TonyG

Anybody ever setup or have experience with transaxle overflow tanks on these cars (or any other car).

I did have a considerable amount of oil go out the overflow last year at a track event. The oil level was correct. I had to take some oil out to keep this from happening again. Sucked.... oil everywhere under the car.

TonyG

User 52121

There is an overflow for the trans fluid?

Huh. Learn something new every day. Where is it?

SoloRacer

My F355 Challenge car has a transmission fluid overflow tank. What did you need to know?

TonyG

On the other thread where the "interesting race car for sale" is talked about.

Look at the pictures of the interior in the rear hatch area.


TonyG

TonyG

How was it plumbed? Was it just a line from the transmission vent to a tank?

TonyG

86 951 Driver

Are you heating up the oil to the point where there is pressure in the case or what?

michaelmount123

Catch tank is required by some sanctioning bodies. The vent is replaced by a fitting to accommodate a line that runs to a standard catch can.

If you're losing gear lube, is it from the vent? If so, something's up, like you're running the level too high. What gearbox?

TonyG

86 951 Driver & michaelmount123,

Last year I had a case where the fluid came out of the overflow.

So I undid the fill bolt to check the level and there was a lot of pressure that had developed and oil was shooting out.

The trans was a 951 box with a Guard LSD using an external cooler with an external pump.

I would fill the trans and turn on the pump to fill the cooler, then add fluid until it reached the bottom of the fill port (as I had done many times before).

For some reason, it was too much. Oil coated everything in the back of the car as a result.

I don't want this to happen again, and is why I asked.


TonyG

KevinGross

I'm not sure how you pressurize the gearbox. Perhaps your external trans oil pump is cavitating, you might want to check that flow to it is of sufficient diameter and not blocked. Was the fluid foamy, did it show signs of churning? Is the radiator designed to cope with transmission fluid's viscosity? I have not seen this problem before in a 944-series gearbox.

Kevin
Catellus Engineering

TonyG

The air and the oil in the transaxle will expand when heated which is how it becomes pressurized...and is why there is an overflow in the top of the transaxle.

By taking out some of the oil, no other changes, the problem stopped.

The fluid was not foamy.

The trans pump is a gear rotor pump designed for very hot oil and has worked fine for several years of track use.

Anyway, like I said... I removed some oil and the problem went away.

Due to the massive oil cooler, the quantity of oil I have to install going to have to be a calculated quantity rather than a known quantity or simply filling to the top of the fill plug.

This is why I want to run the catch can in case I get too much in there.

I'll run a check valve into the catch can which will allow me to know how much is "too much". I can adjust from there until I get no oil in the catch can.

TonyG