The Definitive AU Diff Topic

[Armageddon]

Originally Posted by Dave_Obsession

Thread-mine time.....this has been bugging me for some time, so I asked the guys at Etheridge Ford about AU diffs...



I got the following response this morning from the service manager:



So does this mean that any AU 3.45 diff will fit, regardless of whether the donor car was IRS or live axle - since it's only the diff centre that's being changed, it's all good? Or am I missing something here - is there anything else that would be changed over???

I have an AU series 1 option 20 with live axle LSD and 3:45 gear ratio...so I believe the dealer info is correct.

[Ben]

Looking at putting 3.9s into my manual 01 xr8.

Obviously not something that I will do myself. Will go to a specialized shop on the GC looking at Nerang Diffs. But curious what causes some Diffs to become noisy after changing gearing.

Unsure where I will get the gears from but am hoping Mal Wood still offers something that would suit.

Besides finding the correct speedo gear what else will I need to have the job done or anything else that should be sorted while its opened up.

Cheers.

[mcfly94]

Originally Posted by Ben

Looking at putting 3.9s into my manual 01 xr8.

Obviously not something that I will do myself. Will go to a specialized shop on the GC looking at Nerang Diffs. But curious what causes some Diffs to become noisy after changing gearing.

Unsure where I will get the gears from but am hoping Mal Wood still offers something that would suit.

Besides finding the correct speedo gear what else will I need to have the job done or anything else that should be sorted while its opened up.

Cheers.

Genuine Dana spicers gears can be obtained in 3.91 they are actually a m75 gear set that are supplied with a spacer to fit the m78 housing. Probably around $500 mark for gears.

Noisy diffs generally comes from re-using gear sets after a wear pattern is formed, it’s hard to replicate it. I had no noise in my 3.91 true trac and still don’t after some km.

No speedo gear available for the 3.92 gear set; will need a 4 pin 12v speedo corrector that interrupts the VSS signal to cluster yet supplies the unmodified signal to the EECV.

[auIILTD]

Apologies. Thead mine of the decade.

Did any AU XR sedan come with a live axle?

I thought the live V IRS was in this thread, but it is not.

I am currently planning an upgrade for an AU2 Forte, so 3.08 be gone!

Cheers
Stu.

[MrEL]

3.45 LSD centre from an IRS will go straight into a solid housing.

[auIILTD]

Originally Posted by MrEL

3.45 LSD centre from an IRS will go straight into a solid housing.

Not into a 3.08 housing which my Forte currently has. They are quite visually different.

So I guess that leads to my next question. Where there any AU sedans with a live axle that was not a 3.08?

Stu

[PG2]

HP XR6s came with a live rear axle.

[ebv8]

Originally Posted by auIILTD

Not into a 3.08 housing which my Forte currently has. They are quite visually different.

So I guess that leads to my next question. Where there any AU sedans with a live axle that was not a 3.08?

Stu

the IRS 3.45 centre only will fit in the live axle housing but its only series 1 & 2 XR6 and all XR8 that were LSD, ghia's got the 3.45 but no LSD or series 3 XR6.
there are lots of factory ford ratios for live axles but all crap
3.08, 3.23, 3.28, 3.45... its not really worth the effort unless you can find a bolt in effort. go a 3.9 ratio, talk to a diff shop

i went from 3.08 to 3.45 and i think it was 0.1s quicker to 100kmh

[mad2]

Originally Posted by auIILTD

Not into a 3.08 housing which my Forte currently has. They are quite visually different.

So I guess that leads to my next question. Where there any AU sedans with a live axle that was not a 3.08?

Stu

i have at least three 3.45 ratio AU diffs here that will fit any AU fitted with a solid diff.