8.25 factory LSD mod

So I had thought I had this figured out but I've wanted to mod the friction plate set up in my 8.25 to get more bite than slip and I had read forum after forum and I had seen it was friction/disk/friction/disk/friction/disk/friction. But I have come to light that the mods I have read we're about the 8.8 and not the 8.25 because all the write ups would end with putting the S-shape spring back in between the spider gears.... 8.25 doesn't have one but the 8.8 does.
So my question is there an actual write up to modify the factory LSD for the 8.25 or is it the exact same as the 8.8 but minus the S-shape spring?

Have you tried running it without the friction modifier?

Worked wonders on my 8.8

Wouldn't that possibly destroy the friction plates? I thought the friction additive was suppose to help give it grip?

No, the modifier helps it slip.

The fibers might eventually wear.out, at which point it would be the same amount of work you are proposing now.

Mine was still grippy as heck when I sold the lsd carrier years later

souske said:

No, the modifier helps it slip.

The fibers might eventually wear.out, at which point it would be the same amount of work you are proposing now.

Mine was still grippy as heck when I sold the lsd carrier years later

Click to expand...

Hmmm that I did not know, the diff oil I'm using is just conventional oil that has the additive already in in(think it was valvaline?) so switching to just regular diff oil or synthetic should make it grip better? Ill try that first, if not would following the 8.8 write up be just fine for the 8.25?

Try sime cheap additive free oil first, it might take a bit to get all the friction modifier out

If not, the concepts are the same, add friction/ steels to achieve desired preload.
use some common sense though, some mustang guys have blown up lsd carriers from way overpacking them.

The 8.8 lsd carrier is machined out of an open carrier, not sure if this is the case for the 8.25 or not

As far as I've seen on mine and pics, I don't think think the open or LSD carriers are machined from one or the other but are truly are cast/machined separately
Also I was only planning on adding one extra friction disk to each side making a total of 4 to each side.

8.25 trac loks are machined from a different forging, I just put one in my MJ a few days ago. Here's a pic:

(click for big)

You can see the trac-lok forged (or cast, not sure, but probably forged, the ABS reluctor ring on the edge of the ring gear flange was punched out, which I don't think cast iron would tolerate well, so it's either forged or cast steel, certainly not cast iron) into it on the top. That one's out of a factory vehicle, I got lucky and it had good clutch packs in it still. It's a lot more fun on pavement and fast dirt now, I haven't had a chance to take it out in the rocks yet.

The LSD carriers are much more "square" - they're more of a cylinder and less of an egg shape with holes cut in the sides for the spider gears. I don't think there'd be space to machine out an open 8.25 carrier to fit clutch packs under the side gears.

That's what I thought. Did you get a good look at the plates and see if there is indeed some room for extra friction disks? I know the washers(thrust washers I think?) will need to be shimmed to a smaller thickness to allow a extra disk

I didn't actually bother, it had tight clutches in it when I checked at the junkyard before pulling it (well, tight enough that I couldn't turn it with a breaker bar jammed between two lugs, anyways) so I said hell with it and just stuffed it in and ran it.

8.25s are my favorite axle to set up for sure at this point. C clamped the pinion yoke and housing to a piece of 1/4 plate scrap to keep it from turning, checked backlash with my chinesium (harbor freight) dial indicator and mag base, yanked it all apart, slapped the ring gear on the new carrier (I kept the junkyard carrier bearing races - make sure to mark each so you can put them back where they came from, since they're "worn in" with the bearing they were paired with from the factory) with the same ring gear bolts (I recommend replacing them, do as I say, not as I do!) and stuffed it back in. Then used a piece of black iron pipe welded into an old dana 30 axle nut and a pipe wrench as a side adjuster tool, set backlash back to what it was and got the carrier bearing preload cranked up a little higher than what was left of factory preload. Torqued the bearing caps slapped the cover back on and filled it up... works good.

I only have $150 into the axle (MJ perches, junkyard ZJ disc swap, $50 for the complete axle in the first place) so I really didn't put as much money (new carrier bearings, new ring gear bolts) or time into it as I probably should have. I did use loctite on the ring gear bolts and made sure to use a torque wrench on them and the carrier bearing cap bolts though - the spec for both is 70 foot pounds.

Putting a sharpie mark on each ring gear bolt head as you torque them in a star pattern is a great way to make sure you get them all and don't try and torque one twice, I'm partial to the metallic ones as they show up much better on heat treated or mill scale coated metal than the regular sharpies.