[VICSVX]

I'm looking to to a 4.11 swap due the availability of them at my local u pull.... Out of a 97 impreza... And I've read conflicting info about leaving the power mode on. Is the true or.....?

I've also considerrd a 4.44 but haven't sourced one yet. I have a jdm 5sp out of 95 sti with matching the diff and some pedals if anyone is interested in a trade?

And is the 4.11 really that much less reliable then the 4.44?

Originally Posted by oab_au

The final drive gearing that you use, depends on what type of driving you do. The car was designed with a 3.7:1 diff to be a high speed touring car, that can do interstate trips with good comfort and safely.

The trouble starts when it was fitted with a 3.54:1 diff and used as a city commuter. The higher gearing placed more load on the box that was now rotating slower. Producing more heat from the torque converter, having to work harder to lower the gearing. While the lubricating ATF was circulated slower through the cooler and the gear shafts. The result is overheating of the epicyclic gear sets.

Lowering the diff ratio to 4.11:1 reduces the load on the gears and lets them rotate faster. The torque converter has less work to do so it produces less heat, and as the pump is rotating faster it pumps more cool oil to the gear sets. The 4.44:1 ratio just does this more so. The down side is that the engine now spins faster for the same road speed.

Using the Legacy/Impreza/Outback gearbox can be an alternative as the load reduction can make up for the 1 less plate in the high/Transfer clutches. Where these conversions are put at risk is when the SVX TCU runs them. The TCU will still carry out a soft change, where as the cars that these boxes came from don’t, so they suffer the long sliding shifts. Installing a Quick Change will remove this, returning the box to the same changing conditions it had in the donor car.

To help the box to last longer, the “Power Mod” should be done. It is the easiest way of ensuring that the car won’t be lugged around in too high a gear, as it will change down earlier to reduce the load. If it has a QC fitted, it will prevent the sliding changes that cause much of the band and clutch problems.

Harvey.