Transaxle Basic Questions

What is a super differential?

Why weld the 3 & 4 hubs?

Some tranny's come with aluminum side covers, what's the advantage?

Thanks!

A super diff adds 2 more spider gears to the differential, making the structure able to handle much more HP/torque than the 2 spider gear stock diffs. A welded 3rd and 4 th gears is to eliminate breakage at the keyways in the shafts, again a HP issue. And the heavy duty transmission side plates is also to keep the diff from deforming the side plates under high HP use, like drag racing etc. Keep in mind these transmissions were originally designed for a 25hp engine, later 40 hp and in the end state more like 60 hp....most of us run far more HP than that....hence the need for a lot of reinforcement and improvements

What Jim said plus:the differential casting itself was different and harder to break. In stock tramsaxles the synchro hubs are pressed on 3rd and 4th gears. With modified higher output motors it is possible to spin the hubs, so for most high perf transaxle builds the hubs are welded to the gears.

And if you have a late model type 1 single side cover transmission, most of those are redundant except the superdiff. They already incorporate similar reinforcements. They also have 10 tooth spiders, which are stronger than the older 11 tooth, but you have to be careful about the superdiff you get. Some housings work with only one or the other and are not compatible (the most common 11 tooth superdiffs are like this). Some housings allow either one. Check with a trans builder to make sure.

The next step up in strength would be to go for a bus trans conversion.

Jim, Allen, and Justin, good info for all. I will add that if anyone gets a Quaife diff(Torsen planetary gear type 1 to 99% LSD), the tallest ratio it will work with is 3.88:1. It will not work with the taller 3.44:1 final drive.

Why won't the Quaife work with the 3.44?

If its like a lot of HiPO differentials, the higher the ratio, ie a 4.10 gear, the bigger the ring gear. Say you took a 3.08 gear, the pinion is larger, and the ring gear is smaller. The LSD or Torsen, etc might be larger in diameter than the ring gear, hence not working. The pinion would hit the carrier before contacting the ring gear. I might be way off, but that's what it is in Hewlands, Websters, Emco's etc.

It just won't fit,3.88 is fine though.