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ACD Tuning Options - USDM CT9As, Read!

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Old Jan 13, 2012, 11:40 PM
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Modifying the yaw angle is primarily the rear diff's job. Maintaining some controllable oversteer is a lot easier to achieve with getting a new rear diff (more aggressive ramp angle plate LSD) or just making sure your USDM 8/9 rear LSD was put together properly.

Creating a polar moment with the center diff is much harder, but it works. USDM 8/9's understeer and send a lot of power to the front wheels which just turns into wheelspin. By clamping the ACD earlier and with more force it preserves a more neutral feel and gets the distribution back to 50:50.

Asking which is better to tune or which to tune first is a hard question. Doing the ACD and the rear diff yields great results but doing either individually is kind of a toss up.

It's nice to have AYC because you can do it all electronically.

Generally doing the ACD tuning will yield better braking, better turn in, and better exit speeds, eliminate understeer and promote neutrality. Doing the rear diff upgrade will yield more power oversteer.
Old Jan 14, 2012, 10:31 AM
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Originally Posted by discogodfather
Modifying the yaw angle is primarily the rear diff's job. Maintaining some controllable oversteer is a lot easier to achieve with getting a new rear diff (more aggressive ramp angle plate LSD) or just making sure your USDM 8/9 rear LSD was put together properly.

Creating a polar moment with the center diff is much harder, but it works. USDM 8/9's understeer and send a lot of power to the front wheels which just turns into wheelspin. By clamping the ACD earlier and with more force it preserves a more neutral feel and gets the distribution back to 50:50.

Asking which is better to tune or which to tune first is a hard question. Doing the ACD and the rear diff yields great results but doing either individually is kind of a toss up.

It's nice to have AYC because you can do it all electronically.

Generally doing the ACD tuning will yield better braking, better turn in, and better exit speeds, eliminate understeer and promote neutrality. Doing the rear diff upgrade will yield more power oversteer.
very good post. i would say for X acd tuning may be the first most important, but for 8/9s having proper mechanical rear lsd may be equally important to make up for lack of ayc/ some mechancial that will modify the slip angle
Old Jan 25, 2012, 06:48 PM
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question, is the ACD unit the same thing as the ECU unit? If so will this reflash hurt my performance tune from AMS?
Old Jan 25, 2012, 06:57 PM
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Originally Posted by grey~ghost
question, is the ACD unit the same thing as the ECU unit? If so will this reflash hurt my performance tune from AMS?
No, it's totally separate from the ecu. ACD tuning will do nothing to the ecu at all. The only thing it (acd tuning) does, is make the car handle better and help you lay down the power better entering, going through, and exiting turns.

Matt
Old Jan 25, 2012, 07:09 PM
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awesome, sorry for the dumb question.
Old Jan 25, 2012, 07:46 PM
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Originally Posted by grey~ghost
question, is the ACD unit the same thing as the ECU unit? If so will this reflash hurt my performance tune from AMS?
No and no. The ECU and ACD are two separate units.
Old Jan 25, 2012, 08:15 PM
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Originally Posted by grey~ghost
awesome, sorry for the dumb question.
It's not dumb...no worries man. Nothing wrong with being on the side of caution

If you don't find answers to any other questions answered in this thread, feel free to ask- open forum afterall.
Old Jan 26, 2012, 04:02 PM
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does anyone have any experience running a wide body kit along with the acd re-flash and dif upgrade combo? im planning on doing both upgrades with GTworx springs , whiteline FSB and RSB and maybe later down the line a voltex wide body kit with some 17x10's..im wondering if the wide traction will help or just be overkill..
Old Jan 27, 2012, 08:42 AM
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Originally Posted by grey~ghost
does anyone have any experience running a wide body kit along with the acd re-flash and dif upgrade combo? im planning on doing both upgrades with GTworx springs , whiteline FSB and RSB and maybe later down the line a voltex wide body kit with some 17x10's..im wondering if the wide traction will help or just be overkill..
Yes, George Slavov has a similar setup but he has custom coilovers. His setup can be found in the January issue of Modified Magazine. He is running a modded acd unit as well....

Matt
Old Feb 29, 2012, 04:16 PM
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BUMP stoked to see some more reviews as the season gets underway!
Old Feb 29, 2012, 05:06 PM
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Originally Posted by discogodfather
Asking which is better to tune or which to tune first is a hard question. .


Some folks may disagree but I really feel that the first of those two mods imo would be the acd flash---- IF that flash is one that does NOT cause the binding issue like the GS race flash. I only got rid of the binding after my TRE rear diff was put on. The advantage with an acd tune is that you get a couple different settings of how aggressive you want it to be. That really is a nice feature for when it starts to rain in the middle of your track day.


With the ACD tune you have different maps with different levels of aggresiveness. Just like a swaybar which may have different settings for stiffness, for example. With a TRE rear diff your really limited to changing its aggresivness-- mostly with just using different fluids with different levels of friction modifiers. my .02
Old Feb 29, 2012, 05:28 PM
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What do you guys recommed... ACD tunning or gruppe-s? Looking for a street/track set up (mostly street with monthly trips to track)... Was looking at the race set up from gruppe-s or the acd tunning street, track and autocross setup (Stage 3- 3 map flash) ...Any input is greatly appreciated

Have read about the binding on tight turns on the gruppe-s acd flash but sounds like nothing on the acd tunning flash... Kinda leaning toward the acd tunning flash but find myslef confused...
Also note that I will be ordering a TRE diff once Jon at TRE is back up and running!
Old Feb 29, 2012, 06:29 PM
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Newsflash: Evo X SAWC reading/rom development has discovered many new AYC tables. I have a feeling some key AYC tables are missing from the 8/9 xmls/roms out there.
Old Feb 29, 2012, 06:49 PM
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Originally Posted by foxbear2277
What do you guys recommed... ACD tunning or gruppe-s? Looking for a street/track set up (mostly street with monthly trips to track)... Was looking at the race set up from gruppe-s or the acd tunning street, track and autocross setup (Stage 3- 3 map flash) ...Any input is greatly appreciated

Have read about the binding on tight turns on the gruppe-s acd flash but sounds like nothing on the acd tunning flash... Kinda leaning toward the acd tunning flash but find myslef confused...
Also note that I will be ordering a TRE diff once Jon at TRE is back up and running!
the street flash from Gruppe-S isnt supposed to have that binding issue. I cant vouche for that as I have never tried it, but that is what I hear. I feel that ACD tuning is making advancements with the acd computer that just wasnt available when gruppe-s came out with their flash, like MS Dos vs Windows. Thats my input on it and I own a gruppe-s race flash.
Old Mar 10, 2012, 08:07 PM
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bump for more reviews


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