LSD gearbox Question..

[Big Dave]

Hi Folks
Can anybody tell me why Porsche put the oil cooler pipe onto the transmision.???

Was it becaue the LSD in the box got too hot + expanded etc.???

I cant understand why it was done ... As on pre 88 boxes with LSD,s, there wasnt any cooler.???
Ive heard different "stories/ theory,s" as to why they did it....+ just want to get to the bottom of it all...

The reason also for the ? is i have a 944S2 which i use on track days, BUT i use it hard...
Ive come across a Turbo S trans, with LSD + cooler. [ At the right price ]...I now want to fit the LSD into my S2 trans, BUT b4 doing so i just want to find out wether to fit the cooling pipe also....So i dont destroy my "new" trans....
Hope somebody can help....???????

 

[944Turbo]

I imagine, and it is purely guesswork, it was just a relibility measure. 88 On cars were 250BHP with an increase in torque and a bigger step between off boost and on. I expect that during testing this was found to place extra load on the box. The cooler is there to keep the temps lower and the oil in the optimum temp range. On a turbo you also have a very hot (hotter than the na) exhaust pipe running past the other box, though there is a heat shield as well.

The LSD is a friction device so I believe it also generates heat. Can't see any harm in fitting it, but if it is going to be an expensive option changing to a synthetic oil and changing it regularly might be fine. Probably worth discussing it with whoever is doing the work.

Tony

 

[944turboS]

What Tony says makes sense & as you already have all the parts I would fit the cooler.
If you don't I remember someone on here was looking for a set of cooler pipes not too long ago.

 

[Fen]

I concur with the above - preventative/reliability mod. I would definitely fit one, though it doesn't have to be the factory style finned pipe if that is prohibitively expensive.

 

[John Sims]

The cooled gearbox was one of the many enhancements that the 250 Turbo took on board relative to the Turbo Cup race cars.

Porsche obviously thought it was a worth while addition and I see little point in not using it if you have one.

Gearbox oil coolers are frequently used on racing cars so it is a pretty cool addition to have for that reason alone [].

Fen makes a viable point, and armed with the gearbox oil pump, you could perhaps use a conventional oil cooler matrix. My only hesitance is that gear oil is much thicker than engine oil and will take longer to warm up and thin down. The initial back pressure of a conventional oil rad may cause problems with pump seals. The Porsche cooler is just a coil of pipe with external fins, so would have relatively little back pressure. I'm not aware of anyone fitting a standard oil rad so could be being overly cautious.

 

[GDA]

perhaps they use a simple coil for:
weight
cost
and thermal requirements - they might not want to cool the fluids that much, that a mocal type finned radiator would do

 

[sawood12]

Dave,
Did you sort out the cooler for your gearbox yet? I've offered a 250 gearbox for a very good price because it's missing the oil cooler pipe and the LSD!!