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Old 05-22-2024, 11:54 AM   #1
Apb_pools
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Default 2022+ Subaru VB front and rear LSD install by Cusco

Will be installing a front and rear Cusco unit in my VB wrx oem tranny.

Just wanted to post this here so that people googling "2022+ subaru wrx vb open diff" or "installing LSD into 2022+ subaru wrx vb" can find it.

Link to front diff: https://www.evasivemotorsports.com/s...6mt-only-2022/
Part #: CUS-LSD-180-A

Link to rear diff: https://www.evasivemotorsports.com/s...aru-wrx-02-21/
Part #: LSD 183 L15 (i am using this part number)

There are people online who believe the only way to have a proper LSD is to go full STI driveline transplant. On top of that they aim to get newer is better STI transplant which means FD is 3.54 and what they gain in strength and street cred they will lose in acceleration, which is what most of them are after.

Spreading misinformation through IAG and other sources (vloggers and bloggers) who wish they had something but never actually do more than talk is the norm out there--out there on the interweb is what i mean. On top of that, their channels are moderated and they delete what they dont like or doesnt fits their narrative or sales pitch.

So yes, you can make your 22+ Subaru WRX VB OEM WRX tranny with 4.11 fd into a proper AWD driveline with <2000$ in parts and 1000$ labor. Which is exactly what i am doing.

Otherwise you will spend 5-6k to tell ppl you have an STI driveline and be slower to 60 or 130mph.

Also NOT all STi transmissions are same. Some have splash-shields only and others have a true oil pump inside. Pick carefully.

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Last edited by Apb_pools; 05-22-2024 at 11:46 PM. Reason: added Cusco part numbers
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Old 05-22-2024, 11:43 PM   #2
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Subaru WRX 4-Dr. Sedan, FA24T (2.4L Turbo) - All Parts Catalog 2022

https://cdn.sanity.io/files/jca7vtju...8697606a4f.pdf

Subaru WRX 2015+

https://cdn.sanity.io/files/jca7vtju...e64937826d.pdf

I believe them to be interchangeable between 15+ and 22+ though Cusco splits them into different parts. But we shall find out.
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Old 05-23-2024, 09:40 AM   #3
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I wonder how this goes, I thought about using a similar setup for rallycross if i ever go up classes and to a proper rally tire. It honestly is the only real setup that could be used because the class doesn't allow adding electronic controls or using anything that doesn't fit into a stock trans/diff. Spending a ****load on a 15" wheel swap, coilovers, and 2 diffs, and have to run the stock intercooler, only to find out it is nearly undrivable in parking lots is a check my account currently can't cash.
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Old 05-23-2024, 11:49 AM   #4
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There are 3 main options for diffs. Rs, tmz and hybrid. Rs is entry for less serious enthusiast, thats me.

Then the rs can be had in 1way 1.5way and 2way, and combos like 1 only, 1 and 1.5, 1.5 only or 1.5 and 2 way. So you can set it up 1.5 or 2 way and then you can change ramp angles, both ways. And there are different options for ramp angles.

So if setup properly, it shouldnt be like that in a parking lot unless you decide to have it that way. I am starting with 1.5way at 55/0 ramp angles rear. Then i plan to drive the car like that with oem open front, before installing the 1way front with 55/0 ramps.

My first time doing something like this so i am excited. Also excited about keeping mods to driveline to minimum while staying with 4.11 fd. I am only gonna be ever roll racing and maybe 1-2 track days a year as an amateur. This is my daily workhorse, literally. Looks stock so some V8s are bound to get really mad.
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Old 05-24-2024, 08:07 AM   #5
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If you put anything other than a 1 way or open in the front it will start locking the front wheels on decel and you wont be able to turn. That is why i personally wouldn't put a 2 way in the back of my daily. Too scared of turning around in a parking lot and dragging the outside wheel or emergency braking because of an idiot on the road and going into snap oversteer after locking the back axle. Another thing to consider is you can run more or less clutch packs so if you only want it to lock up say 60% you can take a few clutch disks out.

As for running open in the front weren't you aiming for 600whp? All it would take is 1 front wheel spinning and since it is open all 3 other wheels would get nothing.I personally would just do both at the same time and get it over with.
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Old 05-24-2024, 02:50 PM   #6
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Quote:
Originally Posted by uglywrx View Post
If you put anything other than a 1 way or open in the front it will start locking the front wheels on decel and you wont be able to turn. That is why i personally wouldn't put a 2 way in the back of my daily. Too scared of turning around in a parking lot and dragging the outside wheel or emergency braking because of an idiot on the road and going into snap oversteer after locking the back axle. Another thing to consider is you can run more or less clutch packs so if you only want it to lock up say 60% you can take a few clutch disks out.

As for running open in the front weren't you aiming for 600whp? All it would take is 1 front wheel spinning and since it is open all 3 other wheels would get nothing.I personally would just do both at the same time and get it over with.
So some STI drivelines come open front, viscous center and LSD rear. This would be similar to that, and I assumed one of front wheels spinning means other front wheel would get nothing but rear would be unaffected because has LSD installed (not open). So if that scenario happens car just becomes rwd until front slip is gone and traction happens again.

Yes, rear is 1.5way set to 55/0. Front would remain open for test driving for a while to see my experience and feel, then we can always install front LSD as well, which would be 1way only. Yes, 600+ whp and wtq is goal.

Last edited by Apb_pools; 05-24-2024 at 03:01 PM.
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Old 05-24-2024, 03:00 PM   #7
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Also.. lets see if car survives tuning and some abuse before i dump another 1.5k in it. It may blow up, or my clutch may not be able to hold up the pwr if it doesnt blow up. So then we can always go back in an install something else.

Not a fan of just throwing parts at a car, even if my budget was unlimited (which it isnt).
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Old 05-25-2024, 10:08 AM   #8
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Quote:
Originally Posted by Apb_pools View Post
So some STI drivelines come open front, viscous center and LSD rear. This would be similar to that, and I assumed one of front wheels spinning means other front wheel would get nothing but rear would be unaffected because has LSD installed (not open). So if that scenario happens car just becomes rwd until front slip is gone and traction happens again.

Yes, rear is 1.5way set to 55/0. Front would remain open for test driving for a while to see my experience and feel, then we can always install front LSD as well, which would be 1way only. Yes, 600+ whp and wtq is goal.

Our center diffs are always a 50/50 split. If you are spinning or lift a tire with an open or torsen diff 0 power is going to the back because 50% of 0 is still 0. Maybe that isn't enough to break traction on pavement but 600ftlb and 600whp is a lot of power to put down
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Old 05-25-2024, 12:07 PM   #9
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Originally Posted by uglywrx View Post
Our center diffs are always a 50/50 split. If you are spinning or lift a tire with an open or torsen diff 0 power is going to the back because 50% of 0 is still 0. Maybe that isn't enough to break traction on pavement but 600ftlb and 600whp is a lot of power to put down
I understand what you are saying. But where does the source of power come from? It doesn't magically start or flow from the wheel spinning and then everywhere else.

I suspect, could be wrong, that power is split 50/50 by center viscous diff. Then 50 of what goes to front to the wheel that spins with 5% of (50%) power (5% for example, could be 0) means that other front wheel would get same 5% because the front diff is open. It does not mean 5% flows back to center diff as well and then it spins the rear at 5% (or force equal to front wheel spin). I would propose that rear is still getting 50% of power split from viscous/center diff.

Again, could be wrong. I am an enthusiast not an lsd specialist. Easy way is to test it in real life when i get the car.
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Old 05-26-2024, 09:43 AM   #10
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Quote:
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I understand what you are saying. But where does the source of power come from? It doesn't magically start or flow from the wheel spinning and then everywhere else.

I suspect, could be wrong, that power is split 50/50 by center viscous diff. Then 50 of what goes to front to the wheel that spins with 5% of (50%) power (5% for example, could be 0) means that other front wheel would get same 5% because the front diff is open. It does not mean 5% flows back to center diff as well and then it spins the rear at 5% (or force equal to front wheel spin). I would propose that rear is still getting 50% of power split from viscous/center diff.

Again, could be wrong. I am an enthusiast not an lsd specialist. Easy way is to test it in real life when i get the car.

What do you mean where does it come from? Power goes to the wheel of least resistance. That is why something like a torsen diff that are normally something like 3:1 ratios put 0 power down when you lift a wheel. They multiply the least torque to the other side and 3 * 0ftlb is still 0ftlbs. You don't have to believe me but this is why you can do 1 tire fires. Also in your 5% example that would mean that your back tires only get 15hp each. Not exactly something to write home about. But this only matters if you either pick up a front wheel, or break traction and start spinning a front wheel.
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Old 05-26-2024, 12:36 PM   #11
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Quote:
Originally Posted by uglywrx View Post
What do you mean where does it come from? Power goes to the wheel of least resistance. That is why something like a torsen diff that are normally something like 3:1 ratios put 0 power down when you lift a wheel. They multiply the least torque to the other side and 3 * 0ftlb is still 0ftlbs. You don't have to believe me but this is why you can do 1 tire fires. Also in your 5% example that would mean that your back tires only get 15hp each. Not exactly something to write home about. But this only matters if you either pick up a front wheel, or break traction and start spinning a front wheel.
Its not that i dont believe you. I understand what you are saying i just disagree with it. I believe too that you believe it.

I am saying if my front left wheel gets to spin with 5% of torque the other front wheel gets same but it does NOT mean the rears get 5% as well. See this:


What you talk about is true when both one front and one rear tire spin/slip (slip happening on both front/rear axles), not only with one wheel spinning (one axle only).

At about 2:10 and after (and earlier too 0:16sec) in the video is where he spins one front and one rear and car struggles because now both front and rear are getting only min req to slip. You can clearly see the struggle vs when only on diff slips (front OR rear) whether one or both wheels (on one diff only, front or rear) slip. Disregard tcs vs track differences, focus only on one wheel only on one axle vs one wheel on both front and one on rear axles.

Again, its how half older STi models came with, open front, viscous center and lsd rear. (Same setup i plan to run w Cusco rear lsd installed.)

Last edited by Apb_pools; 05-26-2024 at 12:55 PM.
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Old 05-26-2024, 12:57 PM   #12
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I remembered.. my car:

https://www.instagram.com/reel/C2Bnu...ZidG12bXFvbw==

Notice BOTH front and rear axles spinning. So say 400wtq is split 50/50 and then front slips with 5%. The rear is still getting 50% of 400wtq and is not affected by front diff spin/torque of 5%.

Last edited by Apb_pools; 05-26-2024 at 01:36 PM.
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Old 06-07-2024, 05:10 PM   #13
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Ended up ordering a LSD 6A6 C15, just in case my old unit doesnt fit.



One way or another this will have a proper LSD.
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Old 06-11-2024, 03:39 PM   #14
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LSD 6A6 C15 arrived and in my hands. The other one is at the shop so i cannot measure to compare, but at first inspection (visual) it looks exactly the same, i wouldn't be able to tell them apart. Though this yellow japanese sticker says hybrid rs.

One of them is not like the other.. or is it? We shall find out, will take a measuring caliper to the shop tomorrow.
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Old 06-14-2024, 04:08 PM   #15
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Old 06-17-2024, 03:05 PM   #16
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Is someone making staged shortblocks for the fa24 now?
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Old 06-17-2024, 09:15 PM   #17
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Is someone making staged shortblocks for the fa24 now?
They been making them for a while, Outfront and P2P and Rallispec. But you dont need to buy a staged block, i built my own through Outfront.

Rallispec has a lot of knowledge, by the way and WILLING to share it. They sell front helical LSD and center viscous 12kg and 20kg. Also have transfer gears as well as fd 4.44s. Plus a ton of knowledge, them and Flatirons Tuning. They have a staged block too. I was impressed with their REAL performance upgrades, none of this mamby-pamby fluff you find on other retailers GUI websites.

At this point i am most likely adding a front LSD (plated or helical if it fits). Called them back today but was too late and they had closed shop. My car is at a local shop being assembled back and i feel taken care of by them too. There hasnt been anything that i throw at them w this new platform that they cant handle. GoodSpeed Performance is the name i would highly recommend. Its the only really ready and able to take it on at the time and do what i wanted, not what they usually do.

Last edited by Apb_pools; 06-17-2024 at 11:38 PM.
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Old 06-19-2024, 07:45 AM   #18
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Quote:
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They been making them for a while, Outfront and P2P and Rallispec. But you dont need to buy a staged block, i built my own through Outfront.

Rallispec has a lot of knowledge, by the way and WILLING to share it. They sell front helical LSD and center viscous 12kg and 20kg. Also have transfer gears as well as fd 4.44s. Plus a ton of knowledge, them and Flatirons Tuning. They have a staged block too. I was impressed with their REAL performance upgrades, none of this mamby-pamby fluff you find on other retailers GUI websites.

At this point i am most likely adding a front LSD (plated or helical if it fits). Called them back today but was too late and they had closed shop. My car is at a local shop being assembled back and i feel taken care of by them too. There hasnt been anything that i throw at them w this new platform that they cant handle. GoodSpeed Performance is the name i would highly recommend. Its the only really ready and able to take it on at the time and do what i wanted, not what they usually do.

I was just wondering since i havent seen any in the wild yet. Also a built block would put me in the constructor class against literal ARA rally cars so that will never happen. Same reason i couldnt rally my brz if i wanted to.
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Old 06-20-2024, 03:37 PM   #19
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I was just wondering since i havent seen any in the wild yet. Also a built block would put me in the constructor class against literal ARA rally cars so that will never happen. Same reason i couldnt rally my brz if i wanted to.
This is my daily so no rules apply. If allowed id drop ship a used r167 to ZF Design for LSD install of your choice, Torsen, AP Racing (also helical), or plated by Cusco. They can tune them for you to fit your driving style for a whole 1$ more if you buy LSD from them. ZF Design is the best shop as far as transmission and lsd work goes, they also may machine motors and more but dont assemble them as far as i can tell. I got recommended to them by 2 local shops and chit chatted with owner Zach for about 20-25 mins.

Metroperformance of Socal also should get mentioned for taking 15min of their time to discuss STi swap into VB.

But it boils down to me not wanting an STi driveline, and wanting to stay with WRX driveline, shifting mechanism and gearing, though if car survives tuning and making the power then i will ship to ZF Design to re-gear and possibly even convert to a 4.44 fd setup



Motor, turbo and jpipe in. Rest being finished this week or next week, so coming to a town near you soon...

Last edited by Apb_pools; 06-20-2024 at 03:44 PM.
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Old 06-22-2024, 08:48 PM   #20
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Quote:
Originally Posted by Apb_pools View Post
This is my daily so no rules apply. If allowed id drop ship a used r167 to ZF Design for LSD install of your choice, Torsen, AP Racing (also helical), or plated by Cusco. They can tune them for you to fit your driving style for a whole 1$ more if you buy LSD from them. ZF Design is the best shop as far as transmission and lsd work goes, they also may machine motors and more but dont assemble them as far as i can tell. I got recommended to them by 2 local shops and chit chatted with owner Zach for about 20-25 mins.

Metroperformance of Socal also should get mentioned for taking 15min of their time to discuss STi swap into VB.

But it boils down to me not wanting an STi driveline, and wanting to stay with WRX driveline, shifting mechanism and gearing, though if car survives tuning and making the power then i will ship to ZF Design to re-gear and possibly even convert to a 4.44 fd setup



Motor, turbo and jpipe in. Rest being finished this week or next week, so coming to a town near you soon...
Interesting, once I blow out my dampers and have to upgrade to a real set I could do those things if I wanted. But the order would be 15" wheel swap for rally tires then rear lsd.
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Old 07-18-2024, 10:49 PM   #21
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That's sick!
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