OS Giken - advantages /disadvantages over Torsen
#1
OS Giken - advantages /disadvantages over Torsen
Am in the early fine tuning stages of my road/race car in it's current state.
Pondering my next lap time improvement upgrade/purchases.
A comment I notice Emilio made on a thread just read has me wondering if people have any comment on OS Giken or equivelant v torsen 1 and 2 diffs (I have a 4.3 v1 and a 3.9 v2 - I think I prefer the v1 style).
At this point traction isn't a serious issue but as i improve it will be. I definitely notice the difference between the torsen v1 and v2 but the different ratios probably exagerate that....
So my questions are...
- Significantly faster on track or not? (most races I do are in the 15 minute range, 8-12 laps)
- Huge NVH increase/ no difference?
- Road driveability good / bad ?
- Perhaps the difference is negligible and i should focus on other areas first..track time, more boost, 8-9" rims etc....
Pondering my next lap time improvement upgrade/purchases.
A comment I notice Emilio made on a thread just read has me wondering if people have any comment on OS Giken or equivelant v torsen 1 and 2 diffs (I have a 4.3 v1 and a 3.9 v2 - I think I prefer the v1 style).
At this point traction isn't a serious issue but as i improve it will be. I definitely notice the difference between the torsen v1 and v2 but the different ratios probably exagerate that....
So my questions are...
- Significantly faster on track or not? (most races I do are in the 15 minute range, 8-12 laps)
- Huge NVH increase/ no difference?
- Road driveability good / bad ?
- Perhaps the difference is negligible and i should focus on other areas first..track time, more boost, 8-9" rims etc....
#3
Theoretically it should be better than the torsen. In Practice, the more I deal with gikens the more I want to keep my torsen. Too much lockup and the car pushes like mad, not enough lock up and you spin the inside wheel. Not enough preload its an open diff all the time, too much pre-load and the car pushes. IMO as long as you can keep both drive wheels on the ground all the time the torsen is the better diff. If you cant keep both drive wheels on the ground, then after you spend a couple years dialing in the giken it will be better.
One caveat, I've only dealt with gikens that came from them when they had the drifters running the show. The guy who actually knows things has supposedly come back to giken USA, which means you might be able to get a cam profile that works better for actual racing.
One caveat, I've only dealt with gikens that came from them when they had the drifters running the show. The guy who actually knows things has supposedly come back to giken USA, which means you might be able to get a cam profile that works better for actual racing.
#4
Leafy I've heard pretty much the samething. I am spinning the inside tire on most corners with the torsen diff and was wondering about the giken and have been told what you are saying that it is really hard to get it set up to where you aren't understeering [to much lockup] or spinning the inside wheel [ not enough lockup]. For 2 grand I am sticking with what I have for now. Maybe they well improve it in the future.
#5
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Leafy I've heard pretty much the samething. I am spinning the inside tire on most corners with the torsen diff and was wondering about the giken and have been told what you are saying that it is really hard to get it set up to where you aren't understeering [to much lockup] or spinning the inside wheel [ not enough lockup]. For 2 grand I am sticking with what I have for now. Maybe they well improve it in the future.
The whole "a torsen is better if you can keep the wheel on the ground" is total BS as well - Torsens will only transmit torque in proportion to the force on the inside rear, so as you corner harder and harder, it moves less and less power to the outside wheel (where you want it). The OSG doesn't give a **** - it will always move the torque to the outside wheel like it's intended to. The result is dramatically improved corner exit speeds and lower laptimes in pretty much every example you can think of.
- Significantly faster on track or not? (most races I do are in the 15 minute range, 8-12 laps)
- Huge NVH increase/ no difference?
- Road driveability good / bad ?
- Perhaps the difference is negligible and i should focus on other areas first..track time, more boost, 8-9" rims etc....
- Huge NVH increase/ no difference?
- Road driveability good / bad ?
- Perhaps the difference is negligible and i should focus on other areas first..track time, more boost, 8-9" rims etc....
No NVH increase. The diff doesn't even pop/click in parking lots - it's transparent until it needs to work.
Road driveability is flawless - again, it's transparent.
#6
I never said it understeers on entry. The issue is understeer mid corner and exit when you try to power out and the diff locks. 100% lock is too much, 80% lock is too much, 60% lock is not enough. There needs to be a 70% lock option but that isnt possible without a redesign of the diff that uses more clutches. I can say that because I've physically pulled a Giken apart and flipped around the clutch plates to change it.
The OSG cant move any torque, it is a clutch type. The max TBR on a clutch type is 1, which is lower than the TBR of either of our torsen options. The most torque it can apply to the outside tire is 50% of the total torque, and that would be at 100% lockup.
The OSG cant move any torque, it is a clutch type. The max TBR on a clutch type is 1, which is lower than the TBR of either of our torsen options. The most torque it can apply to the outside tire is 50% of the total torque, and that would be at 100% lockup.
#7
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That's not something I've ever experienced, and I have hundreds of hours in OSG-equipped cars over the last 3+ years. Not sure what was wrong with the OSGs you've driven, but all the ones I've driven have been either factory OSG or 949Racing Hi-power tunes and they've all been magical.
#9
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I had an OSG in my miata.
They are like stock drivability wise and noise wise it was more quiet than my 1.6 vlsd.
As far as the handling issues im not sure what you guys are talking about, you should go learn to drive. if your understeering you should ball up and use the right foot a little more and im not suggesting you go drift.
chances are the understeer is because your not on the gas enough and your trying to slow down to get back on line if your understeering mid corner.
They are like stock drivability wise and noise wise it was more quiet than my 1.6 vlsd.
As far as the handling issues im not sure what you guys are talking about, you should go learn to drive. if your understeering you should ball up and use the right foot a little more and im not suggesting you go drift.
chances are the understeer is because your not on the gas enough and your trying to slow down to get back on line if your understeering mid corner.
#10
I never said it understeers on entry. The issue is understeer mid corner and exit when you try to power out and the diff locks. 100% lock is too much, 80% lock is too much, 60% lock is not enough. There needs to be a 70% lock option but that isnt possible without a redesign of the diff that uses more clutches. I can say that because I've physically pulled a Giken apart and flipped around the clutch plates to change it.
The OSG cant move any torque, it is a clutch type. The max TBR on a clutch type is 1, which is lower than the TBR of either of our torsen options. The most torque it can apply to the outside tire is 50% of the total torque, and that would be at 100% lockup.
The OSG cant move any torque, it is a clutch type. The max TBR on a clutch type is 1, which is lower than the TBR of either of our torsen options. The most torque it can apply to the outside tire is 50% of the total torque, and that would be at 100% lockup.
#11
I had an OSG in my miata.
They are like stock drivability wise and noise wise it was more quiet than my 1.6 vlsd.
As far as the handling issues im not sure what you guys are talking about, you should go learn to drive. if your understeering you should ball up and use the right foot a little more and im not suggesting you go drift.
chances are the understeer is because your not on the gas enough and your trying to slow down to get back on line if your understeering mid corner.
They are like stock drivability wise and noise wise it was more quiet than my 1.6 vlsd.
As far as the handling issues im not sure what you guys are talking about, you should go learn to drive. if your understeering you should ball up and use the right foot a little more and im not suggesting you go drift.
chances are the understeer is because your not on the gas enough and your trying to slow down to get back on line if your understeering mid corner.
#12
The trouble with the OSG seems to be in the control cam. On exiting the corner when you've got the car floored, the diff locks, doesnt allow speed differentiation between the two wheels and the car pushes. If you let off the gas enough to unlock the diff and be able to turn, you're just going slow and giving up time.
A properly setup Salisbury type clutch lsd will be faster than a torsen. Most of us dont have the time or the money to spend hundreds of hours testing and adjusting the Giken to get there.
#13
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Is it possible that Leafy and jmann's buddies are talking autocross-specific experience and Savington is speaking to road course work? I imagine "mid 'corner'" in a parking lot/on an airstrip is significantly different than on a circuit.
#15
That would be correct. Never had a mid corner speed with one over 60. And never in a miata with more than 180hp. And never in a car with smaller than 275 hooisers. I could see how a car with more power or less grip would be able to power on enough to get past pushing and into sliding. But the giken problem is worse and worse the higher speed the corner is at least up until 60.
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Within that narrow specification window (very wide tire, relatively low power, zero elevation change and low cornering speed with tight relative radius), I could see how any clutch-type would push a bit. For every other case, including normal cars on 205/225 R-comps with 150-400whp and cornering speeds ranging from 50mph to 120mph with elevation change and curbs, the OSG does a better job than the Torsen.