Crown Gears

Pommiebrat · Post by **Pommiebrat** » Mon Jul 28, 2008 8:43 am

I have a LSD rear-diff scavenged out of an L-series (I think) which I'm guessing is 3.7:1. How easy is it and what do I have to do to change the crown gear to 3.9:1 to match the 5sp L-series diff I have up front? Do I use the LSD housing or the standard diff housing and put the LSD into that?

Cheers,

John

Outback bloke · Post by **Outback bloke** » Mon Jul 28, 2008 9:34 am

We used to have a thread about this here some where but I can't find the link to it. Maybe it is in the Tech manual. Any way, here it is again.

Take the LSD centre out of your 2nd diff. You will have to undo the plates on the side of both diffs to do so. Do not mix them up. The plates must go back on the diffs they came off.
Remove the crown wheel.
Take the centre out of your first diff.
Remove the crown wheel.
Bolt the Crown from your first diff to the centre from your second diff.
Now lay both diff housings beside each other and compare the opening where the centres came out. You will notice the LSD opening is bigger in one area to allow the centre to be removed.
Stuff a rag in your first diff around the pinion gear so filings can't get in there.
Get a small grinder, I use a 100mm Makita, and grind the housing on the first diff so it is similar in opening shape to the second diff.
Once you have done this you should be able to fit the re-assembled centre in easily.
Clean the inside of the housing thoroughly to remove all metal filings.
Re-assemble the diff with the new centre.

All this should take you under an hour. Doing it this way you will not have to play with the lapping at all on the diff.

Pommiebrat · Post by **Pommiebrat** » Mon Jul 28, 2008 7:00 pm

Mate, thansk very much that's a great help. I may be being a bit dense here but what stops me changing over the crown gears and the putting the whole lot back into the LSD housing meaning I don't have to do any grinding? Or is the bigger crown gear just too big in diamter for it to fit?

YouTube · Post by **El_Freddo** » Mon Jul 28, 2008 7:40 pm

Pommiebrat wrote:Mate, thansk very much that's a great help. I may be being a bit dense here but what stops me changing over the crown gears and the putting the whole lot back into the LSD housing meaning I don't have to do any grinding? Or is the bigger crown gear just too big in diamter for it to fit?

Its not the crown gear, its the pinion gear that needs changing to match the crown gear. If you do this you'll have to re-shim the diff to make it operate smoothly without excessive wear.

The way OB has detailed, it doesn't require as much effort or techical know how (diff shims).

You should beable to pick up a $15 grinder that'll do the job. You got places like bunnings over there (massive hardware stores)?

Bennie

Pommiebrat · Post by **Pommiebrat** » Mon Jul 28, 2008 9:20 pm

Cheers guys that all makes sense just sounds more daunting than I guess it really is.