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#1 Posted : Friday, January 24, 2014 10:08:18 PM(UTC)
I'm trying to understand why the differential settings seem to be all over the place. On RWD cars and Mid RWD cars I'm seeing the open source tunes with very very low acceleration and deceleration settings. Why are my accel numbers so much higher on cars without any noticeable negative effects. Is it just driving style or preference or is their an actual method behind it. Deceleration settings I understand and adjust them as needed to control lift off oversteer but why are the numbers so varied? Seeing MR cars with the decl as low as 15 and others in the 40's and 50's?
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#2 Posted : Sunday, January 26, 2014 8:15:52 AM(UTC)

Because most "tuners" have no idea of how to use a differential. The pre-sets from Turn-10 gives a hint about how it should be used, just check up some pre-tuned cars and you will see high values.

As a basic, 50-55% is a moderate setting for a rear-wheel driven street car, racecars mostly likes a bit higher settings, the 75% std setting might be a bit high though. Too high and the car starts to understeer, too low and you get too much wheelspin.
Basickly I prefer using the about same settings for acc/dec a bit depending on what car..

FWD`s is another story, 25-35% before they loose grip
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#3 Posted : Sunday, January 26, 2014 11:26:32 AM(UTC)
I crank mine way up usually in the 80-90 range
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#4 Posted : Sunday, January 26, 2014 4:09:47 PM(UTC)
See this is why I'm asking. I have seen very low numbers and I have tried them out as well but it seems to feel and drive the same.
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#5 Posted : Sunday, January 26, 2014 4:50:05 PM(UTC)
Originally Posted by: The xx Tyrant Go to Quoted Post
I crank mine way up usually in the 80-90 range



That`s ok for a drift-car going sideways with full wheelspin but ruins turn-in for a roadracer
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#6 Posted : Sunday, January 26, 2014 5:28:51 PM(UTC)
Originally Posted by: unfairlane64 Go to Quoted Post
Originally Posted by: The xx Tyrant Go to Quoted Post
I crank mine way up usually in the 80-90 range



That`s ok for a drift-car going sideways with full wheelspin but ruins turn-in for a roadracer


I'm using RWD not sure if that makes a difference, it starts at 75 so going up to 85 isn't that drastic... I do find that I need to adjust other things to improve turn in but I've found with a higher diff setting I can hold more speed and throttle through long corners without losing traction.
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#7 Posted : Sunday, January 26, 2014 5:49:45 PM(UTC)
Depending on how much power the car has I start between 55-65% and adjust until I find a good balance. Highest I've ever set a RWD car was something like 78%.
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#8 Posted : Monday, January 27, 2014 3:17:52 AM(UTC)
Any ideas on awd? Also does anyone find the 1.5 diff useful.
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#9 Posted : Monday, January 27, 2014 6:27:40 AM(UTC)
It depends on the traction and power of a vehicle, weight distribution, etc. If the rear diff is at a higher percentage, the rate that each wheel spins is closer, if you go around a corner and put down the power, your more likely to oversteer and spin out with higher diff setting, the less the percentage, the less both wheels will spin together causing a car to go sideways. The lower the setting will cause one wheel to spin while the other maintains traction, keeping the rear end from kicking out sideways, this also causes more wheel spin for one wheel, while not having as much traction under acceleration on a straight.
There is usually a fine line between traction and oversteer, too much diff, means more oversteer, you will need to have a light touch on the accelerator to maintain control, too little and you will have less drive out of a corner, and less acceleration, but more control in the corner no matter how much throttle.
You will see a 10% dif setting on RWD cars with higher power and less traction, and a higher setting on RWD cars that have more traction, it really depends on makes and models, distribution of weight, engine power, suspension settings, etc.
As a better example, a positive rear end on a car, when driven in snow, will be almost undriveable as both wheels spin together, causing the rear end to slide everwhere. A limited slip on the same car in the snow will have 1 wheel spinning while the other does not, keeping you in a straight line, under control. 100% dif equals positive rear end, 0% equals limited slip rear end. Tune for your desired result.
The decel settings control the rate the wheels spin while downshifting, again the higher the setting the more both wheels will grab the pavement under decel, under hard downshifting a wheel can and will lock up a little, if both rear wheels lock up, you get the e-brake effect causing the rear end to come around on you, the less the setting, the more likely only 1 wheel locks up, keeping the other wheel rolling to help maintaining control, however too little percentage on this will always cause one wheel to lock up, and that makes it handle erratically, there is a middle ground here, you need to play around with it to see what works, you want enough decel to help keep traction under downshift, but not too much to lock up the rear end, and not too little to have one wheel always locking up.
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#10 Posted : Monday, January 27, 2014 6:28:31 AM(UTC)
On AWD, the more percentage on the front diff will cause understeer while accelerating in a corner.
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#11 Posted : Monday, January 27, 2014 6:45:58 AM(UTC)
Originally Posted by: unfairlane64 Go to Quoted Post

Because most "tuners" have no idea of how to use a differential. The pre-sets from Turn-10 gives a hint about how it should be used, just check up some pre-tuned cars and you will see high values.

As a basic, 50-55% is a moderate setting for a rear-wheel driven street car, racecars mostly likes a bit higher settings, the 75% std setting might be a bit high though. Too high and the car starts to understeer, too low and you get too much wheelspin.
Basickly I prefer using the about same settings for acc/dec a bit depending on what car..

FWD`s is another story, 25-35% before they loose grip




You have to keep in mind that this is not real life. What works IRL may not be close in Forza world. I have some cars with ridiculously high rear diff that work well, some with ridiculously low rear diff that work well. It doesn't matter if some "tuners", as you say, know about diff, it matters if they know about Forza 5 diff. Experiment with extreme highs and lows on all cars when tuning....what feels really good at "normal rates" will be a second slower than something abnormal in some cases.

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#12 Posted : Monday, January 27, 2014 7:25:35 AM(UTC)
Originally Posted by: JKS 9 Go to Quoted Post
It depends on the traction and power of a vehicle, weight distribution, etc. If the rear diff is at a higher percentage, the rate that each wheel spins is closer, if you go around a corner and put down the power, your more likely to oversteer and spin out with higher diff setting, the less the percentage, the less both wheels will spin together causing a car to go sideways. The lower the setting will cause one wheel to spin while the other maintains traction, keeping the rear end from kicking out sideways, this also causes more wheel spin for one wheel, while not having as much traction under acceleration on a straight.
There is usually a fine line between traction and oversteer, too much diff, means more oversteer, you will need to have a light touch on the accelerator to maintain control, too little and you will have less drive out of a corner, and less acceleration, but more control in the corner no matter how much throttle.
You will see a 10% dif setting on RWD cars with higher power and less traction, and a higher setting on RWD cars that have more traction, it really depends on makes and models, distribution of weight, engine power, suspension settings, etc.
As a better example, a positive rear end on a car, when driven in snow, will be almost undriveable as both wheels spin together, causing the rear end to slide everwhere. A limited slip on the same car in the snow will have 1 wheel spinning while the other does not, keeping you in a straight line, under control. 100% dif equals positive rear end, 0% equals limited slip rear end. Tune for your desired result.
The decel settings control the rate the wheels spin while downshifting, again the higher the setting the more both wheels will grab the pavement under decel, under hard downshifting a wheel can and will lock up a little, if both rear wheels lock up, you get the e-brake effect causing the rear end to come around on you, the less the setting, the more likely only 1 wheel locks up, keeping the other wheel rolling to help maintaining control, however too little percentage on this will always cause one wheel to lock up, and that makes it handle erratically, there is a middle ground here, you need to play around with it to see what works, you want enough decel to help keep traction under downshift, but not too much to lock up the rear end, and not too little to have one wheel always locking up.


JKS is correct. You others all have it wrong. The reason for the low accell dif numbers in these tunes is to allow the left and right tire to spin at different speeds to allow for better powering through and out of corners. The low dif setting in the decel is to allow for the wheels to spin while not on throttle. The low numbers allows the car to rotste its rear quicker to finish the turn quicker to start acelerating out sooner,

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#13 Posted : Monday, January 27, 2014 9:40:46 AM(UTC)
I believe I may have figured out what the difference is between the higher numbers and the lower acceleration numbers. It seems to be a lot smoother going back to throttle through the trigger. With the higher diff setting I was feeling a slightly higher vibration through the trigger but not quite breaking the tires loose. After messing around with more than a few cars in the garage I started to notice the vibration would reduce back to the engine vibration through the trigger. The car would still behave the same on throttle exit but the trigger was smoother. Start adjusting the diff from a lower setting and raise the % on the next lap and when it starts getting high you will feel the trigger respond differently with a harsher rumble. Hope this helps it sure did for me.

Thanks everyone for your insight!
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#14 Posted : Monday, January 27, 2014 9:45:40 AM(UTC)
Did you notice any difference in lap times? I think the rumble would mean you are losing grip through wheelspin, even if unnoticeable to the eye, you may be getting enough slip where its slowing you down.

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#15 Posted : Monday, January 27, 2014 10:01:54 AM(UTC)
Honestly I'm sure there was some time made up but I was paying more attention to the cars attitude and lines through the corner and exit. I'm not the fastest driver but I tend to be very consistent with my times within a few tenths. I tend to drive conservatively brake a touch early and roll on power a bit later than needed, witch means I always can find extra time when I push harder.
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#16 Posted : Monday, January 27, 2014 10:10:49 AM(UTC)
A decent rule of thumb, will obviously have the exception here and there. Take the average if you want a place to start.

Front engine RWD
Accel = 25% to 60%
Decel = 5% to 25%

Mid engine RWD
Accel = 20% to 50%
Decel = 10% to 50%


Front wheel drive
Accel = 80% to 100%
Decel = 5% to 12%

All wheel drive
Front Accel = 25% to 40%
Front Decel = 0%
Rear Accel = 65% to 100%
Rear Decel = 5% to 30%
Split = 60% to 75%
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#17 Posted : Monday, January 27, 2014 10:14:48 AM(UTC)
Wow thanks Worm that will be a great help!
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#18 Posted : Monday, January 27, 2014 4:53:09 PM(UTC)
Keep in mind that the diffs are merely one component of the entire system of chassis parts.
You must tune the parts to compliment each other in order to maximize their potential.

You can't just slap someone else's values on your car and expect them to work, it's a more elaborate solution than that.

Edited by user Tuesday, January 28, 2014 8:39:08 PM(UTC)  | Reason: typo

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#19 Posted : Monday, January 27, 2014 5:40:00 PM(UTC)
For RWD set up the accel to get the corner exit power down you want, and set the decel to get the turn-in behaviour you want. Very high settings for accel and very low settings for decel generally favour oversteer behaviour. Some people like that, some people don't. I always configure diff for neutral corner entry and early power down on track out. Generally speaking being able to trail brake is a sign you are in the sweet spot for decel. If the back is breaking loose you have too little decel, if the nose doesn't want to turn into the corner, you have too much. Worm's settings are a very good rough guide, although there are plenty of exceptions to every rule.
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#20 Posted : Monday, January 27, 2014 8:10:46 PM(UTC)
Originally Posted by: The xx Tyrant Go to Quoted Post
Originally Posted by: unfairlane64 Go to Quoted Post
Originally Posted by: The xx Tyrant Go to Quoted Post
I crank mine way up usually in the 80-90 range



That`s ok for a drift-car going sideways with full wheelspin but ruins turn-in for a roadracer


I'm using RWD not sure if that makes a difference, it starts at 75 so going up to 85 isn't that drastic... I do find that I need to adjust other things to improve turn in but I've found with a higher diff setting I can hold more speed and throttle through long corners without losing traction.



Off course this is for RWD only (+ RW-settings on 4WD`s). Yeah, racediffs are pre-set to a 75% brakeforce, that might be ok on some pure racecars with lot of forcedown & grip but on a hotted up street-/sportscar the diff should be adjusted a bit lower to avoid understeer. 56-58% seems to be the magic borderline between over-/understeer on most RWD-cars.

85% is way too tight if you want a good turn-in response, the diff is allmost locked. Good for drifting but not for racing..



Worm; values like 25% is too low. The diff will act as an open diff with values that low. 45-60% is my 2c, or should I say 55-60


Torrider; low diff-settins that allow one wheel (inner wheel that is) to spin is a misunderstanding. To get the best out of the enegine and to avoid wheelspin the diff needs to be tighten up to some 50+ and so on.


JKS 9; a "posi" and a limited slip is the same thing, Limited-slip is the generic term, each manufacture has their own specific name. GM = Posi-traction, Ford = Traction Lock, Chrysler = Sure-grip, DANA = Trac-Lok/Power-Lok. I gave up trying to get my students to use the correct name, to them any limited slip is a "posi".

What you say about winter-driving tells me you are not a scandinavian like me. The last one you describe is an open diff. You will have a hard time selling cars with open diffs up in the north, they are useless in wintertime.

Edited by user Monday, January 27, 2014 8:55:11 PM(UTC)  | Reason: Not specified

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#21 Posted : Monday, January 27, 2014 8:25:14 PM(UTC)
Originally Posted by: TN Eagle Go to Quoted Post
Originally Posted by: unfairlane64 Go to Quoted Post

Because most "tuners" have no idea of how to use a differential. The pre-sets from Turn-10 gives a hint about how it should be used, just check up some pre-tuned cars and you will see high values.

As a basic, 50-55% is a moderate setting for a rear-wheel driven street car, racecars mostly likes a bit higher settings, the 75% std setting might be a bit high though. Too high and the car starts to understeer, too low and you get too much wheelspin.
Basickly I prefer using the about same settings for acc/dec a bit depending on what car..

FWD`s is another story, 25-35% before they loose grip




You have to keep in mind that this is not real life. What works IRL may not be close in Forza world. I have some cars with ridiculously high rear diff that work well, some with ridiculously low rear diff that work well. It doesn't matter if some "tuners", as you say, know about diff, it matters if they know about Forza 5 diff. Experiment with extreme highs and lows on all cars when tuning....what feels really good at "normal rates" will be a second slower than something abnormal in some cases.



Yeah, they can "work well" but would work better if you improved the diff-settings. Forza is not that much unlike real life, but this is also a lot about driving-style and vehicle.
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#22 Posted : Monday, January 27, 2014 10:29:17 PM(UTC)
Originally Posted by: FEUERDOG Go to Quoted Post


You can just slap someone else's values on your car and expect them to work, it's a more elaborate solution than that.


Want to bet?



Originally Posted by: unfairlane64 Go to Quoted Post
Worm; values like 25% is too low. The diff will act as an open diff with values that low. 45-60% is my 2c, or should I say 55-60



There is a reason you guys continue to struggle, and it comes from a lot of people, it's because you don't listen. It's fine to experiment and enjoy the game the way you want to but if you are going to tell me I am wrong when I've used the same basic differential settings for 5 years I don't really like it. You continue to argue when people, not just myself, keep cranking out great car after great car and giving you advice TO HELP YOU OUT. I can put the same tune on virtually every car in the game based on it's drivetrain and it will feel great and if the build is right go fast. Forza still operates under the same generic, one size fits all suspension system (with the exception of FWD which is bugged) that it always has with minor tweaks here and there. Roll bars and camber have changed, nothing else in this game has since the beginning of Forza. Fine tuning that base setting may take off a few tenths, and maybe a half second based on the gearing but nearly everything has values based on a % of the bar that are the same. A 3300 lb car is going to be stiffer than a 2300 lb car but it's going to be in the same area on the bar.

I would bet an absolute ton of money that if I went to Clay, Lee, TN Eagle, Loco, DUST2DEATH, Raceboy, Craviator, and anyone you think of we all pretty much build and tune cars the same exact way. These people rarely, if ever, crank out a bad car.

Just listen to what people say when they are trying to help out. I don't post to run anyone in the wrong direction.

If you want to prove me wrong then tune a better car, I have no other way of saying it. I'll even run it for you and give you honest feedback, and don't come back with that driving style stuff either.
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#23 Posted : Monday, January 27, 2014 10:57:54 PM(UTC)
Originally Posted by: TG Wormburner Go to Quoted Post
Originally Posted by: FEUERDOG Go to Quoted Post


You can just slap someone else's values on your car and expect them to work, it's a more elaborate solution than that.


Want to bet?



Originally Posted by: unfairlane64 Go to Quoted Post
Worm; values like 25% is too low. The diff will act as an open diff with values that low. 45-60% is my 2c, or should I say 55-60



There is a reason you guys continue to struggle, and it comes from a lot of people, it's because you don't listen. It's fine to experiment and enjoy the game the way you want to but if you are going to tell me I am wrong when I've used the same basic differential settings for 5 years I don't really like it. You continue to argue when people, not just myself, keep cranking out great car after great car and giving you advice TO HELP YOU OUT. I can put the same tune on virtually every car in the game based on it's drivetrain and it will feel great and if the build is right go fast. Forza still operates under the same generic, one size fits all suspension system (with the exception of FWD which is bugged) that it always has with minor tweaks here and there. Roll bars and camber have changed, nothing else in this game has since the beginning of Forza. Fine tuning that base setting may take off a few tenths, and maybe a half second based on the gearing but nearly everything has values based on a % of the bar that are the same. A 3300 lb car is going to be stiffer than a 2300 lb car but it's going to be in the same area on the bar.

I would bet an absolute ton of money that if I went to Clay, Lee, TN Eagle, Loco, DUST2DEATH, Raceboy, Craviator, and anyone you think of we all pretty much build and tune cars the same exact way. These people rarely, if ever, crank out a bad car.

Just listen to what people say when they are trying to help out. I don't post to run anyone in the wrong direction.

If you want to prove me wrong then tune a better car, I have no other way of saying it. I'll even run it for you and give you honest feedback, and don't come back with that driving style stuff either.


+1 to this. I put pretty much the exact same starting build/TUNE on all my cars and tweak abit here and there. Run all my own builds and tunes and I run top 10s-20s-30s in various classes (A-P). The exact same builds/tunes from Froza 3 and 4. People really make the tuning harder than it is.

When I try out tunes out from Worm or Crav or any of the guys you see in the top 50 they magically feel like a tune I would do and are within tenths + or - what I run.
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#24 Posted : Monday, January 27, 2014 11:06:11 PM(UTC)
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#25 Posted : Tuesday, January 28, 2014 4:57:22 PM(UTC)
Originally Posted by: DUST2DEATH Go to Quoted Post



+100000 worm!!!!!

look you can go to any of the open source threads and see that low diff settings are the norm and the reason why is that they work for just about every car.... its cool to have an opinion but to be disrespectful to one of the many great tuners on here (not only that he is a mod!!!!!!) along with all of the others who use the same settings he posted earlier is just absurd ...


for future reference use the what worm posted above as a starting point and tweak from there until your car has behaving through the corners
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