[eschaider]

The reduction is gear tooth face is linear with the reduction in torque capacity. Given a 10% reduction in tooth face then you get a 10% reduction in torque transmitting capacity, a 20% reduction will provide a 20% reduction in torque transmitting capacity. There is no second or third order function describing the gear's transmission capacity.

It is both true and troubling that the failure may have occured even if the gears were properly aligned. This is associated with the original designer's margin of safety that he designed into the box. If it is a 600 lbs-ft rated box with a design safety factor of only 2x or so, it is probable the gears would have broke anyhow. Interesting thought to ponder!

The strength of the gears absolutely includes the center to center distance in the calculation. In fact that is one of the parameters I mention in the paragraph where I describe the strength parameters.

By the way Tremec advises me the lateral displacement from edge to edge on the two gears is 0.149". If you look at Greg's (Fordfan) entry in TKO warning post #168 he measures his misalignment at 0.140". Here's the math from my post #169:

"The pictures fooled me. I measured the countershaft gear at 23.5mm wide (0.925")in the photo and the mainshaft gear at 28mm wide(1.10").

If we use your measurements and assume the wider gear was the correct design width then the .975" wide gear has only .835" of face width in contact with its mating gear. The transmission's torque capacity in third gear would then be (0.835/1.01)*600 or 496 lbs-ft.

I used 600 lbs-ft as the transmission torque capacity because that is what Tremec advertises on their website http://www.tremec.com/English/products/TKO.asp"

The bottom line on this is uncomfortable. If you own a TKO 500/600 you have a built in design error that will cost you third gear if you produce somewhere north of 450 lbs-ft of torque, hook up in third and execute a clean, fast gear change from second to third. The shock loads will exceed the transmission's load bearing capacity. This is not complicated.

If you don't own a Tremec and produce these power levels don't get one. If you do own a Tremec and produce these power levels, welcome you have joined those of us who were snookered by Tremec - you're in good company. We have to find a way to correct the problem or replace the transmission with one that is properly designed and performs as advertised.

It would be nice if Tremec would comment on this publicly and say something like we have a fix for you guys that have done so much business with us.

Ed