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Old 12-29-2010, 10:40 PM   #1
dcb504
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Default 2011 WRX rear differential

I have searched the entire internet and have not been able to find the answer to my question: what kind of rear differential is in the 2011 WRX? I would also like to know what kind of diff is in the front as well. I have been told that the center diff is locked, limited-slip in the rear, and open in the front. Anyone have a clue? Thanks
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Old 12-29-2010, 10:55 PM   #2
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I've always thought it's been open front and rear and viscous coupling locking on all wrx's since 08. No?
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Old 12-29-2010, 11:43 PM   #3
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I've always thought it's been open front and rear and viscous coupling locking on all wrx's since 08. No?
correctomundo
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Old 12-30-2010, 09:22 AM   #4
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Thanks!
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Old 12-30-2010, 10:22 AM   #5
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center is 50/50 locked correct?
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Old 12-30-2010, 10:51 AM   #6
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If I remember reading, the '08+ stopped with the VLSD in the rear. They have traction control now. The center diff is a VLSD 'locking' but really it isn't that good.
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Old 12-30-2010, 02:12 PM   #7
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You have no diff in your rear. The rear diff was axed in 2008. You have VDC. VDC is a "ghetto" differential. By that, it's a normal open diff and when VDC senses a wheel is slipping, the computer applies the brakes to that wheel to aid in traction. So it's not a diff per se, but the braking gives it near diff type action in a round about way.
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Old 01-03-2011, 02:05 PM   #8
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Quote:
Originally Posted by Unabomber View Post
You have no diff in your rear. The rear diff was axed in 2008. You have VDC. VDC is a "ghetto" differential. By that, it's a normal open diff and when VDC senses a wheel is slipping, the computer applies the brakes to that wheel to aid in traction. So it's not a diff per se, but the braking gives it near diff type action in a round about way.

They have a differential in the rear, it's just open. it's not a solid axle with no speed differentiation allowed... I'm just saying, you like to argue semantics and that was a large faux pas.
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Old 12-30-2010, 02:23 PM   #9
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I intend to take this car to the track. Considering the fact that this car is AWD, I am now hoping that not having limited-slip on the rear end may not be too detrimental.
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Old 01-01-2011, 08:24 AM   #10
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Interesting. **** traction control.
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Old 01-01-2011, 06:15 PM   #11
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clutch type LSD in the rear makes things interesting. A WHOLE new feeling when you're on the throttle in the turn. hahahaha
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Old 01-01-2011, 07:23 PM   #12
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like a 1.5 or 2 way diff.???

i was wondering the same thing, im sure it would aid in getting the power to the grounf a bit better???

also with the traction control turned off, does the "computer" still limit power to the spinning wheel?
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Old 01-01-2011, 09:25 PM   #13
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Originally Posted by THE_SMURF View Post
like a 1.5 or 2 way diff.???

i was wondering the same thing, im sure it would aid in getting the power to the ground a bit better???

also with the traction control turned off, does the "computer" still limit power to the spinning wheel?
A good 1.5way does real well. It has it's tradeoffs. It has some lockup when off throttle for some stability when engine braking.
A 1way would be better in rotating when you're off throttle because it'll have no lockup off throttle.

Track/roadcourse for AWD, 1.5way.
Gymkhana/autoX for AWD, 1way.

Even if BOTH your wheels are on the ground without a LSD, adding one in changes the way the car rotates out of the turn. Gives it a RWD feel to it. So if you have the car setup for more oversteer with the current suspension, an added good rear LSD will make it more tail happy. So now you just have to tone the rear down with suspension settings like lesser rear swaybar, or say softer springs.

I'm not sure how the new traction control system operates. I know it adds braking and also cuts off power; via throttle? Traction control isn't my thing, although in some cases will probably be useful.
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Old 01-02-2011, 10:02 PM   #14
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wow, thanks for the very useful information. i dont know how "non rice" this sounds but i am thinking of going for the tail happy affect the STIs some what have, of course after added power. it was something i always wanted to do in my 09 wrx but never got around to it.
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Old 01-03-2011, 11:43 AM   #15
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All 08+ Imprezas other than the STI have open front and rear diffs.

OP with VDC/TC off, there are no electric nannys left other than ABS. On the STI, there are 2 levels of turning it off, but on the WRX, it's on or off. You DO want it off for autox/track as it is terribly castrating. With VDC on, it not only brakes individual corners as slip is detected, it uses steering angle and lateral G sensor input to cut throttle too.

Don't get too caught up in the VLSD vs open. VLSDs lock so slowly (speed sensitive) that they really don't help in performance driving unless you are in a humongous steady state sweeper on throttle which is infrequent. They are more for inclement weather driving. A real clutch based LSD would be the way to go in the rear....1.5 way would be good.

However, I think a more night and day decrease in track lap times would be noticed after installing a helical/gear/torsen style front diff. Sure if you get front inside wheel spin, the center VC will xfer torque rearward, but again VCs are slow so keeping traction upfront and exiting the turn on throttle will be much faster.
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Old 01-03-2011, 02:09 PM   #16
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so your opinion is that a front diff. for an 08+ WRX isnt as benificial as a rear LSD upgrade?

I was only thinking about installing one in the rear for some tail happy fun the STIs get, I don't do road courses or autox, I'll visit the 1/4 mile track just to see what times I can run for bragging purposes.
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Old 01-03-2011, 03:11 PM   #17
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I personally think you will get much more out of a front LSD than a rear. It's going to pull you through turns a lot better and you will actually get to use your AWD for what it's good for. The open diffs scare me. Quick slalom style turns where the chassis gets unsettled are absolutely terrifying on the new WRX's. Either you run them with the VDC off and you chirp inside tires and the car jerks around from the diffs wandering power back and forth between sides, or you leave the VDC on and go really slow because of the throttle cutting back. Of course, this stuff is only found in areas of excess cornering loads like on track or an autocross. Most street driven cars will never encounter this phenomenon.
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Old 01-03-2011, 05:57 PM   #18
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Quote:
Originally Posted by THE_SMURF
so your opinion is that a front diff. for an 08+ WRX isnt as benificial as a rear LSD upgrade?

I was only thinking about installing one in the rear for some tail happy fun the STIs get, I don't do road courses or autox, I'll visit the 1/4 mile track just to see what times I can run for bragging purposes.
No I said the opposite. A front lsd would yield faster laps times than a rear.

08whiterex, I autox DS in my 09 with VDC always off and don't have the issues you descibe. I do have better dampers so that obviously changes the lateral dynamics in slaloming. Anyway the open diffs di present a challenge but it'll make you drive better if you can get around car deficiencies with better driving .
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Old 05-24-2011, 03:41 PM   #19
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No I said the opposite. A front lsd would yield faster laps times than a rear.

08whiterex, I autox DS in my 09 with VDC always off and don't have the issues you descibe. I do have better dampers so that obviously changes the lateral dynamics in slaloming. Anyway the open diffs di present a challenge but it'll make you drive better if you can get around car deficiencies with better driving .
I have coilovers and a full menagerie of bushings. I also run slicks and have a good bit of power, so the inside wheels get really light and when you throw in curbing, it is quite the nerve racking experience.
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Old 01-03-2011, 08:55 PM   #20
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I would have to play with Front LSD to get what you guys are feeling. Get the car to rotate is what I would like. Here are some vids of a EVO. However take note that this is on a gymkhana track, which has TIGHT turns and such. On a BIG road course, it's gon be a little different to where a REAR LSD may be more ideal because it gives the car a RWD character when you're on the throttle. Better YAW on the way out.



This is an EVO but it would be similar character.


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Old 01-03-2011, 08:55 PM   #21
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Last edited by FuJi K; 01-04-2011 at 11:48 AM.
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Old 04-03-2011, 01:08 AM   #22
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Default 2011 WRX Diffs

If your WRX is just a daily driver, the stock car should be OK. The VDC is a "poor mans" diff (BMW uses it too). Many more manufacturers are using it instead of an LSD, e.g. the new ford focus torque vectoring.
The downside to all the electronic control is that it uses the brakes to change the car dynamics. This equals more brake wear and heat... not a good thing at the track.
For best turning performance, traction, and less maintenance, I think a helical type LSD would be best. I would start with the rear end, because it's the most accessible. However, I haven't found a commercially available rear helical type LSD for a 2011 WRX.
Guys with a lot of WRX experience... Does anyone know what Helical LSD's are available for a 2011 WRX front and rear? Thanks.

Looked a little. It's possible that a Torsen T2 for a 06 Spec B legacy or 07 STI may work, but am not sure.
http://www.torsen.com/files/Torsen%2...2010-09-28.pdf
I think it needs to be a 3.9 for a R 160.

Also, for dirt.... Cusco's the way to go.

Last edited by Midway; 04-03-2011 at 01:31 AM. Reason: more info
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Old 04-03-2011, 11:51 PM   #23
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Yep no VLSD in the rear for the 08 WRX.

VDC great awesome for a stock street car. It is much cheaper than a proper diff. You need to have the tone wheel on the spindles anyway so all you need to do is add calculations in on the abs to brake the spining wheel. You have all the hardware on any car with four channel ABS that you need to create a stability control system so it only makes sense to cut a few dollars.


Though for the track you need to mod the VDC control program or put proper LSDs in the car. For 99.9% of the population a mechanical refit is easier than changing the code to make a good track setup.
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Old 04-04-2011, 11:47 AM   #24
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Yep no VLSD in the rear for the 08 WRX.

VDC great awesome for a stock street car. It is much cheaper than a proper diff. You need to have the tone wheel on the spindles anyway so all you need to do is add calculations in on the abs to brake the spining wheel. You have all the hardware on any car with four channel ABS that you need to create a stability control system so it only makes sense to cut a few dollars.


Though for the track you need to mod the VDC control program or put proper LSDs in the car. For 99.9% of the population a mechanical refit is easier than changing the code to make a good track setup.
I don't think any reprogramming of the VDC would ever be better than with it completely off ....it is far to intrusive. But yes, true LSDs or a TBD would be the way to go.
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Old 04-05-2011, 10:55 AM   #25
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I don't think any reprogramming of the VDC would ever be better than with it completely off ....it is far to intrusive. But yes, true LSDs or a TBD would be the way to go.
Years ago (2002), motorcycles were flipping people off. It took a real man to ride a GP bike. Now, we've got little horse jockeys pinning the throttle exiting turns. This is all due to electronic controls. Electronics cannot replace the mechanical systems, but electronics can be tuned for difference applications (street/track/sport). Combining the mechanical and electronic systems would give the best results.
Back in 2002, I mentioned to Kevin Cameron that MC's didn't need "traction control", but rather "spin control".
Not long after that, motorcycles were running such systems. (in effect making the technology public domain)
Tuning the VDC could give similar results, not keeping tires from spinning, but rather limiting the rate at which they spin.

http://www.iwsti.com/forums/ecu-tuni...ng-here-2.html
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