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The "Ultimate" IRS Swap for S30s

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The original poster (wfritts911) made these kits in a batch and sold them all.  At the present time I don't believe there are any available for sale but he may do another batch in the future as time permits or he might work something else out if enough additional people show interest.  Your only hope at the moment is to purchase a kit from someone who got one of the original ones.  

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My Z is my midlife crisis car! It used to be my young and rebellious car. Someday it will be my old-timey car.

Lol you guys get butt hurt over the most trivial things. Armchair coaches have always been funny to watch and listen to.

Hopefully sooner rather than later. Planning on learning to run the waterjet this week so I can cut at night, since getting the current operator to cut stuff for me is like pulling hairs. Hopefully ca

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I finally got around to ordering the off the shelf parts today.  It seems QA1 quit making the 2.5"x10" spring with the 300lb/in rate, in a powder coated version. 


The spring is no longer available as an option on QA1's site powder coated silver, either.


Summit/Jegs does have the chrome version.


Part number is: 10CS300


The part number from the pdf that is no longer available:10-300

Edited by bramagedained
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http://m.summitracing.com/parts/qa1-10ht300 silver powder coated. Landrum, ridetech, summit, eibach and a few others also list a 2.5 x 10" in a 300lbs/in rate. Summit's are about the same price, others are all more expensive. Edited by 1969honda
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  • 2 weeks later...

Diffs are actually pretty easy to find for an 8.8 IRS ford.  The Thunderbird Super Coupes, 02+ explorer/expedition have them, Lincoln Mark VIIIs, Mustang Cobras, etc... all have them.  If you watch you can find them with a factory limited slip or pic up an LSD relatively cheap compared to the Quaife/Phantom/OBX/Cusco variety available for the R180/200/230 nissan units.  


A couple good resources for looking for a used diff are http://car-part.com/ and http://www.lkqcorp.com/en-us/

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I just searched on the mentioned car-part and one of the local used parts places had one with a 3.73 and LSD from an 03 explorer, paid $300.


I'm just waiting for the pair of gland nuts from Koni and I have all the parts, my school semester ends on the 18th(giving me the 19th->05JAN without class to get it done) and I plan on starting the swap the next day.


I plan on fully documenting every step of the swap with pictures.


The tag on the diff should have an "L" to denote it's a track-lock LSD.


Copying a post by SunnyZ:




The 8.8 IRS was offered in the following vehicles

99/01/03/04 Cobra

1989-1997 Thunderbird Supercoupe (All Posi-traction)
1992-1997 Thunderbird V-8 models with rear disc brakes(some posi-traction)3.08, 3.27
1992-1997 Lincoln Mark VIII (All aluminum carrier, most non-posi-traction) 3.07, 3.08, 3.27, 3.55, 3.73
1989-1992 Mercury Cougar XR-7, supercharged V-6 (All posi-traction)
1993-1997 Mercury Cougar V-8

02+ Explorer/Mountaineer = 3.55 and 3.73 open, 3.73 LSD , 31 spline

To determine the gear ratio, and whether or not the unit has posi-traction, look at the tag that is attached to one of the differential cover bolts. The first 4 spaces signify the gear ratio and whether or not it has posi-traction. If the unit has posi-traction, then the second space will have an L in it representing (limited slip), the remaining spaces specify the gear ratio. For example, 2 L 7 3 means posi-traction with a 2.73:1 gear ratio. Most people pay a salvage yard between $300-$400 for the donor parts. Also, Ford Motorsports sells a 15lb. lighter aluminum carrier with gears and posi-traction for around $650.



I can't comment on if any mount different on the rear cover, or which have 2 mounts on the snout vs the single that the explorer/mountaineer diffs use and that the kit is designed around.

Edited by bramagedained
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Well. I learned a lesson that not all CVs are the same.


I spent the day tearing them both down and on assembly(both CVs themselves greased and back together) find that the stars/axles on the pair that I bought have different splines than the 930 shafts/CVs.


They are for an F150 in the correct year range.


The CARDONE SELECT 662112(which I'm assuming are what others bought)  are re-man'd FoMoCo ones.


The SURTRACK FD8023 ones I ended up with obviously are not.


Both are on the same RockAuto page when you search the 3L3Z3B436AA number in the pdf from Will.


They do still fit into the intrepid hubs.  Without taking them apart(at least peeling the boot back) there's no way to tell that there is a difference.


Getting the axles that looked like they were $13 cheaper, cost me a whole day and the $100 for the ones I've now cut apart.



I also noticed while cleaning up the 8.8 I bought from a junkyard that one of the rubber washer deals is missing from the mount near the pinion.


The axles in question:






Still fits in the hub:



But, clearly won't work with the 930 axles:




At least having a pipe vise made cutting the axles easy:



I didn't see a reason to take the inboard side apart, I only pulled the boot to see if it would have been worth the trouble.

Edited by bramagedained
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Step by step on the axle thing.



Some of the pictures are of the wrong axles from my previous post.  The steps are the same either way.



First thing's first.


Get the correct axles.  Either from Ford or Ford Remans.  Cardone(online places+amazon) and MasterPro(O'Reilly brand) are both re-mans done by Kragen and are correct.

Masterpro(O'Reilly) part number: 60-2112

CARDONE SELECT part number: 662112


There should be a Ford logo stamped into the CV housing. 


Looking closely at my pictures, I now realize that I could see splines on the shaft of the incorrect axles and could have compared them to the 930 axles and it would have been obvious something was awry.

F150 axles, these need to be cut apart to disassemble the outer CV, which is used along with the new 930 axle shaft and a 930CV as the inner joint.


The shaft needs to be cut off so you can spin the star far enough for the ball bearings to come out so that you can take it apart:

This is the wrong axle, on the correct re-man'd Ford pieces you cannot see any of the splines where the shaft goes into the star of the CV.


Good thing a pipe vise is in the garage, it made this part fairly easy,  I spun the axle around the other way before I actually cut it, this just made for a better picture:



Done with a cutoff wheel, care taken to not ding the CV joint itself:


Outer CV cut free from the rest of it:


Now you can spin the star far enough to get the balls out, which means you can get the whole thing apart:


(Yes, beer belly used to hold it up for the picture, this is before I realized the hubs make a good stand while working on this step.)

Star and balls:


CV Joint separated and cleaned, shaft still needs to be pressed out of the star this is now a picture of the correct axles:



This is the spring clip that needs to be pressed into the shaft to get the shaft out of the star.  As mentioned by Will earlier it's much easier with two people, one to run the screwdrivers and another to give it a whack.  With a ball-peen and bronze drift it popped right apart.



Outer stub fits into the Dodge Intrepid hub like it should:



The hub actually makes a really handy stand to put the whole assembly into while you're rolling the star/cage around to remove the ball bearings.

That leaves you here, with all the parts ready to assemble:




Edited by bramagedained
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Posting to keep them in line.


I assembled the axles today, for the most part it was so simple forgot about steps and only took 3 pictures.


I'll upload the pictures later tonight.


As a note, I had to chase the threads of 3 holes in the diff side flanges as they had paint/powdercoat in them and the bolts would not go in.


I already had the CV greased and sitting on it when I found the first one, for the other two in the second axle I tested all the holes first and found 2 more that needed to be cleaned up.


On another minor note, despite my F150 axles both being from the same place I noticed today that the cage for one of them was just slightly different.   The windows in the side that the ball rests in were just a slightly different shape than the other 3 axles I've had apart.


Notice that this cage is more "D" shaped.  The other 3 axles were all more of a rectangle:




I'm pulling my car apart tomorrow and hopefully getting most of it re-assembled.


Once everything was back together and loaded with grease I used the 930 shaft to work the joint around.  I figured it's better this way to make sure the grease got everywhere vs it happening while it's under load:




I forgot to take pictures of assembling the 930 CVs to the inner stub.  It's really simple.  I did it slightly different tha Mikelly in that I had it bolted together before putting the boots on, so that there was less chance of cross-threading.


Pair of assembled Axles:




I just used zip-ties for the outer boots.

Edited by bramagedained
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I pulled my car apart today.


Except for the fitting on the driver side brake line everything came apart very easy.  Perk I guess of buying a car that had mostly just sat in a garage since 1990 and apparently never saw salt or much rain in it's life.


I had to fight with installing the front diff mount a bit, due to what I assume to be a difference

between the 260 and 240.  There was a tab that an exhaust hanger went to on the driver's side which was in the way, and isn't in pictures of the other installs.  I had to grind down some spot welds to get it out.  It was just above the bolt holes on the driver's side.


Stuff to undo to drop the subframe/diff:


Brake lines:




Parking brake cable:




Since I don't have a transmission jack, I had the diff+subframe supported with two jacks and a 2x6.  I'm sure there's a better way, but, it's what I had and I was working alone.


The order for the rest didnt seem to matter much, I did use some 4' zip ties I had in the garage to hold the struts to the rest of it so they wouldn't flop out when they dropped free.








I did undo the struts last.




Which left me with this on the floor:




The zip ties holding the struts was super helpful.  I had a jackstand under the driveshaft which I completely forgot to disconnect ahead of time.


You need to get the arms free from the stock uprights as they are re-used, which means spindle pins.


...only you don't actually need any of that so I used a tool to make a 10 minute job per side:




Dad's porta-band made short work of the pins. One of the pins I probably could have gotten out, it moved when I hit it with a hammer, but, cutting it was just easier.


What's left of the pins:




Hopefully I will have everything together tomorrow.


Off topic but amusing, check out the quality craftsmanship of the exhaust from when my car was swapped in 1990:





Edited by bramagedained
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The exploder diff had a bad pinion seal:




It's super easy to replace.  The only step that wouldn't have been immediately obvious was to take a paint marker and make a line on the shaft, nut, and flange.  When you re-assemble tighten the nut to just past where it started.


I went by this:



I decided it would have been dumb to replace only the pinion seal.  Today I went and grabbed the two axles seals and replaced them as well, they cost a whopping $10 each and take only a few minutes to replace.


Intrepid hubs bolted up to the provided uprights:




(mostly)Everything laid out for tomorrow:




I'll edit this after everything is back together.


Putting the dandy new coilovers together:


This spacer goes inside the tube, it's contoured to match the bottom of the Koni shock:




I'm not adding camber plates, so I re-use the factory tops.  I had to round out the hole, it's otherwise "D" shaped to hold the threads on OEM type struts:








I didn't take pictures of any other step for the coilovers.  Will provides two washers which go between the top spring perch and the factory top so that everything seats properly:




Dropdown and mustache bar in place:




Instead of fighting with the driver's side bolt I just drilled a hole in the spare tire well that I'll get a rubber plug for:






Eventually I'm going to put in a fuel cell so the spare tire well is going to get cut out at some point anyway.


Diff mounted, this took some effort and help.  A transmission jack would have made this much easier:




I had to clearance the part that goes behind the diff that the control arms bolt to, it just slightly hit the diff.  Unfortunately I never took any picture of it.  A couple wacks with a ball-peen made room.


Admittedly, I did a crap job of taking pictures today while assembling since it only took me about an hour and a half to finish.


Everything goes together really easy after you get the diff wrestled up into place.


Arm, axle, and upright together:




Just throw in the strut and brakes.  I had help with the struts as it was easier to have someone else start the nuts while I just held the thing in place.  Once the three nuts were started I did the two bolts to Will's upright:




Which is also the complete setup.  I didn't take a picture of it on the ground, since until I get wheels it's sitting on a pair of leftover DSM space saver wheels.

Edited by bramagedained
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Edited the teardown and assembly posts.  I didn't get finished today, but, I will tomorrow.


Perhaps budgeting two days to do this whole swap was a bit over ambitious.


I probably could get it done tonight still, but, it's cocktail hour somewhere I'm sure.


Edit: Job finished, assembly post edited.

Edited by bramagedained
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