At my last open track event I noticed the rear diff was leaking some fluid (very slowly) where the side cover attaches to the diff. I applied some permatex ultrablack and was able to get through the event. However after investigating the leak some more I see it is leaking also at the main seal. See attached image. The blue circle was the initial leak, and the red circle was the leak I found after. The diff has 8 hrs on it (as it was brand new in 11/18).
I was wondering if anyone has removed their diff and replaced all the gaskets? Does a person just order a rebuilt kit or can a person just get the gaskets? My car is a 2011 SR3 1500cc. Or if someone has had similar issues with the diff leak and what they have done to fix it?
Thank you for the help in advance!
-Nic H
Nic,
I'm interested to see what others have to say about this too. I've only had my car a few months and it's leaking from the top plug and seeping through the side seals like yours.
This is my 6th race car of different makes and pretty much everyone has had a leak here or there in this sort of stuff. It's been my experience that you can spend a lot of time and money trying to fix all the leaks only to have them still leak or start leaking again. Our race cars see bigger swings in temperature (expanding and contracting of metal cases etc.) than our daily's so it just seems to be part of the animal. As long as it just seeps I wouldn't worry about it too much. I just make it part of my pre and post inspection for each session to make sure it's stable. Then check the level before each weekend.
While we're on the subject of GDU's, how much metal is normal on the magnetic level plug? I had a few more shavings than I'm normally comfortable with on mine when I changed the fluid. Are the plugs normally clean or is it normal to have most of it covered?
There are several places that the GDUs can leak from. If it is leaking high up on the right hand side the GDU is over filled and the gear oil is coming out of the vent. This is easy to correct by filling to the proper level.
Sometimes they leak from the cover on the left hand side. There is an o-ring for that cover that can be changed that should fix the problem. When you replace the o ring it will seem impossibly long. You have to be patient and keep working the o ring into the grove. It will fit.
sometimes the GDU can leak from around the axles if they aren’t shimmed properly. This can be resolved by getting them shimmed properly, but this is beyond my skill set.
Sometimes they can seep between the two case halves. If it is seeping here I would let it go, but if it is leaking badly there the only way I know to fix it is to overhaul the GDU, which should be done every 40 hours. I don’t know if it possible to get the overhaul kit to do it yourself.
another thing to keep in mind is that even when there appears to be a lot of gear fluid on the diffuser, it is usually only a very small a punt of fluid. After I had my GDU overhauled one of the axles wasn’t shimmed properly and there was an oily mess after each track day. But when I would check the fluid level it had actually only lost a very small amount of fluid.
Charley,
When you've changed fluid in the GDU what has the magnetic plug looked like? Was it always clean or did it have some metal shavings on it? Mine was covered with smaller finer metal shavings. It sounds like the GDU might have straight cut gears so maybe it's normal to have some?
@trackmnky, you are right that small amounts of fine metal buildup on the magnetic plug is normal wear, but if you start getting chunks or slivers it is time to take a closer look. When I purchased my car I knew how many hours were on the engine and the chassis, but I didn't have any information on how many were on the GDU. The first time I changed the fluid in the GDU I had some good sized slivers on the magnet which were concerning.
On subsequent oil changes there were less slivers, but still more then I wanted. When I finally had the GDU rebuilt it was obvious where the slivers were coming from...
Yikes, that gear is a little scary looking. My plug was completely covered, but it was a lot finer. I don't have too many hour to go until a rebuild. I'll have to keep a close eye on it.
Can you hear an audible whine? These are straight cut gears so I'm thinking it's normal. If you couldn't hear yours then I might have a bigger problem.
Just how expensive is a set of gears? I'd like to have a shorter set for the smaller tracks around here. My wife always rides with me so the shorter gears would really help. Doesn't seem like it would be too difficult to swap. I've had to swap diff's in a other cars depending on tracks. This seems a little more involved by not by much. 1.5hrs of work maybe?
Yours is probably fine. There is definitely gear noise that is normal. Just have your GDU overhauled when you have your engine overhauled.
Regarding gear changes, they are very simple. You drain the fluid from the GDU take off the side case. Once inside you there are two nuts that you remove change the gears. It takes a little leverage (or an impact wrench works also) to break the nuts loose. A simple way to keep the gears from rotating while you are removing the nuts and re-torquing the nuts is to put a clean rag between the gears. After you re-torque the gears the nuts need to be staked to be sure they wont loosen. A new set of gears cost around $500. By the way, the gear pictured is inside the GDU and isn’t used to change gear ratios.
Here is a picture of what the gears look like when you take the side case off. It is a pretty simple job.
Thank you both for your insight and help. I will try and change the rubber o ring for the left side leak (as it is leaking on the left hand side cover) and then keep an eye on the two case halves. Possibly it dripped down.
The GDU in the car is fairly new and hopefully I don't have to get it rebuilt (only 8 hrs and it supposedly was a brand new unit).
As always thank you for the help. I will get an o ring ordered and see what happens!
There are several places that the GDUs can leak from. If it is leaking high up on the right hand side the GDU is over filled and the gear oil is coming out of the vent. This is easy to correct by filling to the proper level.
Hi Charley, What is the proper level? I filled it from the top until it leaked out the inspection plug on the drivers side removable gear change cover. I took it out on the runway for a test run and took it up to 90 MPH and then when I got home and pulled the rear clam there was oil high up on the right side where it looked like it had come out of the vent. Not sure why since I thought that was the proper way to fill it.
That is the proper way to fill it. Make sure it just barely drips out. If that doesn’t solve the problem, I would recommend giving Spring Mount call.
Charley
@charleyhradicalsportscarregistry-com
Thanks Charley, I'll pull the inspection plug again and make sure it's just barely dripping out. I then plan to pull the rear wheels and with the rear supported and the clam off and the engine warmed up bring it up to six or seven thousand in 4th gear and have someone watch the vent to make sure it's not spraying out. Just really worried about the fire risk if I'm on track and the diff is spraying oil on the exhaust.
I would talk to Spring Mountain before you do that. I believe I was told it wasn’t a good idea to run the car in gear on stands. I could be wrong but it is worth checking first
@charleyhradicalsportscarregistry-com
Glad I posted my idea, I'll give Chris and Bill a call tomorrow after I verify the level.
Spoke with Bill at Spring Mountain. He said that he usually uses slightly less than 1L of fluid when replacing the GDU fluid and that it should be level or barely dripping out of the inspection plug. He also said to remove the vent and make sure the aluminum tube is still epoxied onto the end of the red vent plug as sometimes it falls out and then fluid leaks out of the vent. He said the tube can easily be fished out with a screw driver. I will check that out when I get home.
@crit Bill knows his stuff. He has helped me out at Spring Mountain a couple of time.
