ATTESA system...

[ferni]

I've read a few different things about the ATTESA system and how it detects slip..

From what I know, it checks certain things at 10/100/1000 times per second depending on the model/version of GTR you have...

What I want to know is what are these 'certain things' and do these things differ between model/versions ?

I found this:

The GT-R uses an electronically controlled all-wheel-drive system (similar to Porsche's 959). A 16-bit microprocessor monitors the car's movements a 100 times per second, including wheel rotation and lateral as well as longitudinal acceleration. When slip is detected at a driving wheel, the system electronically distributes torque from this spinning wheel to one without slip.

How does it detect wheel slip? by seeing if front and rear wheels are spinning at different speeds? What if it is just one wheel?

What about the lateral/longitudinal sensors? Where are they? How many are there? at what g-force do they kick in etc?

Are there any other factors that can cause power to be put to the front wheels?

The reason I'm asking is recently I've noticed my torque gauge moving a bit more than normal, i.e. coming on earlier, and a little more aggressive, I can actually feel the front wheels pulling me now when it kicks in...

The recent things I have changed on my car is, a new clutch, and when putting this in we drained the fluid from the center clutch that the ATTESA controls (I think?)

When we started the car again, on the hoist, 4 wheels started spinning (in 1st gear) and the ATTESA reservoir in the boot went from just over 'MAX' to just over 'MIN'... so new fluid in there? (what kind of clutch is in there/how does it work?)

Also just put 4 brand new tyres on, which are a lot better than my old 326 falkens, old tyres were also very scrubbed on the inside....

Thanks in advance

[Emre]

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[Emre]

ferni, (what is your name btw)

Your g sensors are under the centre console in between two front seats.

When changing drive shafts, i noticed gears on the end of the shaft. I suspect they are there to sense speed of each wheel.

The transfer case 7 wet clutch discs in there to lock the system up. It operates in similar fashion to motorcyle clutch packs but are operated by the ATTESA pump. Increasing the amount of clutch packs will give more drive to the front wheels. Ben @ RacePace does this mod and installs 10 clutch packs in there.

ATTESA pump has to have no air in the system to work up to full potential, so it has to be bled if the system is interrupted while taking the gearbox out.

The fluid in the ATTESA and transfer case is not shared. If you emptied the transfer case, you have to fill it back up; it doesn't get its fluid from the reservoir in the boot.

[ferni]

Emre: Name is Andrew I belive you know Brett (SS)...

Sorry may be some dumb questions coming...

The fluid we that came out when taking the gearbox out, came from a thin pipe with heatsheilding around it which we traced to the rear of the car... What is this fluid for? and where does it go? and what type of fluid is it?

As far as i know this was the only fluid that came out when removing the gearbox? Should there have been more?

Thanks for your help.

[Emre]

Yes Andrew, I know Brett.

That is the fluid used by the ATTESA system and is connected to the reservoir in the boot. It's controlled by an electric pump which activates when needed.

The system has to be bled in your case.

Only other fluid that could have come out would have had to be done manually. Like taking the drain plug out from the gearbox or transfer case.

[ferni]

Nope didn't take any drain plugs out, so it was definatly the ATTESA fluid...

So i need to bleed the system then? Will it be doing bad things at the moment since we didn't bleed it?

[Emre]

It just will not work to its full potential, like having some air on your brake lines.

Nothing drastic and to panic about.

The procedure :

Disconnect the plug in the picture to reduce the pressure in the ATTESA system. It's a white long plug and located near the fuses in front of your right knee when driving.

Fill the reservoir in the boot up a little above max. line and start the car.

Lift the car on the hoist and crack open the bleeder valve above the hose you'd disconnected when taking the gearbox out. As the air and fluid coming out the pump will activate to pressurize the system. Bleed the system till air pockets stop coming out.

Lower the car, top up the reservoir while engine is off and connect the plug back.

[ferni]

Wicked, thanks heaps mate

What fluid does it take?

i read somewhere that that white plug your telling me to unplug, you can unplugg it and within 10seconds of starting the car or something if your press the brake pedal 5 times, it disbales the ATTESA, is that right?

thanks again

[Emre]

The system uses ATF.

I heard about the procedure you are talking about but never tried it.

Even if it worked, i wouldn't be comfortable enough to put the car on a 2WD dyno after that procedure. It may bring some extra fun factor on the street, that's about it IMO.

[Guest two.06l]

The system uses ATF.

I heard about the procedure you are talking about but never tried it.  

Even if it worked, i wouldn't be comfortable enough to put the car on a 2WD dyno after that procedure. It may bring some extra fun factor on the street, that's about it IMO.

we use yellow power steering fluid avail from ford dealers seems to work the best

[ferni]

I tried the 2wd thing just to see if it worked, a light is suppose to flash on your dash, but i never got any flashing light so didn't bother - and yeah i wouldn't use it on a dyno

[Emre]

we use yellow power steering fluid avail from ford dealers seems to work the best

You may be correct there.

Nissan recommends to use Nissan special power steering fluid in the ATTESA system.

Anyone know the differences in between ATF and power steering fluid...?

I thought they were pretty much the same thing.

[ferni]

Anyone know how to test/check the g sensors ?

I've noticed what you mean now Emre, i can't get the torque gauge above about 2-30 since i haven't bleed it...

When driving in a straight line on full throttle, which gears and when do you normally notice your getting front torque?

[Emre]

That's something I haven't paid much attention to Andrew, I am normally watching the road on full throttle. The gauge is not scaled linearly as well which makes it little harder to read.

However, you don't necessarily need to break traction for the torque gauge to start moving. On the highway doing 110 km/h in 5th, if I go full throttle, the gauge will start moving slightly.

The g-sensors are an electronic device, so you should be able to test it with a multi meter. I have never done it.

[ferni]

Doing 110 on the hwy and putting my foot down in 4th/5th causes it to come on a tiny bit for me as well....

I guess I'll need to find these sensors, and get a friend to test while im trying to get some G's happening, or i can just assume they are working

[Sydneykid]

Hi ferni, the G sensors in the ATTESA system are not "on" or "off" type sensors. They are calibrated for increasing or decreasing G force as well as the obsolute value. So if you are going down hill at 100 kph and put your foot down in 5th in a GTR with 200 rwkw, the result will be different G force readings to a GTR with 300 rwkw going up hill at 100 kph and putring your foot down in 5th. Since the result is different the readings on the torque split gauge are also different, this is despite the fact that both cars are in 5th gear at 100 kph.

You then need to add in the wheel speed differential ie; if the rear wheels are suffering form lack of traction (even slight amounts) this will affect the torque split.

This is a simplistic example, by the time you add bumps in the road, how steep the hill is, how long the pedal is to the metal, how quick the pedal is pushed, the turbo spool time, throttle response, suspension tune etc etc the results are highly variable. Plus every car is different. We find an ATTESA controller is essential on the race cars.

Hope that helps

[Amaru]

Im having a "problem" with the ATTESA on my R32 GTR (non vspec) and since theres already a thread open about it, thought id ask here

Its constantly putting torque to the front wheels, even on light throttle. When I first got the car, it would rarely start putting torque to the front unless I was full throttle or wheelspinning. Now even on light throttle its putting torque to the front, and just cruising along the highway (flat) in 5th gear its constantly putting torque to the front. Anyone know of what causes this problem?

[meshmesh]

Amaru,

not sure if this helps, but I noticed my torque split playing around when...

1) After filling my tyres with Nitrogen (set to 37psi) the torque split to the front was more than normal, and sometimes constant.

2) Uneven tyre wear from the front & rear

3) different wheel/tyre size front & rear

[ferni]

Thanks SK, that all makes sense.

When you are talking about an ATTESA controller, is this the same as a torque split controller? When on the race track, what exacly do you use it for (i think i know what it does - just adjusts/bias's if it should put power to the front wheels more or less?)

Do you play with it on warm up laps, get it set to how you like for that day/conditions of track? or do you play with it constently during the race, or is it just set to 1 setting and thats it?

[ferni]

Btw Power Steering Fluid and ATF are the same thing