These questions are meant to be discussed in regards to driving on snowy & icy roads.
I have Full-Time 4WD, Part-Time 4WD, and Limited Slip. I also have 4-wheel ABS but I don't think that plays a role in my questions, which are:
1) Can anyone explain how my drivetrain responds when in Full-Time 4WD while having a LSD?
and
2) Can anyone explain how my drivetrain responds when in Part-Time 4WD while having a LSD?
Please Note: I know how the drivetrain responds to FT4WD and PT4WD without an LSD, there are plenty of threads on that, so I hope we can prevent this from a discussion on FT4WD and PT4WD. I just would like to know how the two 4WD options work with the LSD.
Thanks!
I have Full-Time 4WD, Part-Time 4WD, and Limited Slip. I also have 4-wheel ABS but I don't think that plays a role in my questions, which are:
1) Can anyone explain how my drivetrain responds when in Full-Time 4WD while having a LSD?
and
2) Can anyone explain how my drivetrain responds when in Part-Time 4WD while having a LSD?
Please Note: I know how the drivetrain responds to FT4WD and PT4WD without an LSD, there are plenty of threads on that, so I hope we can prevent this from a discussion on FT4WD and PT4WD. I just would like to know how the two 4WD options work with the LSD.
Thanks!
limited slip functions the same in 2wd 4pt or 4 ft, it transfers power from one wheel on the axle to the other when the first tire slips, this ONLY affects the wheels on the rear axle, the front end of your truck has an open differential in it unless you added a limited slip to the front.
So does this mean if one rear wheel slips in 4WD, I then will have 3 wheels spinning, both the rear wheels and either the front right or front left wheel too? Seems like this thing would do pretty well off-road.
it means that in 4 wheel drive if ONE of the back wheels slip that the power will be sent to the other one (which has not slipped yet), the fronts will both have to have traction for them to pull, if one of the fronts looses traction it will spin and the other side will be useless (stupid open differentials)
however this does mean that you will be less likely to NEED four wheel drive however it doesnt really have that big of an effect on it working
however this does mean that you will be less likely to NEED four wheel drive however it doesnt really have that big of an effect on it working
Kind of.
A Limited Slip Differential like those that you have is made up of clutch pads under pressure. When 1 wheel slips and the other is gripping power is transferred to the wheel that is not moving through the clutch disks, thus the wheel that is slipping gets less than full power and the wheel that is gripping gets more. This way the wheels will spin less. Now can the just one wheel spin? Yes, but it is very hard on the clutch disks which make them grip more. Simply, it can be done, but it's very hard.
Now the front end is an Open Differential. This means there is no clutch so no transfer of power. This means that only 1 wheel should spin with full power. Now if you have a lot of power and just the right conditions you can make them both spin, but it's REALLY hard to do this!
Thus meaning, when in 4X4 you should have 1 front wheel, and at least 1 rear wheel spinning at full power and 1 rear wheel spinning right with it but with power transferring between them. So layman terms, I guess there would be 3 wheel drive...lol
Then there is the transfer of power between the rear and front drive shafts.
On the NV242HD Case (no R/T model):
In 4PT (High - Part Time) the drive lines are fully locked together with NO slip. This means every corner you make with no slippage creates axle bind! Do not use this unless you have EXTREMELY slick conditions, and if you use this is, it is only meant for Part Time use so you need to place it back into 4FT (High - Full Time). Now as far as the way the truck would act in an LSD rear axle and in 4PT would equate to the best line of traction available! You would always have the front tires moving the same exact speed as the rear tires no matter what. if a front tire started slipping the rear tire would make up for it and second into the clutch disks to the opposite rear wheel. Same goes with the 4Low (Low Locked). 4Low is fully locked into position with the front end and rear end locked together for maximum traction just like it's partner 4PT, only 4PT is High ratio gearing.
Now for 4FT (High - Full Time). There is a Viscus Coupler that can allow the front drive shaft to move at different revolutions than the rear drive shaft in this position. So you can actually have 90% of the power actually go directly to just the front and just 10% to the rear or visa verse. Now this doesn't happen usually, BUT, it can happen! Because they can move in different revolutions this position is best for all road conditions because axles can turn accordingly. If you are turning on dry road the Viscus Coupler can turn the front the different revolutions from the rear differential. The downfall to this is obviously some loss of maximum traction, and if you use it too much you can ware out the Viscus Coupler causing catastrophic failure of the Transfer case. Now the LSD rear axle is going to transfer power between wheels and that in it's self will help keep the front end from slipping as much, and again the front will help the rear from slipping. But because the front can move differently to the rear you do loose some traction regardless of rear Differential.
In the rear LSD equipped differential, you gain advanced traction over a simple Open rear differential because some power is getting transferred to the opposite wheel unlike Open gearing. The best would be a Posi-traction rear differential or locker to lock them together. Lockers are not good on road surfaces where the LSD is the best bet overall for traction, driveablility, tire longevity, and fuel mileage. Is it the best? No, but that is open to the driving style of the owner.
The LSD is going to transfer power regardless (on just the rear end) no matter what position you are in. However some of that transfer of power will go to gripping so you get the best traction available but with some slip.
Now when I used to 4 wheel REALLY sloppy, Muddy, and VERY slick ALL THE TIME then I would use 4PT, but if there was dry spots even with dirt I would use 4FT because it pulled plenty good with the rear LSD for what I needed, but if I needed that little bit of an edge like climbing muddy raods, I'd lock her down into 4PT lock it in low 2 and give her juice tell I got to the top, then take it out back to FT4.
A Limited Slip Differential like those that you have is made up of clutch pads under pressure. When 1 wheel slips and the other is gripping power is transferred to the wheel that is not moving through the clutch disks, thus the wheel that is slipping gets less than full power and the wheel that is gripping gets more. This way the wheels will spin less. Now can the just one wheel spin? Yes, but it is very hard on the clutch disks which make them grip more. Simply, it can be done, but it's very hard.
Now the front end is an Open Differential. This means there is no clutch so no transfer of power. This means that only 1 wheel should spin with full power. Now if you have a lot of power and just the right conditions you can make them both spin, but it's REALLY hard to do this!
Thus meaning, when in 4X4 you should have 1 front wheel, and at least 1 rear wheel spinning at full power and 1 rear wheel spinning right with it but with power transferring between them. So layman terms, I guess there would be 3 wheel drive...lol
Then there is the transfer of power between the rear and front drive shafts.
On the NV242HD Case (no R/T model):
In 4PT (High - Part Time) the drive lines are fully locked together with NO slip. This means every corner you make with no slippage creates axle bind! Do not use this unless you have EXTREMELY slick conditions, and if you use this is, it is only meant for Part Time use so you need to place it back into 4FT (High - Full Time). Now as far as the way the truck would act in an LSD rear axle and in 4PT would equate to the best line of traction available! You would always have the front tires moving the same exact speed as the rear tires no matter what. if a front tire started slipping the rear tire would make up for it and second into the clutch disks to the opposite rear wheel. Same goes with the 4Low (Low Locked). 4Low is fully locked into position with the front end and rear end locked together for maximum traction just like it's partner 4PT, only 4PT is High ratio gearing.
Now for 4FT (High - Full Time). There is a Viscus Coupler that can allow the front drive shaft to move at different revolutions than the rear drive shaft in this position. So you can actually have 90% of the power actually go directly to just the front and just 10% to the rear or visa verse. Now this doesn't happen usually, BUT, it can happen! Because they can move in different revolutions this position is best for all road conditions because axles can turn accordingly. If you are turning on dry road the Viscus Coupler can turn the front the different revolutions from the rear differential. The downfall to this is obviously some loss of maximum traction, and if you use it too much you can ware out the Viscus Coupler causing catastrophic failure of the Transfer case. Now the LSD rear axle is going to transfer power between wheels and that in it's self will help keep the front end from slipping as much, and again the front will help the rear from slipping. But because the front can move differently to the rear you do loose some traction regardless of rear Differential.
In the rear LSD equipped differential, you gain advanced traction over a simple Open rear differential because some power is getting transferred to the opposite wheel unlike Open gearing. The best would be a Posi-traction rear differential or locker to lock them together. Lockers are not good on road surfaces where the LSD is the best bet overall for traction, driveablility, tire longevity, and fuel mileage. Is it the best? No, but that is open to the driving style of the owner.
The LSD is going to transfer power regardless (on just the rear end) no matter what position you are in. However some of that transfer of power will go to gripping so you get the best traction available but with some slip.
Now when I used to 4 wheel REALLY sloppy, Muddy, and VERY slick ALL THE TIME then I would use 4PT, but if there was dry spots even with dirt I would use 4FT because it pulled plenty good with the rear LSD for what I needed, but if I needed that little bit of an edge like climbing muddy raods, I'd lock her down into 4PT lock it in low 2 and give her juice tell I got to the top, then take it out back to FT4.
Very thorough answer and awesome addition to the forum. Truly appreciate it hydra!
