Gen 2 Rear Diff Durability
 

Not having any issues except for really enjoying wagging the tail in this thing.

It has me wondering if anyone has experienced and rear diff durability issues?

If you did have a problem or failure, were there any initial symptoms or indications that it was starting to go, or did it just outright fail?

Any thoughts of feedback appreciated!

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Isn’t it the same part as the first gens? And weren’t the first gen diffs known to be able to handle a lot more power / torque than the stock specs ?

That I don't know, we never owned a Gen 1 car.

Being able to handle a lot of power is good, but cornering, or sliding through corners is what I would think would torch a diff.

I see some of the track guys have upgraded the diff. For improved durability, or for improved locking?

Hopefully I'm concerned over nothing :)

Yes.

It's to change to a true LSD with a clutch type lock up.

Furthermore it is the same diff that is used in some Lexus vehicles, FWIW...

When I changed the final drive gearing in mine, I spoke at length with a shop that specialized in setting up diffs and they commented how they don't see many of these because "they rarely fail".

What is the benefit of that?

That's good to hear.

The second gen diffs seem to overheat more quickly than first gen diffs, no surprise with the extra power.




More tunable than the stock Torsen, you don't have to worry about tuning suspension setup around inside rear wheel lift.

I'm interested in putting taller gearing in my diff (I assume you went the other way) so any info you can give me to track down parts would be useful.

Gen1 diff rarely fail, even among track folks. It is a torsen unit, which is robust and mostly worry free. People who upgrade the diff are mostly for changing into clutch type LSD for tunability and better locking behaviors (this type of differentials are actually need more attention and are less robust than the torsen) . IIRC the torsen on gen1 (and probably gen2) has a fixed 1:4 bias ratio and it cannot be changed. If one rear wheel lost contact with the ground (which is common with larger swaybar or higher spring rate coilovers), the torsen LSD effectively becomes an open diff.

Clutch kicks/dumps per mileage ratio durability. Who’s tracking?

Among many other things, the ability to effectively get on throttle earlier on corner exit.

Diffs in general tend to be pretty robust, even with high HP as long as you aren't doing clutch dumps or what can happen on track sometimes where on corner exit you're on throttle and drop a rear wheel off the tarmac. It's the shock loads that tend to really hurt stuff.

The differential on my 2014 BRZ wore out after about 130,000 mi. It wasn't exactly kaput, but I could feel a difference with the car up in the air between the original diff and one in very good condition. It also had about 130 track days on it with fluid changes maybe every 20,000 miles.

For Gen1, Gen2 not personally confirmed.

https://www.ft86club.com/forums/show...6&postcount=16

I swapped out my 2022 brz diff with a 2017 4.3….it’s a pretty noticeable improvement in accelation. I can stay in 6th gear on the highway to easily pass. 5th gear feels very peppy.

Hows your highway mileage? Thats the only thing keeping this off of my upgrade list.

Sucks that in 2023 the remaining manuals don't have 7 gears to make everyone happy. "We have the technology."

They don't need 7 gears.

The only reason Porsches and Corvettes have them is they actually have the power to still pull the car at highway speeds and to try to avoid the gas guzzler tax.

How many miles you drive a year?

People on here are trying to decide between acceleration or a mellow cruising experience. GT4 owners are complaining that their high speed gearing doesn't let them row the gears enough. Either you've been brainwashed to think 6 speeds is the be all end all or you are mistaken about the cost and difficulty of adding a 7th. Our car and every other 6MT would be better with a 7MT. Or could you not afford to own a manual Twin that cost the same as an auto Twin?

What in God name's are you talking about? You don't even have a gen 2 yet and you're calling me brainwashed and questioning my finances?

You sound like a young, kid who just reads stuff and hasn't been actually modifying multiple platforms for 25 years or tracking on 2 and 4 wheels.


Go start some more inane threads about weight loss for the car you don't even have in your possession.

For his case I recommend swapping in a 5 speed manual to save weight ;)

yeah do tell us about the exact cost of making a 7 speed transmission that will fit this engine






is there an emoji on this forum for jacking off?

What happened to the gear indicator? I wonder if its functionality is compromised because it is based on load/RPM/speed?

Probably not too related to the twins but NA/NB Miata's also used Torsen diffs, and they are rock solid.

I'm pretty sure the gear indicator is a switch in the transmission and not related to the diff, though I could be wrong.

IIRC, and there is no guarantee I do, at least on the 2nd gens it uses the speed from the ABS Sensors + the RPM to calculate the gear.

Next time you go for a drive, when you shift, you'll notice just a slight lag before it displays the gear you're in.

On the first gen it calculates based on engine revolutions per mile. There is a table in Romraider where you can adjust it.

Which means it would need to use the ABS sensors, right? Otherwise how is it calculating revolutions per mile?

Wheel speed sensors

Wheel speed sensor, ABS sensor, it's the same thing.

It's more about how many highway miles I plan on driving. I'm used to getting 30+mpg @ 80mph highway in my old mini. It's a mild annoyance but getting 30+ with the current final drive has me capped at 75mph.
EDIT: this car doubles as my daily (though I don't drive daily) so it does go on road trips.

Have you considered more eco friendly tires and possibly lightweight wheels?

There's many ways to find more MPG.

He probably thinks the GMA T.50 is garbage and that Gordon Murray doesn't know what he's doing because it uses a 6 speed.

https://www.youtube.com/watch?v=jgZHrzo7SG4&t=461s

I don’t understand people wanting to do a mod that has no return investment or depreciating on sale of car to worry about a few mpgs less of fuel a year and a couple 100 dollars of cost of fuel consumption added for “more torque per gear acceleration” its counterintuitive. You mod for fun… gas consumption is negligible and shouldn’t be a factor in a sports car.

What’s your threshold a 1.875mpg loss? lol you get what I’m saying

The stock gearing to me is perfect for city and hwy balance. 4.3 would be fun for tight curvy roads and annoying on the highway especially with an exhaust.

And the twisties, or track is the only place it makes sense. In a straight line it's typically slower because of the extra shifts. Figured this out on my R6 years at the drag strip and you can even shift way faster on those than a car.

Going through the traps in 5th was slower than going through the traps in 4th.

I have had plenty of sport bikes as well. Rode dirt bikes since I was 8 (36yrsold now) I’ve retired motorcycling. Last bike was 2012 zx10r sold 2 years ago. Felt the brz would suffice my itch for cornering.

600cc need all the gearing they can get -1f +2r sprocket to start.

Yep, that's exactly the gearing change we made on it. Fun when we got to Southern Missouri and NW Arkansas, most of the time you could just leave it in 4th and go.

To keep ourselves in check on the street, we took the motto that if you had to use the brakes you were riding too fast. IE, banging gears when it's straight to nail the brakes and downshift for the corners.

Just keep it nice and smooth. But I haven't ridden in years since I wrecked at the track and ended up with post-concussion syndrome. It's terrible.

You learn to love something like riding so much sometimes you need to learn to let it go. Between skill, confidence and some probable luck eventually the best of riders will be dealt a hand they have to fold. Hopefully they come out unscathed and not permanently injured or dead. I miss it glad you are ok.