Guys,what center section will fit lincoln mark viii?

[466scj]

hello all,
Just got ''the spook'' '97 Mark VIII LSC terminator conversion done and need to ditch the 3:27s.Anyone know what centers/posi/housings will bolt in?I am leaning towards 3:73s.Anyone use 4:10s?Will F150 posi units work,with a 31 spline axle shaft swap?....Explorer centers work with rear cover change?Any info will be appreciated!...thanks!

 

[beerdog]

As far as I remember you can only use the Mark8 pumpkin. I have never heard of anyone installing one from another car but maybe it is possible. I have only heard of people replacing the gears in an existing M8 housing. Most install a Ford IRS traction lock also. Other posi brands can be installed. If you go with a higher gear then you absolutely want some type of posi. I think I have hard of people converting to 31 spline. It is easiest to stick with the 28 spline or you have to also change the half shafts and hubs to match 31. You can also use a non-IRS traction lock from a mustang to save money. The only thing is you need to remove the cir-clips from the half shafts. A good used stang posi is easy to come by. I got one for $30 and rebuilt it for about another 65$.

 

[martin]

I wouldn't go more then 3.55 with the type of setup you have or you will be buying tires a lot. Trac loc aka posi is a must. GL and two thumbs up for the swap

 

[driller]

A Ford 8.8 Detroit True-Trac gear type limited slip differential - no need to complicate things by changing center housing or spline count. Get a cover brace or an LPW cover. Use poly or solid mount bushings with a front brace.

A lot of people have 4.10s, I have 4.30s. Seems most people with boosted setups will pick 3.73s. I'd be tempted to say 3.90s.

 

[466scj]

Driller,
How do you like the 4:30s?I have a set of those,but thought they would be too much.The trans is a built 4R70W overdrive....what RPMs are you running at say 60 MPH?

A Ford 8.8 Detroit True-Trac gear type limited slip differential - no need to complicate things by changing center housing or spline count. Get a cover brace or an LPW cover. Use poly or solid mount bushings with a front brace.

A lot of people have 4.10s, I have 4.30s. Seems most people with boosted setups will pick 3.73s. I'd be tempted to say 3.90s.

 

[driller]

I love the 4.30s! :roll_over:

Using 255/45-18s (27.04" diameter), I roll at about 2250 rpms at 60 mph and I'm pushing 80 mph at 3000 rpms.

 

[466scj]

Thanks JP!I am considering them.My Whipple makes 15lbs boost,so I may go 3:73 if I find a set cheap enough.If not I will try the 4:30s I have..

I love the 4.30s! :roll_over:

Using 255/45-18s (27.04" diameter), I roll at about 2250 rpms at 60 mph and I'm pushing 80 mph at 3000 rpms.

 

[chris2523]

As far as I remember you can only use the Mark8 pumpkin.

t bird and IRS cobra pumpkins fit as well. cobra has a 31 spline carrier though.

Most install a Ford IRS traction lock also.

everyone needs a trac lock!

I think I have hard of people converting to 31 spline.

can be done, not hard. swap the axles out.

It is easiest to stick with the 28 spline or you have to also change the half shafts and hubs to match 31.

all hubs are 28 spline. even from the cobras.

You can also use a non-IRS traction lock from a mustang to save money. The only thing is you need to remove the cir-clips from the half shafts. A good used stang posi is easy to come by. I got one for $30 and rebuilt it for about another 65$.

this exactly what i did and it works great.


in my opinion, 4.10/4.30 is a little much for a eaton/kenne belle/whipple powered car.. 3.73/3.90 would probably be better. cobra's ran 3.55 i believe.

 

[Stealthrider]

2003-2004 Mustang Cobra pumpkins doesn't fit a Mark VIII?

 

[Right on the mark]

Yes they do BUT certain year 2003 or 2004 have different axle spline count. Think 2003 is 28 same as mark and 2004 they upped to 31 spline axles.

 

[466scj]

Awesome,thanks for the imput....going 3:73

 

[Mad1stGen]

Yes they do BUT certain year 2003 or 2004 have different axle spline count. Think 2003 is 28 same as mark and 2004 they upped to 31 spline axles.

Only 1999 Cobras have 28 splined differential. All 01-04 have 31 spline trac-lok. 99-01s are 3.27, while 03-04s are 3.55.

Anything more than 3.73 on a 4r70w with KB or Whipple making 500+rwhp is nuts :err-what?:

 

[driller]

Anything more than 3.73 on a 4r70w with KB or Whipple making 500+rwhp is nuts :err-what?:

NOW I need this!

 

[racecougar]

Lol. Don't fear the gear. I run 4.10's with a 28" tire on my car (5.0L 4V stroker/2.1L Kenne Bell/4R70W). If I went to the track more than a couple times a year, I'd absolutely step up to 4.30's. If it was a track only car, it would need 4.56's to trap near redline (7K rpm) in third at its current power level. As it sits, it's perfect for what I use it for, mostly cruising backroads and highways. It cruises along at ~2800 rpm at 80 MPH in OD. I wouldn't go any lower (numerically) than 4.10's unless I also reduced the rear tire diameter.

 

[Right on the mark]

Only 1999 Cobras have 28 splined differential. All 01-04 have 31 spline trac-lok. 99-01s are 3.27, while 03-04s are 3.55.

Anything more than 3.73 on a 4r70w with KB or Whipple making 500+rwhp is nuts :err-what?:

Thanks for clearing that up. I knew one year had 28 spline.

 

[Gau8mechanic]

Dead thread revival. I'm in automotive technical classes and we're in the drivetrain module. So this is a good thread to help me here. I would like to got trac loc. No money. I know the LSC has the 3.27. I have access to a 3.55 gear set from an '06 GT. First will it fit? Second will this be enough gear to notice a change(is it worth the time/effort), negatively affect my pocketbook(gas/tires)? By the way, I have a '97 LSC and no power adders/tunes/shift mods.

 

[driller]

Not knowing what the '06 GT has, the GEARS on all 8.8 differentials are interchangeable. The differential itself would need to be 28 spline for it to work and if it is not an IRS you need to leave the circlips off the halfshaft going into the spider gears.

 

[Roadboss]

Be mindful that those who are running twin screw super chargers don't need all that gear as they have instant torque. Centrificals often will run a 4:10 because they need to get the rpm's into the boost range quicker. I run 3:73's and I am glad I got talked out of 4:10's as grip is still at a premium at launch. With an automatic there is less a need to step up to the heavier axles, 28 spline are sufficient.

 

[466scj]

I think the two masters (driller,roadboss)have you covered with the gearing/diff questions.I used a 28 spline carbon fiber unit with 3.73s.Also glad I didn't use 4.10s.

 

[racecougar]

Be mindful that those who are running twin screw super chargers don't need all that gear as they have instant torque. Centrificals often will run a 4:10 because they need to get the rpm's into the boost range quicker. I run 3:73's and I am glad I got talked out of 4:10's as grip is still at a premium at launch. With an automatic there is less a need to step up to the heavier axles, 28 spline are sufficient.

That really depends on how you use the car, power produced, rev limit, and the tire you run. As I mentioned above, at my current power level (trapping @ 114 MPH), with a 28" slick and 7k rev limit, 4.56's would be a better suited gear than the 4.10's I currently run. I enjoy cruising down the highway though.