Please ask tech questions in the appropriate forum, in this case Transmission-Rear end, this is the introduction page.

Moving your post.

 

Well, it is more then just wms to wms. Some 9's/8.8 will fit some 60's will fit some 10's will fit, some Dana 44, some 8.25, and so on.

You need to look at the engines torque and transmission multiplication to see what to start with. Now you can build and beef up a Dana 44 for instance but at some point a 60 or 9" may have been a better starting point. On the other side of that you may not need a 9". If your your transmission gearing is in the high 2's. Let's just call it 3 and the engine is putting out 300 ft lbs that's only 900lbs at the pinion. Then you throw in axle ratio which without overdrive will end up around 3.73. Lets call it 4 to keep things simple. So that's 3600 lbs of torque at the wheels.

Now that's plenty within the limits of a light duty axle.


On the other hand if you are putting out 300 lbs at the engine with a 1st speed of the high 3's let's call it 4 with a overdrive that allows you to run 4.56 gearing let's call it 4.5 you now are making 5600lbs at the wheels and will be destroying light duty axle shafts, possibly a diff, and bracing the axle(adding weight) would be a good idea.

As a very GENERAL rule. Use the Dana method. ie Dana 44 has a maximum torque at the wheels of 4400lbs, 60 6000lbs, 70 7000lbs. Comparable axles will be close to the same. Now that is around where stock breaks. You can stuff money into anything and make it stronger.



Find your practical torque at your wheels number and go from there on axle choices.

 

How wide does the rear end need to be? That's the first thing that you have to overcome. The S10 rear end is very narrow at around 56 inches. There are many different widths, and unless you plan to have a rear end narrowed to fit the car then you need to find something that is close to what you need.

Gear ratios, rear end strength and other things need to be considered too. Your transmission gear ratios and tire height will have a lot to do with the gear ratio that you need. You need to provide a lot more information to get a better estimate on what rear end you need to use.

 

The way I have done this in the past to get EXACTLY what I wanted is to jack the vehicle up and remove the differential, then let the body back down to the ride height I wanted and begin fitting tires and wheels into the fenders that will fit and look good doin' it. Once you find a tire and wheel combo that fits and looks good, measure from the inside face of the wheel center on the driver's side to the inside face of the wheel on the passenger side and you have the exact axle width that you need. No muss, no fuss, no guessing.

Personally, I will use a Ford 8.8 on the next build (if there is a next build for me). With springs in place, put the diff in place with spring pads and tack the pads into place on the axle housing. The remove the diff and fully weld the pads in place. Use an oxy-acetylene torch to heat the remainder of the circumference of the axle tube to approximately the same heat you used to weld the pads in place. That will help the alignment of the tubes and prevent them from being "bent" from welding on one side only. Your axle bearings will love you for it. There are jigs that are made commercially for fitting into the housing so that you know the whole mess is straight when you are shortening the housing. Use common sense and you will be ok.

http://www.powernationtv.com/two-minute-tech/2min-296/how-to-shorten-an-axle-housing

http://www.crankshaftcoalition.com/wiki/Narrowing_a_rearend

 

Come on now there will always be another project.






For finding wms to wms I have a very easy way that I have used many times.

Get two 1" high x.25 thick bars that are 2 feet long. They must be flat and straight.

Drill a 1/2" hole in the middle of the 1" bar 2" from the end of each bar.

Now all you do is pull off your tires.
Slap the bar against drum or caliper, laying it on one side of a lug.
Now grab a lug nut and tighten it down over your bar just snug not tight.

Put the other bar on the other side and then run a tape between the two pulling the two towards each other slightly and you have your wms to wms measurment


Pre 2000 this was what I used in junk yards. I still do this today with Craigslist axles and sometimes in junk yards. It takes 5 minutes to check the wms to wms and the stuff to make it can be had for $20 or less. It works on almost any straight axle any lug.

This only works if the bars are straight flat stock. If you manage to bend it just buy another and use the flat stock for something.


Take a caliper and check your axle tube thickness then just buy new perches for your springs. Buy NEW u bolts. Slap the axle under there after you removed the old ones, grind the area smooth, lay your perched against the tube and grind a bit off so the fit is perfect, then lay the axle under under the truck with everything.


Drill another hole on the bar for another lug then tighten the 2 lug nuts down tight. Do the same on the other side.

Now measure from the bar to the frame on each side and adjust the axle back and forth a bit till it is good and centered.

Tighten everything down tight put the tires on and Jack the car up and down a couple of times placing weight on the springs letting the axle and springs settle. 2 or 3 times up and down the axle may or may not move. But if it does you can fix it now.

Once the springs and perches are perfect tack the perches in 2 spots per perch then remove the axle.

Now if your not great at welding you can take it to a shop. If you are then it is easier to weld on a stand kind of deal.