Swiftvision

So is the recomendation for tranny oil....MTL or MT-90? How many quarts do you need?

Road Rage

Nope. It is an 80w90 GL-5. I would not recommend it for any year. Makes a good diff oil though.

Road Rage

Actually it might lead to less - the synchro is like a small clutch - clutches only wear when they are spinning relative to the pressure plate - when engaged, no wear occurs.

modifry

[QUOTE][SIZE=1][B]Originally posted by Asura

modifry

I agree, no slippage = no wear. Additional friction can help synchro action, but the same lube is used in the whole transmission so there must be a point where additional friction turns into a bad thing. Also, I wonder if increased friction couldn't lead to more wear on the synchro teeth.

Here's my recollection of how a synchro works, based on the internals of my '76 914 and a 20 year-ago memory: (experts feel free to correct me)

[Disclaimer - I am NOT a transmission expert.]

There are two "business" ends to a synchro ring. One is the internal conical-shaped surface, usually with concentric grooves cut in the surface, which during shifting is pressed against a mating conical surface on the gear to be engaged.

The other "business end" (outer surface) has little pointy teeth which mate with other little pointy teeth on another synchro, which has it's conical inner surface ready to be pressed into contact with another gear (the other half of the "gear to be engaged").

The idea is that when you move the shifter to change gears the synchros are meshed together by the matching teeth at the same time the conical surfaces of each synchro are pressed towards their respective gears. The conical surfaces have just enough friction to slow down (or speed up) the rotation of the synchros, locking them to the same rotational speed. Further pressure on the shifter causes the synchros to slow down/speed up their partner gears so there is minimal speed mis-match when the gears are meshed together.

If that makes any sense, you'll see there are two wear surfaces on each synchro - the conical "friction" surface that is designed to slip, and the toothed surface that is designed to mesh without slipping.

Wear on the conical surface (the little concentric grooves get worn down and don't grip) will slow down the "braking" action of the synchro and can lead to slower or missed shifts because the gear speeds don't match.

Wear on the toothed surface (broken or worn teeth) can make for harder shifts, and in the extreme can render the synchros useless because they can't lock to each other.

Too little friction keeps the synchros from working properly - they can't slow down/speed up themsleves or their partner gears as quickly. Too much friction may make the synchros grip more, making it harder for the synchros to mesh to each other, causing wear on the teeth.

The point is there is a fine line between a lube with too much friction and one with too little. I wonder if additional friction may make the synchros grip better at the expense of tooth wear.

.

Road Rage

[QUOTE]Originally posted by modifry
The LE guys at Wake the Dragon were implying the 703 IS a good choice for '00 to '03 transmissions, and even threw your name around in the same paragraph (blasphemy!).