Rear end choices.

Red98422

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I’m at the stage now where I need to think about axles to swap into my 280zx, the car in question being IRS and no hope of living behind my caddy.

That’s said there is a kit to convert to an 8.8 ford IRS, but that’s $1200 without center section, or stub-axels and requires a conversion over to 5 lug 72 Datsun hubs....lots of money. so not really that crazy about this route.

my other choices are much more traditional, basically back half and four link in. Then either an cut down an 8.8 ford or spend the money on a new 9” housing.

surprisingly the back halfing option is significantly cheaper if I go with the 8.8, as I can do all the work and I’m not relying on aftermarket parts. When I calculate it with the 9” (which will need additional things to complete like the center section, brakes, and all the miscellaneous crap that you always forget halfway through) the price obviously goes quite a bit up.

a break down as I see it pros and cons:

8.8 IRS
Pros
No back half
Better handling
“Bolt in”
Cons
expensive
Lots of parts fetching
Some required parts getting hard to find

8.8 solid
PROS
Cheapest
Comes with brakes/hardware
Pretty tough
Comes with posi
Easy to find
Cons
Requires back half
Handling penalty
Have to cut the axle down to length
Not a bolt in axle

9” solid
PROS
Strongest
Best aftermarket
Housing comes in custom size
Bolt in axle
CONS
Pretty dang expensive
Brake packages usually sold separate
Third member sold separate
Axles need to be purchased
Back half required

so what does everyone think? I’m leaning towards the 8.8 solid it’s the cheapest and if it’s not strong enough the cars already back halved so I can “install” a 9.
 

Caddylackn

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yes the 8.8 solid is where I would go. It is easy to find the 8.8 in later model crown vics Police Interceptors with the 31 splines and 3.54 with track loc and rear disc brakes at the pick and pull. Just upgrade the clutches and you have a strong rear end. So maybe $200 for the rear at a Pick n Pull, then another $200 for high performance 8.8 clutches. Cut off the spring perches and control arm mounts and weld in new ones where you need them. The crown vics use upper and lower control arms and coil springs so it is already 4 link. These use like a 44 mm wheel offset so it would be best to measure your rear end with tires on and compare to the 8.8 with tires on to check the lengths. I think the 8.8 from an explorer would be narrower, but I don't think those came stock with the stronger 31 spline axles. Many of those explorers did have rear disc brakes and a 3.54 or 3.73 gear ratio. You can also find crown vic rear ends with 2.73 and 3.08 ratios in the civilian cars. Yes, you will have to consider changing your front wheels to match. With the 44 mm offset, you will be limited on matching the front wheels since they probably have a much different offset, you might need 2" spacers on the front to get a matching set of wheels to work with the later model 8.8. The 8.8 solid probably has the best aftermarket support of any axle and custom axles and lug patterns are available.

Another option is the Lincoln Mark VIII 8.8 which is IRS and easier to find than mustang IRS. You can usually find a whole running and driving Mark VIII for under $1500, then you can sell the 4.6 4 valve motor to the mustang guys to recoup some cost. I don't know if the older Mark VII is IRS or not. I bet a 500 would fit in a Mark VIII since the 4.6 4V is so huge.
 

Red98422

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yes the 8.8 solid is where I would go. It is easy to find the 8.8 in later model crown vics Police Interceptors with the 31 splines and 3.54 with track loc and rear disc brakes at the pick and pull. Just upgrade the clutches and you have a strong rear end. So maybe $200 for the rear at a Pick n Pull, then another $200 for high performance 8.8 clutches. Cut off the spring perches and control arm mounts and weld in new ones where you need them. The crown vics use upper and lower control arms and coil springs so it is already 4 link. These use like a 44 mm wheel offset so it would be best to measure your rear end with tires on and compare to the 8.8 with tires on to check the lengths. I think the 8.8 from an explorer would be narrower, but I don't think those came stock with the stronger 31 spline axles. Many of those explorers did have rear disc brakes and a 3.54 or 3.73 gear ratio. You can also find crown vic rear ends with 2.73 and 3.08 ratios in the civilian cars. Yes, you will have to consider changing your front wheels to match. With the 44 mm offset, you will be limited on matching the front wheels since they probably have a much different offset, you might need 2" spacers on the front to get a matching set of wheels to work with the later model 8.8. The 8.8 solid probably has the best aftermarket support of any axle and custom axles and lug patterns are available.

Another option is the Lincoln Mark VIII 8.8 which is IRS and easier to find than mustang IRS. You can usually find a whole running and driving Mark VIII for under $1500, then you can sell the 4.6 4 valve motor to the mustang guys to recoup some cost. I don't know if the older Mark VII is IRS or not. I bet a 500 would fit in a Mark VIII since the 4.6 4V is so huge.

Thank you for the response! I have heard that the Exlorer sport tracs has the beefier axles with the disc braks and trac lock, but that is only what Ive heard no evidence as of yet. something I will look for at the parts yard for sure. Didn’t know about wheel offset, thank you for that info!

either way going to have to do some cutting on the tube to bring the width down, but they’re offset tubes (explorers are at least) so I should be able to trim the one down and get two short side axles....I have lots measuring to do.

front bolt pattern is 4x4.5, same as classic beetle, so wheel choices on the front runners shouldn’t be too terrible...I hope.

as far as the Lincoln MK route, that’s interesting to think of but I’m pretty well stuck on doing this to my Z car
 
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