Limited slip diff
Discussion
I've noticed an odd thing lately. First thing in the morning, when the tyres are cold and the roads are a bit damp, I can turn right and get the back out nicely and reliably with just a little extra gas, both rear wheels losing traction predictably and controllably. If I try to do the same thing turning left, however, one rear wheel (left) spins like an MP in trouble and the other stays put and the rear end fails to misbehave. I can get it to go if I'm stupid with the loud pedal, but it's definitely different.
I thought the LSD was supposed to stop that happening (i.e. one wheel spinning one wheel stationary)? Is it possible I need to replace the oil in the diff, or could there be some other sort of problem, or is it supposed to do that? It's a modded (410bhp-ish) '04 CV8 with a stock diff and about 28k miles on it. The tyres are worn evenly and the rears (Eagle F1s) have a good amount of tread on (for the moment
)
I thought the LSD was supposed to stop that happening (i.e. one wheel spinning one wheel stationary)? Is it possible I need to replace the oil in the diff, or could there be some other sort of problem, or is it supposed to do that? It's a modded (410bhp-ish) '04 CV8 with a stock diff and about 28k miles on it. The tyres are worn evenly and the rears (Eagle F1s) have a good amount of tread on (for the moment
)
I not sure if the tag name is a hint, but if you happened to weigh 3-400 pounds the right wheel is always going to gain more traction. If this is the case sit in the passenger seat and see if your mate experiences the same problem.
Sorry, technically I can't help you and if you are 3-400 pounds than I hope I haven't offended you and I am a wee scottish lad with red hair for when you are looking for me at the next meet.
Sorry, technically I can't help you and if you are 3-400 pounds than I hope I haven't offended you and I am a wee scottish lad with red hair for when you are looking for me at the next meet.
I shall try the same experiment with a passenger on board.Moose,
When you turn right into a road youre making a larger radius turn that probably tightens towards the end. Try finding a deserted road and making identical radius turns to the left and right - pretend you in france turning right, so youre on the right at the t-junction f'rinstance and your joining the lane nearest you in your right turn. I bet the results of each turn come out similar.
Im guessing here but I reckon the tighter turn makes forward motion harder, hence the rear breaks traction easier. Its a tight turn so the difference in radius of the inside and outside arc of each wheel is within the tolerance of the diff (used to be about 15%) so you get one wheel lit and not the other.
For your usual right turn, youre in a larger arc so less forward resistance, its a longer corner so you have more room to stomp on it and because you have more forward speed, the mass at the rear of the car carries more momentum, so it breaks sideways easier when you turn it, at which point both rears will light up anyway.
Its strange old science is burnouts. Any commodore ive ever seen favours the right rear to spin if it is non-LSD anyway. I put this down to the engine torquing over to the left (thus unloading the right rear slightly) against the brakes. My old VS was very even actually, it was 5.0L and LSD equipped. You could hear the tyres ripping the tarmac on low speed, tight left or right turns as the diff locked up intermittently, something I would have thought you would experience also.
Just my 2c worth.
PB
When you turn right into a road youre making a larger radius turn that probably tightens towards the end. Try finding a deserted road and making identical radius turns to the left and right - pretend you in france turning right, so youre on the right at the t-junction f'rinstance and your joining the lane nearest you in your right turn. I bet the results of each turn come out similar.
Im guessing here but I reckon the tighter turn makes forward motion harder, hence the rear breaks traction easier. Its a tight turn so the difference in radius of the inside and outside arc of each wheel is within the tolerance of the diff (used to be about 15%) so you get one wheel lit and not the other.
For your usual right turn, youre in a larger arc so less forward resistance, its a longer corner so you have more room to stomp on it and because you have more forward speed, the mass at the rear of the car carries more momentum, so it breaks sideways easier when you turn it, at which point both rears will light up anyway.
Its strange old science is burnouts. Any commodore ive ever seen favours the right rear to spin if it is non-LSD anyway. I put this down to the engine torquing over to the left (thus unloading the right rear slightly) against the brakes. My old VS was very even actually, it was 5.0L and LSD equipped. You could hear the tyres ripping the tarmac on low speed, tight left or right turns as the diff locked up intermittently, something I would have thought you would experience also.
Just my 2c worth.
PB
Thanks sjc, found it here:
www.pistonheads.com/gassing/topic.asp?h=0&t=228046
Nothing conclusive there. Due for a service soon (and brake upgrade, heh heh) so will get Picador to check it out.
Is it worth me getting Redline oil and friction modifier put in the diff anyway? ISTR reading about it on here somewhere.
www.pistonheads.com/gassing/topic.asp?h=0&t=228046
Nothing conclusive there. Due for a service soon (and brake upgrade, heh heh
) so will get Picador to check it out. Is it worth me getting Redline oil and friction modifier put in the diff anyway? ISTR reading about it on here somewhere.
ringram said:
Also engine torque will twist the car one way pushing that side down.
If you have seen drag cars lift a wheel you will know what i mean.
Maybe I'm wrong, but surely dragsters have a completely locked diff?, (bein as they don't have to go round corners!)
causing the torque twist on the chassis.
>> Edited by skyblue465 on Thursday 2nd March 08:49
The torque twist on the chassis is caused by the crankshaft sending power through the transmission faster than the wheels can transfer it to the ground so the engine tries to flip itself around the shaft instead. Lock diff or not, that will twist the chassis up. Drag cars lift the right front usually.
You can replicate it yourself at the lights in the Munro. Just stab the throttle intermittently from idle (with the clutch in!!) and watch the bonnet in relation to the ground.
PB
You can replicate it yourself at the lights in the Munro. Just stab the throttle intermittently from idle (with the clutch in!!) and watch the bonnet in relation to the ground.
PB
Hi ya
I posted similar question while ago. In the end went to be local ASDA early one morning on way home from a callout at 3am and had a bit of play in carpark, found that effects changed with various turns of lock applied on both left and right radius turns as someone already mentioned, also car was new to me and rear wheel drive(been 11years since last drove rwd) was shocked how quick back came round!!! with hardly any loud pedal, since then have fitted new RE040 bridgestones to rear to replace the Eagle F1's that were there and have noticed car is alot better handling and traction is massively improved (F1's still head 1.5mm above wear limit bars).
In other words get your self down to big open space and play!!! other theories include cold weather and affect on diff oil and how it operates at lower temp etc.Have been posts in past on diff oil, Roger at Monkfish was helpful aswell as Mark at LSV. Try them.
Cheers
Nick
I posted similar question while ago. In the end went to be local ASDA early one morning on way home from a callout at 3am and had a bit of play in carpark, found that effects changed with various turns of lock applied on both left and right radius turns as someone already mentioned, also car was new to me and rear wheel drive(been 11years since last drove rwd) was shocked how quick back came round!!! with hardly any loud pedal, since then have fitted new RE040 bridgestones to rear to replace the Eagle F1's that were there and have noticed car is alot better handling and traction is massively improved (F1's still head 1.5mm above wear limit bars).
In other words get your self down to big open space and play!!! other theories include cold weather and affect on diff oil and how it operates at lower temp etc.Have been posts in past on diff oil, Roger at Monkfish was helpful aswell as Mark at LSV. Try them.
Cheers
Nick
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