9" rear end questions?

[merc91]

someday my 91 marquis will see around a 400hp crate motor for driving around town with some possible NOS for occasional track. I would like a setup that could handle 550hp to play it safe. I'm assuming an 8.8" won't like that to much so I was wondering how difficult it would be to get a 9" rear on the car without changing the track width or general configuration if possible.
Lucky for me the car is mint and rust free and its going to be the car I hold onto for a long long time... so if it is going to cost some money I will spend it to get the right setup back there to last, so I know you guys know your stuff allot better than me or shops around here on the subject, so let me know what's inside those brains.

Thanks to my LOPO, the car will be seeing 200hp or so for the next 3 or 4 years or so, haha, but if I will need a 9" eventually than I will put it in now instead of a newer merc 8.8" since my next project is rear end with disk brakes and 3.73's, and track lok install... and spending it all on an 8.8 that will only be good for a couple years doesn't make much sense.

Well thanks allot guys, here you get answers to what you would only get a laugh from a shop.

[P72Ford]

It needs to be made to fit. There are no "bolt in" apps, that I know of.

You'll probably have to shorten a housing to fit, and you'll need to have some axles made (Moser, Currie, Dutchman). You'll also have to make upper control arm mounts, and either transfer the LCA mounts and such from the 8.8, or make new ones. UCA mounts are not that big of a deal; the geometry has to be exact, though. You can make them from 3/8" plate (bent into an L), or channel. Smaller thickness might work, but I like beefy stuff.

The spring perches will also need to be transferred, or you'll have to make new ones.

When narrowing a housing, its crucial that the ends are square, obviously. A jig works best for ensuring this.

If you're going through the trouble, it almost makes sense to go with a more custom rear suspension setup. I like the 3 link idea, myself, with a panhard.

[mrltd]

Send your 8.8 to currie and have them make a 9" with the proper mounts and brakes. It will require more custom stuff for the brakes. Probabaly be explorer discs. All in all should cost like $1500-2K

[70torino429]

It needs to be made to fit. There are no "bolt in" apps, that I know of.

You'll probably have to shorten a housing to fit, and you'll need to have some axles made (Moser, Currie, Dutchman). You'll also have to make upper control arm mounts, and either transfer the LCA mounts and such from the 8.8, or make new ones. UCA mounts are not that big of a deal; the geometry has to be exact, though. You can make them from 3/8" plate (bent into an L), or channel. Smaller thickness might work, but I like beefy stuff.

The spring perches will also need to be transferred, or you'll have to make new ones.

When narrowing a housing, its crucial that the ends are square, obviously. A jig works best for ensuring this.

If you're going through the trouble, it almost makes sense to go with a more custom rear suspension setup. I like the 3 link idea, myself, with a panhard.

all of this. It's going to have to be custom. Cowtown cowboy on cvn has a custom currie 9" in his 408 powered vic. I would contact moser and have them send you a free catalog in the mail, its a good informative read. I will warn you though, a custom 9" won't be very cheap, but they are very good rear ends.

[mrltd]

or just go online and look at the websites. They have all the info there. Or just call them.

[merc91]

thanks allot guys, I had no idea at all how to go about it and how hard or easy it is... and now I know whats involved. I think i will have my current 8.8 built up with just track lok and 3.73's in the mean time and leave the brakes and all that stock since i will only use it for 200hp or so for a few years.
Then in a few years when I get into a job after school I will do what you guys suggested and get a 9" rear end custom built for me... allong with a better suspention setup and just get it all done at once. I will look into getting currie to do it all for me.

Thanks allot for the info guys

[1980c10]

there is no reason for a 9'' an 8.8 with good stuff in it will take what ever you throw at it mustangs guys beat the sh** out of them. So I would say just get a 31 spline center section and get some 31 spline axles made in panther length. Do a nice rebuild on the teac-loc and the rear end and call it a day

[mrltd]

there is no reason for a 9'' an 8.8 with good stuff in it will take what ever you throw at it mustangs guys beat the sh** out of them. So I would say just get a 31 spline center section and get some 31 spline axles made in panther length. Do a nice rebuild on the teac-loc and the rear end and call it a day

Yeah, an 8.8 with custom axles, custom tubes, and 9" ends.... Mustangs are signifigantly lighter than a panther. I've had lots of problems with the axles and bearings on my car with only 245hp. Granted I autocross, but with more hp doing launches you'll see the same forces and failures.

All the wagon guys here that have mods have blown the rears completely apart. Woody blew his on a 1-2 shift (5 speed) and Uslydawg blew his pinion (and rest of the guts) clear out the back of the pumkin. I have had many axle failures, and destroyed a trac-lock housing. All of us have mild motors-under 300hp.

[87gtVIC]

suspension>suspention

[gadget73]

Just run really crappy little tires. No traction = no need for a better diff.

[P72Ford]

Yeah. 195 50 15s.

[merc91]

Man, P72Ford... that is the best burnout I have ever seen!

I like the idea of going with a custom 9" with better suspension setup... I have heard of lots of 8.8 exploding, but I know there are less 9" but I have heard they are bullet proof and they have backed up there reputation from what I've seen. And with a bigger motor and tranny, sound system, beefing up chassis... the car will not be getting any lighter for sure.

Yeh haha, I could always throw on my old 215/70/15 pizza cutters on the back, lol.

[mrltd]

pfft, almost any car can do that...


now this... 255/50/17's!

[hav24wheel]

To a certain point, more power is easier on a rear axle than, less power. U learn this fact fast in the off-road world. A lot of off-road rigs run the 8.8s with 35-37 inch tires on them, yes they have 31 spline shafts in them. But it shouldn't be too hard to get them made for it. Also the Trac-lock is JUNK! Might as well run a open diff. Get a Power-lock, or a Detroit for the best traction. The strength diff between a 9 and a 8.8 isn't that much(as long as we are compairing stock 28 spline to stock 28 spline). I have blown apart a fair amount of 9 inch rear ends. Seen pinions shoot out the front of them. If I where u I would do some math and see what would be the cheaper, custom 9 or beef up your 8.8.

[P72Ford]

pfft, almost any car can do that...

now this... 255/50/17's!

Your tires... they still hold air. Therefore, I win.