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Another diff question
Mog72 - 8/3/15 at 06:30 PM

As I've said in another thread,I've just changed my 3.64 lsd diff to an open 3.92, I much prefer the 3.92 gearing wise
But I would like the 3.92 in LSD form
I have the 3.92 open diff in the car at the moment & the 3.64 LSD on the garage floor
Excuse my ignorance, but is the LSD a seperate component inside the diff housing that runs in its own oil ?
Also would it be the cheaper option to have my 3.64 LSD diff changed to a 3.92 ratio? Rather than the 3.92 open diff converted to LSD ?

[Edited on 8/3/15 by Mog72]

K13JOB - 8/3/15 at 07:04 PM

I am sure two minutes of Googling will answer all you questions about what a diff is and how it works.

The ratio is all about the crown wheel and pinion the crown being bolted to the diff. It would appear that the obvious answer is to change the Crown and pinion on the LSD but depending on what type of LSD that may be more or less simple. You cannot convert an open diff into an LSD, it is a different beast.

coozer - 8/3/15 at 07:06 PM

Got my 3.9 LSD out of a dohc granada . Think it was a cooking model....

mark chandler - 8/3/15 at 07:38 PM

Sierra LSD sits behind the crown wheel, the planet gears are standard.

All I did was get a seal kit + collaspeable washer off eBay for £15, took the back off, wound out the sides (big castellated nuts, they needed heat and soaking overnight to get moving), pulled it all part, swapped the crown wheel and pinion and bolted it back together.

Pinion out of mesh twiddled the crown wheel bearings until they started to bind then back out a notch, next marched the whole lot into mesh with the pinion, kept going until it started to bind then backed out a notch.

The hard part is getting the casttelated nuts to move, do not hammer them as they lumps fall off.

snapper - 9/3/15 at 04:25 AM

The LSD bit is in the back of the diff where the crown wheel sits



One on the left is the LSD

Johneturbo - 9/3/15 at 08:41 AM

I made my 3.14 lsd. just remove the lsd from the lsd diff and fit it into the 3.92 then you only need to adjust the backlash with the big castellated side nuts! simples

Here's a thread from when i tackled the job!

http://www.locostbuilders.co.uk/viewthread.php?tid=161574&page=2

[Edited on 9/3/15 by Johneturbo]

Matt21 - 9/3/15 at 12:44 PM

I messaged you about a swap with my diffs, but from the sounds of it, we'd both be better off just swapping the lsd units over!


John - what do you mean by the backlash? and how do you know what to adjust it too?
Do you have to buy any new seals etc for doing it?
And is it possible to replace the viscous oil while the lsd unit is out?

sorry to hijack! hopefully we both find the answers useful!

Johneturbo - 9/3/15 at 01:26 PM

quote:
Originally posted by Matt21
I messaged you about a swap with my diffs, but from the sounds of it, we'd both be better off just swapping the lsd units over!


John - what do you mean by the backlash? and how do you know what to adjust it too?
Do you have to buy any new seals etc for doing it?
And is it possible to replace the viscous oil while the lsd unit is out?

sorry to hijack! hopefully we both find the answers useful!


Matt, the backlash is how tight the the crownwheel is against the pinion, as you undo the big side castelated nuts you change the backlash, from memory one side adjusts it, the other side locks everything into place.

you need to adjust them as to remove the lsd you need to undo them.

Matt21 - 9/3/15 at 05:43 PM

And how do you go about setting it right?

Johneturbo - 10/3/15 at 02:01 PM

You need a dial gauge as the adjustment is so small.

here's a thread when i was setting mine up

http://www.locostbuilders.co.uk/viewthread.php?tid=162786