iadr
04-14-2013, 08:16 AM
This would be on ice or gravel, when one wheel has more traction than the other. Yes, you'd think this is somewhat off topic, but it has to do with my understanding of what is happening with my daily, b/c even my daily comes in for modifications.
We all know when an open diff has one wheel jammed to the ground and one up, the wheel up goes 2x normal wheel speed.
So what happens in braking? Driveshaft is turning at a fixed speed. One wheel stops. Isn't that the same thing? I'm pretty sure the non-locked wheel does NOT get some force applied to it to double its speed. Help me understand why?
Several more scenarios- What if I have a Torsen diff and one wheel locks under braking? It's the same as an open, right? key words in this link are :
"The Torsen differential will not support any appreciable torque "wind-up" between the two rear tires during braking" http://www.maximummotorsports.com/store/index.php?main_page=index&cPath=50_157
Ok, what if I *want* it to "support wind up" (I have no ABS)? Clutch type limited slip- they are rated anywhere from 40 to 200 lb ft, and some none in braking direction ("1, 1.5, 2 way"). Not much at all compared to brake torque, except you have a small advantage in that initial break away torque is a little higher than rated, and on slippery surfaces Mu=.125-.20, so brake torque when you are soft pedaling it, is a lot less than we normally have. So I'm thinking of going clutch type which in my application ironically means actually paying slightly more than the torsen option.
What made me think about this was running on icey roads here in Canada with a vehicle with a "part time" 4x4 transfer case. Best anti lock brakes ever.
Seriously. Totally stable, and made traction out of nothing. In 2wd not so much, actually horrible. Now this is a veh with drum rears. If the Transfer case is locked, then all I've really changed is front rear bias, right? But then the first question comes up- am I somehow connecting left and right axle pairs?
Reason being I'm thinking I'll go viscous coupler AWD transfer case in my daily. I'd hate to loose that good braking. I am doing a disc conversion on the rear, though. Parts are mocked up on the new axle and the rotors are shipping as of Friday. So maybe if all I am seeing is F-R bias issues, I have so much less to worry about.
We all know when an open diff has one wheel jammed to the ground and one up, the wheel up goes 2x normal wheel speed.
So what happens in braking? Driveshaft is turning at a fixed speed. One wheel stops. Isn't that the same thing? I'm pretty sure the non-locked wheel does NOT get some force applied to it to double its speed. Help me understand why?
Several more scenarios- What if I have a Torsen diff and one wheel locks under braking? It's the same as an open, right? key words in this link are :
"The Torsen differential will not support any appreciable torque "wind-up" between the two rear tires during braking" http://www.maximummotorsports.com/store/index.php?main_page=index&cPath=50_157
Ok, what if I *want* it to "support wind up" (I have no ABS)? Clutch type limited slip- they are rated anywhere from 40 to 200 lb ft, and some none in braking direction ("1, 1.5, 2 way"). Not much at all compared to brake torque, except you have a small advantage in that initial break away torque is a little higher than rated, and on slippery surfaces Mu=.125-.20, so brake torque when you are soft pedaling it, is a lot less than we normally have. So I'm thinking of going clutch type which in my application ironically means actually paying slightly more than the torsen option.
What made me think about this was running on icey roads here in Canada with a vehicle with a "part time" 4x4 transfer case. Best anti lock brakes ever.
Seriously. Totally stable, and made traction out of nothing. In 2wd not so much, actually horrible. Now this is a veh with drum rears. If the Transfer case is locked, then all I've really changed is front rear bias, right? But then the first question comes up- am I somehow connecting left and right axle pairs?
Reason being I'm thinking I'll go viscous coupler AWD transfer case in my daily. I'd hate to loose that good braking. I am doing a disc conversion on the rear, though. Parts are mocked up on the new axle and the rotors are shipping as of Friday. So maybe if all I am seeing is F-R bias issues, I have so much less to worry about.