Is there any interest in a 8.8" diffential kit?

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Hello again gentlemen,
I'm the guy who was here about a month or two ago asking about drag racing the LS/Thunderbird IRS. Well I purchased the complete assembly from an '03 Tbird and took it over to one of my best freind's fabrication shop. He is also a Tbird SC enthusiast but he makes a large portion of is income doing custom fabrication and part manufacturing for the Ford MN12 chassis. We looked it over really hard and compared it to the MN12 rear sub-frame and things are looking good for this to work. He'll be cutting a rear floor off one of his parts cars soon and making a jig for the prodject.

But here's where you all might be interested. We did some measurements and comparisons between the 8.5" and 8.8" differential and it looks like that with the appropriate braketry that the 8.8 would slide between the axles. It's only about 0.25" wider and there was plenty of slack in the CV joints to absorb 1/8" on each side. I can't guarantee you we can do it yet as axle spline count and pinion flange differences have yet to be investigated but just so we don't ignore a viable market option I have to ask you guys.

Is there a market for an 8.8" Ford diffential swap among the LS performance crowd? Benefits would be readily availiable limited slips of every design. Gear ratios of any count from many manufacturers. All the while with greater strength. This could go either as just a bracket kit or with a differential set up to customer specs. These posi 8.8's can be found in current production Cobra's, the Ford Racing catalog, or even salvage yards under Thunderbirds, Cougars, and Mark 8. The iron case was most widely produced but the Cobra and Mark 8's were aluminum with a 15 lbs. wieght difference.

I don't have any price specualtions or any of that type of thing. It's too early for that. I will say that my freind has been in the business for many years and has a good reputation in the community that can be checked out on Ebay and multiple enthusiast Buy/Sell forums. His web site is www.texasthunderbirds.com . He is an excellent fabricator and we have an inner circle of friends that acts as a brain bank for doing these sort of prodjects. We work as a team combining experiences from all areas of welding, fabrication, metaluragy, racing, mechanicing, merchandising, etc.

If you believe you would actually be interested in this please post up. Include any requests or suggestions that will help us determine what we would need to do to make this something you'd want to purchase. How much work would you be willing to do and what would be too much. Also please suggest the price range you would be willing to work with as that is an important factor in him determining if it would be a worthwhile endevor.

Thanks again for your time,
Vernon
 
IIRC, the LS/T-Bird rear is 8.0, not 8.5. Not to say it can't/won't work. Just calarification.
 
If it would work as a reasonably priced swap, I think there are a bunch of us who'd be interested in it from the standpoint of getting a limited-slip differential under the rear ends of our LSes.

There's a project in the works to develop a limited-slip differential for the LS as it sits; if this project succeeds, I think the interest in this punkin conversion would drop significantly. For my part, while I have an interest in limited-slip, I don't particularly care about doing rear-end gearing changes, which would be the only other significant potential advantage.
 
I would also like to look into the swap. especially if it is a DIY type job with a good price. the gear ratio would be around 3:55 or 3:73 with a posi. On a side note how hard would it be to convert the lug pattern to 5.5 bolt patern? (standard mustang)
 
Thanks for the replys guys. Roger on the 8.0" size, wasn't sure. I'm not sure how much a custom limited slip will cost but if it's anything like the one the SHO camp brought to market it was very costly. I wouldn't be surprised if it was more than our idea. But it would be easyer so as always it comes down to what exactly you want to accomplish and or spend.

gt95coupe said:
I would also like to look into the swap. especially if it is a DIY type job with a good price. the gear ratio would be around 3:55 or 3:73 with a posi. On a side note how hard would it be to convert the lug pattern to 5.5 bolt patern? (standard mustang)
Click to expand...

I can only tell you what I had to do to covert one of my T-birds. It should be very similar. Use '99-up Cobra Mustang rear hubs and install them into your rear spindles. It was a direct swap. I used '94-up Mustang front wheel bearing hubs and install them onto your spindles. On mine I had to pull the ABS ring closer to the spindle. I used a large three jaw puller like the service manual says for replacing just the ring, but I just pulled it a little. I don't know where yours is but it was easy to line it up with the sensor. Make sure to get a new set of one use locking hub nuts when you're at the Ford Dealer spending your $350 or so bucks. The threads are all the same but make sure the retaining washers fit into the hubs you're going to use. I took all my brake rotors to a local circle track racing shop (Smiley's in The Woodlands, TX) and had thier fabricator redrill the Mustang 5-lug bolt pattern inbetween the existing Tbird holes. Actually I converted to Mark 8 front rotors and calipers at the same time but that's inconsequintial. It was also necessary to enlarge the hub hole in the rotors so they would slide over the larger Mustang flange centric. Which they did also, I think I spent $125 there. They had the new hubs to go by. That was it. Then I bolted some '94 Mustang Cobra 17 x 8 mags onto my arrest me red '94 5-speed SC. It looks real good. Now my back brakes look puny. It is possible to use Cobra brake kits now on my car. The rear calipers would require a new bracket that is sold by a vendor on www.tccoa.com.
 
Very interesting idea here. When you start looking at what pumpkin to use, I'm sure you'll find that all the T-bird and Mark VIII diffs will utilize 28 spline axles. 99 Cobras were also 8.8 diffs with 29 spline axles. All Cobras from 2001 up used an 8.8 with a 31 spline axle. I'm not sure what the 200 Cobra R used, but I'm betting it was 31 spline. Who cares...you won't find a Cobra R unit anyway.

We're not talking big horsepower here. The Cobra IRS will easily handle 450 hp bone stock and will handle 500 hp if you keep it out of wheel hop and don't use slicks. Neither of these should be a problem with the LS since it's an automatic and I wouldn't think those power levels are achievable on a street driven car.

If axle spline, size, bearing and seal size, etc are an issue, I would look into figuring out how to graft the 8.8 axle to fit the LS hub. It may be no more than replacing one of the ends...or it may involve someone building a whole new axle.

I would imagine the pinion flanges would be the easiest problem to overcome. Use the 8.8 driveline flange on the LS driveline. You may have to weld another end on it. You also may have to change it's length.

This could be a very interesting idea all the way around. Your choice of gears would be huge!
 
Holy Thread Resurrection..

What happened to this? Were there not any prototypes made?

I am asking because, I have a TL 3.73 8.8" IRS Rear from my Tbird, and I am looking for some shop to fabricate it to my LS..

Thanks......
 
Hi Guys
The hubs are now available from for racing and they list for $49.00 each and sell to you for $42.00 each. The bearings are also available for $37.00 each and your cost would be $30.00 each. The complete knuckle and brg assy for the mark8/t-bird sells as a kit of 2 for $449.00 and your cost would be $358.80 you would only need the hub with this kit and of course the lock nut p/n FOSZ-4B477-A $9.06 retail and your cost each of $6.80. All are in stock!!

Max
 
I'm doing it again... RESURECTION!

What happened to this?
 
2001LS8Sport said:
If axle spline, size, bearing and seal size, etc are an issue, I would look into figuring out how to graft the 8.8 axle to fit the LS hub. It may be no more than replacing one of the ends...or it may involve someone building a whole new axle.
Click to expand...

If you can get the carrier under the car, it probably would not be very expensive to have one of the numerous drag racing axle places make a custom axle with the Lincoln hub splines on one side and the correct flange to mate to the 8.8 rear on the other side... no?
 
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