Who has the recipe for limited slip independent rear end in a LS powered LBC?

Time to put my efforts into figuring out my rear end situation in the LS3 powered TR8. I have a narrowed Exploder rear end that would be a simple bolt in. I also have the entire rear end still under the 2010 Camaro SS donor vehicle. Exploder will weigh in around 175 pounds and the Camaro will be close to twice that much, and is way too wide. Ideally I'd like to be in the 57-58" wheel mounting face to wheel mounting face and have a 5X4.5" Ford bolt pattern when I'm done. Gas tank, which normally sits above the rear diff, is gone and now a fuel cell resides where the spare tire well was in the trunk. Nothing where the rear end sits now but a huge void, a forward bulkhead and two overhead frame rails. Infinite possibilities exist. Fabricating mounts, control arms, etc won't be an issue. What are my best, lightest, cheapest, strongest options? Heard mumblings about Ford 8.8 aluminum center sections, and custom axles. What are the Miata and Cobra guys running? There is a junk yard right around the corner that always has tons of Ford 8.8 stuff in there. Got my last two Exploder limited slip disc brake rear ends there for $75 each. For now, I will just install the Exploder and make up a four link so I have a roller again, but I'd like to explore the independent idea over the winter. What cars in the junk yard should I be crawling under?

99,01,03-04 Cobras.
89-97 Thunderbirds/Cougars/Mark VIIIs.
02-Current Explorer/Mountaineers.

What I read was that the iron case T-bird was preferred - stronger.

If you want irs, I would suggest that you cant go wrong by following the Miata V8 crowds. Not sure of the Face to Face spacing, but it does provide a 56" thread width. The field seems to be divided between the Getrag and the 8.8 differentials.

The getrag differential seems like the more expensive option, the 8.8 the more grassroots option. My go to site for this stuff is http://miatav8.blogspot.ca/search?updated-min=2014-01-01T00:00:00-08:00&updated-max=2014-04-04T21:13:00-07:00&max-results=6&start=6&by-date=false

I followed Mikes method to mount an alloy 8.8 posi out of a lincoln into the Miata suspension cradle. For axles I went with the broached Miata hubs and axles from Monster Miata.

And while it got me ridiculed on the MG swap forum, I will just leave this here:

For the cost of a bit of welding, you get a nice solid mount for the Miata rear suspension and a new location for the fuel tank in space that is not really utilized in the TR. Note that the whole thing was harvested with nothing more than a cordless drill.

In reply to NOHOME:

Wish I knew what I was looking at. Is that the floor pan from a Mark 8? Seems like a great idea.

floatingdoc wrote: In reply to NOHOME: Wish I knew what I was looking at. Is that the floor pan from a Mark 8? Seems like a great idea.

Miata rear section to include the entire suspension and fuel tank. It's like a big Lego piece that you can plug into anything once you get over the audacity of grafting cars together.

I think the Mk8 would be too wide for the TR7.

Cadillac CTS-V or 5th gen Camaro rear. The 8.8 is big and heavy and overbuilt. Given the price of a brand new Camaro rear compared to refreshing a junkyard 8.8, it's a bargain.

Seeing how there is a donor Camaro in my back yard now, I think I should explore that option first. Wasn't aware they were being used by the Miata guys. All I hear from the Camaro guys is that they break. Seeing how there are tens of thousands of these Gen5 Camaros just waiting to get wrapped around a tree, and very few T-birds left to pick over, the Camaro Getrag looks like a winner. Wonder if my driveshaft guy can do something with the Camaro driveshaft or if I should just have a new one made up without those rubber guibos.

It takes some time, effort, and money, but I’m happy with the way my MN-12 (T-Brid/Cougar/Mk VIII) setup is coming together. The T-Bird and Cougar come with either a 7.5 (V6) or 8.8 (V8/SC V6) with an iron center, and the 8.8’s were available with the Trac-Lok limited slip. The Mk VIII got the ~10lb lighter aluminum center, but no limited slip. The design of the uprights lends itself well to the simple SLA/double wishbone geometry we all know and love.

I pulled a complete rear subframe assembly from a Mk VIII being parted on CL for $100, getting me the needed diff and uprights/brakes and axles. Sold the aluminum Mk VIII lower control arms with fancy-bolts (PITA to remove) to a T-Bird owner for $75 and scrapped the rest, leaving me at $25 net cost. Since many Cobras get big power and the associated upgraded axles, I snagged a pair of standard Factory Five axle shafts for around $120 shipped, to use with the CV's from the stock axles. These are supposed to be 2” shorter (each) than the stock Mk VIII/T-Bird axles. If my math is correct, this should result in a brake hub face-to-face measurements of 59-59.5, which should be almost exactly the same as an NA/NB Miata.

The uprights (and new rotors) will probably be going to IRS Machining to be taken apart, cleaned up, redrilled to 5x4.5 bolt pattern, and rebuilt with new bearings (~$350). I may pick up some reman calipers while I'm at it though, since mine look pretty rough. Optional would be to have them rebuilt with IRS Mustang Cobra hubs (~$160 each) instead of reusing the MN-12 hubs, which could be somewhat beneficial on the brake hub register if upgrading to the Cobra rear brakes too, although that requires an additional caliper adapters ($150/pair) as well.

On a budget, Energy Suspension polyurethane bushings for the uprights run ~$45 and rebuildable Trac-Loks can certainly be found cheap. Alternatively, for a fancier setup, Whitby Motorcars sells spherical bearing kits for $425 and a Detroit Truetrac runs ~$470.

That being said, if you can get an appropriately shortened set of axles and can figure out the geometry, I'd definitely try to stick with the donor IRS that you've already got. Sure it may not be fully up to drag strip duty behind modified engines in 4000 lb cars, but if that's not what you're doing with it...

If you can live with the work to narrow it, stay British and run Jag IRS. It's pretty strong, fairly low unsprung weight for how strong it is, etc. Ideally, you want the later (88+) version with the outboard brakes. IIRC, any version prior to 98 has LSDs available. The 98 - 03 diff has minimal LSD options though.

Pulled the rear end out of the Camaro. It was remarkably easy. This thing, like everything on this car is overbuilt, over heavy, and not well thought out. I saw somewhere that the entire thing weighed 340 pounds. Pretty sure its heavier than that. Anybody have an idea why the two axles don't look exactly the same? One looks like a solid axle and the other looks much bigger. I'm assuming its hollow.

In reply to tr8todd:

I'd guess to control wheel hop. The different diameter axle shafts mean that each one "wraps up," so to speak, at different rates. That keeps the tires from losing traction at the same time and hopping.

Pretty much have the Camaro rear end stripped down, and it has something like a 64" wheel mounting face distance between the two sides. A buddy of mine offered up whatever I need from a parts Miata. Probably going to grab that whole rear assembly, figure out what year its from and see if the wheel mounting face distance lines up with what I need. Stock TR8 is 57.25, but I want something an inch or so per side wider. Higher offset wheels are easier to find. Longer axles mean better geometry for bump stop. I have flared fenders and want to run at least 10" wide wheels. I have not ruled out just building a new subframe, but one look at the Camaro bearing hubs, and I would rather not use those.

hub to hub I believe the Miata is 59".

Never realized they put an IRS in the Camaro. Looks heavy. I know Keith likes the getrag differential for roadcourse work, but I hear the word "broke" a lot when I was doing the research for what path to follow. The plan with the getrag seems to be 'buy new or stay away".

Its insanely beefy and really thin in other places. Whole car is like that. The worst part is everything you try an unbolt wants to take a pound of flesh. Not a rounded edge anywhere to be found. Mine was on the ground, only had 11,000 miles on it, no rust anywhere and I still ended up with three major cuts on my hands. Ruined a perfectly good GRM Tee shirt when the front snapped on an edge as I reached for another sized socket.

If you weren't already going down the Camaro path another rear to consider would have been a 2wd Toyota pickup. Already the right size and bolt pattern, the drop in center section is like a Ford 9" and has lots of support from the 4x4 crowd for strength and limited slip options.

NOHOME wrote: hub to hub I believe the Miata is 59". Never realized they put an IRS in the Camaro. Looks heavy. I know Keith likes the getrag differential for roadcourse work, but I hear the word "broke" a lot when I was doing the research for what path to follow. The plan with the getrag seems to be 'buy new or stay away".

Camaro's been IRS for the last two generations.

I'd probably pick the Camaro over the Getrag - the latter works, the former gets rid of all the people who tell you how it's going to break Seriously, the Getrag has more lash and is less happy in a light car. The early Getrags did have problems, which is why all those cheap ones are cheap. Spend $900 and get a brand new one and you're solid. Both are smaller and lighter than a Ford 8.8.

Keith, tell me something about those axles you sell with the 5 lugs. What year Miatas are we talking? Whats the overall face to face measurement going to be? Do I need to use Miata Bearing carriers, and if so are they different from the earlier 4 lug cars or do I need to source a set from a later 5 lug car. Seriously think I'll use the Camaro center section, order a set of 5 lug axles, find a set of Miata bearing carriers and build the rest. A buddy of mine offered up anything I need from his 92 parts car, but I'm guessing those carriers won't work with the 5 lug axles.

None of our axles have lugs. They're halfshafts, lugs are the job of the hub. The 2006-15 NC came with 5x4.5 bolt patterns, but they're set up for a multilink suspension. In your case, I'd probably reuse the Camaro parts and have the halfshafts shortened.

If you need some pictures or measurements of the 8.8" option in an NC just holler. Be more than happy to break out the ramps and the camera and share a few pics.

Keep in mind that the Camaro diff is in a nearly 4000lb car often driven by idiots, it would probably hold up better in a much lighter TR8.

In reply to tr8todd: want a simple bolt on? Crawl under Jaguars.. they come with a cage that will easily adapt to most cars. Kit car and hot rod guys have been doing it for decades.. Hint; Jaguars in Junkyards are cheap! Or find a non-running rust bucket on Craigslist/Facebook because the rear end is so heavy duty it will still be fine!!! PS. up to about 1997 in some models they still used NON metric nuts and bolts!!So get out that 9/16ths!

Here's the good news.. Dana 44 that's the center section.. Oh well some of them were Salisbury but they are so close you can even switch gears if your willing to do a little minor machining

They come in 3 different widths.. early XK-E's and 3.8 sedans are about 50 inch wide.. XK-E V12's and small sedans from the 70's are about 55 inches wide and later 70's XJ-s and XJ sedans up to about 1996/7 are about 70 inches wide..

Bolt pattern is Corvette so wheels will be easy to find..

Power limits? Plenty of 427 cobra kit cars made really serious power with big fat wheels.. Corvette itself went back to Dana 44's for a while..

How about Supra rearends. Lots of 'em here in the local Pick a Parts.

C4 Vettes are cheap too.

If you want to mod a C-4 let me Know I have 1 more than I need.

When i read the title i was hoping so hard that LBC stood for Lebaron convertible.

Took the driveshaft and the axles to my driveline guy. He said he could shorten the shaft no problem and even recommended keeping the two part shaft, center support bearing, and rubber donuts. For the axles, he said build everything and then cut a chunk out of the middle of the axle shafts, and then install everything. Once the ends of the shafts are installed and flopping around, weld a bar across the two pieces to give a fixed lengthy. He has a guy here in Ma. that can make up new splined shafts for me using the old ones as templates. Best part is I get to barter the install of a water heater at his house for the axle/driveshaft work. Time to go get some steel and fire up the plasma cutter.