Smoke While On Track

[krisk]

I’m currently at Roebling Road Raceway with my 2024 Mustang GT. Both yesterday and today I’ve had several people tell me they are seeing smoke coming from the back of my car at the end of the front straight while braking for turn one. This is a very hard braking zone where I’m coming in at about 143 mph. I’ve checked the everything on my car and do not see anything leaking and my brakes have plenty of pad. I’m a novice driver and have an instructor driving with me, and he checked the car out as well and did not see anything. I am running G-Loc R10 front R8 rear. Is it possible this is just something normal or does it sound like a problem. The track did not black flag me, but did say something when I came of track to let me know they saw it. It’s not heavy smoke at all, but can be seen.

Anyone have thoughts? My next session is in about 2 hours. I’m going to pull the wheels before then just to confirm the inner brake pads are fine as well. Could not be tires? I’m running Continental ExtremeContact Sport 02 (340 TW), but I’m not locking the brakes in the heavy braking zone.

 

[blacksheep-1]

I’m currently at Roebling Road Raceway with my 2024 Mustang GT. Both yesterday and today I’ve had several people tell me they are seeing smoke coming from the back of my car at the end of the front straight while braking for turn one. This is a very hard braking zone where I’m coming in at about 143 mph. I’ve checked the everything on my car and do not see anything leaking and my brakes have plenty of pad. I’m a novice driver and have an instructor driving with me, and he checked the car out as well and did not see anything. I am running G-Loc R10 front R8 rear. Is it possible this is just something normal or does it sound like a problem. The track did not black flag me, but did say something when I came of track to let me know they saw it. It’s not heavy smoke at all, but can be seen.

Anyone have thoughts? My next session is in about 2 hours. I’m going to pull the wheels before then just to confirm the inner brake pads are fine as well. Could not be tires? I’m running Continental ExtremeContact Sport 02 (340 TW), but I’m not locking the brakes in the heavy braking zone.

I've got a lot of laps at Roebling in a laydown kart. Turn 1 is actually a series of turns, but it is at the end of a 140mph straight.

I don't have any magical solutions for you, but you are definately doing all the right things with regards to checking. Look inside the exhaust and see if any oil is accumulating there, or whether there is any residue on the bottom of the car, which would indicate leakage from the driveline.
A couple things to check are the fluid levels in the trans and diff, but I suspect the cause is that you are over pressuring the crank case ( blowby) on rapid deceleration, there are several fixes for that, windage trays, oil separators, etc. So it's not uncommon. The important thing is to not leave residue on the track.
Behind the rear spoiler, on the back of the car, there is a low pressure area, any significant residue will accumulate there.
If there's no residue, I wouldn't sweat it too much as long as all the gauges stay in the normal range.

 

[krisk]

I've got a lot of laps at Roebling in a laydown kart. Turn 1 is actually a series of turns, but it is at the end of a 140mph straight.

I don't have any magical solutions for you, but you are definately doing all the right things with regards to checking. Look inside the exhaust and see if any oil is accumulating there, or whether there is any residue on the bottom of the car, which would indicate leakage from the driveline.
A couple things to check are the fluid levels in the trans and diff, but I suspect the cause is that you are over pressuring the crank case ( blowby) on rapid deceleration, there are several fixes for that, windage trays, oil separators, etc. So it's not uncommon. The important thing is to not leave residue on the track.
Behind the rear spoiler, on the back of the car, there is a low pressure area, any significant residue will accumulate there.
If there's no residue, I wouldn't sweat it too much as long as all the gauges stay in the normal range.

Thank you! I got under the rear of the car and there is absolutely no residue. I do have an oil catch can and I emptied it before the track weekend, but I’ll check again before I go back out. Previous track days only produced less than 1tsp of oil. Thanks again, and I’ll keep checking everything out.

 

[TMSBOSS]

I had a similar issue a few years back. Black flagged for smoke while braking. Trans oils was exiting the breather and dumping onto the exhaust under hard braking.

 

[byronj]

I'm of no help. Hope you sent it and had a fun day. Any update?

 

[krisk]

I had a similar issue a few years back. Black flagged for smoke while braking. Trans oils was exiting the breather and dumping onto the exhaust under hard braking.

Thank you! I made it all weekend without getting black flagged, and it really seemed to be intermittent. The instructor I had riding in the car with me for one of the sessions watched for it the next time out and saw it one time when braking early in the session, but didn’t see it again. Now that I’m home I’ll get up under the car and check it out fully to see if it could be the transmission fluid.

 

[krisk]

I'm of no help. Hope you sent it and had a fun day. Any update?

I definitely sent it and had a great time. The last session of the day from 4:30 - 5:00 was great because there were only three people on track since most had already packed up. I’m still fairly new to the track, but I’m loving it!

 

[Nbjeeptj]

I had this exact issue also. I fixed it by extending the transmission vent line on the top of the bellhousing all the way over the engine and then down onto the top of my splitter. I figured that way if it did make it all the way up there it would at least hit the top of my splitter and not hit the track. I guess a small catch can would work for this also. So far I have not seen any make it all the way up there.

 

[krisk]

I had this exact issue also. I fixed it by extending the transmission vent line on the top of the bellhousing all the way over the engine and then down onto the top of my splitter. I figured that way if it did make it all the way up there it would at least hit the top of my splitter and not hit the track. I guess a small catch can would work for this also. So far I have not seen any make it all the way up there.

Sounds as though the transmission vent is the likely culprit based others’ experiences. I’m likely done on the track until spring, so I’ll have some time to check it out and report back. Thank you for the help!

 

[991GT]

@Nbjeeptj I am having this issue with my 2020 PP2 car and would like to correct it over the winter.
Did you extend the breather tube when you had the trans out for some reason. Not sure how you reach the breather to do this with it in the car.

 

[Nbjeeptj]

I did mine with the transmission in, and it was not fun. I took a long pair of right angle needle nose pliers to pull the rubber hose off the factory breather if I remember right I ended up breaking the factory plastic breather in the process, but once I had the hose pulled loose I was able to pull it down the side of the transmission to add a barb hose coupling and ran a new line over the engine to the front of the car with a new breather on it. You could also land it in a catch can but since I have not had fluid come out of it since the extension I just did the hose breather. I currently have my transmission out so when I get home I will take a picture of this hose and it’s original location so you can see what you are looking for since you cant see the whole line with the transmission installed.

 

[991GT]

I did mine with the transmission in, and it was not fun. I took a long pair of right angle needle nose pliers to pull the rubber hose off the factory breather if I remember right I ended up breaking the factory plastic breather in the process, but once I had the hose pulled loose I was able to pull it down the side of the transmission to add a barb hose coupling and ran a new line over the engine to the front of the car with a new breather on it. You could also land it in a catch can but since I have not had fluid come out of it since the extension I just did the hose breather. I currently have my transmission out so when I get home I will take a picture of this hose and it’s original location so you can see what you are looking for since you cant see the whole line with the transmission installed.

Thanks...anything that makes it easier is greatly appreciated!

 

[Nbjeeptj]

 

[991GT]

@Nbjeeptj Thanks for the pics! Not looking forward to trying to fix this.

 

[Nbjeeptj]

Dont know for sure but I believe if you take the intake manifold off (probably only a 10min job looks way worse than it is) it will give you access to this hose and breather from the top. I did not think about that at the time I was doing it, but it may help with access.

 

[gusnav]

What I did when I was working to install transmission cooler on my boss, removed the cross member, supporting the transmission and lowering enough to work on the new breather hose up and over the firewall to Joe racing breather tank. It was tough with fat hands short fingers.

 

[krisk]

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Thank you for the photos! I'm currently building a new shop after hurricane Helene destroyed my previous one. Once I get my lift installed, fixing this breather hose will be my first project.

 

[EF1]

What I did when I was working to install transmission cooler on my boss, removed the cross member, supporting the transmission and lowering enough to work on the new breather hose up and over the firewall to Joe racing breather tank. It was tough with fat hands short fingers.

I forgot to install the breather on mine before reinstalling the trans. I could not get my hands in there to push the hose back on. I finally gave up after a couple hours of fighting with it. My wife’s small hands had it in place in a couple of minutes.

 

[blacksheep-1]

Thank you for the photos! I'm currently building a new shop after hurricane Helene destroyed my previous one. Once I get my lift installed, fixing this breather hose will be my first project.

Where r u located?

 

[krisk]

Where r u located?

Valdosta, GA