The Differential Between You and Me

[Toonces]

Diff... the line is:
https://www.taylor-race.com/sites/default/files/DIFFERENTIAL ESSAY W PHOTOS2.pdf
....
To finish, there are a lot of very technical books out there but, for many readers, going through those can be quite harsh. Many years ago, I learned a lot from a little book that was a breeze to read: Four Wheel Drift by Steve Smith. The guide that came with Grand Prix Legend. The people who did not go through it found GPL undrivable. The racers who did... learned to drive.
^^^^

Truer words were never spoken!

 

[Kyuubeey]

@MarkR

Suspension setup is more important than diff adjustability IMO. Purely because any diff that's not 0% or 100% will have an optimized left/right load ratio for maximum yaw/maximum lateral or longitudinal G/maximum combined G.

Not so noticeable in AC where we basically just have clutchpacks and bodges of others, but on some more uncommon suspensions, the result can be catastrophic if both driven wheels are on the ground at the same time with a similar, or only one is, and your car won't go anywhere or will make a one-tire-fire. You optimize with droop length, dampers, ARB, spring and so on for specific corners where you want a specific amount of inner wheel lift or plant. Optimizing that for clutchpacks is more important than the diff itself IMO.

 

[Pauli Ahonen]

I just go lower settings for tighter tracks.
Usually quite low anyway to maximize the speed in slow corners since more time is spent in them than in high speed corners.

 

[Kyuubeey]

I just go lower settings for tighter tracks.
Usually quite low anyway to maximize the speed in slow corners since more time is spent in them than in high speed corners.

Why lower for tighter tracks? Generally more difflock will allow point and shoot driving like coming out of hairpins to work better, but it'll bog the engine down in faster high G turns. Unless with tight you mean a mountain pass or hillclimb, with a lot of neutral cornering.

 

[BrunoBæ]

One of the reasons some people get confused or give up understanding if/how diff works in their prefered racing game is - that you cannot always believe that higher power/coast number equals higher lock value.
Its my experience that this issue is worst conserning the coast and specially if you go from one sim to another.

EDIT: I just re-read this sentence and maybe(!!) its the same this poster talks about.

As well as what the numbers actually translate to 'gear-wise' in the diff.

 

[RasmusP]

Differential who?

Oh come on Dirk. No adult content allowed on here

 

[Dirk Steffen]

Oh come on Dirk. No adult content allowed on here

Now, now, I did NOT show any naked pics of anything … ;-)

 

[apex11]

LSD is a driver aid

 

[mulkkensson]

LSD is a driver aid

Might be if you get the space ship, but watch out for monsters

 

[JackCY]

Highly depends on each simulator/arcade, they often implement only 1-2 types in their code and that's it, values are almost always "virtual" and do not use realistic forces, frictions, etc.
Some sims you have to lock up the diffs to get best times, other sims you can use more realistic levels of lock.
How much and what diff to use depends what you have available and what CG balance car you are working with. For LSD these settings are very easy in sims.

 

[BrunoBæ]

Differential who?

 

[Raiod_1478]

Depends on the car and how much hp it has, I tend to use more conservative settings on high power cars and a more aggressive one when driving cars below 400hp or so... Specially to get that on throttle rotation through corners right, but I guess aliens use really aggressive settings even on +600hp cars...

 

[Pauli Ahonen]

Why lower for tighter tracks? Generally more difflock will allow point and shoot driving like coming out of hairpins to work better, but it'll bog the engine down in faster high G turns. Unless with tight you mean a mountain pass or hillclimb, with a lot of neutral cornering.

You are right but i found the rF2 LMP2 to be much quicker coming out of especially Interlagos slow turns with low settings on power. They were not exactly hairpins. So on other tracks i should experiment more and use your technique.

 

[Motowntom]

For me in the real world of track cars I find adjustable suspension, tyre choice, good reliable braking and sometimes an ecu map far more important than the differential. Sure I want the car to have a good differential(s) but only the cars with electronic systems have ever had the ability to adjust them in my experience.

The endless settings available in sims and racing games is where they differ most from real life track cars for me. Sure the very top of motorsport may have this level of adjustability and teams of engineers to set them up properly, track the data, run the hundreds of laps and simulations required to know if it's faster.

For front wheel drive the VAQ differential on my daily driver Cupra is a good compromise, in comfort mode for road driving the differential effect is mild and unobtrusive. At the highest Cupra setting, paired with Michelin Pilot Sport Cup 2 tyres it'll cling to the apex on track in a way that takes some getting used to. It'll even leave a set of 11's on the tarmac in the tighter corners - crazy for a FWD car. It helps that the damper stiffness can also be adjusted with the diff because they all need to work together to be effective imo. As technology that enables cars to work on the road without being overly harsh and still fun on track it's a decent compromise (anyone who's driven a fidgety Audi RS car on standard dampers will know how annoying that can be). It still in't as good as a specific track car like my Megane R26.R and that has almost no adjustability at all. Superb front suspension setup and diff work together in perfect harmony though, hit the apex and the throttle just pulls the car around.

The centre differential adjustment on the Impreza was fun too, but more of a gimmick than really impacting the performance that much. It was fun to move the power rearwards on an empty, damp Pembrey trackday and slide about for a lap or two. Again adjustable suspension to be able to soften for the bumps or wet conditions on the track made far more difference imo. The Evo 8 MR had no driver adjustment but the active yaw control in that car was incredible, it could make almost anyone look like a driving god.

None of the lightweights Westfield's, Caterhams, Atom etc have - to my knowledge - had any differential adjustment but they all worked superbly. The ability to adjust the ride height and damper stiffness and tyre pressures - manually - is by far the best way to change real car behaviour imo.

So that's my take on differentials froma trackday enthusiasts perspective. It's good to be able to adjust them in games but I don't think it's the height of realism for anything other than the most elite motorsports (even then I believe many racing series prevent this to keep costs down.)

Ha Ha Ha Ha Ha Ha Ha... You deserve an academy award!!!!!!! Rubbish.

 

[MarkR]

Ha Ha Ha Ha Ha Ha Ha... You deserve an academy award!!!!!!! Rubbish.

Don’t be shy, give us an explanation and enlighten with your wisdom.

 

[Giuseppe Abagnale]

Differentials have to be combined with a proper vehicle setup as someone already said. A good TorSen diff on an offroad vehicle would be almost useless since in its most critic situation (a wheel off the ground) the diff would be perfectly open and unable to drive the car...
That said, in a theorical way, it's very easy to describe all the differentials. Basically each differential (a part the open one) increases the preload that is linking together both outputs. What differs is the way it does it.
And that's the difficult part when one wants to simulate. The equations controlling the instantaneous preload of a certain diff have many many intedependent variables that cannot be exploited by actual game engines. For example a 30° ramp is not always giving the same locking % but it depends on number of clutches used and their material. Same with viscous unit: number of clutches, their type (number of holes in them), silicon fluid type and operating temperature are all interdependent.
So we have to accept some very basic equations that don't resemble the real characteristic when using same settings.
It's not devs' lack of notions, just physic engine complexity and capability -> Development costs...

 

[ivanalesi]

On some cars, mostly GTs and McLarens, I play with the diff in order to avoid the rear stepping out under heavy braking. I love trail braking and cars that allow it.
I don't agree about LSD being TC, getting used to the throttle on corner exits is easy, TC works mostly when the slip occurs due to bumps, changing grip levels etc. It's not like you can smash the throttle and the LSD will take care of traction. TC is far more reaching...