Brake Booster Recall Symptoms?

[N800MRG]

Hi Guys,

The other night I was doing some Dragy runs. After doing a 0-130 pull, I slowed down quite abruptly back to 0. I felt like the car took longer than I would've normally expected to come to a stop, and I needed to press the pedal harder than I normally do to get the car to slow down. I got out to make sure everything was ok, and there was a smell of burnt brakes and my discs had some heat discolouration (dark ring with blue spots). They were also screeching every time I applied them, but this has since stopped.

Since that night, I've felt like my brake pedal is slightly firmer (although nowhere near being rock solid) and the stopping distance/pressure required seems to be increased. Although this could all be in my head... It's almost like all the stopping power is still there, but I have to press the pedal harder to get it.

I haven't had the recall done, and the garage I use is 4 hours from me, so I'm just looking for some feedback on whether what I'm experiencing may be a failed brake booster? I'm swaying towards no, as from a few other threads I've read, people have needed to use two feet to stop after just backing off their driveway, mine is nowhere near that level. There is also no fault codes stored, but I'm not sure the brake booster would throw one anyway?

Maybe I got some pad deposits on my discs after doing a lot of pulls? Would re-bedding the pads help this? I have checked my fluid level, all looks ok.

TL/DR - Pedal feels firmer, stopping distance/pressure required increased, what could be the cause?

Thanks in advance,
Marcus

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[zrk]

Hi Guys,

The other night I was doing some Dragy runs. After doing a 0-130 pull, I slowed down quite abruptly back to 0. I felt like the car took longer than I would've normally expected to come to a stop, and I needed to press the pedal harder than I normally do to get the car to slow down. I got out to make sure everything was ok, and there was a smell of burnt brakes and my discs had some heat discolouration (dark ring with blue spots). They were also screeching every time I applied them, but this has since stopped.

Since that night, I've felt like my brake pedal is slightly firmer (although nowhere near being rock solid) and the stopping distance/pressure required seems to be increased. Although this could all be in my head... It's almost like all the stopping power is still there, but I have to press the pedal harder to get it.

I haven't had the recall done, and the garage I use is 4 hours from me, so I'm just looking for some feedback on whether what I'm experiencing may be a failed brake booster? I'm swaying towards no, as from a few other threads I've read, people have needed to use two feet to stop after just backing off their driveway, mine is nowhere near that level. There is also no fault codes stored, but I'm not sure the brake booster would throw one anyway?

Maybe I got some pad deposits on my discs after doing a lot of pulls? Would re-bedding the pads help this? I have checked my fluid level, all looks ok.

TL/DR - Pedal feels firmer, stopping distance/pressure required increased, what could be the cause?

Thanks in advance,
Marcus

Since you were able to stop at all, it wasn't the break booster than failed. It's pretty bad when it happens.

 

[N800MRG]

Since you were able to stop at all, it wasn't the break booster than failed. It's pretty bad when it happens.

Thanks @zrk, that was my gut feeling, but puts my mind at ease hearing it from someone else.

I went out last night and re-bedded my brakes, seems to have improved the issue quite a bit.

 

[armenh7]

If the brake booster wasn't doing its job, you wouldn't have been able to get the rotors hot enough to have coloration. You're probably experiencing pad fade or fluid boiling

 

[RAWSupra]

Hi Marcus ... sounds like you've boiled the brake fluid .... any water in the lines will steam off and cause this .... i would bleed of some from,at least front brakes, to be safe. use a water check tool to ensure <1% water in lines ... preferably none.

ive had this many times on runway days and speak from experience.

BTW your spoiler and front splitter are still on my car.

 

[N800MRG]

Hi Marcus ... sounds like you've boiled the brake fluid .... any water in the lines will steam off and cause this .... i would bleed of some from,at least front brakes, to be safe. use a water check tool to ensure <1% water in lines ... preferably none.

ive had this many times on runway days and speak from experience.

BTW your spoiler and front splitter are still on my car.

Apologies for the time it’s taken me to get back to you, I’ve been without the car for the past few months. Got it back last week and bleed the brakes, sure enough a tonne of air in the system…

Pedal feel is back to normal now!

Going to be ordering some uprated brake fluid though, as I’ve obviously boiled it by simply doing a couple of 0-130 pulls back to back. It’s not like I was slamming the brakes on after the pulls either.

Anyway, thanks for the advice, I wouldn’t have thought of it myself, as I usually attribute a spongey pedal to air in the lines, not a hard pedal…

 

[lucky phil]

Sounds like you cooked the pads. They will never come back to what they were but you can remove some of the surface glaze by removing them and dry sanding the face on a piece of glass with same 100 grit wet and dry. Checking the brake fluid as suggested would be a good idea as well. as suggested
I crewed for a WSB ride once that wanted me to do this before every race and practice session as well as a light rub over the disk faces as well. In his case it was more a "mind" thing though.

Phil

 

[lucky phil]

Hi Marcus ... sounds like you've boiled the brake fluid .... any water in the lines will steam off and cause this .... i would bleed of some from,at least front brakes, to be safe. use a water check tool to ensure <1% water in lines ... preferably none.

ive had this many times on runway days and speak from experience.

BTW your spoiler and front splitter are still on my car.

I have one of these and have checked their calibration and they are accurate. Well mine is anyway.

Phil

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