THE Transmission Thread 2.0, Now with Pictures

[Bob_n_Cincy]

So you don't subscribe to the "case flex theory" that the gears are fine and excessive case flex breaks all these gears?

Thanks Ironhydroxide for the response

Hi longislandwrx..
Let me put on my mechanical engineering hat on.
When you have a engine spinning at 4000-5000 RPM there is a lot of stored inertial energy in the engine, flywheel, and clutch cover.
If the clutch had teeth to grab the flywheel and the car was strapped very tightly to the trailer. When the clutch was engaged, all stored energy would be released instantaneously. TORQUE SPIKE. Weakest link would break every time.

There are 2 protection to prevent this from happening. Tire slip and clutch slip.

My 3 reason transmissions fail.
1. AWD with sticky tires override the tire slip protection.
2. High torque aftermarket clutches override the clutch protection.
3. Aggressive driving fatigues the gear teeth. Three strikes your out.

I believe the gear teeth in the transmission are failing when the torque spike flexes them. With repeated flexing the teeth start to crack and eventually break off. Then all S*** hits the fan.

Bob

[Scargo]

Am I correct to say that an optimal transmission for the 818 needs to be a Phase 2 type transmission (No Plate on top of Differential) and NOT one from a normally aspirated vehicle having the "narrower gearsets" (found in the 02-03 WRX transmissions and all PRE 02 WRX and STI as well, except for the special editions, S201, 22B, RA, R, RA-R)?

I don't think the transmissions listed in the spreadsheet reflect that limited selection. Could those be notated as such or have they been eliminated from the list? In what years/models does the Phase 2 transmission appear?

The gear failures mentioned here, in this thread,... were in the "better" transmissions? What tranny was the FFR car running that lost third gear? In sponaugle's?

[TahoeTim]

Am I correct to say that an optimal transmission for the 818 needs to be a Phase 2 type transmission (No Plate on top of Differential) and NOT one from a normally aspirated vehicle having the "narrower gearsets" (found in the 02-03 WRX transmissions and all PRE 02 WRX and STI as well, except for the special editions, S201, 22B, RA, R, RA-R)?

I don't think the transmissions listed in the spreadsheet reflect that limited selection. Could those be notated as such or have they been eliminated from the list? In what years/models does the Phase 2 transmission appear?

The gear failures mentioned here, in this thread,... were in the "better" transmissions? What tranny was the FFR car running that lost third gear? In sponaugle's?

+1
It would be handy to highlight the preferred rows in green and/or the weak ones in yellow. I seem to be finding a lot of TY755VB1AA for sale but that particular transmission has very little info about it on the net. good? bad?

[Scargo]

I have a transaxle rebuilding question. I an putting close-ratio fifth and sixth gears in an '04 tranny. I have it apart to the point of the driven gear cluster and the main shaft with gears.
I need to know how I can safely hold the driven shaft gear cluster so I can remove the nut that holds it all together. It requires 400 foot pounds to loosen/tighten the nut. It's not a matter of having or obtaining sockets or wrenches to apply leverage on the nut, but how best to hang onto the gear cluster while I break the nut loose. I only have a 1/2" impact.

EDIT: Nevermind. I sprung for an El Cheapo 3/4" drive impact. I made a punch tool to undo some of the four indentions of the nut's locking ring. Having an assistant hang onto the main shaft with a chain wrench around the the middle of the fifth/sixth gear set, I was able to remove the nut fairly easily. There's still a lot of metal particles scraped off the nut that you need to be aware of as you clean it and proceed with the gear swap.