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Overheating brakes - driver or equipment issue?

dmichaels

Papa Smurf
547
30
CT
Did a quick search, didn't see much, so sorry if this is covered elsewhere...

Anyways, got back from 2 days on the track last weekend with my 2014 GT track pack, and at the event the brakes were getting soft every session. I was pushing fairly hard (for me), running ~1.23 at NJMP Lightning on street tires, but don't think I was overusing the brakes. I know I do sometimes get on the brakes to slowly and am a bit slow getting back off them. But I have the Brembo's with Pagid RST-2's up front and the Ford Racing brake cooling setup, along with Motul RBF600 which I put in last year and re-bled with right before the event. Really did not expect to keep getting air in the lines. Not much air, but enough to get a bit of a soft pedal by halfway through the session.

My thoughts are either its my driving or the OEM fluid still is not completely bled out? I don't drive so hard that I would expect to overheat the fluid each session, and bleeding the brakes between every session is getting rather annoying. Any suggestions?

Thanks
 

dmichaels

Papa Smurf
547
30
CT
To clarify - I replaced OEM fluid with RBF600 last season just after purchasing the car - used up 2 pints (4 bottles) of RBF600 for that bleeding. This season, I bled the brakes utilizing 1 litre, so probably replaced 75% of the system fluid? I'm not sure system capacity. I did not drain the system and replace with RBF600, I bled out most of the reservoir initially, added about 1/2 litre of RBF600, bled out the reservoir again (most of the way) and refilled and so on. So there was definitely a bit of mixing of OEM fluid with the RBF600, but by now I would think there is almost nothing but RBF600

Hope that helps clarify
 
What do you mean by "bled out the reservoir again"?

Are you doing this:
1) remove old fluid from reservoir (like with a turkey baster)
2) adding new fluid
3) bleeding the brakes at each corner, all 6 bleed screws?

are you pressure bleeding, or pumping the pedal?
 

dmichaels

Papa Smurf
547
30
CT
Bob said:
What do you mean by "bled out the reservoir again"?

Are you doing this:
1) remove old fluid from reservoir (like with a turkey baster) - bled the brakes until fluid level was down close to empty, added new fluid, repeated.
2) adding new fluid
3) bleeding the brakes at each corner, all 6 bleed screws? Bled starting at rear passenger, used about 1/2 litre per corner I guess initially.

are you pressure bleeding, or pumping the pedal? Speed bleeders, so pumping pedal.

Input above! Sorry if I'm not being clear. Have bled brakes many times and never had issues tracking my previous car with a Stoptech setup up front.

I've always read not to let the reservoir level go below where the tubing connects for bleeding, but for se (dumb) reason the thought never crossed my mind that I could suck all the fluid out and immediately replace which would fully replenish the reservoir fluid, then commence brake bleeding. Just had a "duh" moment.

Going to get a couple more rbf600's i think and redo the bleeding with the clutch suggestion above too.
 

dmichaels

Papa Smurf
547
30
CT
TMSBOSS said:
Yep.

The best reason to install a second reservoir for the clutch.

I start with the clutch when I bleed the system.

Relatively easy putting in a separate clutch reservoir?
 

dmichaels

Papa Smurf
547
30
CT
cosm3os said:
If you have any year-old Motul in there, you have a lot of moisture in the system. That stuff needs to be changed often (like after every event).

Have considered biting the bullet and switching to castrol srf as their wet boiling is untouched. And I do drive the car a couple times a week too
 

Grant 302

basic and well known psychic
Sounds like you weren't getting all the old fluid out. Having any old fluid in the caliper is like you didn't change the fluid at all. Your effective boiling point hasn't changed.

Turkey baster and clutch pumping really help keep the fluid clean. With the reservoir full of new fluid, pump fluid out the caliper until you see new fluid.

Vacuum bleeding may also help too:
https://trackmustangsonline.com/index.php?topic=1856
 
You probably had some old fluid in the ABS module as well, which usually for us mostly activates at the track, so you'll get older fluid mix at the track.
 
745
352
If I remember correctly, you have speed bleeders. If that is true, get rid of them. A lot of board members will disagree with me, but I would never use them on a tracked vehicle.

Also, since you do not flush your brakes on a regular basis and daily drive, I would switch to srf.
 
38
0
I use the ATE Blue/ 200(Gold) for normal everyday driving. Still a very good DOT4, and about 15-18 dollar a liter. Using this fluid system gives a clear indication when you have completely flushed the old fluid out..
If your pushing the car hard enough on the track to really need Motul or even SRF, use the ATE blue as a flush, then follow with your expensive fluids.
I find i can flush the system with about a liter. YMMV.
 
You can't buy Blue anymore. If you take 4 oz's out of each corner for a change, and 2 for a bleed, you should be ok. I've been using that system forever and never had a fluid problem.
 

Bill Pemberton

0ld Ford Automotive Racing Terror
5,583
4,108
Exp. Type
W2W Racing
Exp. Level
20+ Years
Blair, Nebraska
Kyle likely hit on it. Most of us who track bleed fluid after every weekend , at best every two weekends. By the time you go through numerous heat cycles, plus the fact that brake fluid has an affinity to moisture, it really isn't surprising to me that you had a soft pedal, etc. Your initial note I found confusing, so appreciate the explanation, but I would just suggest changing your fluid alot more often. Bet your concern goes away with a full, clean , bleed, but do note the issue with the clutch , as that is also a concern with the Boss ---- part of the reason I do that after each weekend also as I tend to get things a bit hot, ha,ha!!
 
Another thing to check if you haven't already - the caliper dust boots. I burned mine up after a few events. Doubt this is the cause of your soft pedal but something to check out while you're at the caliper.
 

PeteInCT

#LS-378 - So many Porsche's, so little time....
Moderator
2,848
14
Connecticut
DMichaels said:
Did a quick search, didn't see much, so sorry if this is covered elsewhere...

Anyways, got back from 2 days on the track last weekend with my 2014 GT track pack, and at the event the brakes were getting soft every session. I was pushing fairly hard (for me), running ~1.23 at NJMP Lightning on street tires, but don't think I was overusing the brakes. I know I do sometimes get on the brakes to slowly and am a bit slow getting back off them. But I have the Brembo's with Pagid RST-2's up front and the Ford Racing brake cooling setup, along with Motul RBF600 which I put in last year and re-bled with right before the event. Really did not expect to keep getting air in the lines. Not much air, but enough to get a bit of a soft pedal by halfway through the session.

My thoughts are either its my driving or the OEM fluid still is not completely bled out? I don't drive so hard that I would expect to overheat the fluid each session, and bleeding the brakes between every session is getting rather annoying. Any suggestions?

Thanks

You may not have the lines fully flushed, but bleeding a little after each track day is what is probably required (I do it, sometimes after 2 runs). Also, air gets trapped in our ABS sensors.

Per Ford Engineers: Take car out on street, get up to about 60 mph and hit the brakes hard. Do this 2 or 3 times invoking the ABS heavily. After you do this watch the brake pedal firm up. The air will release form the abs module and get back up into the lines, where it does less to impact the fell of the pedal. After you do this, doing a quick bleed is a good idea. It works, I've done it.

-Pete
 

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