Jump to content


Photo
- - - - -

GT-R has a limited slip diff in the front?


  • Please log in to reply
24 replies to this topic

#21 RPM

RPM

    R33 Member

  • Members
  • PipPipPip
  • 727 posts

Posted 17 June 2013 - 09:19 AM

Resurrecting this thread to see if any race teams have feedback on running a front LSD? TSM?

Edited by RPM, 17 June 2013 - 09:20 AM.


#22 earico

earico

    Lake Bum

  • NAGTROC Certified Member
  • PipPipPipPipPip
  • 2,631 posts
  • Location:SA TX

Posted 17 June 2013 - 01:42 PM

Watch this video. It's worth the watch.


It makes sense to me the GTR is RWD with FWD assist. IMO this is why the car does so well in the corners and I think the use of a front open diff was genius.

For instance in a left hand turn with the open diff the right tire can turn more revolutions than the left tire (left tire is allowed to turn less and not loose traction also). If you put an LSD in the front the LSD would try to make both front tires spin the same amount of revolutions (until a certain TQ load that releases the lock). This would cause the left/inside tire to loose grip and spin. This would be very apparent on tight corners. Also the ECM is always monitoring the ABS sensors as well. So if the car can't perform the way it should in the corner from a pure mechanical standpoint then the ECM steps in and applies brakes on the front wheel that needs it. Thus making a synthetic LSD if you will.

I would only put a LSD in the front for a drag only car. Just my opinion.
Posted Image
2012 BE GT-R - Built 3.8L / PTE-5858 CEA
Ecutek tuned by Bill @ SIR

#23 RPM

RPM

    R33 Member

  • Members
  • PipPipPip
  • 727 posts

Posted 17 June 2013 - 02:31 PM

An open diff will route power through the path of least resistance (tire wil least amount of grip). If you are making a hard left, your front inside tire will be the least unloaded during corner exit, power will be routed to that tire, and it will spin. A LSD will, to a certain extent, match the front wheel speeds so you limit tire slip and maximize available grip.

If the AWD system in the GTR is braking the inside spinning tire to slow it down (using the ABS system), it is effectively doing the same thing as a LSD: limiting wheel/tire spin to route power to the wheel with the most available grip.

#24 earico

earico

    Lake Bum

  • NAGTROC Certified Member
  • PipPipPipPipPip
  • 2,631 posts
  • Location:SA TX

Posted 17 June 2013 - 04:17 PM

An open diff will route power through the path of least resistance (tire wil least amount of grip). If you are making a hard left, your front inside tire will be the least unloaded during corner exit, power will be routed to that tire, and it will spin. A LSD will, to a certain extent, match the front wheel speeds so you limit tire slip and maximize available grip.

If the AWD system in the GTR is braking the inside spinning tire to slow it down (using the ABS system), it is effectively doing the same thing as a LSD: limiting wheel/tire spin to route power to the wheel with the most available grip.


True that the inside tire would be the least path of resistance on hard corner exit and if full power was sent to the front that inside tire would most likely loose grip. But aren't you assuming that the rear has already lost traction for the power to have been sent to the front? Being a corner exit wouldn't you already be on the throttle thus shifting the weight of the car to the rear anyways? Doesn't the car only send power to the front when rear tire slip is sensed? Plus it doesn't send all of the 50% available to the front immediately. Doesn't the ECM compute how much power the front can handle without slip and send the appropriate amount of TQ to the front?

Sure you could find an 1 way LSD for the front that may improve cornering exit in certain corners but I think you would be hard pressed to find one that performed well in all situations. I believe that is where the combination of open diff and ECM braking shine. They have created a synthetic diff can be used only when needed and performs well in all types of corners as it doesn't have a mechanically set TQ threshold to meet to allow the front tires to travel independently of each other.
Posted Image
2012 BE GT-R - Built 3.8L / PTE-5858 CEA
Ecutek tuned by Bill @ SIR

#25 Boombotix1

Boombotix1

    GTRLIFE Newbie

  • Members
  • Pip
  • 42 posts

Posted 11 January 2017 - 11:50 AM

Yup, that's the only article I have read which provides feedback on the effects of a front LSD for the GTR. I am hoping race teams who run a front LSD can chime in as well or if we can get additional feedback from Cobb if they solved the issue with the AWD system turning into RWD mode only.

 

I was just looking at the Quaife diff set and Tim over there provided this response when I asked him about setup of front + rear. Josh installed the Nismo diff on F/R and said it's the best mod he's made since the carbon ceramic brakes. It does wonders for understeer especially mid-corner to exit. Apparently you just drop it in and turn the VDC off. I'm gonna run a couple days with VDC off and then I think my next big mod will be either the Quaife front diff or the Nismo.

 

Thanks for your inquiry. I would highly recommend the front, because there
is no 'limited slip' in the front from Nissan. Whereas the rear already has
either a viscous 'A-lsd' or a traditional plate type limited slip as
standard fit from Nissan depending on which model you have. So we sell maybe
75% more front than rear. Dont get me wrong, the rear is great, but by far
the biggest change is made by changing the front one.
Hope it helps you

 


 




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users