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Differential Vent Tube venting on track days

This was an issue on my GT500 and I'm having the same issue on the Boss. I didn't have it my first track day, but after having my dealer change out the fluid I have had it each time. It's pretty common to have them somewhat overfilled by the dealer when you have them change out the fluid since there's really not a "fill" line per se. On my GT500, the tech took a short piece of hose and attached a breather filter to it. The fluid would collect in the breather filter and drain back into the axle. There's apparently a TSB for the 5.0s you can have done at the dealer:

http://mustangforums.com/forum/s197-handling-section/638332-diff-spit-up-a-bit-on-track-cause-for-concern.html


Given that our vent tubes are on top of the diff, I'm not sure this will fit. Has anyone else experienced the fluid venting on track days yet? Any solutions? A friend of mine with a 98 Cobra ran a long hose up vertially so the fluid would travel up the hose and drain back into the axle tube before making it all the way out. It makes for a greasy mess when tying the car down on the trailer. :mad:
 
Where exactly are you seeing the overflow? I will do a double check for you but I remember it being very clean under there after every track day. So far my Boss has treated me well, except the trans shifing thing.
 
I have only replied to topics started at MustangSource, I never started my own (I don't think). I had my side pipes adjusted at the dealer and have a black spot on the wheel well lip in the paint but nothing else, no noises, lights or any other issues that have been reported.
 
2012Boss said:
Where exactly are you seeing the overflow? I will do a double check for you but I remember it being very clean under there after every track day. So far my Boss has treated me well, except the trans shifing thing.
It vents (sprays) from the little bell shaped vent on top of the diff. It will cover the underside of the gas tanks, and drip down the axle tubes and diff itself. You will see it all over the diff cover and if bad enough dripping from it. It results from the diff heating up under track use. The fluid expands and vents through the tube which it's designed to do. That's why they have the TSB for the GT, but I don't think there's enough room above the diff for that little balloon shaped thing they're describing as a turkey baster. It's obviously an issue for others since they came up with that TSB, but I'm surprised I'm the only Boss owner to have it happen yet. It's not necessarily the car "letting you down". It's just something that happens when road racing. We just need a way to capture the fluid and return it to the diff rather than spraying all over.
 
I did not mean it that way, just saying so far so good. I was under the car a few days ago checking out the axle when a friends diff cover came in. It was very clean but I will check the other points. I have less miles then you and don't push the car as hard but I certainly have not "babied" it.
 
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For a race car they run a tube into a catch bottle. The top of the bottle is open and the tube runs down to the bottom of the catch can. This is required by many organizations. On a race car you would run the hose into the trunk and the catch bottle would be tied to a frame member or part of the roll cage.
 
2012Boss said:
I did not mean it that way, just saying so far so good. I was under the car a few days ago checking out the axle when a friends diff cover came in. It was very clean but I will check the other points. I have less miles then you and don't push the car as hard but I certainly have not "babied" it.
Sure, understand. I'm wondering if you've changed the diff fluid yet? It didn't happen until I had the dealer change it, just like on my GT500. When at the factory fill level it was fine, but after changing it, I think they tend to err on the side of overfilling, thus the overflow.
 
908ssp said:
For a race car they run a tube into a catch bottle. The top of the bottle is open and the tube runs down to the bottom of the catch can. This is required by many organizations. On a race car you would run the hose into the trunk and the catch bottle would be tied to a frame member or part of the roll cage.
That's essentially what my friend did with his race prepped 98 Cobra. I'm looking for a simpler solution not drilling into the trunk, but may have to go that route. I need to look at his design again.
 
cloud9 said:
Sure, understand. I'm wondering if you've changed the diff fluid yet? It didn't happen until I had the dealer change it, just like on my GT500. When at the factory fill level it was fine, but after changing it, I think they tend to err on the side of overfilling, thus the overflow.

No I have not yet. I am waiting on a cover I ordered to drill and tap first. I will take of the original and clean/check it then replace with the new tapped cover.

What did they add for the friction modifier, the same stuff as a limited slip diff?
 
I assume they added what it calls for in the supplement. I'd have to verify on the invoice, but that's what we talked about.

Rear axle fluid friction modifier 5 oz. XL-3EST-M2C118-A
 
ArizonaGT said:
I'm surprised the Torsen even needs the modifier, since there are no clutch packs.
I know we went round and round about that, and ultimately landed on the fact that the supplement calls for it, so we put it in there.
 
I just crawled up under the car and there is no oil anywhere. My best guess is they added a little more then the car had from the factory. That would be easy to do since there is not fill line on the factory cover. I am not saying they are bad mechanics but why else would it only happen after you had it changed?

On the friction modifier, I don't doubt the need for it for whatever reason but I want to know if it is the same as limited slip cars. I need to research the number you posted.

Edit, it looks like that is the standard modifier for all Fords with a LS
 
I ordered the turkey baster today. Not sure exactly how we're going to configure it yet, but we'll make it work. I looked at a GT500 on the showroom floor when I went in to order the parts. Looks like the axle tube has a bolt in it, potentially plugging the standard axle tube vent. (The GT500PP has the same diff and cover as our Boss). I'm going to look at my axle tube when I get home tonight and see if it's the same. If so, we should be able to just remove the vent tube from the top of the diff and plug it with the axle plug. Then put the turkey baster on the axle and be golden ;D Part cost me like $36.
 
ArizonaGT said:
You got a PN for that?

Also--please check the clearance to the body on that when the rear suspension is fully compressed.
The part number is AR3Z-4A058-B. Suggestions on how to do that? Just jack one side of the axle? I'm assuming it clears since Ford issued the TSB with this part number attached to the rear axle as a fix.
 

steveespo

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I have a 2011 GT and had the venting problem Gary describes, only at the axle tube vent. I changed my fluid when I added the GT500/Boss cover and then had 2 vents. Did not see any more leakage but still added the turkey baster on the axle tube. 2 100 mile track days and not a drop out of either vent. As others have said most sanctioning bodies would require a catch can to collect lube and condensed vapors but I don't think open track or HPDE clubs tech that deep.

Can't wait for 7/11 at Watkins Glen!!!
Steve
 

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