1-Way vs 1.5-Way Rear Differentials
Aug 19, 2024 | 05:40 AM
#301
Evolved Member
Joined: Mar 2008
Posts: 2,064
Likes: 288
From: Croatia
I suppose a poor choice of wording on my part, but what I should've said was the system can be bled, so it's possible to move new fluid through the system.
The ACD/AYC system was advanced for its time, but designed close to 30 years ago, there are superior systems that have come around since. The newer electronically controlled viscous couplings can react faster, all they have to do is energize a solenoid that pushes on a ball and ramp system on one side of the clutch pack, it's a pretty instantaneous response. The main advantage of the ACD system is the fact that people have come up with better control calibrations and being that it has its own computer it's a fairly isolated system from the rest of the car other than ABS, newer systems require much more digging to figure out what it would take to alter calibrations for them. It's also a system that's more easily repaired than a lot of the newer systems since it's so mechanical.
The ACD/AYC system was advanced for its time, but designed close to 30 years ago, there are superior systems that have come around since. The newer electronically controlled viscous couplings can react faster, all they have to do is energize a solenoid that pushes on a ball and ramp system on one side of the clutch pack, it's a pretty instantaneous response. The main advantage of the ACD system is the fact that people have come up with better control calibrations and being that it has its own computer it's a fairly isolated system from the rest of the car other than ABS, newer systems require much more digging to figure out what it would take to alter calibrations for them. It's also a system that's more easily repaired than a lot of the newer systems since it's so mechanical.
yes, it can also be equipped with a cooler if nedeed.. (both ACD and AYC)
I have been toying with the idea of an aftermarket diff controller, for both the ACD and AYC... only to be able to reprogram it to my liking and more easily than OE stuff.. I did some work on the maps to make it better on snow and the thing just rocks. Stock logging is **** though..
fun fact.. the team developing a well known hypercar that uses 4WD torque vectoring used the ACD/AYC evo9 as a demo car to teach the young engineers how it can be done..
Aug 19, 2024 | 09:11 AM
#302
Its hard to say if that's front or rear diff related. I don't recall which diffs you have but either can cause that. The wavetrac with 2nd gear torque can be overwhelmed on inside tire when really leaned over. Its basically a torque multiplication of its grip and there's not that much at high steering angles.
But the rear can also cause this if you are trying to put power down and have no or little preload in the rear diff. Once the inside tire spins up it tries to lock the center and cause the car to push out. With front and rear diffs working well, we can roll on throttle at apex and leave every corner with a neutral 4-wheel power slide. This is one of those things I wish everyone could drive my car and feel it. Its probably the easiest car to get 90% out of.
But the rear can also cause this if you are trying to put power down and have no or little preload in the rear diff. Once the inside tire spins up it tries to lock the center and cause the car to push out. With front and rear diffs working well, we can roll on throttle at apex and leave every corner with a neutral 4-wheel power slide. This is one of those things I wish everyone could drive my car and feel it. Its probably the easiest car to get 90% out of.
thank to this slight rub I was able to get an idea how much my car would sit. I had no idea 1200# rear spring actually gets compressed this much when the torque hits at 4k (was 3.7k) rpm
I'll definitely look into LSDs after I sort out some other issues
Aug 21, 2024 | 09:23 PM
#303
EvoM Guru
Joined: Mar 2009
Posts: 1,406
Likes: 275
From: New Zealand
can you bench flash the evo ACD computer? I have a spare one i wouldnt mind trying to flash but the OBD system has been removed in my custom loom so id have to power it on a bench and flash it on the bench.
Also regarding alignment i have gone to 2 - 3 mm toe out all round also. definitely helps with rotation
Also regarding alignment i have gone to 2 - 3 mm toe out all round also. definitely helps with rotation
Aug 22, 2024 | 09:07 AM
#306
I think its more appropriate for AutoX with the direction of setup we have gone. The "american" style of 50-100% more rear spring would do better on my current tune. But the "euro/jdm" style of heavy front springs and swinging the rear around things would do better with the ER tune.
Major difference is the ER tune tries to break the rear free, but if that doesn't happen then the center feels very bound up and its hard to do anything at that point. My approach is to let the suspension and driving dynamics rotate the car and the diff is there to mostly just help with putting power down and braking. My tune heavily relies on good diffs too, so the better the diffs the less we need from the center.
Major difference is the ER tune tries to break the rear free, but if that doesn't happen then the center feels very bound up and its hard to do anything at that point. My approach is to let the suspension and driving dynamics rotate the car and the diff is there to mostly just help with putting power down and braking. My tune heavily relies on good diffs too, so the better the diffs the less we need from the center.
Aug 22, 2024 | 09:19 AM
#307
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