View Full Version : Please help....8.8 install

05-04-13, 09:24 PM
Ok I need help. I installed the 8.8 diff in my cts-v today and went to put the axles in and they will not clip in. I put the rear diff together myself using a stock carrier from a explorer with 31 spine spider gears. Is the irs spider gears the same as a solid rear? I've looked on the internet and they appear the same and does not state any difference. Please help

Shark city V
05-05-13, 05:29 PM
If im not mistaken They're not the same IRS vs solid. I believe on the IRS style spider gears the cv axle clips into a grove machined on the inside of the gear where the splines are at. The solid axle has c clips and they rest face of the spider gear ( if that makes sense)

05-05-13, 09:06 PM
That makes sense. Any ideas where I can find a set. I've been looking and can only find 28 spline IRS spider gears.

Shark city V
05-05-13, 10:47 PM
I believe cobra IRS diffs came with 31 spline. If the diff you have in the explorer is a locking style they should work.

Shark city V
05-06-13, 03:03 AM
Google: LRS 4215 B spider gears. Might be What you need.

05-07-13, 01:54 PM
The 31 spline carrier from the solid axel to IRS are the same! They are no different.

05-07-13, 02:15 PM
I thought I replied to this thread yesterday but I don't see my post so.....

I thought that all 31 spline carriers are the same as far as fitment goes too, I have looked at several sites and none of them reference a different carrier for a solid axle and IRS rear ends. If they were different there would be different part numbers for each or some other designation. They are the same. If your axle is not locking in, but slides in far enough that the CV is about a 1/4" from the axle seal in the housing, take a screw driver and SLIGHTLY stretch the retaining ring, re-install axle. Repeat process until axle snaps in.

Hope this helps,


Shark city V
05-07-13, 09:48 PM
I found these pics on a ford forum.

05-07-13, 10:00 PM
Well, did not know that. Good find sir. Sucks, as now I feel I must change my spider gears in my brand new 8.8, but at least that can be done with out removing the carrier and disturbing the diff setup.

05-07-13, 10:13 PM
Very well done Shark city V, that's great info for all interested in doing a partial kit 8.8. That's one less mystery on what will work and what won't(without modification), check your PMs

Shark city V
05-07-13, 10:18 PM
Lol. I've worked on 8.8, 9", and Dana's for a long time. Could not remember for the life of me wat the actual difference was. Never paid close attention. I looked in my old parts bin and couldnt find irs gears. But I did know there was different part numbers and alot of superceeded parts from year to year. I'm sure you can get the axles to lock in sometimes with the solid axle gears but it will be a pain to get them off. If they do come out, the clip is mostly popping off inside the diff.