Shortening a solid axle?

My LS1 MG project is supposed to get Miata subframes front and rear. But I'm starting to reconsider the rear end. The car was built for a solid axle rear, and my 1998 Camaro donor has an LSD rear in it. So I'm thinking of using it - no questions about the strength of the components and it'll save me a fair bit of fabricating as well as the cost of custom axles and a new CTS rear end as per the original plan.

But the Camaro rear is too wide. According to the specifications I've found, it's a 1539 mm (60.5") rear track. The Miata is 1427 (56.1"). I've read about shortening solid rears, how much of a big deal is it? Chop and reweld the housing, that I can understand. Is an axle shortening something an amateur can do, or should it be left to the pros? I can see real problems if it's not straight!

How about changing the Camaro rear to a 4x100 pattern? It looks like it would just be a matter of redrilling (or replacing) the flanges with the right pattern. I'd probably adapt Miata brakes, simply because it makes it easier for me to use the parts in my garage already.

Thoughts?

I'm currently narrowing an RX7 axle for my J-H project. aeronca65t steered me onto a Website where a guy did this.

http://the-mite.com/mite22.htm

So far, I have all the brackets cut off, the housing has been narrowed and the bearing housings are welded into place. I have to put my suspension brackets on next.

The hardest part is aligning everything before welding. I turned my alignment 'spuds' out of 2.5" 6061 aluminum and used a 1.125 OD tube for my jig. In my case, the bearing carriers have a machined stub which is a drive fit into the housing. I cut the original welds with a whizz wheel and then turned them flat in the lathe, leaving the original alignment stub in place. After completing the housing, the alignment bar was within .003 of the center of the axle housing as measured from the differential mount face, close enough for me.

RX7 axles have a tapered housing, his was narrowed past the point where the taper starts so he had to cut off the alignment stub and build a jig for the center to keep his alignment bar centered with the differential bearings. I see no reason to build a jig for the center the way he did, I would just make two more 'spuds' to clamp into the differential bearing bores.

I have the axles at Dutchman Motorsports for shortening and resplining. They are also redrilling the flange for 4x100 mm. I wouldn't attempt resplining at home, I see too many ways to screw up. I also learned the hard way that getting the axle shaft too hot leads to brittleness. Dutchman (and Moser etc) respline the axle in a bath of coolant, the metal never gets over 200 degrees so loss of the factory heat treating is not a problem.

http://www.dutchmanms.com/

As far as adapting Miata brakes, I would think a set of caliper adapters would be easy to make. The Camarobird axle flange would need to be machined to allow the Miata rotors to be used, again Dutchman should be able to swing that for you.

2wd S10 housing + axles, swap the camaro guts

same 7.5" rear end, and narrow. i can measure one if you need it.

If you want detailed info go to www.pirate4x4.com and search their forums. It is quite common in the off-road community.

Shorten the housing yourself and just buy custom axles. That way you get and width/bolt pattern/strength you want. the S-10 housing will still need to be modified, theres just less crap to cut off.

According to Motor Trend (I know it's a rag, but they have a good online specification listing) the 2WD S10 has a 1384 mm (54.5") rear track. That's almost perfect as it would give me more room for tire in the back. The modification would be limited to cutting and welding bracket and adapting it to 4x100 and disc brakes - which would be required of any rear end I'm looking at.

Great tip, I'll look into that!

The S10 axle also won't have the torque arm and LCA brackets to cut off, just two leaf spring pads.

If I'm not mistaken I think the hot rod version of the S10 (I think they called it the Lightng) had rear discs and LSD from the factory. You could possibly use the rear calipers already on it. I just looked it up it is called the EXTREME (insert your own dramatic voice)

Check out the article i wrote on shortening stock Toyota rears for dwarf cars.

http://www.dwarfcarracing.com/tech_info_.htm

It starts around 2 inches down the page. If you want it to handle it needs to be done right to be straight.

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Remember the Camaro rear brakes are LARGER than the fronts... meaning IF you are going to use the Camaro brakes you will likely need 15"+ wheels with the correct offset. If you use the Camaro rear make sure you use Miata rear discs and the 4x100mm pattern.

I'm not going to use the Camaro brakes, I'll probably run Miata ones on all four corners. Same with the 4x100 pattern. Life's so much easier when all your cars can swap wheels back and forth!

According to Wackypedia, the hotter S10s used a different 8.5" rear end. So that means I can't use my existing diff. Pity, I would love to have an EXTREME rear end in the car.

Swapping to discs shouldn't be that hard, just a couple of custom brackets - he says with great confidence. We'll see once I get my hands on an S10 rear, I really like that idea.

By the way, the Mite website that Jensenman posted looks like a hell of a read. I know what I'm doing tonight.

http://the-mite.com/

Also I know it sounds boy ricer and all but if you can dredge up a "pre loading diff cover" you will be a lot happier. The 8.5" diff while stronger is still known for driving the ring out the case and chewing up a ring and pinion like the 8.8" Ford unit. Plus if you powder coat the diff cover it will look dead sexy ;)

Ya know, there's no real reason you couldn't do a 3 link and get rid of the olde skool MGB leaves. In fact, Syd Enever originally designed the B with a coil spring 4 link and the Panhard rod mount tore off of the frame on a preproduction car, there wasn't enough time to retool the shell. Legend has it the shell was made 2"? longer to accomodate the leaf springs, though.

The most important thing about the 7.5" diff is that there's one parked in my driveway. So that's what I'm going to focus on the for the time being

Here's a good tip from the LS1Tech forum:

You need to use a 2wd S10 rear from a 98 up S10. That will have the 28 spline axles already. the older ones had 26 spline axles and wont go into the later model diff. 4WD S10 housings are 4" wider than the 2WD ones. I believe they are close to the 60" hub to hub width that you will need for the B.

I'm not convinced that 60" hub to hub is what I want on the B, seems too wide - time for a little more measuring and calculating. But that bit about the spline count is really good to know.

patgizz, do you mind taking a hub-to-hub measurement for me? I'd also love a couple of photos of the end of the axle if possible.

I never considered keeping leaf springs. Just never crossed my mind! How would I tune the handling? I'd rather set up a suspension that can use the 2.5" springs I have piled on the shelves. I'll probably take very close inspiration from this build for locating the rear end: http://www.britishv8.org/MG/DanMasters.htm

http://www.aluminumv8.com/

This guy sells S10 rears 'already narrowed', so it appears the S10 is actually wider than the B axle. As near as I can tell, the stock B axle is 52" face to face, the S10 is 54 1/2" face to face (only 1/2" longer than a Jensen Healey axle BTW and I am going with 52" on my car) so unless you are planning to do some pretty serious fender flaring you'll need to narrow the S10 axle as well. If that's the case, you won't save much (if any) by starting with an S10 axle.

EDIT: A bit more Googling turned this up:

http://www.mgb-stuff.org.uk/axletext.htm

Banjo axle with wire wheels 44.5", with steel wheels 46.25". This is the old axle with the diff that comes out the front like a 9" Ford etc.

Salisbury/Tube axle with wire wheels 47", with steel wheels 48.5" This is the later axle with the diff carrier integral with the housing and a removeable stamped rear cover, like a Chevy etc and IIRC was the only axle available in a BGT. So it looks like a lot o' choppin' is in order.

keith,

bear with me - i'm heading back out to work then doing some xmas shopping, i can get you pics and measurements tomorrow but i might need an email reminder as i've had way too many concussions to have much of a short term memory. and i'm going to pick up my 6.0 shortblock tomorrow - LSfun for something is going to happen shortly - probably a 450 horse upgrade for the belair or some other such nonsense.

i have one s10 rear exposed on frame that the 40 is being built on, one sitting on wheels and nothing else, and one under my dad's 99 so i'll try to get you different shots.

http://dave.h-body.org/Build%20a%20Better%2010-bolt%20H-body%20Rear%20End.htm

This page has info on S10 and Explorer rear axles being used under Vegas and Monzas. It appears the Monza rear axle is 49.8" long, the Explorer/Ranger is 51" and the S10 is 54.25".

Jeez, the more I Google this, the more stuff I learn.

http://www.locostusa.com/forums/viewtopic.php?t=1086

S-10 rear info from the locost forum

The MG is already getting fender flares from a Rabbit, so I've got an extra 2-3" per side to play with. I'm also going to use Miata wheels, which have more positive offset than MG ones and thus tuck in more. I need room for rubber!

I want to come close to the track width of the front Miata suspension, which is 59" face-to-face or 55.5" between wheel centerlines with +45 wheels. Looks as if the 4WD S10 version might actually be preferable if it's around 60" face-to-face. A little bit less would be better, that means I can run a fatter tire. According to this thread, the 4WD version is 58.375" face-to-face. Sounds almost perfect.

You can also get this rear with discs from some of the SUVs, but I'm not sure that will save me any effort really.

There's loads of info out there, thanks for putting me on this track. I'll do more research tonight on my own time.

There's been quite a few V8 MG guys who've used post office jeep axles. Dana... good width. May be too narrow for your purposes, though.

i measured one of mine.

48" from flange to flange on the ends of the axle tubes

54" from face to face of drums

38 1/2" centerline on spring perches.

i took some pics too, i can put them up tomorrow if you need them

Pictures would be appreciated so I can start building the modified disc brake setup in my headOr maybe I'll just adapt the SUV axle, assuming I can make sure to get a 7.5" one. Sounds as if the 4wd version would actually suit me better.

Thanks a bunch!

Jensenman wrote: http://dave.h-body.org/Build%20a%20Better%2010-bolt%20H-body%20Rear%20End.htm This page has info on S10 and Explorer rear axles being used under Vegas and Monzas. It appears the Monza rear axle is 49.8" long, the Explorer/Ranger is 51" and the S10 is 54.25". Jeez, the more I Google this, the more stuff I learn.

Too bad Rangers and Exploders have that goofy offset housing.

They mention on a couple of sites that the offset housing can be a good thing because you may only need to shorten one side.