Diff Fluid and Oversteer

[ansibe]

Originally Posted by FRSBRZGT86FAN

Why do drifters lock their axles together?
Because drifters care very little about handling, they want both wheels locked together so they spin at the same time and at the same speed. Alternatively they may go for 2 way LSDs

Come on dude, you're pushing it, in what world would the Diff fluid effect over-steer on this car? have you owned other cars that induced over-steer because of the fluid? What led you to that conclusion?

Also your mclaren and lotus examples don't even apply here

McLaren P1: They use frictional balancing with brakes/electric motors so they don't need an LSD system as they can be more precise without it.

Mclaren MP4,670s, 570 etc: Use brakes on the inner wheels at times moments, also the suspension is adjusted on the fly, they also have NO sway bars everything is connected electronically or hydraulically and adjusted in split second intervals (this is in the P1 as well)

For the lotus: A limited slip differential matters more in wider, heavier cars than it does in narrow lightweight cars, FYI, because the different radius paths of travel are smaller, and the distribution of weight left-right during a corner is smaller as well. They are famous for saying it here:
http://www.lotustalk.com/forums/f25/...06/#post552007

How plain do I need to be...

The point of my rhetorical questions was that differential behavior affects chassis balance. I think the oil you run in your diff will affect the way it reacts, and therefore the car's balance.

I used Amsoil GL-5 in my transmission, and it sucked. My bad, switching to Redline GL-3 made a huge difference.

I used Amsoil in my diff .... and I have oversteer.

[mav1178]

Originally Posted by ansibe

I think the oil you run in your diff will affect the way it reacts, and therefore the car's balance.

You don't know how a Torsen diff works, hence the misunderstanding.

[ame="https://www.youtube.com/watch?v=JEiSTzK-A2A"]Torsen Differential, How it works ? - YouTube[/ame]

[ansibe]

Originally Posted by irax

LOL changes springs and doesn't understand that it will affect handling characteristics.

Your brain fluid needs to be changed.

Look, from the fact that you know the FRS springs are stiffer and you changed them on the rear it should be no surprise to you that it would induce oversteer.

Why would you even think that its related to the fluid ?

Of course I knew FRS springs would move grip to the front. Because I'm using BRZ fronts (also stiff), I'm still softer (relatively speaking) at the rear than the FRS.

If you're not contributing to the discussion, go troll another thread.

[ansibe]

Originally Posted by mav1178

You don't know how a Torsen diff works, hence the misunderstanding.

That video is awesome! Thank you. This is just the response I needed. I guess as long as the diff fluid 'lubricates', I'm good. I wonder why there are different specs for transmission and Diff oil. Must be materials ...

[cdrazic93]

Originally Posted by ansibe

If you're not contributing to the discussion, go troll another thread.

Im sorry if what you dont want to hear is critism and you assume its trolling. Welcome to the internet.

[mav1178]

Originally Posted by ansibe

That video is awesome! Thank you. This is just the response I needed. I guess as long as the diff fluid 'lubricates', I'm good. I wonder why there are different specs for transmission and Diff oil. Must be materials ...

My problem with this thread (and thread title) is that I spent more time (~15 seconds) researching the problem online than you did.

And found the solution you wanted faster than you were able to type responses to trolls, which is to be expected given the noob nature of the thread title.

-alex

[FRSBRZGT86FAN]

Originally Posted by cdrazic93

Im sorry if what you dont want to hear is critism and you assume its trolling. Welcome to the internet.

This is the type of person I wouldn't want modding the car, does everything all at once and then blames the wrong thing for oversteer.

[cdrazic93]

Originally Posted by FRSBRZGT86FAN

This is the type of person I wouldn't want modding the car, does everything all at once and then blames the wrong thing for oversteer.

Not nessecarily blaming, but just misinformed. Then draws conclusions based off of, well I dont know. The way he worded the OP was a matter of fact kind of statement rather than conceding that he may be wrong in his assumptions. Regardless, I was there at one point but I also googled and googled when I was younger. I only asked questions when I was 100% confused and had exhausted my research capabilities, which does extend to the search function on this forum (not to say this topic has already been covered, but theres a whole heap of topics that have).

[NissanGuy]

You seem convinced, and I'm not saying you're wrong. change the fluid back and see if it corrects the oversteer.

[solidONE]

Originally Posted by ansibe

We have almost identical setups. The Koni's seem to have far less compression damping than OE, which may be allowing the front to drop with corner loads.

Your alignment is more aggressive than mine, but you don't seem to be having any trouble. What tires are you running?

I'm no longer using this set up. I did run hankook rs3 tires in 215/45/17 and 225/45/17 as well as Goodyear F1 assimetrical 245/40/17 with that set up.

[irax]

Originally Posted by ansibe

Of course I knew FRS springs would move grip to the front. Because I'm using BRZ fronts (also stiff), I'm still softer (relatively speaking) at the rear than the FRS.

Even though the shock is still from your brz, you put in a stiffer spring. This is what changed your handling characteristics. What did you think was going to happen ? What was your planned outcome from this ?

[CSG Mike]

Originally Posted by FRSBRZGT86FAN

Why do drifters lock their axles together?
Because drifters care very little about handling, they want both wheels locked together so they spin at the same time and at the same speed. Alternatively they may go for 2 way LSDs

Come on dude, you're pushing it, in what world would the Diff fluid effect over-steer on this car? have you owned other cars that induced over-steer because of the fluid? What led you to that conclusion?

Also your mclaren and lotus examples don't even apply here

McLaren P1: They use frictional balancing with brakes/electric motors so they don't need an LSD system as they can be more precise without it.

Mclaren MP4,670s, 570 etc: Use brakes on the inner wheels at times moments, also the suspension is adjusted on the fly, they also have NO sway bars everything is connected electronically or hydraulically and adjusted in split second intervals (this is in the P1 as well)

For the lotus: A limited slip differential matters more in wider, heavier cars than it does in narrow lightweight cars, FYI, because the different radius paths of travel are smaller, and the distribution of weight left-right during a corner is smaller as well. They are famous for saying it here:
http://www.lotustalk.com/forums/f25/...06/#post552007

Don't confuse traction control with a "simulated electronic limited-slip differential"

[FRSBRZGT86FAN]

Originally Posted by CSG Mike

Don't confuse traction control with a "simulated electronic limited-slip differential"

What do you mean? I'm not talking about electronic brakeforce distribution or traction control, it's literally just brakes the inner wheel, it was in their press docket, they use frictional balancing with brake.

[CSG Mike]

Originally Posted by ansibe

I made several changes to my BRZ at once, and now I have a slight oversteer problem. Mods:

-dampers changed to Koni Yellow
-rear springs swapped to OE FRS (stiffer)
-Aligned to -1.5 camber and 0 toe all around.
-Diff fluid changed to Amsoil 75w-90 GL-4
-No change to the sways. I'm on OE BRZ

I Think the component changes are pretty conservative, so I'm surprised how much more oversteer I have. It's fun, but I'm not a drifter so I want grip.

Could this be caused by the diff locking early because of the fluid I'm using? I think I should have used GL-5.

The bolded parts promote oversteer.

I need more details on how and when you are oversteering, to give you guideance on how to possibly eliminate it. Corner entry? Mid corner? Exit? On-throttle? Off-throttle? On i ncreased throttle? On decreased throttle? On lift?

There are many variables, none of which I've seen anyone commenting on this thread really thoroughly examine. Everyone is examining a piece of the puzzle, that they've had experience with.

Instead, lets look at the whole picture.