V2Rocket

Considering getting my 951 trans refreshed, wondering if it's possible to delete the cooling loop off of a trans that had it fitted originally?

Trans has ~150k miles, from a 1986 951. If you scrub hard enough through the dirt and grease, you'll find xsboost90's fingerprints on it...

KevinGross

Spencer, yes, you can delete the loop. I would recommend replacing the side cover (with the oil pump built into it) and the end cover. And you can remove the large aluminum drive sprocket from the differential. I think you know that the differential carrier bearings will have to be reshimmed as part of this process.

In fact, I'm willing to supply you with the replacement covers plus some cash in exchange for the take-off parts. Let me know if you're interested. Of course if you'd like me to do whatever transmission refresh you have in mind, happy to assist there. Please, please, I beg you do NOT take a short-cut by hacking plugs into the existing covers! They are getting scarce, and yours can find a good home in the future for some 944 owner.

Regards,

Dash01

Why would you want to delete the cooling loop, thereby raising operating temperature of the transaxle?

Seems to me, the cooling loop feeds cooled oil to where it's needed most, and that if modified, it should be for even better cooling, or at least cleaned so the fins and case properly dissipate heat.

Further, Redline, Royal Purple, or similar synthetic gear oil are said to reduce friction, especially at startup, further reducing heat at its source...

V2Rocket

Ask Porsche the same thing...the cooler loop was either fully deleted or just optional (after 86) for 87/88 and apparently didn't come back until the 951S , IIRC.

Dash01

Could be, Porsche deleted the cooler loop to save money, as with forged pistons, etc., in post-'86 cars. And/or they considered the cooling loop unnecessary engineering overkill. After all, most cars get along just fine without such devices, in normal operating conditions.

Still, since my '86 already has the factory cooling loop, and the loop is part of the lubricant/coolant path that's worked fine for 30 years and it ain't broke, I'm not fixing it.

Besides, the climate here in the US is much hotter in summer than in Stuttgart, so what may not be needed in Stuttgart may well be useful here.

blade7

My 91 Turbo has the gearbox oil cooler, AFAIK all 250 bhp cars have it. If Porsche thought it wasn't necessary I expect they would have saved some money.

Droops83

If your transaxle has a LSD, the cooling loop is very important, as the normal slipping of the LSD clutches heats up the fluid a lot.

If this is a street car with open diff, then the cooling loop is not critical.

KevinGross

For a street car or autocross, you'll never heat the oil to the point of needing the cooling. For a track car, it will depend on the actual temps you see in the oil.