Irs superdiff info

[Ninho/DKM]

Helloto everybody.
I'm going to install a new IRS superdiff in to my AT code transmission. New superdiff arrived to me in a box with axles, pins and a single 0.20mm shim. had got a second pair of 10 theeth spider gears and with my old one had done a set of four.
Now i had a wet assemble of it and added the given 0.20 shim to the original of standard diff and putt beside left side gear and had measured the spider gear backleash that results in 0.10mm.
now i suppose i need a second 0.20 shim more to add on right side to get same backleash but i have no idea where to find it.
Could someone tell me about values of backleash to have a good preload on spider gears and where i can find additional shims to get it?
Just tried VW heritage and said that there are no more available, Wrote to Long ent but they seems not to answer me.

Many thanks in advance to anyone will answer.

[Jee Ent.]

I'm sorry. But you can't just put in a new diff and add some shims here and there. There's a little more to it.

First you measure all the dimensions on your old diff. The total width from bearing to bearing. The distance from ring gear to diff bearing on both sides etc. Then you take the same measures on your new diff. Add/remove shims so that your ring gear will be located at the exact same place as before.

If you are putting in a new sidecover, you will have to measure up the distance from bearing to the sealing area of the sidecover as well.

Your lucky you have your old stuff to measure from. When building from scratch it's much more work.

When your finished you should have 0,2mm preload on the sidecover (when you back the sidecover off at ring gear side, a 0,2 feeler gauge should slip in). And the backlash should be zero, when you tourqe down the preload.

The easiest way to get shims is to tear down old gearboxes. Or give Weddle or Rancho a call.

No part is machined the same. And new parts need to be measured up before assembly. When done right it won't break.. If just put together it will most likely run. But for how long  

[Ninho/DKM]

Ok,
at first thank you for answering.

I know that this is a no threw in work, i have a long enterprises cd rebuilt course and have just seen how complicated it is.
Anyway i have a few original vw tools like the backleash diff tool and will use it when i will close the side cover.

I will do as you said about measuring from old diff and report same measures on superdiff.

Can you confirm anyway that in the box i should have found a couple shims instead of only one single piece?

[Jee Ent.]

I don't know understood the question...

The diff shims comes in two different styles. The thin ones, 0,15-0,3, if I remember correctly, are not that usual. I believe they only got used when the parts was way off.
 And the thick ones (with a gap) from ca 2,8-4mm. Always used. You got one on each side of your diff. Behind the bearings.

[dangerous]

There may be some confustion here.
I think the shims you are asking about are INSIDE the diff?
I have seen some superdiffs that are a little "off" and needed a shim inside
to reduce the backlash between the side and spider gears,
and I am assuming that yours is one such example.

The one I had, only needed an extra VW shim on the right side,
and with the factory hemishpere cover on the Left side, it only the one original VW shim.

All IRS diffs have these shims, so any VW repair shop will have some floating around if they work on trans.

The other issue, about setting backlash and preload of the crownwheel and carrier,
will also likely need another type of shim,
which you will need a source of as well.

[Ninho/DKM]

Dangerous, you're right, i was talking about shims that goes inside the superdiff. Excuse me for get you misunderstanding but my english could be not so clear or sharp in description and understanding while translating.

So i had found just a 0.20 shim inside the box with new superdiff case.
i had left original shims and added the 0.20 they gave me on right side of the diff.
Had measured backleash on both sidegears splined part.

rigth side where are both original and 0.20mm shims to add it is now 0.10mm
while on left side where i had left just original shim it is 0.30mm, so i suppose i miss an additional shim that should have been in the seller box to obtain  0.10mm

Dangerous, you wrote you had seen some superdiffs that are a little "off" and needed a shim inside, it seems mine need more than one, that's why i'm here.
How could you affirm that spider gears backleash is good? how do you understand it?
Could you tell me anything about backleash of splined part on both gearsides? could 0.10mm gap forward and back be enought?

Should i had to find two additional shims instead one in the seller box?
 

[Jee Ent.]

I'm sorry. I see now that you have a IRS setup. I was talking about Swing axle diff's. My bad.

[Ninho/DKM]

Jee, thank you anyway.
Could you help me in IRS troubles anyway?

[dangerous]

The ones I used, that had a problem,
only required one shim extra, plus the original VW ones.

The extra one was an original VW one, since they have one from the factory on each side.

I do not measure the spider gear back lash but DO measure the end float of the side gears.

I would do a trial assembly and either machine or shim, or both
to get the setting as per factory in the Bentley or VW specifications.

Make sure also,
the superdiff body has plenty of oil holes as well, since some (ALL) lack enough lubrication.

[Ninho/DKM]

Dangerous, the fact is that i have non bentley of vw specifications and i' askin for them. Could you get them for me?I will work on oil holes, thanks.

[dangerous]

The book says zero to 0.14mm.
Knowing that the original diff controls this float with the inner spacer,(that is NOT used in a super diff),
I would personally like no less that 0.05mm,
so that oil can get between the teeth and shims.

I have experimented with no clearance and actually some preload, for a short-use application,
but it did not work as I had hoped, and the shims became concave due to heat distortion.

[Ninho/DKM]

Ok, i have measured the side gear float on both sides and it is 0.30 on both sides with original diff in. Adding the 0.20mm single shim the seller gave me on the right side it decreased to 0.10mm so i need another 0.20 on left side i will both 0.10mm and it would be ok. Are you agree? I think, there is that need of shims couse spider and side gears are not new but used and lightly worn.