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Discussion Starter #1
Good day all!!

I have read a lot of posts about converting a non-IRS LSD (or TL) to use in our IRS cars... I have done this numerous times and many have done the same thing... I have read some posts where this machine work is not needed, but I do this for peace of mind...

I have converted my 3.08 8.8 open diff to 3.55 locker... I got the 28 spline locker from a used Mustang... It is said that most or all new lockers have the IRS machine work done... If you can't afford a new unit, you fit into my category... As time marches on, the number of 99 Cobra rear diffs (stolen from the Mark 8 line) are becoming more avail... These are bolt in units for our cars...

First, it is best to remove the ring gear from the LS carrier... Now is a great time to upgrade to those better gears you have always wanted...

This is an open 3.07 from a Mark 8... The whole diff on the Mark 8's are aluminium and are marginally lighter... They will bolt right into your T-bird!!



You may notice the machine work where the splines are cut back about 0.14 inches (I measured it)...

With the axle pushed all the way to the pin, you can barely see the expansion ring on the end of the CV joint...



and again with the ring sitting up against the machined lip...



There is very limited play, and knowing it is limited to this movement is worth this work to me...

I only have a 31 spline TL carrier, so this is just for reference, but the measurements should be nearly identical if you wanted to upgrade the halfshafts to those from a 01 and up Cobra... Most 96 and up Explorers have the 31 spline TL... That is where I got this one from...

Remove the 8mm bolt holding the pin in place, and remove the pin... Note: no ring gear as this pin will not slide past most of them...



Slide the pin out and tap the "S" spring out... This does have a little tension on it, so be careful!!



Once out, rotate the smaller spider gears so they can be removed... Don't lose the shim that is on the back of these gears... Remove the main spider gears, and pull off the clutch packs... These were really used up, so a replacement set will be in order before I use this... I still have to get the Cobra half shafts anyway...



Here is the main spider gear that will need to be machined to accept the expansion ring on the end of the half shaft... You only need to cut away just the splines here... It would also be a good idea to bevel the new edge of the splines so you can remove the axles should you need to remove them later on...



I use my dremel and the 1 inch stone cut off wheel... It is the perfect diameter for the 28 spline units... If you have a machine shop in your area, I think they will be able to do this small machine work for you...

If I have missed something, please feel free to add, delete, or modify as needed...

Hope this helps!!

Cheers!!
 

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Good day all!!





Cheers!!

Well this got my curiosity. I just went and checked a set of side gears that I have that came out of a 93' mark 8 parts car that I have. They looked machined to me compared to the pic above! Did some come from the factory like that? Sorry for the bad pic, but this is no do it yourself job with a dremel either.......Or do I even have the right gear??? I noticed the original pic has less teeth than my pic. Sorry but I'm not much of a rear end guy

 

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Discussion Starter #5
Well this got my curiosity. I just went and checked a set of side gears that I have that came out of a 93' mark 8 parts car that I have. They looked machined to me compared to the pic above! Did some come from the factory like that? Sorry for the bad pic, but this is no do it yourself job with a dremel either.......Or do I even have the right gear??? I noticed the original pic has less teeth than my pic. Sorry but I'm not much of a rear end guy
Good day,
The reason you have the machined lip is cause it came from an IRS car, as stated by davis97rx7... The reason mine has 31 spines to your 28 splines (or teeth) is because mine came from a 97 Explorer... It is hard to tell from your picture if it is an LSD... If you have the 'S' spring putting pressure on these gears, it is an LSD... If you convert an open diff for an IRS car to LSD, you may need to do the machined lip... unless you get the whole rear from a 99 Cobra...

It does take a while to do with a dremel, but it does work... It won't look like a machine shop did it, but looks won't matter when it's got the cover on... I think the machine shop is the best bet, though...

Cheers!!
 

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Good day,
The reason you have the machined lip is cause it came from an IRS car, as stated by davis97rx7... The reason mine has 31 spines to your 28 splines (or teeth) is because mine came from a 97 Explorer... It is hard to tell from your picture if it is an LSD... If you have the 'S' spring putting pressure on these gears, it is an LSD... If you convert an open diff for an IRS car to LSD, you may need to do the machined lip... unless you get the whole rear from a 99 Cobra...

It does take a while to do with a dremel, but it does work... It won't look like a machine shop did it, but looks won't matter when it's got the cover on... I think the machine shop is the best bet, though...

Cheers!!
I was acutally talking about the big teeth going around the outside of the gear. My pic has more teeth than the one in your pic. Mine has 16 teeth vs. yours with 13.

The whole 31/28 spline deal I understand.
 
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