2.93 LSD Unit in a 3.73 Open

[cavpilot]

I have read more threads, articles and websites about LSD's than I ever intended to. However, I still haven't read a straight answer if you can take the LSD unit from a 2.93, swap the ring gear and install it back in the 3.73 case. If it can't be done, tell me why. Gracias!

[TobyB]

It can't be done because the 3.73 crownwheel (ring gear) is thicker than a 2.93 crownwheel,
since the 3.73 pinion is so much smaller,
and the difference is made up for in the carrier.

The reverse can be done with a spacer, or so I hear.
On the internet.

t

[cavpilot]

It can't be done because the 3.73 crownwheel (ring gear) is thicker than a 2.93 crownwheel,
since the 3.73 pinion is so much smaller,
and the difference is made up for in the carrier.

The reverse can be done with a spacer, or so I hear.
On the internet.

t

Thanks for the info. That makes sense.

Sent from my SM-G920P using Tapatalk

[TobyB]

Wait. No, it doesn't make any sense, now that I read it-
I must have been high.
The ring gears are about the same thickness, and THAT's
the reason the carriers are different- the 2.9 is spaced farther from
the pinion axis, and the 3.7 is closer, since the 3.7 pinion's a lot smaller than the 2.9's.

I THINK there are just 2 carriers, and the change happens with the low 3 ("3.07 and below is one size, 3.15 and up is the other" says George, below)
gear, with the ring gear thickness of the low ratios changed to make them work with the 'low'
carrier, and the high ratio thicknesses likewise will all work with the 'high' carrier.

THUS, with a spacer, you can use the 2.93 carrier with a 3.73 gear, but not the other way around.
Since the 2.9 carrier has more space between the mounting flange and the pinion axis.
NOW, as to who makes such a spacer (and is it such a good idea, anyway?) I dunno.

Metric Mechanic's website has some of this,
and one can only presume they were less
baked when they wrote it than when I wrote the above.

sorry,

t

[itsonlygeorge]

3.07 and below is one size, 3.15 and up is the other.


Sent from the woods of Maine.

[cavpilot]

Wait. No, it doesn't make any sense, now that I read it-
I must have been high.
The ring gears are about the same thickness, and THAT's
the reason the carriers are different- the 2.9 is spaced farther from
the pinion axis, and the 3.7 is closer, since the 3.7 pinion's a lot smaller than the 2.9's.

I THINK there are just 2 carriers, and the change happens with the low 3 (3.23 or something)
gear, with the ring gear thickness of the low ratios changed to make them work with the 'low'
carrier, and the high ratio thicknesses likewise will all work with the 'high' carrier.

THUS, with a spacer, you can use the 2.93 carrier with a 3.73 gear, but not the other way around.
Since the 2.9 carrier has more space between the mounting flange and the pinion axis.
NOW, as to who makes such a spacer (and is it such a good idea, anyway?) I dunno.

Metric Mechanic's website has some of this,
and one can only presume they were less
baked when they wrote it than when I wrote the above.

sorry,

t

Hmmm, ok then. That raises more questions. If the only dimensional difference is in the mounting flange, then it stands to reason that a spacer could be fabricated (along with longer mounting bolts) and work just fine. However, if the LOA (length over all) is different that changes everything.

But then again, would it really be worth the effort to do any of this?

[TobyB]

Yep, a spacer can be fabbed, and it'll work.
Said the internets, a number of years back.
It's just the flange that was moved on the
carrier.
The pinion depth (relative to the ring) stays the same.

As to effort, I wouldn't think so. And I'd worry
about a spacer moving, and letting the bolts loosen.
That makes a royal mess out of small case diffs, which
do it occasionally.

hth
t

[cavpilot]

Yep, a spacer can be fabbed, and it'll work.
Said the internets, a number of years back.
It's just the flange that was moved on the
carrier.
The pinion depth (relative to the ring) stays the same.

As to effort, I wouldn't think so. And I'd worry
about a spacer moving, and letting the bolts loosen.
That makes a royal mess out of small case diffs, which
do it occasionally.

hth
t

So the next logical question is what is the thickness of a 3.73 mounting flange? The 2.93 flange is ~ 11.5mm.

Sent from my SM-G920P using Tapatalk

[TobyB]

It's not the thickness, it's how far offset from the center of the pinion it is.
They moved the flange towards the pinion for the higher numeric (smaller diameter)
pinion.

t