Worm gear swap.

[KimVanOrder]

Anyone interested in posting a step by step disortation on how to swap low speed worm and ring gear for High speed. I have the low speed in the truck and the high speed laying on the bench. Also I have a Lincoln Over/ under drive. What will it take to install that? Different drive shaft and tube?

[1crosscut]

Well I'm not sure I'm up to a step by step dissertation on how to do the swap but it is pretty straight forward. Just a heck of a lot of nuts and bolts to take apart. Here is a link to some pictures I posted showing the innards of a worm drive rear end.
http://forums.aa-fords.com/viewtopic.ph ... ive#p20582
Basically you will need to pull the rear end out of the truck. Pull the hubs, brakes and backing plates off both sides. Pull the speedometer gears, bushings and seals out. Go ahead and order all new seals for the rear axles, torque tube and the seal in the differential where the torque tube attaches. You will also need the worm drive differential gasket set plus the replacement pin that is used to re-attach the drive shaft to the worm drive gear. If I remember correctly when separating the drive shaft from the worm drive gear drill out and remove the pin closest to the differential. It has more room around it to allow for the extra length of the replacement pin.
The bolts that hold the two halves of the differential together can be a bugger. Lots of cotter pins to get out. The cotter pins can be pretty fragile and often will not come out of the castle nuts. I find that using an accetaline torch to basically vaporize the two ends of them with a quick hot flame. You can then run the nuts off fairly easily. After you get the bolt out punch or drill out the remaining bits of cotter pin left in the body of the bolt. Check the tapered bearings and races on the differential really well and replace if necessary. The bearings and races are quite spendy so if you can get by with the ones you have in there great... but if there is any question of them being bad bite the bullet and replace them. Check over the bearings on either end of the worm drive gear. If bad let me know I have a good spare set of them if yours are bad. When you pull the bronze driven gear check the two halves of the spider really good for any cracks.
Take lots of pictures as you pull it apart and keep your parts and pieces labeled and in order. If you do this you should have no problems doing the swap.
Sorry I can't help you with the Lincoln under/over drive.
Dave

[KimVanOrder]

thanks for your input. It is a great help. I need to do a bunch of reseach on the Lincoln Over / Under drive and decide if I should try to put it in while I have the rear end out. If I remember it is 25% overdrive. With the higher rear gears and the overdrive I start to think of just how much torque that 4 cyl. has. Of course I always have the dual speed tranny up front to shift down if needed. Starts to sound like too many transmissions.

Any thoughts?