70_Steve
Old Guy
- Joined
- Dec 13, 2002
- Messages
- 8,317
In light of kaisermusic's upcoming Dana20 rebuild, I thought I'd start a thread as a collection of all the helpful tips we've found for rebuilding these Dana 20 transfer cases. When all is said and done, if I'm motivated, I might consolidate all the info into a Tech Article.
First off, here's a link to the Dana 20 Service Manual.
http://www.classicbroncos.com/dana20/dana_20_manual.html
To disassemble the T-shift front output shaft assy, the book says to pry the front bearing away from the drive gear far enough to remove the snap ring. I've had the best luck by using two large flat screwdrivers, one on each side of the shaft, and tapping them into the gap. This will drive the bearing forward enough to get at that snap ring. Accept you will distort the snap ring when removing it, but it can be straightened and reused.
Lately it has been an accepted practice to assemble the rear output shaft with a bearing preload, rather than a shaft endplay, as specified by Spicer. The torque values most often used are 5-9 inch/lbs rotational torque on the shaft, before installing the seal. This seems to help prevent the transfer case from popping out of rear low.
When reassembling the transfer case intermediate/idler shaft, it's helpful to cut a wooden dowel or piece of PVC pipe to hold the assembly as it's lowered into the case. Cut the dowel or pipe to just fit the inside of the case. Assemble the intermediat gears and bearings. Slide the dowel inside the bearings. Set the assembly inside the case, and use the real idler shaft to push out the dowel/pipe.
To seal the ends of the idler shaft I push the shaft into the case until it just enters the front bore of the case. I then clean the front bore and rear part of the shaft and o-ring with brake cleaner. Then coat the inside of the front bore, and the rear o-ring with an RTV gasket sealer. Then finish installing the idler shaft.
To seal the front output shaft shims, set the proper end play first. Then disassemble the rear flange and shims, lay the shims and flange on something (paper, cardboard, etc) and spray one side with a copper gasket sealer. Then reassemble so there is gasket sealer between each surface. I've also heard that HiTack spray works as well.
The t-shift front output shaft sucks. If you have a chance, replace it with a J-shift front output shaft. Just, remember you did this the next time you order a rebuild kit, cause the bearings are different.
Come on guys. Add what you've learned!!!!
First off, here's a link to the Dana 20 Service Manual.
http://www.classicbroncos.com/dana20/dana_20_manual.html
To disassemble the T-shift front output shaft assy, the book says to pry the front bearing away from the drive gear far enough to remove the snap ring. I've had the best luck by using two large flat screwdrivers, one on each side of the shaft, and tapping them into the gap. This will drive the bearing forward enough to get at that snap ring. Accept you will distort the snap ring when removing it, but it can be straightened and reused.
Lately it has been an accepted practice to assemble the rear output shaft with a bearing preload, rather than a shaft endplay, as specified by Spicer. The torque values most often used are 5-9 inch/lbs rotational torque on the shaft, before installing the seal. This seems to help prevent the transfer case from popping out of rear low.
When reassembling the transfer case intermediate/idler shaft, it's helpful to cut a wooden dowel or piece of PVC pipe to hold the assembly as it's lowered into the case. Cut the dowel or pipe to just fit the inside of the case. Assemble the intermediat gears and bearings. Slide the dowel inside the bearings. Set the assembly inside the case, and use the real idler shaft to push out the dowel/pipe.
To seal the ends of the idler shaft I push the shaft into the case until it just enters the front bore of the case. I then clean the front bore and rear part of the shaft and o-ring with brake cleaner. Then coat the inside of the front bore, and the rear o-ring with an RTV gasket sealer. Then finish installing the idler shaft.
To seal the front output shaft shims, set the proper end play first. Then disassemble the rear flange and shims, lay the shims and flange on something (paper, cardboard, etc) and spray one side with a copper gasket sealer. Then reassemble so there is gasket sealer between each surface. I've also heard that HiTack spray works as well.
The t-shift front output shaft sucks. If you have a chance, replace it with a J-shift front output shaft. Just, remember you did this the next time you order a rebuild kit, cause the bearings are different.
Come on guys. Add what you've learned!!!!
