DOT4 Brake Fluid Change and ABS - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Black Tire · 04-19-2013, 07:22 PM

After a move last year, I don't have many track/race experienced mechanics in my area, so I thought I'd ask about changing brake fluid.

I need to change the stock DOT3 fluid to DOT4 fluid for the track. My mechanic did not know if the FR-S required a release of the ABS system to completely flush the old DOT3 fluid. Does anyone know if this is an issue? Does the clutch need to be cycled at the same time because it uses the same fluid and reservoir?

CSG Mike · 04-19-2013, 07:40 PM

Wait wut?

We just did a "normal" bleed and we've been fine... I wasn't aware there were extra steps (and if they were taken, I'm unaware of that as well)

renfield90 · 04-19-2013, 07:58 PM

A normal bleed will suffice. DOT 3 and 4 don't have any harmful interactions with each other. I don't happen to know if the clutch uses the same reservoir though.

Edit: I see what you're asking. I believe someone posted a pdf of the factory service manual, this question should be answered in there.

THEmailman · 04-20-2013, 11:40 AM

I have seen this before but only on older cars (90 300zx and an early c5 vette). Those ABS modules looked very different than the one in our cars though. I searched around and couldn't find an answer so I just did a normal bleed. If you do find out let us know. And the clutch and brake cylinders are separate so you can drain the brakes without affecting the clutch.

xwd · 04-20-2013, 07:24 PM

It should be in the manual. On even recent Subaru ABS models it was sometimes necessary to cycle the ABS pump to properly bleed the brakes, although I never ran into issues with not doing it on my WRX.

04-20-2013, 11:40 AM	#4
THEmailman Senior Member Join Date: Mar 2013 Drives: Raven 6MT Location: Eastern NC Posts: 113 Thanks: 30 Thanked 14 Times in 10 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	I have seen this before but only on older cars (90 300zx and an early c5 vette). Those ABS modules looked very different than the one in our cars though. I searched around and couldn't find an answer so I just did a normal bleed. If you do find out let us know. And the clutch and brake cylinders are separate so you can drain the brakes without affecting the clutch. __________________ Goodridge SS brake lines//ProjectMu 999's//Motul DOT 5.1 brake fluid//GrimmSpeed master cylinder brace//Jackson Racing Oil Cooler//Whiteline camber bolts//Raceseng CamCas plates//Kosei K4R 17x8//BFGoodrich Rivals 225/45

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04-19-2013, 07:40 PM	#2
CSG Mike Join Date: Jul 2012 Drives: S2000 CR Location: Orange County Posts: 14,562 Thanks: 8,942 Thanked 14,211 Times in 6,854 Posts Mentioned: 970 Post(s) Tagged: 14 Thread(s)	Wait wut? We just did a "normal" bleed and we've been fine... I wasn't aware there were extra steps (and if they were taken, I'm unaware of that as well)

04-19-2013, 07:58 PM	#3
renfield90 The Stig's German cousin Join Date: Mar 2013 Drives: 2013 FR-S Location: Tempe, AZ Posts: 1,071 Thanks: 140 Thanked 519 Times in 345 Posts Mentioned: 8 Post(s) Tagged: 2 Thread(s)	A normal bleed will suffice. DOT 3 and 4 don't have any harmful interactions with each other. I don't happen to know if the clutch uses the same reservoir though. Edit: I see what you're asking. I believe someone posted a pdf of the factory service manual, this question should be answered in there.

04-20-2013, 07:24 PM	#5
xwd Senior Member Join Date: Feb 2012 Drives: 2013 DGM Subaru BRZ (Subie #9) Location: ATL, US Posts: 2,667 Thanks: 123 Thanked 861 Times in 552 Posts Mentioned: 32 Post(s) Tagged: 0 Thread(s)	It should be in the manual. On even recent Subaru ABS models it was sometimes necessary to cycle the ABS pump to properly bleed the brakes, although I never ran into issues with not doing it on my WRX.

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