Borg Warner T5 Gearbox.

[PeterCrespin]

What melts in a gear set? I've seen burned out gearboxes and the gear sets are the only bits left in a puddle of melted alloy casing. I take it you mean overheated bearings or ancillary parts, not the actual gear sets melting?

Pete

[5speeds]

What melts in a gear set? I've seen burned out gearboxes and the gear sets are the only bits left in a puddle of melted alloy casing. I take it you mean overheated bearings or ancillary parts, not the actual gear sets melting?
Pete

No actually in the T5 it is quite common if the wrong oil is used, or the box is overheated or a low oil level condition is present the front end of the gear train will get so hot that the gear teeth roll over and melt.

Here is something most people who copy gearboxes and lack gearbox design experience don't understand. Think of one gear rotating in a box. Draw a circle, then a box around the circle. If you try and make the box more compact to the circle think what happens when you use a high viscosity oil compared to one of lesser weight. The force to overcome the shear of the higher viscosity oil within closer quarters generates more heat. So trying to make a closer tighter case out of a T5 such as billet, with no fins or way to dissipate heat is poor design. Yes it may work, but again is something not done. People can make claims all they want but poor design is poor design. Your gear backlash clearances and gear to shaft clearances as wells as yoke bushing clearances are designed to run on ATF viscosities in T5 platforms. The people who think they are going to use heavy duty alloys superior to those used in OEM gears need a reality check. YES en36 / 9310 alloys have greater impact resistance, but they fatigue faster. So what you see in those gearsets is pitting on the surfaces and they think that a higher viscosity will help the situation.... which it won't, its just the nature of the alloy. Chryler's A833 Hemi 4 speed ran 9310 nickel gears on ATF in the 1960's. The gears were bushed for tighter shaft clearances ( more precision ) reduced drag using ATF, thus more horsepower to the rear wheels..

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