Rx LSD l series

pzs · Post by **pzs** » Sat Aug 30, 2014 11:18 am

Would it be possible to mix and match 3.7 Rx LSD with a 3.9 open auto diff to get a LSD for my auto l series

tambox · Post by **tambox** » Sat Aug 30, 2014 5:05 pm

The internals of small (L series style) 3.7, 3.9 and 4.1 are interchangeable.

pzs · Post by **pzs** » Sat Aug 30, 2014 8:36 pm

Going send both diffs away for 3.9 LSD, I want find someone who just won't whack it together, but spend the time to shim up correctly. Can anyone recommend a diff rebuilder?

YouTube · Post by **El_Freddo** » Tue Sep 02, 2014 9:42 am

Do a search on the forum for a DIY - Andrew_T did a good write up about it ages ago. I'd drop a link in here but I'm on my phone so searching isn't fun or easy...

Cheers

Bennie

tambox · Post by **tambox** » Tue Sep 02, 2014 6:12 pm

I've done a few 3.7 to 3.9 or 4.1.
The theory is the housings and centres are machined to a set size, its the gears that vary, so keep the shims with the gears.
Although the crown wheel bolts vary in size/style, use the same bolts on the crown wheel, as the thread sizes are the same but the shaft thickness varies.
Then follow the OEM manual to "blue" it and check.
Worst case, you end up with a slight noise @ a specific speed.

pzs · Post by **pzs** » Tue Sep 02, 2014 9:09 pm

I've made some enquiries and the pro rebuild is looking between 700-1000. So I will have a go myself. I will no doubt need to swap pinion gear with matching crown shell? If so how do I do the pinion bearing preload, on crush tube.....if it Has a crush tube?

AndrewT · Post by **AndrewT** » Tue Sep 02, 2014 10:00 pm

El_Freddo wrote:Do a search on the forum for a DIY - Andrew_T did a good write up about it ages ago. I'd drop a link in here but I'm on my phone so searching isn't fun or easy...

Cheers

Bennie

Did I? Wow must have been SO long ago. Yeah I pulled a 3.7 RX diff apart and moved the centre into a 4.111 open diff. From what I remember it was easy. Trick is to use the complete diff for the ratio you want - the only thing you change is the centre. Shims etc should all be the same when it goes back together.
Ideally it would be best to get a pro to do it and ensure all is good. Mine did whine, but I never ran the 4.111 first so could have already been like that.

Smokey · Post by **Smokey** » Wed Sep 03, 2014 2:03 pm

El_Freddo wrote:Andrew_T did a good write up about it ages ago. I'd drop a link in here but I'm on my phone so searching isn't fun or easy...

showthread.php?t=4177

AndrewT · Post by **AndrewT** » Wed Sep 03, 2014 5:00 pm

lol, that's a terrible writeup of mine. wow 8 years ago.

pzs · Post by **pzs** » Wed Sep 03, 2014 6:43 pm

Ordered a new crush tube (ex japan) new seals, cover gasket, pinion collar, all parts still active on subaru dealer parts list, all for the price less than $100. Local mechanic will help me set up pinion preload and check my backlash for a few beers. That's a little less than $700-1000. Will match up with Rx k frame and disc brake rear.....also to be overhauled.

tambox · Post by **tambox** » Wed Sep 03, 2014 7:54 pm

That writeup does mention a little grinding, you generally need to grind the casting humps where two bolts go.
Easy with a die grinder.

pzs · Post by **pzs** » Wed Sep 03, 2014 8:46 pm

Righto I'll look out for that

YouTube · Post by **El_Freddo** » Sat Sep 06, 2014 11:53 pm

Might not be worded the best Andrew_T - but it gets the point across and is an easy way to do it - much better than paying a grand for something that doesn't need to be done that way...

You're pretty lucky having a cLSD!

Cheers

Bennie

pzs · Post by **pzs** » Sun Sep 07, 2014 7:38 am

if I can get my act together I'll post some photo's of build.....I have learn't heaps off this site , so I should pay back by posting photo's