Brake Fluid Question

[Caballus]

Anyone know of any drawbacks to AP Racing Radical R4 brake fluid; i.e., hard on lines or seals...corrosive; compressibility issues, etc? Especially interested in learning about any street use issues.

https://www.apracing.com/products/ra...id-cp6005.aspx

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[hinch]

Anyone know of any drawbacks to AP Racing Radical R4 brake fluid; i.e., hard on lines or seals...corrosive; compressibility issues, etc? Especially interested in learning about any street use issues.

https://www.apracing.com/products/ra...id-cp6005.aspx

don't waste your money on stuff like that the dot4 that comes in it is more than sufficient if you need something that can take higher heat cycles put in a good quality dot4.5 as thats directly compatible if you move up to a dot5 then you'll need to flush lines first as 4 to 5 is a mismatch.

in all reality for fast street use even driving it like you stole it the factory fluid is more than sufficient if anything under temperature you'll get bulge on the factory lines to the calipers replace with braided hoses goodridge / steeda etc and that'll be more than good enough for anything you can achieve on the road.

 

[Caballus]

don't waste your money on stuff like that the dot4 that comes in it is more than sufficient if you need something that can take higher heat cycles put in a good quality dot4.5 as thats directly compatible if you move up to a dot5 then you'll need to flush lines first as 4 to 5 is a mismatch.

in all reality for fast street use even driving it like you stole it the factory fluid is more than sufficient if anything under temperature you'll get bulge on the factory lines to the calipers replace with braided hoses goodridge / steeda etc and that'll be more than good enough for anything you can achieve on the road.

Thanks. The OEM set up has turned out to be good so far (Nürburgring, Autobahn, etc). However, I hope to start doing more tracking and want a good fluid that I don't have to change after every couple sessions or swap out for street driving. Leaning toward Castrol SRF, but considering this stuff as well.

 

[hinch]

Thanks. The OEM set up has turned out to be good so far (Nürburgring, Autobahn, etc). However, I hope to start doing more tracking and want a good fluid that I don't have to change after every couple sessions or swap out for street driving. Leaning toward Castrol SRF, but considering this stuff as well.

swap out your lines the current will be fine and you won't have to change it after every couple of sessions. just do it once a year if you really must (having said that i haven't done my track car in 4 years and it still stops so violently it hurts)

going to a proper track fluid like a dot 5 will make the brakes quite crappy under normal driving it really needs to be up to temperature to work well.

just put a good quality dot 4 in (check its boiling points before purchase) and it'll be more than sufficient either that or your day job involves driving in F1/DTM/BTCC

drop these guys an email https://www.opieoils.co.uk they'll be able to advise on the best fluid for your usage and they're independent of manufacturer too.

 

[Caballus]

swap out your lines the current will be fine and you won't have to change it after every couple of sessions. just do it once a year if you really must (having said that i haven't done my track car in 4 years and it still stops so violently it hurts)

going to a proper track fluid like a dot 5 will make the brakes quite crappy under normal driving it really needs to be up to temperature to work well.

just put a good quality dot 4 in (check its boiling points before purchase) and it'll be more than sufficient either that or your day job involves driving in F1/DTM/BTCC

drop these guys an email https://www.opieoils.co.uk they'll be able to advise on the best fluid for your usage and they're independent of manufacturer too.

Brake lines used to be one of my first mods on a car. However, I haven't been convinced that there is any value in doing it on the GT350. The brakes are massive, and I don't know anyone who has experienced boiling or significant fade on OEM brake set ups, with the OEM HiPo dot 4. However, most, including me, change it relatively often, which is what I want to get away from.

Thanks for the dot 5 advice. The low temp/post-track performance is a concern, so I will heed. I know it's not an issue with SRF, but may be with the AP Racing.

I'll shoot the guys a note. Thanks!

 

[hinch]

With regards to the line the rubber hoses that run to the caliper from the fixed line flex and bulge when the fluid gets hot getting some good quality braided just stops them bulging and so all the fluid pressure gets to the caliper.

you really really really don't need to change your brake fluid often even if its under high duress its a concept thats older than me and its even more bullshit now than it was then.
if you really track it that often then sure change it once a year but failing that have at it and don't give it a 2nd thought.

 

[Caballus]

With regards to the line the rubber hoses that run to the caliper from the fixed line flex and bulge when the fluid gets hot getting some good quality braided just stops them bulging and so all the fluid pressure gets to the caliper.

you really really really don't need to change your brake fluid often even if its under high duress its a concept thats older than me and its even more bullshit now than it was then.
if you really track it that often then sure change it once a year but failing that have at it and don't give it a 2nd thought.

I agree that many people flush their brakes more often than necessary. Howevr, I gotta respectfully disagree with the blanket rule of once per year.

Heating and cooling break fluid from track events causes condensation. With water comes a lower boiling rate. Further, with boiling water comes vapor (air), which results in greater compresability; e.g., brake fade.

The OEM fluid (HiPo dot 4 LV) is good quality and when coupled with the 6-piston Brembos on the GT350, it can handle a track session or two. However, putting more than three track sessions on OEM fluid without a flush is introducing unnecessary risk. Brakes should also be flushed if the car sits all winter. It's cheap insurance, as is top quality fluid.

 

[hinch]

where on earth did you hear / read that bullshit ?
its a sealed pressurised system filled with oil you don't get water/condensation/air in the system unless there's a break in the system that's why the boiling point of the oil is many hundreds of degrees not 100 degrees.

 

[Caballus]

where on earth did you hear / read that bullshit ?
its a sealed pressurised system filled with oil you don't get water/condensation/air in the system unless there's a break in the system that's why the boiling point of the oil is many hundreds of degrees not 100 degrees.

Heard, read, and experienced en route to my ASE brake certification many years ago (actually NIASE back then), and science has not changed. No matter how hard you try, the system is not devoid of all air/water. That is why there is a wet and dry boiling temp. Wet applies after the fluid has absorbed 3.7% water. No break in the system is necessary.

 

[hinch]

Heard, read, and experienced en route to my ASE brake certification many years ago (actually NIASE back then), and science has not changed. No matter how hard you try, the system is not devoid of all air/water. That is why there is a wet and dry boiling temp. Wet applies after the fluid has absorbed 3.7% water. No break in the system is necessary.

well learn something new every day have never experienced that at all infact my track car hasn't had fluid changed in about 4 years and still as strong now as when it was first put in.
only problems I ever experienced was line related trouble and shitty oem fluid boiling off but thats because it was operating miles beyond rated temps after a caliper upgrade, replaced with a good quality dot4 and fixed the dodgy lines never had any issues since.

 

[draconis123]

Brake fluid certainly gains moisture and air gets in the system over time and with heat cycles. I never really look at dry boiling temps as I believe they are in accurate unless you're swapping fluid before every event.

SRF is definitely the way to go. Their wet boiling point is higher than most anything I've seen.

 

[Caballus]

well learn something new every day have never experienced that at all infact my track car hasn't had fluid changed in about 4 years and still as strong now as when it was first put in.
only problems I ever experienced was line related trouble and shitty oem fluid boiling off but thats because it was operating miles beyond rated temps after a caliper upgrade, replaced with a good quality dot4 and fixed the dodgy lines never had any issues since.

I'm with you on learning every day. This site constantly reminds me of how much I don't know. In the case of the GT350, the lines are super and the fluid is sufficient for a session or two. So, my main question is specifically about AP Racing R4. Looking to learn whether it performs well under non-track conditions and whether it has any adverse effects on our specific cars. Otherwise, I am 100% sure that it's among the best available for tracking...race quality.

 

[hinch]

all dot 4 will perform fine on the road as dot 4 is the standard its just some dot 4's are better than others just remember don't mix 4 and 5 and you're good

 

[kapiteinlangzaam]

Any half serious track work will quickly roast the std. GTPP set up.

I did 4 laps on a short (but brake heavy) circuit a few weeks ago. End of lap 4 I had smoke out of the front brakes and significantly reduced braking action.

Thats a std. GTPP brake set-up, albeit with StopTec Posi-Quiet front pads.

 

[hinch]

Any half serious track work will quickly roast the std. GTPP set up.

I did 4 laps on a short (but brake heavy) circuit a few weeks ago. End of lap 4 I had smoke out of the front brakes and significantly reduced braking action.

Thats a std. GTPP brake set-up, albeit with StopTec Posi-Quiet front pads.

he's got a GT350 little bit different setup

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