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Differential Vent Tube venting on track days

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I did one session on Saturday that was about 20-25 minutes long and saw indicated 140 on front straight at Summit main. After my session I parked and went to talk to a buddy and was called on the radio by a co-worker to inform me that I was leaking brake fluid from the right rear. After inspecting I noticed it wasn't brake fluid but was gear oil. That wheel took an impact from an inattentive driver a while back that caused the right rear caliper to stick. I'm thinking the excessive heat from the caliper sticking killed the seal. Further inspection revealed that the pumpkin blew a TON of fluid all over the place and actually had dripped onto the pavement.

The fluid was replaced by dealer last month, and perhaps overfilled, but it ain't the first time it's puked. Has the turkey baster been successful for those that are using it in preventing overflow?

Also, since I need to replace the axle seal, should I also do the bearing on that side? Should I do both sides since it isn't that much for the parts? And lastly, do the bearings need a special tool to remove them?

Thanks!
 

steveespo

Lord knows I'm a Voodoo Child
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I had overheating diff fluid cause the drivers side seal to fail and since most turns are clockwise the fluid is pushed to that side and weeped out onto the inside of the rim. Replaced the seals and bearings. You need a slide hammer to pull the bearings and a seal removal tool if you just want to change the seals. Harbor Freight sell both at very cheap prices and I have used the slide hammer puller for 3 jobs now.

To install a seal and bearing driver set is preffered but the correct size socket, an extension and dead blow hammer can be used. Clean the bores and outside of the seal with alcohol wipes and apply a thin film of Permatex RTV Black around the outside, will ensure no leaks at the tube. Apply coating of gear lube to the lip of the seal and oil the bearing rollers too.
I use the Bobs Super Snake reservoir with vent and also have a vent in the axle tube. With differential cooler I keep temps to a max of 245 degrees, without it I had peak temps of 295 which is not good.
Steve
 
YellowBoss said:
IMHO, this is the best setup for the overflow issues unless you have a full blown oil cooler

pics from here: https://trackmustangsonline.com/index.php?topic=1696.msg36914#msg36914
another pic: https://trackmustangsonline.com/index.php?topic=1696.msg81327#msg81327

Just thinking, why is the vent line not going straight from the rear axle into the base of the trunk mounted vented breather in order to fill it when expanding and flowing back in when cooling...? And of course the vent should be plumbed outside of the vehicle to avoid the smell.
 
LostPony said:
Has the turkey baster been successful for those that are using it in preventing overflow?
Thanks!

I have had good luck with the turkey baster. Also, make sure the diff is not overfilled. It should be below the fill plug hole by about a 1/2 inch or more.

And speaking of rear axle seals, I noticed this fall that I had a slight right rear axle seal leak. My dealer replaced both axle seals under warranty for me.
 
patrickshelby said:
Just thinking, why is the vent line not going straight from the rear axle into the base of the trunk mounted vented breather in order to fill it when expanding and flowing back in when cooling...? And of course the vent should be plumbed outside of the vehicle to avoid the smell.

Simple answer - because race car ;D This is the setup that comes on the 302S if I remember correctly.

The canister is not a "catch can" but a breather, it does not and has not collected any gear oil over the past two years. While some gear oil may make it up in the hose it will then just drain back into the diff. While my car is not involved in racing the can is mounted inside the trunk as per rules of different racing bodies I believe. The smell is something you have to deal with if you want to play. However the only time I have ever had the gear oil smell is at Daytona off the tri-oval at speeds of 165 or greater. Never on the other tracks, street or even the bus stop where speeds are 158 or greater and at my last event I did not get the small even off the tri-oval.
 
Has anyone just tried a long hose line with a loop in it?

On my race car we simply put a 1/4" NPT nipple in place of the axle vent and run about a 2 ft hose up from the vent to a high point under the car. I've never had a problem with it and we run 30 min sprints up to 3 hour races in this fashion. Line still allows for air to escape but is long enough of a path that if fluid climbs up the tube a bit it doesn't get high enough to spew all over.
 

TMSBOSS

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TMSBOSS said:
Shelby has their KR version of the expansion tank on sale now. $30.00 off.

Effective solution. One track day with this tank and no issues. Simple install. You may need a longer hose, at any auto parts store, if you have changed the diff cover. Mine is the FRPP girdle which required the vent be moved to the axel tube. I installed a 90 degree compression elbow to the Shelby set up with a longer hose.

Works great. ;D
 
patrickshelby said:
Just thinking, why is the vent line not going straight from the rear axle into the base of the trunk mounted vented breather in order to fill it when expanding and flowing back in when cooling...? And of course the vent should be plumbed outside of the vehicle to avoid the smell.

Mine was plumbed with the line going into side and i had overflow problems twice. re-plumbed in the bottom problem solved, drains back every time, plus makes a great fill point during service :)
 
Ron Earp said:
Has anyone just tried a long hose line with a loop in it?

On my race car we simply put a 1/4" NPT nipple in place of the axle vent and run about a 2 ft hose up from the vent to a high point under the car. I've never had a problem with it and we run 30 min sprints up to 3 hour races in this fashion. Line still allows for air to escape but is long enough of a path that if fluid climbs up the tube a bit it doesn't get high enough to spew all over.

That would work but - number one - some racing originations will not allow that and two, why even take the chance on not having a can on the end? With respect to you - I just don't see you would not want the security of the can there even if the chance of oil making it to the can is very low. Again, nothing personal against you but there is a right way to do a job and all other ways.

Having said this I have a trans line run to the engine bay with a filter on the end of the hose and no canister but really, there is no comparison between the rear and the trans when it comes to over flow type problems.
 
Yes, the correct way is with a can and I eventually added one for piece of mind. But if someone needs to fix the job at the track, which is where I discovered my problem some years ago, the ghetto hose trick will take care of business. The "dead whale" smell of diff fluid is fairly pungent and easily tracked.
 

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