scotty
07-29-2000, 10:54 AM
to continue the debate from earlier,it doesnt matter if the rear axle is open or locked. i.e., it doesnt matter if one rear wheel slips,or both rear wheels slip. the front axle is always pulling every bit as much as the rear is pushing while youre driving straight on a surface that gives equal traction to all 4 tires. it is not really correct to say that the rear axle is always pushing,until the transfer case notices that the rear wheels are spinning. it would take some mechanical means other than a differential to be able to distribute all power to the rear until it senses tire spin. back to the example from the other post(229 operation),this is like saying that while you are driving along in a 2wd anything,with a limited slip diff, that only the right tire is driving the vehicle,until that tire spins,and then the diff says "oh no,the right tire is spinning,id better kick in the left". when traction is equal,the whole carrier spins,with no spider gear movement whatsoever.so both tires are propellig said vehicle. if you have an open diff,and either of the tires hits a patch of ice,mud,green jello,whatever, the power can now be transfered to that tire- the carrier spins,but the side gear that is conected to the axle that is connected to the tire with tration stops.the spider gears rotate around it,wich causes the no traction side gear,axle and tire to spin uselessly. take the same situation,but add a limited slip(clutches,cones,a silicone filled coupling,doesnt matter) and the traction difference has to be great enough to overcome the clutches that want to keep the side gears spinning with the carrier.
now imagine the diff in the center of 2 driveshafts. it is basically the same situation,a diff with 2 shafts going to drive wheels.the only difference is that these shafts dont drive the wheels directly,like axleshafts,but they drive the gears that drive the wheels. for the sake of argument,lets say that both front and rear diffs have spools.no axle diffs to confuse the issue.youre driving in a straight line on a high traction surface. the diff is behaving the same-the center carrier is spinning,all wheels traveling the same speed,so a both side gears(that are connected to the front and rear outputs) are spinning the same speed. NOW at this moment,all 4 wheels are recieving the same power. a differnetial cannot send its power through its spider and side gears to only the rear axle. so youre cruising along and you once again hit that pesky pool of green jello-now if we have a 228 or 203,with an open center diff,one set of wheels(theyre spooled together,remember) can spin,causing the other output and its side gear to remain stationary,leaving the other set of wheels spinning uselessly. now add the limited slip again. now you have to have a great enough traction difference to overcome the clutches(or shear thru the silicone fluid) in order for one set of wheels to spin uselessly.hopefully the traction difference between the jello and the pavement is not great enough that the clutches cant continue to keep both side gears spinning,and will safely propell us thru the jello.
now think of it one more way-if all the power were really going to the rear axle,until it started slipping,then if you place a rollable jack under the front axle and lifted the front off the ground,the rear should push you along. after all,the rear tires are not slipping,right? they still have plenty of traction and should still push even if the front is off the ground. in reality, we have created the no traction situation which can cause one side gear to stop spinning and let all the power spin uselessly out the other side. wether the vehicle will still move depends on the condition of the clutches,and wether or not the traction difference is great enough for them to continue to keep both side gears spinnig enough to overcome the friction of rolling on the jack.
just ask porkchop-hell tell you,your rig wont move if you take out the front driveshaft.
whew! im not much of a typer,either,im gald thats about it. maybe this is alittle nitt-picky(SP? enven a real word?) but i just wanted to try and clarify what is actually going on while youre driving down the road in full time 4 hi- its alittle confusing to say that the rear axle is doing all the work until it starts to slip. a more accurate statement would be something like:" both axles do equal work,until one or the other starts to slip"
if there is something that makes a transfer case diff different than another diff,id definately like to be educated on these differences...
THIS is the stuff i like about this forum-discussions and debates...
------------------
scott
85 grand wagoneer
258/904/twin stick dana 300/dana 44/welded amc 20
38x15.5 gumbo mudders
snorkel/dual batteries/onboard air/"custom" convertable
3 inch body lift/mostly stock suspension/"modified" fender openings
custom front/rear bumpers and brushgaurd
[This message has been edited by scotty (edited July 29, 2000).]
now imagine the diff in the center of 2 driveshafts. it is basically the same situation,a diff with 2 shafts going to drive wheels.the only difference is that these shafts dont drive the wheels directly,like axleshafts,but they drive the gears that drive the wheels. for the sake of argument,lets say that both front and rear diffs have spools.no axle diffs to confuse the issue.youre driving in a straight line on a high traction surface. the diff is behaving the same-the center carrier is spinning,all wheels traveling the same speed,so a both side gears(that are connected to the front and rear outputs) are spinning the same speed. NOW at this moment,all 4 wheels are recieving the same power. a differnetial cannot send its power through its spider and side gears to only the rear axle. so youre cruising along and you once again hit that pesky pool of green jello-now if we have a 228 or 203,with an open center diff,one set of wheels(theyre spooled together,remember) can spin,causing the other output and its side gear to remain stationary,leaving the other set of wheels spinning uselessly. now add the limited slip again. now you have to have a great enough traction difference to overcome the clutches(or shear thru the silicone fluid) in order for one set of wheels to spin uselessly.hopefully the traction difference between the jello and the pavement is not great enough that the clutches cant continue to keep both side gears spinning,and will safely propell us thru the jello.
now think of it one more way-if all the power were really going to the rear axle,until it started slipping,then if you place a rollable jack under the front axle and lifted the front off the ground,the rear should push you along. after all,the rear tires are not slipping,right? they still have plenty of traction and should still push even if the front is off the ground. in reality, we have created the no traction situation which can cause one side gear to stop spinning and let all the power spin uselessly out the other side. wether the vehicle will still move depends on the condition of the clutches,and wether or not the traction difference is great enough for them to continue to keep both side gears spinnig enough to overcome the friction of rolling on the jack.
just ask porkchop-hell tell you,your rig wont move if you take out the front driveshaft.
whew! im not much of a typer,either,im gald thats about it. maybe this is alittle nitt-picky(SP? enven a real word?) but i just wanted to try and clarify what is actually going on while youre driving down the road in full time 4 hi- its alittle confusing to say that the rear axle is doing all the work until it starts to slip. a more accurate statement would be something like:" both axles do equal work,until one or the other starts to slip"
if there is something that makes a transfer case diff different than another diff,id definately like to be educated on these differences...
THIS is the stuff i like about this forum-discussions and debates...
------------------
scott
85 grand wagoneer
258/904/twin stick dana 300/dana 44/welded amc 20
38x15.5 gumbo mudders
snorkel/dual batteries/onboard air/"custom" convertable
3 inch body lift/mostly stock suspension/"modified" fender openings
custom front/rear bumpers and brushgaurd
[This message has been edited by scotty (edited July 29, 2000).]