Brake Booster (Poor braking performance)

[swiftie]

Quick question ! Does anybody have experience relating to swapping out the brake booster on LC200 please. Specifically concerning either the replacement of the accumulator only from the assembly (cheaper but is it simple/practical/even possible ?) or is it best to replace the entire unit ? Thank you

 

[Oakleyguy]

Wrong forum, but:

I haven't heard of issues with the accumulators on the 200. Most people (myself included) upgrade the brake pads first to improve braking performance. Others have also upgraded the rotors, as well as swapped in the late model 2016+ rotors as they are a slightly bigger diameter.

I personally use Hawk LTS pads and while a little squeaky they perform much better than the OEM ones in my experience.

(Edit: post was originally in the 250 forum)

 

[TeCKis300]

Quick question ! Does anybody have experience relating to swapping out the brake booster on LC200 please. Specifically concerning either the replacement of the accumulator only from the assembly (cheaper but is it simple/practical/even possible ?) or is it best to replace the entire unit ? Thank you

View attachment 3650601

I've swapped the whole unit and it wasn't bad. Swapping the accumulator only is probably a tad more difficult and there is the critical high pressure seal.

Curious what your symptoms that you're trying to solve.

The unit is a safety critical component, meaning it has failure modes covered by Diagnostic Trouble Codes (DTCs) and alarms. The accumulator pressure is definitely monitored and you won't likely get softer braking without first having an alarm. Just trying to help diagnose before throwing money at this expensive part. Which I unfortunately did as the Toyota troubleshooting guide for electronic transfer case errors led me to change the part wrongly.

 

[swiftie]

Dear TeCKiss300,

Thank you for your very helpful reply. I'm based in Scotland and corrosion is a big issue as the road salt is endemic. Basically I have had endless brake problems (probably caused by my driving !) and I regularly change pads and rotors and at the moment I have four new rotors/discs and new pads (Toyota standard parts) however both my rear cylinder assemblies failed (corroded beyond saving) and in the process of fitting them I/we had issues in getting fluid to rear units. Eventually we manually bled them out but braking, while passing a standard roller brake test, is soft with quite a bit of effort and travel on the pedal to achieve anything exciting. Naturally our attention was then drawn to the brake booster; is it faulty, worn, or just normal ?

Any help would be gratefully received as LC200's are thin on the ground in the UK as only a few hundred ever got sold so workshop expertise is hard to find.

Did we mess up the bleeding ? Should we have used the TechStream method ????

Kind regards Julian

 

[swiftie]

Wrong forum, but:

I haven't heard of issues with the accumulators on the 200. Most people (myself included) upgrade the brake pads first to improve braking performance. Others have also upgraded the rotors, as well as swapped in the late model 2016+ rotors as they are a slightly bigger diameter.

I personally use Hawk LTS pads and while a little squeaky they perform much better than the OEM ones in my experience.

(Edit: post was originally in the 250 forum)

Thank you ! I have a LC200 from 2014 so one of the later models

 

[TeCKis300]

Dear TeCKiss300,

Thank you for your very helpful reply. I'm based in Scotland and corrosion is a big issue as the road salt is endemic. Basically I have had endless brake problems (probably caused by my driving !) and I regularly change pads and rotors and at the moment I have four new rotors/discs and new pads (Toyota standard parts) however both my rear cylinder assemblies failed (corroded beyond saving) and in the process of fitting them I/we had issues in getting fluid to rear units. Eventually we manually bled them out but braking, while passing a standard roller brake test, is soft with quite a bit of effort and travel on the pedal to achieve anything exciting. Naturally our attention was then drawn to the brake booster; is it faulty, worn, or just normal ?

Any help would be gratefully received as LC200's are thin on the ground in the UK as only a few hundred ever got sold so workshop expertise is hard to find.

Did we mess up the bleeding ? Should we have used the TechStream method ????

Kind regards Julian

Thanks for the context. That helps and looks like it's been quite the journey. I think you're on the right path.

What I think I'm understanding is that you're getting low flow through the brake circuits. The rears are brake by wire and do rely moreso on the accumulator. When I've bleed them, it's a pretty solid stream. Almost sounds like there is contamination in circuit. Yet the accumulator must be meeting its threshold pressure as alarms would be going off.

If it is contamination, it would be more likely in the ABS block part of the assembly rather than just the accumulator. Could also be in the lines?

 

[swiftie]

Have changed the fluid several times over the years so tried to do the right thing ! I might try the main dealer (really looking forward to that !) as at least they have the Techstream program which I don't have and get the brakes power bleed out ? How can you get the Techstream program ?

 

[TeCKis300]

Have changed the fluid several times over the years so tried to do the right thing ! I might try the main dealer (really looking forward to that !) as at least they have the Techstream program which I don't have and get the brakes power bleed out ? How can you get the Techstream program ?

In the states, we can get techstream knockoff on Amazon and Ebay.

 

[bloc]

Yes, many of us have gotten this working from EBay.

Look for the “VCX Nano” versions which are a bit more expensive but much more full featured and reliable than the MiniVCI version.

 

[swiftie]

Thanks to Everyone for the help; just shows what a bloody useful forum this is ! "Bye the nou" as we say and thanks