TimIacobucci
10+ Year Contributor
- 82
- 5
- Jun 21, 2009
-
Orlando,
Florida
I did just post this on an engineering forum looking for suggestions too http://www.eng-tips.com/viewthread.cfm?qid=378095. I have re written it here but I apologize if it sounds like I'm repeating stuff most dsmers already know, I originally wrote it for a general audience.
This is the w4a33. Currently there is no aftermarket support for the center differential The small spider gears are a weak point on this and the manual version of this transmission. Combined with a lack of responsiveness in the viscous coupling which acts externally to the open differential to limit slip many people simply weld the center differential to create a spool. This works well for drag racing but obviously creates problems for most any other diving situation besides offroad use. So some type of front to rear differentiation is required for any sort of corner turning with any amount of grip.
This is the kaiser locking differential, not really a differential at all technically but it seems to work pretty well. It is very similar to the wiesmann locker that Carroll Smith praises in his books. Here is a simple video demonstrating it's function.
[link
I may add a solid axle and this locker to my car at some point but for now I have a clutch type salisbury in the rear and a modified torsen (wavetrac) in the front. I am trying to apply the priciple sprag locking function of this lsd to the center differential.
In the w4a33 there is a driven gear splined to the case of the center diff housing through which the engine torque is transferred. The other end of the carrier is splined to the viscous coupling. The other side of the viscous coupling is splined to the front output shaft which drives the front differential.
My idea is to weld just the rear output shaft spider gear to the center differential housing and remove the rest of the spider gears. Then to gut the visous coupling and use it's intenal space to house a high strength sprag assembly such as that used in lenco transmissions to connect the center differential housing to the front output shaft.
[link http://www.lencoracing.com/Sprag info.htm]http://www.lencoracing.com/Sprag info.htm[/link]
These are rated for well over 2000 hp in pro mod cars. I am trying to overbuild this part as it will see full output shaft torque AFTER the transmissions gear reduction unlike it's intended use in the Lenco. For a margin of safety if I use 800 ft lbs for engine torque x 2:1 reduction in the torque converter (not sure how accurate that number is) x first gear ratio of 2.846:1 x the reduction to the center diff driven gear at 1.125:1 it works out to just over 5000 ft lbs. That is quite allot of load but the kaiser has been designed to take more torque than this so it can be done, they have a no questions asked warranty if you break their locker.
My thinking is that this system would act as a constant rear wheel drive car that will drive the front wheels when their speed is equal to or (attempting to be) slower than the rear wheels. This should give no understeer on corner entry or tight turns like even a perloaded salisbury center diff would give let alone compared to a welded diff, and fully lock even if the rear wheels have no traction at all. I cannot envision a scenario in which the rear wheels would need to turn faster than the fronts, am I missing anything?
The one problem I do see is there would be no front drive in reverse with a simple one way sprag. Is there any application which uses a high torque two way sprag like has been designed into the kaiser I might be able to retrofit?
Please let me know if you have any suggestions or ideas or see any other potential problems with the idea that I have presented here.
You must be logged in to view this image or video.
This is the w4a33. Currently there is no aftermarket support for the center differential The small spider gears are a weak point on this and the manual version of this transmission. Combined with a lack of responsiveness in the viscous coupling which acts externally to the open differential to limit slip many people simply weld the center differential to create a spool. This works well for drag racing but obviously creates problems for most any other diving situation besides offroad use. So some type of front to rear differentiation is required for any sort of corner turning with any amount of grip.
You must be logged in to view this image or video.
kaiserThis is the kaiser locking differential, not really a differential at all technically but it seems to work pretty well. It is very similar to the wiesmann locker that Carroll Smith praises in his books. Here is a simple video demonstrating it's function.
[link
You must be logged in to view this image or video.
I may add a solid axle and this locker to my car at some point but for now I have a clutch type salisbury in the rear and a modified torsen (wavetrac) in the front. I am trying to apply the priciple sprag locking function of this lsd to the center differential.
In the w4a33 there is a driven gear splined to the case of the center diff housing through which the engine torque is transferred. The other end of the carrier is splined to the viscous coupling. The other side of the viscous coupling is splined to the front output shaft which drives the front differential.
My idea is to weld just the rear output shaft spider gear to the center differential housing and remove the rest of the spider gears. Then to gut the visous coupling and use it's intenal space to house a high strength sprag assembly such as that used in lenco transmissions to connect the center differential housing to the front output shaft.
You must be logged in to view this image or video.
lenco sprag[link http://www.lencoracing.com/Sprag info.htm]http://www.lencoracing.com/Sprag info.htm[/link]
These are rated for well over 2000 hp in pro mod cars. I am trying to overbuild this part as it will see full output shaft torque AFTER the transmissions gear reduction unlike it's intended use in the Lenco. For a margin of safety if I use 800 ft lbs for engine torque x 2:1 reduction in the torque converter (not sure how accurate that number is) x first gear ratio of 2.846:1 x the reduction to the center diff driven gear at 1.125:1 it works out to just over 5000 ft lbs. That is quite allot of load but the kaiser has been designed to take more torque than this so it can be done, they have a no questions asked warranty if you break their locker.
My thinking is that this system would act as a constant rear wheel drive car that will drive the front wheels when their speed is equal to or (attempting to be) slower than the rear wheels. This should give no understeer on corner entry or tight turns like even a perloaded salisbury center diff would give let alone compared to a welded diff, and fully lock even if the rear wheels have no traction at all. I cannot envision a scenario in which the rear wheels would need to turn faster than the fronts, am I missing anything?
The one problem I do see is there would be no front drive in reverse with a simple one way sprag. Is there any application which uses a high torque two way sprag like has been designed into the kaiser I might be able to retrofit?
Please let me know if you have any suggestions or ideas or see any other potential problems with the idea that I have presented here.
