Quaife now installed... with LSD-flavour pix
- Thread starter PerryGunn
- Start date
///M cars are built with an eye on track performance and clutch pack diffs are definitely better than torsen for track usage - but I think that the characteristics of torsen diffs make them better for normal road use than clutch pack diffsTomK said:I think if they thought torsen diffs were better for the application they would have used themjamesbond said:. Torsen diffs are most commonly factory fitted to FWD or AWD cars, not RWD, not to say they can't do a good job in RWD applications.
'Splitting hairs'.... on an Internet forum... whosoever heard if such a thing... :wink:TomK said:Splitting hairs really. Your diff will be a massive improvement on the standard open diff in all situations.
Enjoy
It's just like a drunken discussion down the pub on a Friday night... but without the beer.... and the hangover... :lol:
I don't know if clutch pack style is better for track.
I do know that they are best for drag racing as a clutch pack behaves as a solid axle when power is applied (more power=more lockup force). So there is no rpm difference possible as long as power is applied. Great for a straight line as the drivetrain has an automatic tendency for that once throttle is applied. Thats why they're popular in the US for an aftermarket install. The land of the 1/4mile.
M diff is not clutch pack style but gerotor actuated clutch pack. It does not lock under power but under rpm difference. It has greater lock up force possible than the atb or clutch pack (I think), but lockup is created by rpm difference, not by torque needed. So there needs to be loss of traction before lockup can occur. (or lockup can be induced in tight corners even if no traction is lost)
For the /m type gerotor diff, 10rpm difference on both wheels is (for example) 200Nm lockup force, 20 rpm difference is 400Nm lockup force etc
Also hysteresis is a risk (pulsating on/off; lockup induces 0rpm difference->lockup is lost->rpm difference->lockup->lockup induces 0rpm difference->lockup is lost->etc). This pulsating is compensated by dampening, but dampening the gerotor also means that lockup and freeing up the diff gets slower.
So they act on 3 totally diffent factors:
clutch pack: lockup on power (more power=more lockup)
gerotor/m diff: lockup on rpm difference (more rpm difference, more lockup)
ATB/quaife lsd: torque biasing: the wheel that is unable to convert the torque to traction induces lockup. That means if the wheel is unable to roll along with the car (inner wheel wants to spin, outer wheel doesnt accelerate accordingly), lockup is induced. In theory rpm difference is no issue as it is a balancing system, but lots of rpm difference means more friction on the cogs, so that is a force that may help induce lockup partially (I don't know how much this is an issue). Also lockup is in a ratio of torque (e.g. 1:4)
I do know that they are best for drag racing as a clutch pack behaves as a solid axle when power is applied (more power=more lockup force). So there is no rpm difference possible as long as power is applied. Great for a straight line as the drivetrain has an automatic tendency for that once throttle is applied. Thats why they're popular in the US for an aftermarket install. The land of the 1/4mile.
M diff is not clutch pack style but gerotor actuated clutch pack. It does not lock under power but under rpm difference. It has greater lock up force possible than the atb or clutch pack (I think), but lockup is created by rpm difference, not by torque needed. So there needs to be loss of traction before lockup can occur. (or lockup can be induced in tight corners even if no traction is lost)
For the /m type gerotor diff, 10rpm difference on both wheels is (for example) 200Nm lockup force, 20 rpm difference is 400Nm lockup force etc
Also hysteresis is a risk (pulsating on/off; lockup induces 0rpm difference->lockup is lost->rpm difference->lockup->lockup induces 0rpm difference->lockup is lost->etc). This pulsating is compensated by dampening, but dampening the gerotor also means that lockup and freeing up the diff gets slower.
So they act on 3 totally diffent factors:
clutch pack: lockup on power (more power=more lockup)
gerotor/m diff: lockup on rpm difference (more rpm difference, more lockup)
ATB/quaife lsd: torque biasing: the wheel that is unable to convert the torque to traction induces lockup. That means if the wheel is unable to roll along with the car (inner wheel wants to spin, outer wheel doesnt accelerate accordingly), lockup is induced. In theory rpm difference is no issue as it is a balancing system, but lots of rpm difference means more friction on the cogs, so that is a force that may help induce lockup partially (I don't know how much this is an issue). Also lockup is in a ratio of torque (e.g. 1:4)
PerryGunn said:'Splitting hairs'.... on an Internet forum... whosoever heard if such a thing... :wink:TomK said:Splitting hairs really. Your diff will be a massive improvement on the standard open diff in all situations.
Enjoy
It's just like a drunken discussion down the pub on a Friday night... but without the beer.... and the hangover... :lol:
Well as we are splitting hairs. I feel I have to point out that It's Thursday night.
:wink: PerryGunn said:I did a double-take when I first noticed the plate - I thought another b*gger had cloned yours... :lol:srhutch said:PerryGunn said:Even found a new DD for Steve - he won't even have to change the plate :lol:
I could live with that as my DD. Plate only one character different to mine.
It started off as an 840i but it's been worked on - amongst other enhancements, it's been supercharged :evil:
I did a double take as well :lol:
[hairsplitting]buzyg said:PerryGunn said:'Splitting hairs'.... on an Internet forum... whosoever heard if such a thing... :wink:TomK said:Splitting hairs really. Your diff will be a massive improvement on the standard open diff in all situations.
Enjoy
It's just like a drunken discussion down the pub on a Friday night... but without the beer.... and the hangover... :lol:
Well as we are splitting hairs. I feel I have to point out that It's Thursday night.
Yes, but I don't go to the pub on a Thursday night, I go to the pub on a Friday night, so I wouldn't have a drunken discussion down the pub on a Thursday night
[/hairsplitting]
I can't wait to read all of this tomorrow at lunch....
I'm lost.
I'm calling birds tomorrow though
I'm calling birds tomorrow though
PerryGunn said:[Seriously though, amongst all the 'engine swap' threads you do learn some interesting stuff on here
You certainly do - enjoyed reading through this post and checking through the photos - excellent and thanks for posting.
Interested to hear how you get on with this diff Perry over time.
