The Definitive AU Diff Topic

[auIILTD]

Originally Posted by auIILTD

Cheers James. If I find any different, I will be sure to post it here for future reference.
Stu

Nearly forgot about this. For my AU with BTR97LE (should be same for all I believe):
3.23 Diff - Brown Speedo gear with 20 teeth.
3.45 Diff - Dark Grey speedo gear with 22 Teeth.

Stu

[ford_rabbitoh]

G'day all. First timer here so go easy on me OK !!
I just replaced the diff centre in my AUI 98 Fairmont Ghia but the bloudger is still knocking. It appears the problen is the propellor shafts that fit into the diff. After I put it all back together I noticed one of the shafts is loose/wobbly.
Question: Where do I go from here. Is there someone around who sells reconditioned versions of these propellor shafts? Preferably in Sydney. Any advice greatly appreciated.

[K_Man]

Originally Posted by EvilChief

A possibly usefull or useless fact, R31 manual Skylines ran 3.7 differential that will also fit falcons and commodore BWs and ran 28 spline axles centers. This is actually my most favorite diff ratio in all my Falcons, as they are common and cheap.

IIRC auto skylines 3.9, r31 pintara 4.11. And skyline silhouettes had lsd's, but finding one that isnt shagged would be difficult.

[philbec15]

Originally Posted by EvilChief

The good old BW 8-3/4" Differentials (solid axle only)

Any BW diff prior to EA had a different housing and center, but same same diff gears as newer BWs.

Housings between E-series Falcon, A-series Falcon, Commodore Vl - VS and R31 Skyline are different in terms of tube length, but housing is the same, hence any center carrier (open or LSD or spool) is the same right across the above mentioned models.

The axle splines are determined by the guts of the centers, regardless of Open, LSD or locker. VP, VR VS (possibly VN), R31 and most Falcons run 28spline axles.

The carries between Open and LSD are different and are not interchangeable, as the LSDs are "friction cone" based with a spring loaded center, where as the opens use spider gears with pins, however these are again identical across commodores falcons and skylines and are interchangeable. (Note to "tighten" LSD centers, shims under the center springs increase the cone pre-load, which retains the LSD in locked position and rises the break away friction load, to do it on the cheap regular washers can be used instead). (Please note there are aftermarket LSD options available that are not friction cone based, but come with their own carrier specific to their design).

When changing any component within a differential they must be re-shimmed. First off the pinion needs to be shimmed, in order for the pinion and crown to mesh on the full face of each other. If the pinion is not shimmed out correctly (not enough) then it will run on the toe of the crown and whine. If its shimmed too far out (too many) then it will run on the heal and once again whine. Either way it will lead to premature failure of the diff, by destroying the teeth on either the crown or pinion. It is imperative that they are shimmed so that the pinion contact surface is exactly in the middle of the crown contact area (use engineering blue to test). This may require several removals and re installations of all components to get right and is quite labor intensive.
Ensure to set preload on pinion when making up pinion nut (crushing the collapsible ring). There are tools available that will measure the preload based on the friction of bearings against their seating cones, or you can do it by feel. It should feel fairly firm with some effort to turn, but without nodging or hanging up.
Now the crown needs to be also shimmed in order to set the backlash. Determine the overall width off the original diff center including shims, bearings, cups etc, when fitted to housing, and compare that to the new overall width of the new center, if one is being fitted, if old center is reused, usually the shims are still correct, just mark right and left accordingly). To determine the backlash, use a dial gauge to determine the free play (rocking crown forwards and backwards and forwards with pinion stationary and observe gauge. Off the top of my head this should be between 7 to 11 thou. Adjust shims until this achieved.

A possibly usefull or useless fact, R31 manual Skylines ran 3.7 differential that will also fit falcons and commodore BWs and ran 28 spline axles centers. This is actually my most favorite diff ratio in all my Falcons, as they are common and cheap.

ok just to clarify..No.1:- the LSD center (carrier) out of an E series diff will fit in a AU 2 series wagon or ute (live axle) housing .. No.2:- other clarification the crown wheel and pinion can be used from the from the E series (if I wanted to use the ratio) in the AU 2 series housing...i hope i have this right ..many thanks phil

[EvilChief]

Originally Posted by philbec15

ok just to clarify..No.1:- the LSD center (carrier) out of an E series diff will fit in a AU 2 series wagon or ute (live axle) housing .. No.2:- other clarification the crown wheel and pinion can be used from the from the E series (if I wanted to use the ratio) in the AU 2 series housing...i hope i have this right ..many thanks phil

correct

[EvilChief]

Originally Posted by K_Man

IIRC auto skylines 3.9, r31 pintara 4.11. And skyline silhouettes had lsd's, but finding one that isnt shagged would be difficult.

plausible, all 3.7s I have fitted to my commodores and falcons have come from r31 manual skylines (as I have removed them myself)

[ian861]

I have a AU11 Fairmont Ghia and there is a tag on the diff filler but it doesn't mention anything about LSD but performance diff oil which doesn't explain much, considering it had traction control I would have thought a LSD wouldn't be needed

[peterljohnson55]

Originally Posted by ian861

I have a AU11 Fairmont Ghia and there is a tag on the diff filler but it doesn't mention anything about LSD but performance diff oil which doesn't explain much, considering it had traction control I would have thought a LSD wouldn't be needed

Ian, From what I have read on this thread (mainly page 1) the AUII Fairmont Ghia ... VCT6 ... IRS ... doesn't have LSD, no option for LSD, but traction control fitted.

On the Diff link Elsewhere, http://www.fordforums.com.au/showthread.php?t=11291903 , Jimmyd says 'had to order the Tickford Sports Supsension Option to get LSD.' but this is against the 'no option for LSD' as mentioned above.

[ian861]

Originally Posted by peterljohnson55

Ian, From what I have read on this thread (mainly page 1) the AUII Fairmont Ghia ... VCT6 ... IRS ... doesn't have LSD, no option for LSD, but traction control fitted.

On the Diff link Elsewhere, http://www.fordforums.com.au/showthread.php?t=11291903 , Jimmyd says 'had to order the Tickford Sports Supsension Option to get LSD.' but this is against the 'no option for LSD' as mentioned above.

I thought that to be the case since LSD and traction control would be the same animal, from what I could see that the brake locks the spinning axle as the clutches would in the LSD but I guess the tag on the filler usually comes with LSDs but I guess it is handy to help find the filler hole

[Rfordsfun]

3.45.1 HP AU2 F/ghia, Donor car XR6 02, 3.45.1 LSD ? can i just do centers/axles? interesting thread, the hard road. ;)

[Rfordsfun]

Hi All, I want to change my AU2 fairmont ghia 3.45 single for a AU2 XR6 3.45 LSD and axles that I have, I seen the axle removal write up. ( thanks ). Is there another tech doc for the diff ? etc. I have a falcon manual in PDF, But want to ask wiser men, before turning my car into a 2 wheeler lol cheers p.s. How many beers does it take to change a diff ?

[auIILTD]

Your diff housing will be a like for like replacement. Assuming you are talking about an IRS setup, your existing axles will be fine. Take your rear brakes off (hang the cliper from the spring), undo the top bolt of your hub assembly and use the hub (pivoting on the lower hub bolt) to yank the drive shaft out of the diff. Undo your tailshaft and then undo the three bolts holding the diff housing in. Swap diffs and reverse.

Some pics in my how to thread here:
http://www.fordforums.com.au/vbporta...articleid=1143

Cheers
Stu

Edit: You will also need to undo the toe adjuster from the hub assembly so that you can use the hub as a fulcrum to pull the half shaft from the diff.

[Rfordsfun]

thanks au 3 . yeah read the write up, and theres only 3 bolts, not wotrhing exchanging diff internals, old dif / axles have 300km new 90km ,was told to the lot as they were together ,like starters and drive plates, 3.45 single for 3.45 lsd, fun fun , thanks for your reply. Fords should be like pizzas, you buy to order. yup to many drinks, making no sense, and yet i dont work for ford.

[auIILTD]

If your old axles are not noisy, I would leave them in and keep the 90K ones as spares. It does not take much room to store them. Just my thoughts.

Cheers
Stu

[Rfordsfun]

Cheers, yea auII the diff is making a small whine, dont know if axles or diff. some pot of fish, ?? going to do it next week. anyone want some pics or info ? while im doing it. Wheres a thread for engine mounts ? ive got hydraulic, but a replacement i got seems to sit higher, a v8 style mount looks exactly look the hydraulic ? is it solid, so i guess ill need to do both, -.- beeeeeer.... needed.

[auIILTD]

Originally Posted by Rfordsfun

Cheers, yea auII the diff is making a small whine, dont know if axles or diff. some pot of fish, ?? going to do it next week. anyone want some pics or info ? while im doing it. Wheres a thread for engine mounts ? ive got hydraulic, but a replacement i got seems to sit higher, a v8 style mount looks exactly look the hydraulic ? is it solid, so i guess ill need to do both, -.- beeeeeer.... needed.

Rfordsfun - yes they are.

My forum name is auIILTD, not auII or auIII. Please use Stu, as that is a name I happy to be used on the forums, hence how I sign off from each post.

Axles don't wine, diffs do. Fish?

Hydraulic engine mounts? Ok I am lost. On an AU? I do not believe there is a thread on engine mounts. This thread is about Differentials, not engine mounts.

It is encouraged to use the search function of this site, rather than relying on those in the know reposting time and time again. If you cannot find an answer, then, please post a thread in the appropriate area asking if anyone has had the same experience. Please do not post your questions in threads not related to your question. Off Topic posts are contrary to this site's terms and conditions. If you have any questions, please do not hesitate to send me a PM.

My final thought, given that forums use the written word, it would help if you could use some correct grammar (use of texting style abbreviatons of words is also against site T&Cs). It is very difficult for users to provide answers to your questions if the question is not really known.

Here to help if you need it.

Regards
Stu.

[Rfordsfun]

cheers.

[Rfordsfun]

Originally Posted by Rfordsfun

cheers.

STU. had some trouble navigating forum,

[Rfordsfun]

Originally Posted by auIILTD

Your diff housing will be a like for like replacement. Assuming you are talking about an IRS setup, your existing axles will be fine. Take your rear brakes off (hang the cliper from the spring), undo the top bolt of your hub assembly and use the hub (pivoting on the lower hub bolt) to yank the drive shaft out of the diff. Undo your tailshaft and then undo the three bolts holding the diff housing in. Swap diffs and reverse.

Some pics in my how to thread here:
http://www.fordforums.com.au/vbporta...articleid=1143

Cheers
Stu

Edit: You will also need to undo the toe adjuster from the hub assembly so that you can use the hub as a fulcrum to pull the half shaft from the diff.

Thanks STU gonna take your advice and just swap out diff, any info on bolt sizes? following the axle removal write up i got a 21mm and a 18/9 mm ? i think I only need the size for the actual diff housing bolts ? if you can obliged. kind sincere regards, I'll take a few pics, so anyone else searching later, can have the benefit Happy SAFE Easter to all

[Rfordsfun]

Thanks STU had to lever axles out via abs sensor ring. The bolt that holds upper hub ? what is that bush called ? please. As the top one is definitely had it. Been searching, is it upper lateral ?? do they have to be pressed out/in? rear left is clunking, so best to change them, to prevent wear n tear. thanks again for you advice, definite made things clearer, enjoying a fresh LSD cheers. Only took 6 hours, first day hangover :P yuk!

[LyleXR8]

Im a miner, so im gunna do some mining! anybody tried an EL wagon diff in a AU ute?

[ebv8]

I have a 3.08 in my au1 futura and want a 3.45 lsd, I can get an ef/el xr6 diff for $250 can i bolt this straight in and use 35mm adaptors to fit stock wheels with no other mods?
Or should i just pay $500-600 for an au xr6 diff when one pops up

[XC50077]

Ended up buying a AU2 "low klm" 3.23 diff from the wreckers that needed a rebuild but results were worth it in the end, despite the expense. Cheers.

[Xr302]

Does anyone know if a m86 out of a ba sedan would fit in to an au2?

[mad2]

Originally Posted by Xr302

Does anyone know if a m86 out of a ba sedan would fit in to an au2?

whole diff? ... no don't believe so . . . . diff centre, no idea

[Xr302]

Originally Posted by mad2

whole diff? ... no don't believe so . . . . diff centre, no idea

I’m building a turbo stroker motor at the moment to put in an au, will have 650rwhp.
Wouldn’t mind something a bit stronger than the M78...

[mad2]

Originally Posted by Xr302

I’m building a turbo stroker motor at the moment to put in an au, will have 650rwhp.
Wouldn’t mind something a bit stronger than the M78...

if yours is a solid diff try a ute/wagon diff

[pete r]

Hi,
Could you guys tell me if the the XR8 3.45 diffs are the same in both auto and manual cars? I need a new diff for my manual, I’ve located one but am not sure if it’s out of an auto or manual.
Many thanks for any advice!
Pete

[PG2]

Originally Posted by pete r

Hi,
Could you guys tell me if the the XR8 3.45 diffs are the same in both auto and manual cars? I need a new diff for my manual, I’ve located one but am not sure if it’s out of an auto or manual.
Many thanks for any advice!
Pete

They're exactly the same.

Come to think of it, I am currently running a diff out of an auto in my manual XR8.

[pete r]

Originally Posted by PG2

They're exactly the same.

Come to think of it, I am currently running a diff out of an auto in my manual XR8.

Bloody legend, thanks PG2!

Pete