944 transaxles 85.5 and up

It is repeatedly said that turbo transaxles are the strongest. But what exactly makes it stronger? I’ve read that the 1st and 2nd gears in some models are “blasted” which I assume means shot peened. Are there other differences?

LSD is self explanatory, do the diffs interchange between all turbo and n/a models and do the ring and pinion sets interchange between LSD and open diffs in all models?

Turbo S trans have a hardened first and second gear but besides that, the gearing is the only difference I know between the rest of them. Curious to see what comes back here

There was some discussion about building a Turbo box Vs buying a Turbo S box....similar to your questions.
https://944hybrids.forumotion.com/t2458-looking-for-a-good-aor-w-lsd

Without having compared a NA main shaft against a Turbo myself I would make a guess....strength for shaft and gear teeth typically come from materials with higher UTS and a tooth that has a larger root width...

Turbo Vs Turbo S boxes

948 wrote:....The only real difference between the AOR and any other Turbo box is the shot peening of 1st and 2nd gear teeth on the input shaft and beefed up inner clutch plates, which can be bought brand new for about $330 and $100 respectively....

948 wrote:Any of the 016 series Turbo boxes, with a 3.375 final drive and LSD, would make for a good starting point if they can be found for cheap. They come in many different flavors, so look here to figure out which boxes have what.... http://www.clarks-garage.com/shop-manual/trans-04.htm
IIRC some of the NA 016/083 boxes have the same input shaft as the Turbo boxes (you should check part numbers to be sure). This could be a cheap way to build up a box too, from parts.
Also, you can find vendors that can bead/shot blast the gear teeth for you; which would be effective even on good used parts.
However, if you can get a good low mileage AOR for $1000 - $1500 all this effort might not be worth it?

Over the years I have bought, on Ebay, 2 turbo boxes for $340 and $400. One without an LSD and one with.....so they are out there.

Yes the R&P can be swapped on the NA and Turbo 016 boxes.

Thanks, That's the info I was looking for.

Does anyone know if the Turbo S (AOR) box has a different percentage of lock-up of the LSD then a regular Turbo box with LSD?

phlip wrote:Does anyone know if the Turbo S (AOR) box has a different percentage of lock-up of the LSD then a regular Turbo box with LSD?

I didn’t know the answer when you first posted but the short answer is no. The best I can tell, all 944/951 LSDs are 40%. The AOR uses a .5mm thicker friction disc in it but also uses a .5mm thinner thrust ring (what I would call a clutch backing plate), So the surface area, spring tension and stacked dimension is all the same. The guys over on RL claim to get 60% by using 2.1mm clutch plates instead of the 1.9 or 2.0 to increase the tension but my math suggests a little better than 50%. (There is also wear and machining tolerances involved which is why there is three differnent plates.)

When I get new parts and a mic in my had, I may see if I can squeeze the AOR plates in with the standard thrust ring by machining the thrust rings by less than .5mm. The limiting factor of the dimension would be the side gear thrust washer not gaining clearance and the Bellville washer compressing which would basically create a spool. I think 60% or better is very doable.