Brake Improvements

motoken · #1

I'm dissatisfied with the braking on my 1986 Turbo. When I bought the car, it had been along time since the fluid was flushed and replaced. Initially, I replaced the fluid with ATE 200, but found the brakingto be way too soft. My mechanic recommended using a DOT 3 fluid. This improved braking, but I am curious as to why this was the case. I plan to take this car to the track, and want to be able to trust the brakes and keep the fluid from boiling over.
Looking for suggestions and opinions.
Thanks in advance.
Ken

whalenlg · #2

Don’t be this guy.

The consensus appears to be that dot3 was the culprit.

https://www.roadandtrack.com/news/a4043 ... t-170-mph/

motoken · #3

OK. So definitely moving back to DOT4.

blueline · #4

whalenlg wrote: Fri Aug 29, 2025 11:39 am Don’t be this guy.

The consensus appears to be that dot3 was the culprit.

https://www.roadandtrack.com/news/a4043 ... t-170-mph/

Good grief. 'Chillin' with Chet' is an idiot and, whether intended or not, the video should be a wise warning to others. The dude is lucky to be alive - the comments in the R&T article point out his idiocy quite well, way beyond the bone-headed brake fluid oversight.

The video reveals the scary results of being stupid. He's also lucky the Plaid didn't catch on fire.

Thanks for posting that.

motoken · #5

I think I'll be replacing brake lines as well. The ones on the car are original. Figure it might be time...

blueline · #6

We have a thread in the Racing sub-forum for sharing ideas regarding track-focused and spirited-driving-focused brakes and upgrades. Here's a link that's on the 3rd page of that thread that might help with the fluid questions but there are also several links to other Carpokes brake threads at the beginning of same.

viewtopic.php?t=3638&start=20#p46869
viewtopic.php?t=3638[i]

One thing I wrote on a post there: "An ultra high-quality, high-temp racing brake fluid is a must. Motul RBF 660 would be one of several good choices, assuming your car is suitable for non-silicone synthetic."[/i]

Let us know what you end up doing - always good to see what others figure out.

(I'm going to add a link to this thread there.)

motoken · #7

blueline wrote: Fri Aug 29, 2025 2:34 pm We have a thread in the Racing sub-forum for sharing ideas regarding track-focused and spirited-driving-focused brakes and upgrades. Here's a link that's on the 3rd page of that thread that might help with the fluid questions but there are also several links to other Carpokes brake threads at the beginning of same.

viewtopic.php?t=3638&start=20#p46869
viewtopic.php?t=3638[i]

One thing I wrote on a post there: "An ultra high-quality, high-temp racing brake fluid is a must. Motul RBF 660 would be one of several good choices, assuming your car is suitable for non-silicone synthetic."[/i]

Let us know what you end up doing - always good to see what others figure out.

(I'm going to add a link to this thread there.)

Thanks for the links!

Pumba1983 · #8

I am not getting the problem fully at the moment. Are the brakes too soft in general or are they soft when hot.
Anyway brakes on this car have been enough for racing in 1986. So they are not bad if in good condition, but early calipers are expensive to refurbish die to their old sealing design.
Cooling can be improved using 968 ducting.
In the end you can always go for medium or big blacks.
If pedal feel is your only concern get rid of the brake booster

motoken · #9

Pumba1983 wrote: Sat Aug 30, 2025 9:41 am I am not getting the problem fully at the moment. Are the brakes too soft in general or are they soft when hot.
Anyway brakes on this car have been enough for racing in 1986. So they are not bad if in good condition, but early calipers are expensive to refurbish die to their old sealing design.
Cooling can be improved using 968 ducting.
In the end you can always go for medium or big blacks.
If pedal feel is your only concern get rid of the brake booster

You know, that's a good question. Too soft in general. When i first bled and replaced the fluid, a lot of gunk came out. We bled the heck out of them and then refilled the system with ATE 200 DOT 4 (my go to fluid). The responded to this work horribly. the brake pedal required a lot of effort to get the car to respond. We tried bleeding again, and still, pretty poor pedal feel and responsiveness. Went to DOT 3 at the suggestion of my mechanic, and that seems to improve things. But far from perfect. The hoses as original, so i figure, replacing them might help. I hope so.

chrischrischris · #10

The advice to switch from DOT3 from DOT4 is idiotic. DOT3 has a lower boiling point vs DOT4. Any difference in pedal feel while driving around town is not due to the fluid. Your issue is related to the quality of the bleed or something else in your braking system.