Ralliart Active Center Differential Controller
Feb 16, 2010, 08:41 PM
#61
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I don't have any significant experience on gravel (yet), but I would hazard a guess that the new trick-diff cars probably also benefit from a more tidy line on loose surfaces. Sliding sideways steals forward speed, so if the diffs can help you with transitions such that you can run a less dramatic style than I'd imagine you could probably be quicker overall. Speculation, but I'll be testing my hypothesis more this year when the car is converted to gravel.
Feb 16, 2010, 08:44 PM
#62
That's not true. You can make the lock-up be the same, but the reaction times and how it behaves under certain conditions are going to be different between the various types.
The other thing you need to remember is that Helical-type diffs stop working when one wheel gets in the air (basically sends all power to the wheel in the air). So, if you're running a set up that lets you lift a rear wheel (which many auto-x guys do), then a standard LSD is going to work best.
The other thing you need to remember is that Helical-type diffs stop working when one wheel gets in the air (basically sends all power to the wheel in the air). So, if you're running a set up that lets you lift a rear wheel (which many auto-x guys do), then a standard LSD is going to work best.
Feb 16, 2010, 08:56 PM
#63
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oh? I understand that about the different types working in different ways, but I wasn't aware that they all provided at least very similar amounts of lock up. From what I've seen, at least Carbonetics claims that it gets twice the amount of lock up that standard LSDs do, and I've heard that the Cusco allows for more power oversteer than the Tre unit, which I assumed to mean it transferred more torque.
At some point you hit the law of diminishing returns. You don't always need MORE lock-up, or we'd all just run welded diffs and deal with the massive understeer that creates. What you want are good behaviors at turn-in, part-throttle, power-on, etc. That's why a car like the BMW X6 uses what is effectively an ACD in the rear diff as well as the center -- you can tune those behaviors based on steering input and throttle. The alternative for us is to find a diff with the behaviors we like and then tune the suspension to use it properly.
This does raise a good question -- what suspension are you running? Spending all of this time and money on diffs is only going to be worth it if you have already maximized the suspension components, and then tuned it to your car.
Feb 16, 2010, 08:57 PM
#64
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Watch Sebastian Loeb, Gilles Panizzi, Francois Duval, etc. The tarmac masters don't throw the car around at all. If you're scrubbing the tire sideways you are losing speed -- that simple. The principles of physics and how a tire contact patch works the same regardless of whether that pavement is on a public road or a closed course. Even Mikko went to some road racing schools to improve his performance on tarmac against the Frenchman. ;-)
http://www.youtube.com/watch?v=bEyaZX30qWc
Dave
Feb 16, 2010, 09:02 PM
#65
It all depends upon how it is set up. You can weld a standard LSD together and get 100% lock-up if you choose. ;-) TRE has different levels of lock-up they can build to, and a custom diff builder can do others. My understanding of the carbonetics is that it's designed to be tuned in this way easier than a stock rebuild can be done. The helical types will have a set lock-up under certain conditions.
At some point you hit the law of diminishing returns. You don't always need MORE lock-up, or we'd all just run welded diffs and deal with the massive understeer that creates. What you want are good behaviors at turn-in, part-throttle, power-on, etc. That's why a car like the BMW X6 uses what is effectively an ACD in the rear diff as well as the center -- you can tune those behaviors based on steering input and throttle. The alternative for us is to find a diff with the behaviors we like and then tune the suspension to use it properly.
This does raise a good question -- what suspension are you running? Spending all of this time and money on diffs is only going to be worth it if you have already maximized the suspension components, and then tuned it to your car.
At some point you hit the law of diminishing returns. You don't always need MORE lock-up, or we'd all just run welded diffs and deal with the massive understeer that creates. What you want are good behaviors at turn-in, part-throttle, power-on, etc. That's why a car like the BMW X6 uses what is effectively an ACD in the rear diff as well as the center -- you can tune those behaviors based on steering input and throttle. The alternative for us is to find a diff with the behaviors we like and then tune the suspension to use it properly.
This does raise a good question -- what suspension are you running? Spending all of this time and money on diffs is only going to be worth it if you have already maximized the suspension components, and then tuned it to your car.
Feb 17, 2010, 02:02 PM
#66
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Totally true - I'm on a very simple suspension set up, aftermarket bilsteins and springs. Car is totally not a race car by any means, just a simple street car that I'm toying around with. I love a good power oversteer, so I went with a diff that I believed would bring that to the table. I do, however, regret not moving to a decent set of coilovers right away. It's on the list. Otherwise, my main mods to the suspension are some bushings for geometry fixes. Definitely not claiming that I have or want a race car, just looking for some effective mods for my evo
If I were in your shoes, I would spend the money on a proper set of DA coilovers with spring rates that work for your street driving as well as a proper set of swaybars from the car (I like the Whiteline stuff). That will make the car more neutral. You can then finish balancing the chassis with the Ralliart controller and a TRE rear diff.
IMO -- if you want power-on oversteer, you're in the wrong car. I daily drive a BMW M3 and road race BMWs and Porsches. Those cars have power-on oversteer. The best you can hope for with an Evo is neutral turn-in and a nice drift on the exit. :-)
Feb 17, 2010, 02:06 PM
#67
No offense, but if this is true you are likely spending big $$ for small increments when you could be spending the same money for bigger increments. If you buy a MoTeC ACD controller and trick front/rear diffs, you'll spend more than you would have for a high-end set of Ohlins race shocks, but you'll only see 1/10th of the performance increase.
If I were in your shoes, I would spend the money on a proper set of DA coilovers with spring rates that work for your street driving as well as a proper set of swaybars from the car (I like the Whiteline stuff). That will make the car more neutral. You can then finish balancing the chassis with the Ralliart controller and a TRE rear diff.
IMO -- if you want power-on oversteer, you're in the wrong car. I daily drive a BMW M3 and road race BMWs and Porsches. Those cars have power-on oversteer. The best you can hope for with an Evo is neutral turn-in and a nice drift on the exit. :-)
If I were in your shoes, I would spend the money on a proper set of DA coilovers with spring rates that work for your street driving as well as a proper set of swaybars from the car (I like the Whiteline stuff). That will make the car more neutral. You can then finish balancing the chassis with the Ralliart controller and a TRE rear diff.
IMO -- if you want power-on oversteer, you're in the wrong car. I daily drive a BMW M3 and road race BMWs and Porsches. Those cars have power-on oversteer. The best you can hope for with an Evo is neutral turn-in and a nice drift on the exit. :-)
Dec 26, 2012, 06:30 PM
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Ralliart ACD ECU for sale
Hey guys-
Just listed a new Ralliart ACD ECU I've had as a spare on ebay:
http://www.ebay.com/itm/110993747233...witem=&vxp=mtr
PS the GEMS ADC ECUs absolutely burn pumps - for fast response time they keep the pressure wound up constantly. I have a GEMS backup mounted in the car and use it to bleed the system or in case of ABS sensor fail, but it's a very aggressive strategy. After testing almost everything, we found (surprise) Ralliart knew what they were doing.
ACP
Just listed a new Ralliart ACD ECU I've had as a spare on ebay:
http://www.ebay.com/itm/110993747233...witem=&vxp=mtr
PS the GEMS ADC ECUs absolutely burn pumps - for fast response time they keep the pressure wound up constantly. I have a GEMS backup mounted in the car and use it to bleed the system or in case of ABS sensor fail, but it's a very aggressive strategy. After testing almost everything, we found (surprise) Ralliart knew what they were doing.
ACP
Last edited by ACP; Dec 26, 2012 at 06:34 PM.
Dec 28, 2012, 09:30 PM
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In truth, I'm not really here much. Sadly, I drive for Toyota now. But I have a truck-load (literally, this came out of the truck) of parts. Get in touch with needs. I don't use the PMs here, email me at acp(at)acpracing(dot)com.
ACD ECU sold on Buy it now today. Hope it was someone here! Evolutionm has always been very supportive of our efforts.
Best,
ACP
www.acpracing.com
ACD ECU sold on Buy it now today. Hope it was someone here! Evolutionm has always been very supportive of our efforts.
Best,
ACP
www.acpracing.com
Dec 30, 2012, 02:59 AM
#75
Faster - more customizable. For start my GEMS has 5 settings from the start including a fully lock to the fully open stages. For motorsport those ecus are much better then the oem one's.
In my case here is a picture when my tuner sets up my ACD ECU to my tarmac set up and for my driving style. He looking the throttle - brake - speed and rpm relation to my ACD ECU tarmac settings , and fine tunes -customize the maps on the ACD ECU to those values. To make the car behave better in braking -turning - accelerating when i am driving the car. He needed a full race day to set up the way he thought it will be fine for a time being.
SO we did took a whole hillclimb event to set up the car for tarmac with my driving style.
That is a reason why you need something like aftermarket ecu for you engine and acd.
Funny way to say it, its like compering the Commodore 64 to the Alienware.
the picture:
