rebuild kit 04493-60330 ($68)
Accumulator o ring 90301-13014 ($4)
Hose 44571-60010 ($11)
5 bottles of DOT4 brake fluid ($50)
Brake bleed kit off amazon as I couldn't remember where mine was or the size of hose needed ($6)

Couldn't find my flare wrenches, so ordered a new one. Plan to get started on this today along with finishing up replacing the bushings on my rear aftermarket lower control arms that started to have some wear/play to them.

 

[Jram100]

Did the rebuild about 5 weeks ago and the pump quit yestersay. Total brake failure experienced - new oem pump on the way. Will fill w oe fluid and maybe take it in for a proper bleed, dealer wants $209.

 

[zhloea]

Hi, I got my new brake master assembly replacement, two new rear calipers, brake hoses replacement, and full brake flush/bleeding done last week. Here is a write up of some good and bad things I experienced during this project.

Thanks to all the contributors of this post, the info and help you provide here really help me to get this done. I very appreciate it!

- Overall
Before this project, I got a lot of friendly warnings about "the risk of working on master cylinder", and this is the first time I really work serious brake stuff (of course, I changed pads and rotors many many times). Honestly, I am pretty dread to do this. But, actually, this work is much easier than I think, for example, if we consider the difficulty of front CV axle change as 50 points, this probably only 30 points of difficulty. And If you don't have a trusted shop to do this, do it by yourself could be a very reasonable choice, because any half-ass mechanic and shop could hide a lot of things from this work. For example, I called three shops for this, two of them don't even know LC100 requires ABS bleeding, and the one who knows ABS bleeding does not have a tool to do this...

- First, be careful about the shipping damage when you choosing purchase a master cylinder assambly from a non-local dealer with free shipping.
For this expansive part, you can save almost 200 dollars if you purchase it from some tax-free state dealer with Toyota free shipping. But the problem is how Toyota package this 2000 dollar more part, they use very cheap cardboard box without any shockproof material. And the damage usually comes from the bottom of that cheap package, the hoses and motor at the bottom will be easily got some dent during the shipping. To avoid this, I decide to buy it from local dealer with local picking up and have to pay more for tax, even though the first coming assembly was damaged on some bottom hoses and the side plastic case. But I can easily return or refuse to accept it because it is a local purchasing part. And even though the customer service is great and they are very sorry about that, I have to wait for another week for another one.

- Second, it impossible to replace the master assemble without taking off the kick panel and all the bottom parts under the steering wheel. break loosing the brake hoses on the assembly before you took off all the mounting nuts from the cab.
Here is a video that could clearly show how to remove all these panels/cases.
For a 04 LC100, you'd better have some swivel socket and, in my opinion, you have to have some long extensions to get all the mounting bolts out there. And a 1/4 extension and socket set will make this work easier. 3 of the MC assembly mounting bolts except the one in the right top corner is accessible for a torque wrench.

- Third, All brake line connector includes the connectors on the calipers and matter assembly are accessible for a torque wrench.
you can use a crowFoot and extension to torque them. Here is a set I bought for this work.
Amazon product ASIN B000N7DHFK


- Forth, I got the bleeding include abs bleeding done with "Motive power bleeder" and Techstream, I'd say it turned out awesome.
By this bleeding method, I used totally 7 bottles of OEM brake fluid (covered two new rear calipers replacement)


If you go with "Motive power bleeder", you have to buy the adapter "BA10" reservoir cap adapter, I bought from here and It cost 50 bucks and two weeks shipping Power Probe BA10 TOYOTA SMALL BRAKE BLEEDER ADAPTER | Tool Discounter - https://www.tooldiscounter.com/product/power-probe-toyota-small-brake-bleeder-adapter-pprba10?gclid=CjwKCAjwoNuGBhA8EiwAFxomAx6ZbWWjGtvRjLWAMjTIicdrMfL9-
When I use this adapter, it still got some kind of losing pressure when I do the test, But it is working fine during the whole real bleeding process.
The bleeding order I follow is "FR, FL, RR, RL".

For the Techstream, I used v7.0 on a window 7 32bit system, the installation is pretty straightforward. And if your version of Techstream is too high, you probably can not find the "utility" for the ABS bleeding from the interface of Techstream. (For example V15.0+++). Additionally, if you have a very new laptop you might experience some difficulty with Win7 installation. Because, technically, most of the motherboards of the laptop from today's market do not support Win7 installation right away, you need a lot of tricks for making it work. If this is the case for you, then you'd better buy a used laptop. Below is the ODBII adapter I used for the Techstream:

 

[scurvydigdog]

Really interesting read, I have replaced my abs accumulator and pump with a new unit, and rebuilt the MC. Bled the system but still I cannot get any high pressure feed to the accumulator.
does any one have any ideas, I have spent months trying to solve this problem and it’s just getting no where. Any help much appreciated.

 

[2001LC]

If you've new OEM booster assembly (motor, wire, pump, accumulator) and you can hear the booster motor run. Than you've air in system or a leak.