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Is my diff LSD?
Rob55 - 19/12/12 at 09:55 AM

Bought a diff off eBay, meant to be 7" Sierra 3.62 LSD. Before I leave the guy feedback I want to double check it is what he says it is.

When I rotate the prop flange, both drive flanges move forward easily
When I hold the prop flange, I can't make the drive flanges move
If I push the drive flanges in opposite directions with all my force I can just about get them moving a few mm in opposite directions

The code on the diff casing is 83BG-4033-BA

With that info, can any of you gurus confirm the ratio and whether it is LSD or do I need to open it up to have a look inside?

Ps here's a pic:



Rob

bob - 19/12/12 at 10:08 AM

Easy way i check is to turn one of the drive flanges forward, if the opposite drive flange goes in the same direction its LSD and if it turns opposite way to what you are turning its an open diff.

rodgling - 19/12/12 at 10:10 AM

Yes, sounds like it's an LSD.

minitici - 19/12/12 at 10:12 AM

There have been a few similar threads!
http://www.locostbuilders.co.uk/viewthread.php?tid=172826

As above if the LSD output flanges both turn the same direction when you rotate the input flange it is a standard viscous coupled LSD.

As I suspect you don't have the tag on the rear cover bolt, then you would be best to take off the rear cover and check the ratio.
Ratio is usually marked on the rim of the crown-wheel.

Rob55 - 19/12/12 at 10:14 AM

That's great guys thanks for the advice

bob - 19/12/12 at 10:18 AM

Diff Codes

Link above is from the sticky posted at the top of the Engine and Transmission section, might be helpfull.

blakep82 - 19/12/12 at 10:18 AM

quote:
Originally posted by bob
Easy way i check is to turn one of the drive flanges forward, if the opposite drive flange goes in the same direction its LSD and if it turns opposite way to what you are turning its an open diff.


if they turn the same way, then its LSD which is good, or welded which is even worse than open.

the way you can turn the outputs a little bit in opposite directions is good, and sounds most likely to be an LSD

Rob55 - 19/12/12 at 12:10 PM

Great stuff, will open it later and check the ratio. Cheers all

loggyboy - 19/12/12 at 12:45 PM

quote:
Originally posted by Rob55
Great stuff, will open it later and check the ratio. Cheers all


No need to open it. Just see how many turns the of input shaft you make to turn the output shafts once. (or is it the other way round. Either way, just mark a point on both and do some rotating and counting!

mookaloid - 19/12/12 at 02:00 PM

quote:
Originally posted by Rob55



When I hold the prop flange, I can't make the drive flanges move
If I push the drive flanges in opposite directions with all my force I can just about get them moving a few mm in opposite directions



This is the bit which makes it almost certain that you have a LSD there.

And as said count the turns of the output flanges for one full turn of the input to get the ratio.

Rob55 - 21/12/12 at 07:04 AM

Good point guys Counted them and it's 3.6ish turns. Thanks