R50-D21 diff swap

[Roy]

Hey, Guys and Gals across the ditch, Roy in Ballarat, Victoria, STRAYA here. just wondering if anyone has tried fitting a diff centre from an R50 pathy into a D21. Rear diffs, this is. R50 has am LSD, whilst my '91 D21 is an open centre. I have complete R50 unit, drum to drum, so if axles need to be exchanged to do the job, that's no drama, just not certain that the two actually interchange.

[Crash bandicoot]

Hey, Guys and Gals across the ditch, Roy in Ballarat, Victoria, STRAYA here. just wondering if anyone has tried fitting a diff centre from an R50 pathy into a D21. Rear diffs, this is. R50 has am LSD, whilst my '91 D21 is an open centre. I have complete R50 unit, drum to drum, so if axles need to be exchanged to do the job, that's no drama, just not certain that the two actually interchange.

you will need the complete entire rear end as the LSD carrier has different bearings and splines from memory...h233B should be the code for the R50 axle.

The front has different spline count as well so you will be needing the R50 or 97 onwards R20 SE front axles

[Roy]

Thanks, mate, yeah, have the entire, rolled over R 50, so swapping fronts should pose no problems. Was hoping to leave my rear housing in place and just swap out axles and diff centre, but seems like not, huh. All diffs are identical gearing, so front doesn't have to be done immediately.

[lax2wlg]

Was hoping to leave my rear housing in place and just swap out axles and diff centre, but seems like not, huh.

Sadly not.
The R50 uses the 33-spline Safari rear center, whereas the older WD21 uses the 31-spline Safari front center. But the WD21 has disc rear brakes which are a seriously good thing to have in an offroad vehicle.

The bottom line is even the 31-spline unit is a bit of a ridiculous overkill in a vehicle this size/weight/power output. I recently noticed that the Toyo 8" rear has more ground clearance on 31s than the Nissan 9.25" rear on 33s. Looking back I probably would have kept the Nissan 8" C200 rear with 4-pin LSD, because its plenty strong enough, has almost double the clearance and weighs a shit-ton less than the H233. But then, you don't get disc brakes, so its always a compromise.

Is the unibody R50 rear diff a bolt in deal to a full frame WD21? I think you need to investigate this. Otherwise, wouldn't it be easier just to get a 31 spline LSD centre from an old WD21 Pathfinder, shim it and install it?? But then, a shimmed Nissan LSD is basically just a complicated spool, so it becomes a whore to deal with on the road. So again, its always a compromise

[Crash bandicoot]

... it becomes a whore to deal with on the road. So again, its always a compromise

yeah but it is fun though