CamminC5

I've had this C6Z diff and DSS CV axles in the car for a year and half without a single issue. I pulled the driveline for an auto conversion and everything went back together smooth. First time I drove the car I noticed it was slinging gear oil out the left side (between the axle and lip seal) enough to cover the cradle and make the exhaust smoke. So I changed the seal thinking I damaged it somewhere along the way.

Fast forward a few days (the next time I take the car up the road). I notice smoke coming out the back of the car and realize it's the same seal doing the same thing again.

I called RPM and was told to polish the hubs on the axles as they have seen the thick coating cause issues before. So I put them on the lathe and polish with 600 grit and finish with scotchbrite, installed a new seal, then took the car up the road. Same issue again.

I swap axles from side to side. Still have issue.

Ran the diff with the vent open. Still have the issue.

Reassembled the vent and new seal. Still have the issue.

Fluid level is 1/4-1/2" below the fill hole, and has been the whole time. The CV is secure in the diff because I have to pop it off the circlip during disassembly every time.


Guys....I'm at my wits end...... I have searched and searched this forum and others for some sort of explanation and have come up with nothing. I've been on the phone with Jeremy and the guys at RPM multiple times a day.


Please help me! I've never been this defeated....

C5 Pete

Are you certain its coming out of the seal? I've had a similar issue with a C5 diff. Thought it was the seal. Replaced it and still leaked. Upon closer inspection, found a hairline crack in the cover about 3" long going outward from the seal.
New cover. Leak fixed.

Good luck with the repairs!

CamminC5

I needed to take some time away so I haven't touched the car since Friday. I have one more seal I was going to try tomorrow, but will do a real good inspection of the cover. Once the oil hits the CV it goes everywhere. There's no way I have messed up the install on 3 seals.

C5 Pete

Yeh. It's highly unlikely you messed up three seals.

Clean it up really well and take a look with a bright light.

If it is cracked, it'll probably be easier to get the crack welded up vs trying to find a used one not attached to an entire diff. I don't know the cost of a new replacement. Might be worth looking into.

CamminC5

I've been texting Jeremy. He said he's seen cracks in C6Z side covers, and would send me a new one if needed.

C5 Pete

CamminC5

Found the issue.

There's a bushing on the inside of the side cover that the axle rides on. It had come out of its bore. New parts will be here tomorrow.

It's very flimsy plastic. When I tried to put it back in the bore it fell to pieces.

Pounder

Well you certainly know how it comes apart !!

CamminC5

The axle had to catch it just right during installation and push it out. I knew it was something stupid.....Always is.

C5 Pete

Good find!!

CamminC5

Well...This is cause of the leak....But something is causing the Left OPS to be slightly cocked.

I removed the clip from the OPS and tried to slide the axle hub in the diff and it stops. After further inspection I see the shaft is favoring one side of the cover.

Now to pull the driveline and disassemble the diff.

CamminC5

Tore the car down last night, and took the diff apart.

So....

There is a washer behind each spider gear. Somehow I zoned out and put both washers behind one of the gears. So this made the left OPS sit to one side, making the axle hub run to one side, and resulted in the leak.....Lucky there was no damage. Now all is well.

Sometimes we are our own worst enemy.....

Pounder

It is hell being Human !!

C5 Pete

Whenever my car breaks, I blame the mechanic - That would be me.

We all do stupid crap from time to time. Glad you found the issue.