Cap'n Pete

After running ~15 - 20 minutes on track, my tranny (and/or diff?) heats up to the point that the fluid starts puking out the vent (I think that's where it's coming from?) and spits onto the exhaust, which of course, starts to burn it off, creating plumes of blue smoke behind my car!!

Is this a "normal" or "expected" problem for a base C6? I realize that the Z51 / Grand Sport / Z06 come factory equipped with tranny/diff coolers.

I'm just not sure what the best solution for me would be?

A) install the factory system from one of those models? (at what cost?)

B) go aftermarket? (ie: LG Motorsports, for $2885)

or

C) sell this base C6, and go get a C6 Z06 that's already got the cooling in place (as well as suspension, power, etc.)??

I bought this car brand new about 1 year ago, and have had problems at the track with the transmission getting hot ever since. I'm very disappointed / frustrated, to say the least .

Appreciate any/all advice!

J.R.

1st check to see if it is filled to the correct level. Overfilling will sometimes cause this. Also, check to see if vent is functioning properly and not clogged.

I have used GM trans fluid and Royal Purple diff fluid (per RPM trans) with very good success.

My 1st C5 street/track car did not have these issues in 15-20 min sessions but I had wrapped (header tape) exhaust system and above fluids.

The next step would be a diff cooler (DRM makes a great setup) as the diff seems to experience more issues than trans.

Finally add a trans cooler (Randy-DRM- also does the diff/trans setup) if you still have issues. You may want to use an infrared temp device to check temperatures of trans and diff as you make changes.

AU N EGL

Trans and Diff coolers. Plus Dry sump and cooler for the engine LS3*. That is the normal mods needed for any track / DE car.

*LS2 and LS6 can use a accu-sump with cooler, dry sump is still better

Normal track mods.

Cap'n Pete

I guess it would be helpful to know for sure whether it's the transmission or the diff over-heating, eh?! Thinking about it, the smell is almost more like gear oil than ATF. For some reason I thought that the trans-axle shared the same fluid, but apparently not!?

As far as the engine, I put the GM "LS3 Batwing" pan on the car, after reading some horror stories, as well as the Z06 oil cooler. So far, no problems there (knock on wood! ). Wish I could say the same for the hot drivetrain.

Cap'n Pete

Anybody else experienced this with a base C6? I'm curious whether it's a "normal" issue (happens to many/most), or if something is actually "wrong" with my car??

Cap'n Pete

So I did some further "investigation". It appears I have a leaky driver's side axle seal (that would explain WHERE the diff fluid is coming from).

It has been suggested that it's likely a problem with the VENT on the diff, not venting enough/properly (causing the diff to get hot, pressurize, and subsequently puke fluid from the axle seal).

Anybody had this happen to them? I'm still concerned whether or not the diff is actually running too hot (and needs a cooler) or if it would be fine by just being VENTED properly?

Any feedback would be appreciated!

RX-Ben

Are you sure the seal is leaky as opposed to fluid coming out the vent? They will look similar from below.
I always have some vent leakage, assumed it was normal due to high Gs though at the same time how do high g's push fluid out the top?

NOSLO6

I run the DRM cooler as a precaution and it was in the $600 range. Give Randy a call and he can help you-- great guy, knows his stuff.

Note also that Z51s do not get a factory diff cooler, only the Z06+.

davidfarmer

Overfilled or axle seal.......

argonaut

As a point of reference, on my C5 I ruined one diff due to high heat. Replaced with new unit from GM. I also overheated my tranny (MN6) so bad that it now whines something fierce (cooked gears 1-3 apparently, 4th is quiet, 5-6 very slight whine). Since then I've installed the DRM coolers. So far the diff seems fine and the tranny still whines but is hanging in there. The Diff still pukes oil though, as RX-Ben states, it could be the high G forces in cornering and stopping.

Its weird - some folks never use coolers and never report issues. Other folks, like me, have issues. I would even say I'm pretty easy on the tranny, I short shift it a lot, I always rev match, etc. I like the idea of wrapping the pipes, I think I'll have to do that.

Cap'n Pete

It's absolutely the axle seal that has leaked (or is leaking still). I cleaned up oil around it a couple days ago, and want to get back under to check again if it's still an "active" leak. Even with normal driving on the street, I can smell burning diff fluid after a few minutes of driving (that ain't right!).

Since I'm not just a "leisurely" driver (street or track! ) I'm afraid of doing any long-term damage to the car, hence, I'm not sure that simply fixing the vent will "solve" anything, so thinking I should either A) invest in coolers, or B) just bite the bullet and upgrade to the Z06 .

Cap'n Pete

Spoke to my local race shop who work almost exclusively on 'Vettes, and was told that the factory vent is prone to failing, and allowing a pressure build-up in the diff. Apparently the fix is to pull the vent, tap a fitting in there and run a short hose with a breather filter on the end ... should have no more issues.

However, for various other reasons (as well as the diff cooling), I ended up pulling the trigger and trading up to a Z06 . I've wanted one forever, so obviously didn't need much of an "excuse"!

Regardless, good info about properly venting the diff. Sounds like there was likely nothing "wrong" with my C6 other than the heat/pressure build-up.

sothpaw2

Do you run Hoosiers? I don't have a problem with diff or tranny but I only run nitto-RII, nothing stickier. I did get trans over temp warning light just once--105 deg ambient day, 40 min long session. I think on a hot day I should quit after 20.

Z11409

Insulate the exhaust pipes with header wrap.A samll wing mounted on the rear cross bar that supprts the tranny diff will direct more air into the body cavity.

Cap'n Pete

Do you have any pictures of that setup? I've heard that idea mentioned before, but never seen exactly what the finished product looks like.

Thanks .

Z11409

No pics-sorry but just use a piece of cardboard to make a template.A 12 volt boat bilge fan works also.It just moves the super heated air traped by the floor panel.

argonaut

When I did the "damage" I was running Hoosier scrubs from the Grand Am series. From what I understand they are not as sticky as something like As or Rs. I know several guys with more horsepower, on Rs and very fast who do not have coolers and have not thus far had issues. So, I can not say with any certainty that my issues were heat related. But I did ruin both a Diff and my current Tranny. Cooler temps are always better and I got the serup used & installed myself - so the investment was small and any additional longevity they yield will be worth it.