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I've been reading and learning a bunch from this site. I started looking around to see if there were any Thunderbird rear ends locally I could purchase as I start to collect parts. I did actually find one! BUT it is from a 2002 Thunderbird. Everything I read is about the older models, and I can't find anything about the newer ones. Would they work?

Here are the specs: (only $250!)

3.58:1 Ratio, sub frame, differential, axles, hubs, 11.3" disc brakes with E-brakes, calipers, NO SPRINGS

What do you think? (the assembly is about 2 hours from me, so I don't want to drive all the way down there for nothing!)

thats the point of building a car yourself, make it fit.

True, however since I've never tackled anything like this before (I'm a software developer), I'd rather attempt to do something that has been tried and tested. I'm just a little concerned since I have not found anything on any site regarding these differentials. It makes me wonder if there is something that prevents them from working well or if they simply require way more work then I can do.

Sure just about anything can work, including those DEW98 ("new" Thunderbird, LS, S-Type) chassis components. That's definitely a pretty attractive price. I'm not sure what differential is in them, but I am pretty certain it's not the 8.8 IRS most people are familiar with from the MN12 chassis cars. As such, there may or may not be a limited slip readily available if you require one for your build. While they both use a 5x108 wheel pattern, the MN12 has the option to swap hubs to those from an IRS Mustang Cobra to convert to 5x114.3 which substantially broadens wheel availability. Whether or not anything similar can be done with the DEW98 components is open open to research and debate, but ultimately will require somebody with a vested interest hunting down the facts. As a starting point it appears the wheel bearings might share a common ID with the MN12 (just wider?) and the CV axles look to use a 28 tooth spline like the MN12...So maybe there is some potential there.

I've been scouring the internet all day trying to find information on this diff. I finally just found a site that says the new Thunderbirds use a Ford 8.0" IRS differential. I did want LSD, and I was able to find one that would work, but I also read posts that indicated some 2002 Thunderbirds did come with a LSD. (which I do want for sure)

Here is what I found out about the differential:

• Ring Gear Diameter: 8.000
• Cover Bolts: 10
• Ring Gear Bolts: 10
• Spline Count: 28
• Dropout: False
• Pinion Support: False
• Carrier Breaks: none
• Rear Suspension: Independent

It looks like the differential won't be as strong as the 8.8", but should be stronger then the 7.5". I'm leaning towards using an LSX motor, so I'm not sure if it would be quite strong enough...

Another thing to consider is the overall width, wms-wms. Are there shorter axles that can be swapped in to reduce the overall width. That is the problem with the MN12 diff, the overall width is too wide for anything but a +4.

Were you planning on using the subframe as well? I cant see how the spindle looks in the pictures, but those arms look very light.

I was thinking about using the whole subframe. But the more I've read about that 8.0" differential, the more I think I better pass on it.

Please elaborate and share what you learn. Personally, I think even the 7.5" is strong enough. In our case the limiting factor is probably much more the torque available at the rear wheels then the torque available from the motor. They have to balance each other. That would be for "normal" use anyway. If you're building it for use just at the drag strip, things might be different...

I don't think building that sub frame into your car is a good idea. It will weigh a lot and then you have a suspension designed for a car 3 times your weight with a bunch of bump steer. I don't think it will save you much effort either.

Along this line, a few years ago I read that the Ford 8" (I'm sure it is not related to this 8", but size is certainly similar) was suitable for street use (no slicks) in an under 3,000 lb car regardless of engine size. Just not enough traction to do it in. Does this unit have a glaring weakness?

Bill

This Ford 8" is completely different then the Ford 8" of the past. It is called the Ford 8.0"IRS. I was unable to find any gears or limited slip for it. So you get what you get and you can't change it.

Also, since this setup was only used for a few years, I was unable to find anything that would lead me to believe the axles could be changed out to use different tires.


Those two items turned me off from it. It might work for others, but not for my plans.

Well that's interesting. It's a big subject....