STX Rules and Setup Questions

[strat61caster]

I don't think I've seen anyone break a diff on here unless they're pushing like 400+ whp. If it's broken it's not drivable right? I'm surprised your not more urgent for a solution...

At $1k+ for a quaife you're only a few hundred away from a cusco and a few hundred more to os giken. I'd say save yourself several hundred bucks ($1k?) and grab a used or junkyard diff based on what you posted or go all in. But I don't have experience with a diff on this car.

https://www.ft86club.com/forums/show....php?p=3088684

[NARFALICIOUS]

Reading on some of the recent posts, I've been curious about this: Can you get a higher ratio diff and still be legal for STX? Not sure if it would be a benefit or a detriment, just wondering.

K. Limited Slip Differentials
STS – No limited slip differentials are permitted except for factory standard viscous coupler-type units.
STU, STR, STX, STH – Only standard (as defined in Section 12) limited slip differentials (LSD) are allowed on AWD vehicles. For AWD vehicles that did not come with any type of limited slip differential (including center differential or transfer case), a single aftermarket mechanical LSD may be added. 2WD vehicles may use any mechanical LSD unit.

This part doesn't seem clear to me.

[CoolHandMoss]

The way they use the term "differential" does not apply to the ring gear/pinion gears if I understand correctly. What is open is the pumpkin of the diff.

[kinghurl]

Originally Posted by NARFALICIOUS

Reading on some of the recent posts, I've been curious about this: Can you get a higher ratio diff and still be legal for STX? Not sure if it would be a benefit or a detriment, just wondering.

This part doesn't seem clear to me.

Cannot change the ratio. Rules are very clear. Does not saw you can....Means you cannot. Cars are geared pretty well as is for most autoxes.

Sent from my SM-G930V using Tapatalk

[tony_r]

I wouldn't consider anything but an OSG if I was going to change from the Torsen.

[NARFALICIOUS]

Originally Posted by kinghurl

Cannot change the ratio. Rules are very clear. Does not saw you can....Means you cannot. Cars are geared pretty well as is for most autoxes.

Sent from my SM-G930V using Tapatalk

Thank you, still reading the rules and taking it all in.

[BE4VER]

Originally Posted by strat61caster

I don't think I've seen anyone break a diff on here unless they're pushing like 400+ whp. If it's broken it's not drivable right? I'm surprised your not more urgent for a solution...

At $1k+ for a quaife you're only a few hundred away from a cusco and a few hundred more to os giken. I'd say save yourself several hundred bucks ($1k?) and grab a used or junkyard diff based on what you posted or go all in. But I don't have experience with a diff on this car.

https://www.ft86club.com/forums/show....php?p=3088684

I have other vehicles and this is a garage queen that mainly just sits. Was trying to get it prepped for the end of summer and fall NNJR schedule but now Im scratching my head about this stuff.

Laying it all on the table then since I thought this was a regular occurrence. If this indeed a failure, I'll explain what I've had on the car and what evidence I'm look at right now.

Started hearing clicking, creaking, popping and lunking noises like something was loose in the rear suspension. checked torque on every thing i do still believe I'm hearing some of it from my shocks that may need a rebuild? 17k on Feal 441's? so whats throwing me for a loop is that i might be hearing that while I'm trying to diagnose the noises coming from the dif too.
While slowing driving in reverse over bumps and backing into my driveway while turning its the worst but can hear and feel it slunk around while driving slow and turning. it's clunking creaking and just feels like somethings loose.
So I brought it to a performance oriented shop I've been to before and they change the diff fluid for motul and find what looked like my thumb stuck into a peanut butter jar worth of gunk and large cluster of metal shavings. They thought it was abnormal. it looks larger than I've ever seen shown from others with common build up and they suggest a differential rebuild based on the symptoms they were able to replicate. The car is drivable and it's not noticeable besides low speeds. But I have noticed when I push the car slaloming about the rear end just feels off like and feels inline with the the idea that its on its way out. The axels don't feel loose and no leaking around the cv joints. The shop also ruled out the axel nuts and replace them to rule that out too.

[BE4VER]

Originally Posted by tony_r

I wouldn't consider anything but an OSG if I was going to change from the Torsen.

I know I know. really trying to avoid service intervals, buying different springs and swaybar combinations to compensate for the cars new behaviors, the extra heat load to manage if I decide to get back into road course days, and adjust to something that drastic with this car. I really don't mind the way the stock torsen behaves for what it is. I might just rebuild, I might even say fuck it and try that Kaaz with the Q treatment or buck all the way up for the OSG. I had planned on another drift car build though and was trying to leave this car alone though and just enjoy some auto cross events with it.

But now.. Im realizing how obscure my quiafe inquiry is because after calling Mountune(quiafe USA dist) and asking them if there is any evidence that this ATB unit performance improvement to the stock torsen in operation or quality and even they dont know or know anyone who's even installed it yet. Currently emailing Quiafe UK to see if they can answer that.

[strat61caster]

@BE4VER I don't think your diff is broken and I don't think it can be rebuilt, the shop's story seems a bit fishy to me but idk, it seems like they're angling to charge like $500-$600 and just replace the seals and bearings, if you get lucky they'll retorque all the suspension back there and identify anything else that could be called noisy and your car will be 'fixed' but idk. Like I said, I don't think a rebuild kit exists, at least not for the differential itself, it's whole differential unit (currently $1.5k new from the factory) or nothing meaningful is broken or will be changed. Lots of metal gunk is pretty normal for these things especially for the first change. Suspension gets noisy quick if there's anything not torqued properly after adding a bunch of stx parts.

http://www.ft86club.com/forums/showthread.php?t=124275
https://www.ft86club.com/forums/show...5&postcount=21
https://www.ft86club.com/forums/show...6&postcount=40
https://www.ft86club.com/forums/show...0&postcount=49
https://www.ft86club.com/forums/showthread.php?t=88048


I'd love to be proven wrong, but time and time again when it comes to fixing a worn out Torsen, the answer is throw it out, buy aftermarket or used with fewer miles.


Here's the exploded differential assembly and parts list, at a minimum I'd get a list of parts they plan on purchasing on your dime and make a judgement on whether or not it's fixing what you think it is.

https://www.subaruparts.com/auto-par...ber=4130153020

[CoolHandMoss]

Originally Posted by strat61caster

@BE4VER I don't think your diff is broken and I don't think it can be rebuilt, the shop's story seems a bit fishy to me but idk, it seems like they're angling to charge like $500-$600 and just replace the seals and bearings, if you get lucky they'll retorque all the suspension back there and identify anything else that could be called noisy and your car will be 'fixed' but idk.
https://www.subaruparts.com/auto-par...ber=4130153020

Generally speaking, seals, bearings, and races are pretty much the extent of most differential rebuilds. Looks like around $250 in parts from the supplier you linked, though it doesn't look like they sell the seals. There certainly could be damage beyond that, you never know. Just saying that it sounds like his diff may just have had a bearing failure if anything. My point is, it's worth cracking it open to see if he's even somewhat considering a rebuild.

[BE4VER]

Originally Posted by strat61caster

@BE4VER I don't think your diff is broken and I don't think it can be rebuilt, the shop's story seems a bit fishy to me but idk, it seems like they're angling to charge like $500-$600 and just replace the seals and bearings, if you get lucky they'll retorque all the suspension back there and identify anything else that could be called noisy and your car will be 'fixed' but idk. Like I said, I don't think a rebuild kit exists, at least not for the differential itself, it's whole differential unit (currently $1.5k new from the factory) or nothing meaningful is broken or will be changed. Lots of metal gunk is pretty normal for these things especially for the first change. Suspension gets noisy quick if there's anything not torqued properly after adding a bunch of stx parts.

http://www.ft86club.com/forums/showthread.php?t=124275
https://www.ft86club.com/forums/show...5&postcount=21
https://www.ft86club.com/forums/show...6&postcount=40
https://www.ft86club.com/forums/show...0&postcount=49
https://www.ft86club.com/forums/showthread.php?t=88048


I'd love to be proven wrong, but time and time again when it comes to fixing a worn out Torsen, the answer is throw it out, buy aftermarket or used with fewer miles.


Here's the exploded differential assembly and parts list, at a minimum I'd get a list of parts they plan on purchasing on your dime and make a judgement on whether or not it's fixing what you think it is.

https://www.subaruparts.com/auto-par...ber=4130153020

I'm suspect too now hearing that. And walking in here to the STX discussion is what I'd hoped to find.. some great info. The shop hinted at a new unit being 1,500 worst case scenario. I've had a go pro pointed at virtually every single connection point the rear end has to offer while replicating noises and it's awkward how I basically have no syptoms at all while the car is in motion at full speed but lunking around like that when reversing and turning on uneven surfaces. I've scoured every "whats this noise' thread and read about plenty of axel failures, even the frame in the trunk needing tack welds cause it was shifting so I've tried so much already. Im gonna get second or make that 3rd opinion now actually. Thanks a ton for the info listed if it actually is cooked.

[BE4VER]

http://www.ft86club.com/forums/showthread.php?t=124275
https://www.ft86club.com/forums/show...5&postcount=21
https://www.ft86club.com/forums/show...6&postcount=40
https://www.ft86club.com/forums/show...0&postcount=49
https://www.ft86club.com/forums/showthread.php?t=88048

WOW looking at those pics makes me worry again now cause I had at least double the one people thought was fishy. like double the silver gunk and a big ole chuck of shard build up.

[BE4VER]

So here's what I got from Quaife UK. My car had sat in a garage the last few years and I'd been out of the loop with the latest STX mods and assumed that some one had to have tried it, and did not know our cars differential failing was so rare. So hopefully this is some decent info for someone who's differential fails even if mine hasn't.

So it appears the main benefit of this Quaife ATB unit in our cars would be for lots of shock load and looks great for drag racing but should still perform just the same as the stock torsen for autocross. If someone kills there diff and a new oem torsen is $1,500, this thing appears to be a no brainer costing only $1,150 with a lifetime warranty.

"The Quaife ATB differential works on the same principles as a Torsen differential i.e. they are both gear driven.
However the design of the Quaife ATB allows for more pinion gears to be used therefore increasing the tooth contact inside the diff making it stronger.
We had a third party test an ATB diff on a test rig which reached 19,000Nm before breaking the rig so the diff will be more than capable of withstanding any amount of power your car is producing.
This is why we give a lifetime warranty for all our ATB diffs."

[CoolHandMoss]

But when your stock torsen goes out it will still need a rebuild when the quaife goes in. The quaife unit is just the pumpkin. So the bearings and whatever else is broken in the stock diff will run the cost up to more than a stock replacement, and well more than a rebuild of the stock unit.