ALFAGTV6.COM

[kevin]

Rossogtv thanks for input. I was at the track last wednesday watching a 3.7 gtv practising. The car runs cv upfront with uj centre and rubber bm coupling rear, straight cut box - no cooler. Anyway after eight laps the oil started to come out of the breather. This also happened to me before but only on that very long high speed circuit. I have now put the breather into the car via long pipe to stop it from spewing onto the disc.
Question is why does this happen ?, is it it because it is cooking. Ruled out overfilling because both cars were accurately measured. Needles to say this car stripped box following outing just like mine. High g's pulled...etc

[Giuliettaevo2]

I had the oil coming out of the breather pipe once while drifting with a 75 TwinSpark. after quite a long time i noticed smoke coming from the rear wheels and found a small amount of oil under the car. This was after a fair amount of abuse..

Isn't it possible the oil is foaming? that way it would kind of blow up inside the gearboxhousing and it could come out of the breather that way.

[kevin]

Point taken. What causes foaming?. heat plus continous swishing around in box, heat, just swishing around, bad oil. Could a cooler help prevent all the above except bad oil.

[Mats]

well, if the oil is boiling you will have problems in any case.

Foamin is usually not a problem in race boxes, generally it is around freezing (+/-10*C) you have the biggest problems with foaming. Even the most die-hard gearbox oil will have anti-foaming agents.

[Zamani]

Mats,

Why are you installing the cooler? Is it because you believe in its benefits or just because you have the parts? What kind of pump do you have for it?

I've had 2 gearbox failures (the center piece where the 2 casing sandwiches) so I wouldn't mind adding a cooler if it sort of helps. Although I'm inclined to believe that the failures I faces have nothing to do with heat...

[kevin]

Mats, if your oil starts to foam from all the swish surely the temperature will rise dramatically creating knockon effect, bearing failure- bigger tolerances, stripped pinion. Our only supply of oil for LS boxes here in our banana republic is Castrol LSX 90. and this is same oil that foamed right out of box onto caliper. Just trying to find any logic here (Md comments ?)

[Mats]

Zamani: Well, I will probably need to torque limit my new engine to keep the gearbox from shitting itself. In any way the gearbox will be the weak link so why not give it the means to survive?

My pump is an OEM Nissan, from a final drive cooler in a 200SX

kevin: Believe me, the oil will be plenty splashed around even in normal driving conditions. One of the given steps when developing a final drive or gearbox is to make a clear housing to do spin-tests, that way you can actually see what the oil does. I.e. the whole casing is just oil splash but you can se where the majority of the oil travels along the casing. The breather position is incredibly time consuming to find, usually it's a job that spans the whole product development phase. So if you perhaps changed something inside the box like grind down a "useless boss" or similar you can make the box into a drooler.

If the oil is foaming you will have a dramatic loss of lubrication and that will heat stuff up in a hurry.

[MD]

Kevin,

I think we all need to roll our sleeves up and do some information research on a suitable transmission fluid for our transaxles WITH AN LSD.

For argument sake, at the moment I cannot trust what Castrol has to say. For example they do not understand the 116 transaxle. Why? Because they contradict themselves in their own recommended product use for various fluids. eg. In the "lube guide" they suggest you can use CASTROL SYNTRAX 75W/90 for the 75 twin spark transaxle which we all know has an LSD fitted. When you examine the product specific information, it says it is not suitable for LSD's!!

Check it out for your self: http://www.datateck.com.au/lube/castr_au/default.aspThen, look under "Features and Benefits" headings at : http://www.castrol.com/liveassets/bp_in ... 278983.pdf

It clearly says Not recommended for limited slip differentials !

Kevin, how can you be sure that LSX 90 is actually a correct fluid?

[kevin]

MD, the castrol container says on it for limited slip differentials so this LSX 90 is hopefully correct.
My tow car to take my GTV to Phakisa raceway(400km away) this weekend was under repair(no steering rack rubbers) so I joined the BMW club and went to their track day at Kyalami. This is not full racing but just made up of a few classes with five fifteen minute sessions.
After an excelent day overtaking about eight M3 's on the main straight in front of a BM crowd my gearbox or spiders gears 'BROKE'.
After all this I forgot to put the heat sticker on as I thought sessions of five laps would be to short to get a racing temp so I have no record(stupid). I can say I did not smell hot oil out breather but this was probably to late if any damage was caused from overheating from last race anyway.
Im not sure what broke but I could not push the car backwards to load it. (I did drive to the track as this was not to far). After removing sideshaft bolts I towed it home.
The break occured when changing from second to third about 300m from start line. I was on my fasted lap and could have got first in class but ended up third. This was probably the most satisfactory gearbox break an Alfa owner could have. Just remember these BMW's all run on semi's and are track prepared.
Not to deviate to much , Domingoes in his monster tt GTV got third fastest behind an Ultima and beat a skyline gtr which had an ex works rally driver behind the wheel.
Back to gearbox. I will only know this week what really broke .

[MD]

Kevin. Apples aren't always apples.
There are various types of LSD's and they don't work in the same way. Some lubricants are suitable for gear type LSDs but not for Clucth type (fitted to transaxle).

The lubricant must be suitable for a clutch type LSD if it is going to be good for our boxes.

This is the start of the problem...

Saying it is suitable for LSDs means stuff all..(sorry mate)

[MD]

A job for our Italian members

If you live in Italy, could you please contact AGIP and find out which AGIP synthetic transmission fluid is actually suitable for the 75 series twin spark transaxle gearbox and post the information here.

Thanks

[Giuliettaevo2]

Ferrari and Porsche also use a transaxle with a LSD. What oil goes in there?

newer Corvette is the same story...

[Micke]

There are gazillions of LSD oils. Me don't see the problem

[MD]

Me don't see the problem

...hey dont you guys have 6 months of no daylight in the arctic circle ?

Yes I totally agree Micke but at the moment I am having trouble identifying a good brew for racing applications that is suitable specifically to a transaxle with clutch type limited slip differential. I prefer a synthetic oil.

By all means if you are confident of some oil types out there please name some.

[Micke]

Mobil, Castrol, Motul, RedLine

A Torsen type LSD does not need friction modifiers.