metaruss

The new trans seems to be working well.  It’s an A555/A520 hybrid (A555 with the mainshaft and ring gear from an A520) with a 3.50:1 ratio.  This is the perfect gearing for this car.  This setup with the OBX torque biasing differential is a great combo.  The only weak point is the mainshaft bearing surface.  The bearing near the pinion gear rides right on the shaft and eventually the area starts to break up from surface fatigue.  This shaft has a bit of life left in it, but when it goes I won’t have anything to put in its place.  The later transaxles (A523/A543/A568) have a real inner bearing race here.  The bearing itself is the same, so it may just be a matter of machining the shaft down to accept the race.  My main concern is the weakening of the shaft from removing the hardened surface in that area.  It may create a stress point at the base of the pinion gear.  If it were to break, the transmission would be destroyed.  That is not something I am willing to risk with this tranny.

The OBX is an interesting piece.  The car really wants to accelerate in a straight line, as the torque tends to get biased to the inside wheel.  The effect goes away when coasting.  I didn’t beat on it too much since it is brand new and I also put in a new clutch that needs a little break-in time.  It is made in China and is basically a cheap knock-off of the Quaife unit that was designed for the Dodge Neon 420A transmission.  It definitely needs to be gone-through when received.  There are issues with the spring washer orientantion, the case bolt torques, and the axle fitment.  The machining on the element gears, the axle holes in the case, and the splines are also pretty rough and need to be checked/honed/deburred.  Time will tell on how they hold up down the road, but at one third the price of a Quaife they are an attractive option even with their flaws.  I will be changing the trans fluid once it gets a couple of hundred miles on it.