Best Choice For A GM Rear End Swap

[FINE'49]

In my recent post, I asked for advise as to whether I should use a disc or drum brake S10 rear end. I have access to either for $250.00. I asked because I had seen so many guys using complete S10 chassis, I figured that was a perfect way to go, maybe even the leaves would line up and I could use them as well. Tonight, I measured both the '49 and the S10 rear end. Backing plate to backing plate... the S10 is
about 7" narrower. How are the guys compensating for that? very deep dish wheels? Are there issues with tire rub on the inside? With all this in mind, I got to wondering if there was a better choice for rear ends. My Mustang II front has a GM bolt pattern, So I'd like to maintain the same pattern in the rear.
Thanks To All!

[joedoh]

wheel mounting surface to wheel mounting surface is the correct way to measure. the 2wd rear is 54" wms to wms (disc rear is about 1/4 wider) the 4x4 axle is 59" wms to wms. the original track width should be 59" wide, at least the 1/2 ton I measured was.

with a 4x4 axle and an 8" 4" backspace (+15 offset) wheel, it will look just right in the rear fender.

[dsraven]

I have a ford 8.8 from a ford explorer/ranger. I think it is 59.5 inches from wheel mounting flange to flange. check out the ranger station for info and which are more desireable than others. mine had disc brakes etc. I used one of the brake discs, marked for a chevy pattern between the ford pattern, to lay out some chevy wheel studs on the ford wheel flanges. the new rotors will get the same treatment when the time comes. I just cut the rotor part off so I was left with just the mounting surface. then had a machinist lay out the chevy pattern and drill 1/8 holes. then bolted it onto the axle flange with the existing ford wheel studs and drilled through with a 1/8 bit to mark the new holes. easy peasy. drill the new holes the right size for the chevy studs, push out the ford studs and press in the chevy studs. off and running. the ford 8.8 is pretty strong, as strong as a chevy 12 bolt they say (read the ranger station page for what stuff to pick at the wrecker). the centre section is offset so I also grabbed a stabilizer bar from a ranger to mount up. brackets are easy to make up just be carefull not to warp the axle tubes, if you go this way. you can use a spring mount from a 3" trailer axle for your leaf spring perches.

[dsraven]

there is also the S10 zr2 which had a wider stance. good luck finding one though.

[FINE'49]

Thanks Joe & Raven! So much info here....I LOVE IT!

[dwcsr]

This is a 2001 S10 4x4 ZR2 axle with 18x8 4.5" backspace wheels

[dsraven]

That is a nice looking truck.

[1project2many]

ZR2 trucks are more common in east coast yards. Everything rusts out here... even plastic Saturns!

[dsraven]

lookks like the wheels fit the rear fenders well. did you have to do a little tub work in the box?

[dwcsr]

I got it from LQK. They seem to be the one for used parts now that they bought up most of the independent salvage yards

[dwcsr]

Originally Posted by dsraven

lookks like the wheels fit the rear fenders well. did you have to do a little tub work in the box?

No bed work to any of it other than centering the rear and welding on new perches. tires are 235/60r18. this is bed off so yo can see how much clearance there is, its a perfect fit.

[OrrieG]

Looks like a mid 60's truck swing axle with coil set up??

[mr48chev]

I have to ask, what front end are you running and if it's a MII style have you bought rotors yet? Reason being that you could buy front rotors with a 5 on 4=1/2 pattern just as easily as the 5 on 4-3/4 and you have no extra cost machining and eliminate the possibility of trouble on the road if you indeed ruined an axle and had to replace one. DSraven's suggestion is interesting but most of us don't have a buddy who will do the work and the cost of that work equals the original cost of the complete axle if not more plus buying a pair of rotors to replace the rotors that came with the axle. The case for doing that might be of you already had a set of expensive rims that you wanted to run and That was the way to keep them.

[dsraven]

the case for me was I wanted the rear wheel bolt pattern to match the front. I have done this before with some posterboard and geometry tools from a school kids math set. the rotors I got with the diff were actually useable, I just grabbed an extra rotor at picknpull while I was there getting the diff just for this purpose. plus now I have a pattern for future use.
blank axles are possibly also available.

[dwcsr]

front is a S10 based sub frame from Scott Danforth, bolt pattern is 5 x 4.75, rear suspension is 67-72 truck arm from ECE and fits without a lot of fab work.

[mr48chev]

True and not a bad deal for a guy who has full access to the machine tools or a buddy who will do the machine work for free or at low cost but my point is that the steps you described doing or having done will run several hundred dollars in shops around here when you find a shop that has the time and can do it.


The Explorer axle is of the design that runs the wheel bearing rollers on the axle shaft meaning that if one looses a rear wheel bearing he/she may also loose the axle just as often happens in a Nova rear axle from the mid 70's . Not that big a deal if you can just snag a replacement axle shaft and stick it in the new bearing and go again but a real big deal if you have to have custom machine work done on it miles away from away home on the way to a major show or on vacation with your significant other.

We can change out some parts easily and that chrome alternator can be swapped for an Autozone cheapie to get us on the road in an hour or two and rebuilt later but any part that is critical and has to have custom work done to it to get you back on the road raises a red flag with me.

[dsraven]

yup, I hear ya. hoping it is maintained well enough so that doesn't happen. if it did I would need a ford wheel and some wheel studs/nuts as well as the wheel bearing and etc. I am thinking it would be easy enough to find that stuff if i am down for a wheel bearing/ axle shaft/ rear fender, etc etc. ha ha.

[1-ton of fun]

On disc brake c-clip rear ends you don't lose the wheel/axle anymore due to a sheared axle. The disc brake caliper holds it in place somewhat.

My sons 55's knew steel wheels are a dual pattern, which works out as his fronts are the Chevy pattern and the rear will be ford. It does keep the truck to off the shelf parts. I just ordered an explorer rear for him as it really is a better rear end than a 10 bolt
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[1-ton of fun]

And cheaper and the right width.
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[72Mountaineer]

A 70-81 Camaro also works well. You can get some good gear choices with them, too.

[xaircav]

Originally Posted by 72Mountaineer

A 70-81 Camaro also works well. You can get some good gear choices with them, too.

Agree, I used a '76 Camaro 8.5" 10 bolt with 2.73 gears. It's a freeway flyer turning 2200 RPM at 70 MPH. Easy install with a CPP kit.

[1-ton of fun]

my '59 got the 8.5" 10-bolt from the 77 nova the clip came from.