R33 GTST MSPEC ACTIVE LSD NEED HELP!

[niZmO_Man]

Someone can make a "one-off" run of 100, and sell them for double the cost price, easy money there (considering the asking prices of used parts + GT-R tax these days)

[GTSBoy]

Should really go talk to a gearbox&diff specialist who might have knowledge of the internals of these active diffs to find out what they think it would take to jam one of the available mech centres in. When you get right down to it, they are still an R200 case and otherwise very similar. Maybe it's just the side bearings spacing or something that makes it hard, and with a little effort or shim/spacer swappsies or use of a centre intended for a Toyota.something else or any of a bunch of hopefully not difficult things, make something work.

Ideally you'd want to use the original stubs and half shafts, but if you had to swap to something else, say the Nismo ones that come with Nismo centres, that would surely have to be palatable enough to the wealthy GTR owner with a bung active diff.

Edited September 3, 2020 by GTSBoy

[joshuaho96]

What is wrong with the active LSD? My understanding is that it basically locks up on throttle and unlocks off throttle, that's all there is to it. What would be interesting is if someone actually added some form of feedback control to it.

[GTSBoy]

26 minutes ago, joshuaho96 said:

What is wrong with the active LSD?

Like all Nissan electronic control ideas of the era, the technology wasn't as good as the idea, and after 25 years, they don't work properly (as in, not even as well as they worked when they were new).

Even in the EVOs, which at about EVO9 era (ie much later than GTRs) had something very similar, the active diff is a piece of shit that everone who drives them hard wants to rip out and replace with the simple mech diff out of an RS. They offer very changeable performance and you can't trust them to always give you the drive you need.

HICAS sucks. The active diffs suck. Viscous diffs suck. Ceramic turbos suck. There is a lot of suck to be removed from these cars.

[joshuaho96]

36 minutes ago, GTSBoy said:

Like all Nissan electronic control ideas of the era, the technology wasn't as good as the idea, and after 25 years, they don't work properly (as in, not even as well as they worked when they were new).

Even in the EVOs, which at about EVO9 era (ie much later than GTRs) had something very similar, the active diff is a piece of shit that everone who drives them hard wants to rip out and replace with the simple mech diff out of an RS. They offer very changeable performance and you can't trust them to always give you the drive you need.

HICAS sucks. The active diffs suck. Viscous diffs suck. Ceramic turbos suck. There is a lot of suck to be removed from these cars.

Ceramic turbos suck admittedly if you want to run more than 1 bar boost but it seems to me that HICAS and the A-LSD are more suffering from relatively archaic control systems than actual problems with the actuators. I have a feeling if you could put in modern sensors and modern control algorithms these systems would not be as maligned as they are now. 

[GTSBoy]

41 minutes ago, joshuaho96 said:

HICAS and the A-LSD are more suffering from relatively archaic control systems than actual problems with the actuators. I have a feeling if you could put in modern sensors and modern control algorithms these systems would not be as maligned as they are now. 

Yuh, but that's the point. They sucked when new and they only got suckier as they aged and wore and stopped working even as well they originally did (which was not that well).

Aussies have been living with this shit for >20 years. We have no rose-tinted glasses when it comes to this sort of piss poor engineering.

[joshuaho96]

11 hours ago, GTSBoy said:

Yuh, but that's the point. They sucked when new and they only got suckier as they aged and wore and stopped working even as well they originally did (which was not that well).

Aussies have been living with this shit for >20 years. We have no rose-tinted glasses when it comes to this sort of piss poor engineering.

Right, but the point is that it's possible to have a HICAS and A-LSD controller that does a lot better, much like the replacement ATTESA controllers out there. The electric HICAS systems, properly refreshed, are probably not that far off from a modern 4WS system in the actuator, just stone-age era design in the control logic. The A-LSD seems to be comparable in that regard, lots of modern cars have actively controlled LSDs as well. 

[GTSBoy]

Yeah, but you're arguing that it could be better. As in could be made better.

it wasn't made good to start with and it has only gotten worse. The only active LSDs that have been of any value are in the last 10 years or so, and they only turn up on very expensive cars and they rely on the massive increase in computer power to get the job done. The shitty 3-bit half analogue bullshit used in the early Japanese versions was not up to the task. Same with 4ws. Only comes on expensive cars (Porsches, various supercars, etc), for the same reasons. And, in 10 years when all those cars have a few miles on them and it starts malfunctioning, it will be a f**king nightmare for the owners

Normal cars don't need that shit. More to the point, people who want to flog a Skyline (ie, not a normal car, because we're all modding the f**k out of them to make them "track") around want something hard edged and reliable/repeatable.

And the whole argument will go away soon because when all cars are electric then your get per wheel torque vectoring for free anyway.

[PLYNX]

Yep frigged around with this system back in 2009 and posted what I was going to do in the A-LSD section.

Worked very well in the end but I have to agree with the vast majority for the amount of effort to get it to work it would be better to get rid of it. 

[joshuaho96]

It’s definitely possible to retrofit modern ABS controllers to these old cars, so why not try and improve A-LSD and HICAS control? Bosch Motorsport sells an M5 ABS kit that can do some incredibly trick stuff, people have retrofitted these systems into stuff like SW20 MR2s. HICAS might be difficult but not impossible to improve upon.

The A-LSD controller is also definitely possible to improve upon. Nismo did it for real in the Super Taikyu cars so they weren’t a glorified gimmick. The HICAS was disabled and the yaw sensor was wired to the ATTESA controller.

Edited September 4, 2020 by joshuaho96

[joshuaho96]

Edits seem to disable themselves after some time, I found an interesting thesis paper on the subject of A-LSD and TVD control, could be interesting: https://repository.lboro.ac.uk/articles/Vehicle_handling_control_using_active_differentials/9219482

[GTSBoy]

The reason to not try to upgrade the brains is that the hardware is a million years old and failing. Who wants to have to find alternative pumps, solenoids, and all the other shit? Just dump the electronic crap, retro in known good analogue equipment and know that you're not overcapitalising on a 30 year old dirty Datsun.

Edited September 5, 2020 by GTSBoy

[joshuaho96]

10 minutes ago, GTSBoy said:

The reason to not try to upgrade the brains is that the hardware is a million years old and failing. Who wants to have to find alternative pumps, solenoids, and all the other shit? Just dump the electronic crap, retro in known good analogue equipment and know that you're not overcapitalising on a 30 year old dirty Datsun.

It's a little late to not overcapitalize on a 30 year old shitbox, I'm in way too deep at this point. My car already has an A-LSD anyways so rebuild is probably cheaper than doing a full mechanical diff conversion.

[BK]

No it's not regarding rebuilding and for the result, here anyway. I have a Quaife arse end in the 32 and I wish I could have that in the 33.

[joshuaho96]

1 hour ago, BK said:

No it's not regarding rebuilding and for the result, here anyway. I have a Quaife arse end in the 32 and I wish I could have that in the 33.

I still think that if someone actually went through the effort to get a modern control system and not whatever half-assed solution Nissan shoved out the door the A-LSD would be a clear step up. Many modern cars still use electro-hydraulic A-LSDs, stuff like the F430, 458, 991 GT3 PDK variants, etc. The sensors are basically all there already, it's just not being used properly.

 

[Nostalgia]

I've also got the a-lsd on my '97. never really noticed the diff. probably because i've never taken it to the tracks.

If it ever starts causing problems do you think it's better to get a modern KAAZ 1.5 SUPER Q or keep it? the torque split / pump device is apparently 4.5k brand new from nissan.