Diff build

[canyons]

Finally got all the time, money and parts to get the rear diff properly upgraded.

My 2013 BRZ came with a 4.1:1 final ratio, whereas the 2019 BRZ comes with a 4.3:1 final ratio.

I sourced a new 4.44 ring & pinion (shout out to JacksTransmissions.com) coupled with a Quaife ATB Automatic Torque Biasing differential. This equates to about an 8% rise in RPMs for a give highway speed, over stock.

I had the idea to buy a used, empty diff carrier and clean it up, then take all the parts to a performance builder near me who has all the shims and indicators and gak to ass-emble a new rear end.

When the new pumpkin was ready, we swapped it in. Works like a charm!


.

.

.

.

.

.

Extra capacity finned diff cover sourced from Harrop USA.

-----------------

Driving notes: Noticeably different torque management esp. in the wet. Better acceleration and less delay for lockup/transfer under hard cornering. Still managed 28 mpg on a 6th gear hw cruise recently.

[x808drifter]

What was the reason for swapping the factory torsen LSD for another geared aftermarket one?
Far as I can tell they both do the same thing and act the same way.

[86TOYO2k17]

Pretty sure factory LSD is basically an open diff if only one wheel lifts or loses traction.

[soundman98]

Originally Posted by 86TOYO2k17

Pretty sure factory LSD is basically an open diff if only one wheel lifts or loses traction.

with the car, i've left 11's all over town on the oem 'open diff'.

every other vehicle just unloads the inside tire to a smeary smoky 1 in the same spots. so not sure what this is about...

[DarkPira7e]

Originally Posted by soundman98

with the car, i've left 11's all over town on the oem 'open diff'.

every other vehicle just unloads the inside tire to a smeary smoky 1 in the same spots. so not sure what this is about...

It's a different story when there's no resistance on the tires, vs pavement that provides resistance

[soundman98]

Originally Posted by DarkPira7e

It's a different story when there's no resistance on the tires, vs pavement that provides resistance

am i missing something that you're not driving on the surface of the earth? does your car float above the surface or something?

did you get the hovercar conversion?

[DarkPira7e]

Originally Posted by soundman98

am i missing something that you're not driving on the surface of the earth? does your car float above the surface or something?

did you get the hovercar conversion?

Ice, snow. A torsen isn't anything like a clutch type diff in the snow or on ice

[Capt Spaulding]

Originally Posted by DarkPira7e

Ice, snow. A torsen isn't anything like a clutch type diff in the snow or on ice

Or wet grass. No kidding. I've gotten stuck on wet grass.

[x808drifter]

Originally Posted by 86TOYO2k17

Pretty sure factory LSD is basically an open diff if only one wheel lifts or loses traction.

The Quaife he replaced the OEM one with does the same.
OP bought another gear LSD, not a clutch pack LSD.

[NoHaveMSG]

Torsen diffs are torque sensing. Until it feels a difference in torque from each wheel it is an open diff. It is also an open diff if there is zero load on one wheel. I don’t know how sensitive they are but it’s possible that extremely low traction surfaces may not put enough load to immediately engage it. Ive gotten stuck on grass before, you can slowly pull your parking brake and sometimes get it to engage both sides in this situation.


Sent from my iPhone using Tapatalk

[86TOYO2k17]

Originally Posted by soundman98

with the car, i've left 11's all over town on the oem 'open diff'.

every other vehicle just unloads the inside tire to a smeary smoky 1 in the same spots. so not sure what this is about...

https://www.ft86club.com/forums/showthread.php?t=66516

[churchx]

As torsen needs some traction even to wheel with least grip, to be able to multiply torque to it to other, so when one wheel completely looses traction, it's almost acting as if open diff. Be it due wheel hop in air after kerb, ice or wet grass.
Normally during DD it's supposed to be fixed/complemented by electronic nannies that apply brakes individually to wheel, that lost traction. Hence sometimes it's worth to NOT switch all nannies off on regular basis at all driving patterns, to have e-diff to help with mechanical specifics/limitations of torsen type diffs.
Do clutch type diffs provide more grip in wider range of scenarios? Yes. But they are also noisier and require more maintenance, so no wonder that manufacturers usually prefer torsen to clutch type diffs, as most cars (including ours) are mostly driven only on public roads, and with electronic nannies left on.

[Turdinator]

OP hasn't been online since he posted. I would be curious to know if he has noticed any difference with the LSD. I know that there can be differences in the gear type of LSDs, such as the torque multiplier and even some with a tiny plated setup in the middle for exactly those situations where one wheel is in the air.

To my mind the cost benefit ratio isn't there to go from the OEM gear type LSD to and aftermarket one but I could be wrong

[NoHaveMSG]

Originally Posted by Turdinator

OP hasn't been online since he posted. I would be curious to know if he has noticed any difference with the LSD. I know that there can be differences in the gear type of LSDs, such as the torque multiplier and even some with a tiny plated setup in the middle for exactly those situations where one wheel is in the air.

To my mind the cost benefit ratio isn't there to go from the OEM gear type LSD to and aftermarket one but I could be wrong

That’s my thought too. I don’t think any aftermarket LSD’s prevent spinning up a tire if it’s in the air which is the only thing I’d like improved. At my driving level anyway.


Sent from my iPhone using Tapatalk