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traction control
- Thread starter TED CRUD
- Start date
You seem to have a bit more knowledge about diffs so... I know how it all works in theory and I would completely agree with you however I fitted one myself and after finishing the job and mounting the wheels I found they are very hard to turn when in gear. Very much unlike a open diff! Also I once drained the battery by accident an then tried to push-start the car but I failed as I had to do a little turn and it was just as if I was pushing the brake. In both situation there is barely any torque available so I can hardly believe that if one side looses grip it really behaves just like an open diff. Of course in this situation the ATB is never as effective as differential plates or torque clutch but shouldn't it be better than an OEM diff?Lankan":3j9gz4b9 said:
Please give me the insight [cmilie=iconcheers.gif]
Firstly my understanding of how the Quaife ATB Diff works is still thoeretical (based on what I have read up and discussed with Quaife). I haven't installed one in my Vee as yet, but will have one by April/May. Secondly, as I understand it the Quaife ATB cannot really be called an LSD (Limited Slip Differential) in its truest sense of the word.hualpa_jo":3r0x5ryy said:
Torque Biasing Diffs (TD
are a gear driven design, the gears only transmit power one way, so they only work on acceleration and act as an open diff under deceleration, which the key difference between a TBD and a plate type diff.An LSD limits the degree to which it allows the driven wheels to slip as per set locking ratios for acceleration/decelaration. As such, besides limiting wheel spin when under load, a (plate type) LSD also stabilises the car under braking, a TDB does not do this, and the higher the lockup (even up to 100%) the better for braking.
For example, my 993 RS (and the 964RS) has a plate type diff with a 40/65 ratio. If the LSD is working correctly, it would display the chracteristics you describe in your post above. When turning tight corners you would hear the diff plates judder, and braking stability is vastly improved. A quick way to check that the LSD is functional is to jack up the car with both driven wheels off the ground and then (try to) rotate one wheel. If the diff is working properly both wheels will rotate in the same direction, and one should not be able to spin the driven wheel at all when only one driven wheel has been jacked up. Obviously the car needs to be in neutral. With the Quaife ATB I would expect the wheels to rotate as it does with an open diff if both wheels are jacked up, but offer up resistance if only one driven wheel is jacked up. Note to self: try this out.
As such, are you talking here about a Quaife ATB diff that you installed in your Vee? If so, are you saying that you found it hard to turn the car through a hard right or left corner when in gear – was this when driven or being pushed? If both wheels were in contact with the road surface, and they had equal grip, then I believe that would be the correct behaviour.hualpa_jo":3r0x5ryy said:
Yes I'm talking about a Quaife ATB. When both wheels off the ground, in neutral, and one turns one wheel the other goes the same direction. With only one wheel jacked up it takes roughly 30Nm (maybe less) to turn it. So one is able to turn it but with a substantial resistance. That's why I thought it might be not as useless as an open diff in a "no grip on one side"-situation.
Do you agree with me that it has some "locking effect" on deceleration as long as there is some drag torque available?
So far it always kept my inner wheel from spinning so, ignoring al the technical correctness, to me it is a limiting slip diff because it's what it does
As for the topic: The car has great drivability with the Quaife unit fitted. Though I never pushed it with the OEM diff but from what I heard about OEM drivability it seems to be better.
Do you agree with me that it has some "locking effect" on deceleration as long as there is some drag torque available?
So far it always kept my inner wheel from spinning so, ignoring al the technical correctness, to me it is a limiting slip diff because it's what it does
As for the topic: The car has great drivability with the Quaife unit fitted. Though I never pushed it with the OEM diff but from what I heard about OEM drivability it seems to be better.
Give me you 964 diff please Dulan! It fits my audi box perfectly. I'm struggling like mad to find a reasonable second hand one.
Sorry, back to subject.
Primative tration control systems don't work well on open diffs. Not enough to rely on anyway. The only one I've seen work well was a set up that applied the brakes to the spining wheel and then limited power if it sensed both wheels were still spinning faster than actual road speed.
Sorry, back to subject.
Primative tration control systems don't work well on open diffs. Not enough to rely on anyway. The only one I've seen work well was a set up that applied the brakes to the spining wheel and then limited power if it sensed both wheels were still spinning faster than actual road speed.
Excellent.hualpa_jo":1xx60ld8 said:
Appears to be the case.hualpa_jo":1xx60ld8 said:
Have you tried having one wheel on a zero grip surface (e.g. wet grass) and the other on dry tarmac? If so, what was the outcome? Would be interesting to know.hualpa_jo":1xx60ld8 said:So far it always kept my inner wheel from spinning so, ignoring al the technical correctness, to me it is a limiting slip diff because it's what it does
Great stuff, better than I had expected so look forward to having mine fitted. I would really like to see what the decelaration stability is like under braking, since that is key for me.hualpa_jo":1xx60ld8 said:
Lastly, of course the Quaife ATB would have a longer lifespan since there are very few parts to wear out unlike plate type diffs. So seems like a win-win situation for the Vee. How many miles/kms have you done since you fitted yours?
