Mythbuster: continuing project thread of my 1303 '75

[Wally]

After a lot of work pulling the engine forward far enough to get the thicker diff back in, I got the engine back in its place again. Filled tranny with new synthetic 75W90 Valvoline and reused the O-ring n the side cover (even though I still have a new one from the gasket set). If you turn one wheel, the other one turns in the same direction as it should with a LSD It turns nice and smooth by hand.
Got the engine running again and went for a test drive.

No extra noises, all seems just fine and dandy. Did a deliberate lighting of the tires in second gear (cold and damp road) and that felt different somehow, more aggressive in a way, but not out of control.
Car is still stupid fast and seemingly effortless at doing so.
At home, tranny is still bone dry as before.
All in all, this was relatively easy sailing, though I didn't know that up front..
Gotta love orginal parts

[scourtaud]

Hi,

Nice job but before you go any further, are you sure about the oil you put into the tranny?

Usually in a 911 with LSD (old ones), oil is something like 75w140 (not sure about the exact values but sure about the range). I can check if you need the exact values.

Seb

[Wally]

Originally Posted by scourtaud

Nice job but before you go any further, are you sure about the oil you put into the tranny?

Usually in a 911 with LSD (old ones), oil is something like 75w140 (not sure about the exact values but sure about the range). I can check if you need the exact values.

Seb

Hi Sebastian,

Yes, very sure: besides the fact that this is not an old tranny 911 type with porsches' own syncro system (which indeed needs a different oil), its actually counterproductive to use thicker oil or specially formulated LSD oil:
The latter usual has friction modifiers, which reduce the effectiveness of the friction plates. In that sentence alone, you can see/read how weird this is...
Those 'special' lsd gear oils were made because they reduce noise of the friction plates (in slow corners or in the parking lot), which is very liked by the typical Porsche owner who wants a comfortable a relatively quiet car.
I just want performance

[Bruce.]

Good luck with the diff!

I wouldn't go too crazy with the burnouts though. Replacing the clutch pack with "cup spec" (not the crappy road clutches) costs over £600 from Porsche.

[Wally]

Originally Posted by Bruce.

I wouldn't go too crazy with the burnouts though. Replacing the clutch pack with "cup spec" (not the crappy road clutches) costs over £600 from Porsche.

If you hadn't noticed already Bruce, I now have a Guard Transmission clutch pack in there, that's supposed to be better then even the 'cup-spec' clutch disks
Both in performance as in duration

[scourtaud]

Originally Posted by Wally

Hi Sebastian,

Yes, very sure: besides the fact that this is not an old tranny 911 type with porsches' own syncro system (which indeed needs a different oil), its actually counterproductive to use thicker oil or specially formulated LSD oil:
The latter usual has friction modifiers, which reduce the effectiveness of the friction plates. In that sentence alone, you can see/read how weird this is...
Those 'special' lsd gear oils were made because they reduce noise of the friction plates (in slow corners or in the parking lot), which is very liked by the typical Porsche owner who wants a comfortable a relatively quiet car.
I just want performance

Thanks for the intel, I'll pass it along to one of my friends who doesn't really care about noise (1983 RUF SC) and I'm glad I was wrong but I'd rather be wrong than hear about a broken lsd...

Have fun on the track...

Seb

[Wally]

It was great weather last sunday, I'll update later some more. In short I gained a lot on my time and even got a prize!