I had my first track day with the boss Saturday at eagle canyon raceway outside of denton texAs. I had a blast and I have lots of video to upload as soon as I get a second. I have a question though. I didn't have te to get the dot3 changed out for dot 4 so I ran the stock brake fluid. The first two
Sessions I had no issues at all. Later in the third session and most of the fourth session I had problems with the clutch and hints of brake fade here and there.

The clutch issue was the most irritating. Once I can post the vids you will see I was missing shifts on one particular part of the track constantly. The track had one of the tightest and most technical sections that spit me out onto a short straight then a long sweeping corner and onto the front straight. The technical sections used a lot of brake. Once I hit the straight the shift from third to fourth was impossible. The tranny would go into fifth but fourth was impossible.

The clutch pedal didn't feel right coming onto the straight. It was spongy and didnt feel like it was coming all the way back to the top like normal. I'd fight it then have to coast through a small chicane and then aroung a few more bends where brakes and shifting weren't needed as much. Once I hit the highspeed back straight it would shift flawlessly again and then the process would start over.


My question os this. If the brakes overheated and boiled the stock fluid could that have affected the clutch since the fluid is shared? It shifts fine right now and the brakes are fine too. Anyone else had that issue?

 

Sorry to hear of the issues with your clutch. So you ran your car completely stock on the track? I plan on changing to DOT 4 and adding the brake cooling ducts before I hit the track for the first time.

 

I plan on doing it B4 I take the car

 

Like I said the clutch was the only real issue. So could overheated fluid cause the clutch issue or not?

 

the fluid doesnt "overheat" per say; it either boils or it doesnt. the clutch issue doesnt seem to be related to the fluid, since from what im reading you didnt boil your fluid, you probably just glazed the pads a little if you felt a little bit of fade towards the end of the day. if you boiled your brake fluid you wouldnt have a little bit of fade... the pedal would go to the floor with air building up in the lines.

not only that, but you said you could go into 5th fine, but not 4th. if the clutch pedal was spongy as a result of boiled fluid, you shouldnt be able to go into any gear. sounds like a larger underlying problem.

also, how is the fluid reservoir set up? you said that the clutch and brake fluid is shared; are you saying that they use the same reservoir, or just the same type of fluid?

in my CTS-V i've got regular DOT-3 brake fluid for the clutch fluid, and SRF DOT-5 fluid for the brakes. I've got about 5 track events on the car and have never once cooked the clutch fluid, and I drive the **** out of it, heel-toe downshifts in every turn, etc. It doesnt get nearly the stress that the brakes get on it unless you are powershifting every gear and shifting like a maniac.

 

They have a shared resiviour. I was thinking the fluid might be the issue since it was only on that one bit of track on the last sessiOn and a half and there is no issue now with shifting and on other parts of the track there was no issue.

 

Really?? Then yes, I would say that you were boiling the brake fluid at times at this would allow air bubbles in the system which would give you a spongy brake pedal and on the clutch slide, the effect would be less clutch dis-engagement resulting in shifting difficulty. In the clutch, some of the normal "travel" will be consumed with the compression of the bubbles which would result in less clutch travel and therefore NOT full dis-engagement.

Frankly, I'm not sure I've heard of a car that shares the reservoir. The good news is that you just have one volume to fill with the DOT 4 although you might consider bleeding BOTH systems and not just the brakes.

 

The brake and clutch share the same hydraulic fluid--if you were cooking the brake fluid, that means your clutch would be less effective. Definitely flush everything out to DOT4 before next time.

 

Can't really help you on the clutch issue, but I'm in for the videos!

 

On a side note my instructor drove the first few laps or the first session to show me the track. He is a very serious Porsche club racer in a spec boxter. He goes around the country and owns the track record for the class at 4 of the 6 tracks the series runs at. Anyway he says to me I'm not going to push your car hard then he goes wow this car is so neutral and handles great. Then we were hauling **** around the track like crazy he really liked the boss.

 

yes, but boiled fluid doesnt go away. if there were air bubbles in the lines from boiling either fluid, you would still feel the effects even after the event and when the car was cooled down. thats the reason i can tell you didnt boil either fluid.

 

spongy?? you have never boiled brake fluid then my friend. the pedal dissapears when you boil brake fluid.

again, air bubbles just dont magically dissapear... if he boiled the fluid the pedal would still be the same way even after the event.

 

I agree with smbstyle. If you over heated the brakes, the fluid in the calipers would heat up not the fluid in the reservoir. Once you get air bubbles in the system, the only way to get them out is to bleed the system. That said, I don't have a answer for your clutch issue.

Maybe when you get the video posted I'll see something that would caused this.

 

Agreed, sounds more like glazing than boiled fluid. However, Ford is quite specific about using DOT 4 fluid for track use - I am willing to bet the solution for your issues is following that recommendation :-)

 

Shane, could skip-shift be in any way involved? Did you disconnect the skip shift solenoid on your boss?

 

no i didn't disconnect skip shift, and from reading the tracking insert it says recommended not required. It was weird for sure.

this starts exactly on the long corner i mention and then you hear the car rev as i try to get it into fourth coming onto the straight. it was like it was stuck and just wouldn't go into gear, then it slips into 5th. the pedal didn't feel as if if was coming all the way up under my foot. after i get through the next four turns the clutch feels normal again and will hit 4th fine. you can also hear the instructor telling me I'm trying to force it. i was doing the shifting exactly like i was everywhere else on the track and not having any issues. it was that one spot each time and the issue didn't surface until later in the day when the temps were near 100 ambient.

 

was the issue in left hand corners? have been following a few threads on different sites that have had that issue.. if so it is a shifter bracket issue.

also what you describe about the clutch not coming back up has happened before, but rare. one case it was an restriction in the slave cylinder.

btw, neat looking track!

beers

 

the issue was after a left hand corner but already on the straight so i don't think it would be the bracket issue. i would like to see those threads though if you cant post here please pm me. i had the fluid changed out to high temp 650 wilwood and had them flush it all from the clutch to with a suction machine. i hope to get back on the track next month and see if that makes the difference.

FWIW the car seems to shift better now that it has new fluid than it did when new. the tranny is much smoother and i only feel the slight crunch when cold on 2-3, i used to feel it on 3-4 too. i wonder if the car had some air in the lines for the clutch or something.

 

linkage and slave info

lots of useful info in this thread.. mostly technical and not much speculation. pm me if this link does not stay up..

beers

 

Shane,

I boiled my brake fluid on the weekend and no problems with my clutch. Yes I had changed the fluid to DOT 4 but obviously not a very good fluid. I am changing to DOT 5.1 this weekend and will try and figure out how to bleed the clutch fluid as well.