AU xr6 diff into AU2 futura - help!

blueoval · 14-12-2008, 11:05 AM

HI guys, sorry for posting this in the wrong section but I kinda need some answers as soon as possible.

AU xr6 diff live axle, non IRS. 3.45 gears. LSD

I got my AU xr6 diff fitted last night, got everything swapped over ok.

I took the car for a test drive and noticed a rather heavy vibration which sounds like its coming from the diff. The vibration occurs mainly when not under load and slowing down. Under load its still there but less noticeable.
I know when my mate put the diff in, he checked both axles to see if they were bent which the werent.

We rang up a few people about this, and was told that this vibration could be the fact that I have re-used the futura trailing arms, and not used the xr6 ones. It was mentioned that the xr6's had a different geometry as they sat lower as opposed to the futura geometry which sits higher. (ride height Im talking about)

So if I was to get the xr6 trailing arms fitted, do you think this will fix my vibration issue?

**Whoosha** · 14-12-2008, 01:10 PM

Carn't see the arms making that much differance ,if that was the case as soon as you dumpt ssl in anything they would all vibrate. I would be more inclined to rotate the tail shaft around to another set of holes as it could be the balancing thats gone haywire But I M!te be wrong at that too ( any one else notice you carnt type the word M !TE in )

JC · 14-12-2008, 03:49 PM

Woosha - try "might".

I was going to suggest loose tail shaft bolts, but Wooshas theory makes sense too - try that.

josh_hartman · 14-12-2008, 04:23 PM

same thing happened to my car when i got mine fitted. there is a bolt each side of the axel housings. there is also two holes there that changes the angle of the diff. when they changed it over they would have put it in the wrong hole because the xr's use the different hole for some reason. its hard to explain and im trying to remember. its near your springs. all you have to do is jack the car up with both wheels off the ground, once you have done that put a jack under the diff to take the weight and undo the botls either side and adjust the angle of your diff so its more upright. that should fix it. this also might not be the problem but easy way to tell is look under your car and if your diff is pointing down a bit then its in the wrong holes. easy fix

Racecraft · 14-12-2008, 04:30 PM

the XR trailing arms are slightly shorter and use the top hole on the diff bracket iirc.. as josh said you can use your standard arms but you have to move the capture nut to the other hole. You need to alter the angle the diff sits in relation to the floor.. The arm length needs to be in the right hole or you'll get the vibration you describe...

blueoval · 14-12-2008, 04:57 PM

thanks guys, this could be the clue Ive been looking for.

Josh - your a dead set legend if this works. If it does, remind me if we meet in the city to buy you a beer!

Im gonna go take a look.

EDIT: I took some pictures for all to see. I'm posting them up now on photobucket. Let me know if anything looks odd in the pics.

blueoval · 14-12-2008, 05:30 PM

bodes-sh · 14-12-2008, 05:42 PM

yep, definitely needs to be rotated, that's way too much of an angle for it to be on...

blueoval · 14-12-2008, 05:51 PM

thanks bodes-sh.

just stuck our heads under and saw the alternate hole on the diff housing that Josh referred to. So yes, it looks like the diff was fitting in the wrong hole.

Gonna grab a bite to eat first and then we'll jack that car up and correct it. Its just too dangerous to drive at the moment for my liking

bodes-sh · 14-12-2008, 05:59 PM

fair enough, sounds good, just out of interest, how much was the complete diff?

josh_hartman · 14-12-2008, 06:29 PM

haha no worries mate

blueoval · 14-12-2008, 07:37 PM

Quote:

Originally Posted by bodes-sh

fair enough, sounds good, just out of interest, how much was the complete diff?

I paid $500. A bit much, but its in good nic and apparently has low k's

blueoval · 14-12-2008, 08:19 PM

ok here is the situation.

Question to you guys, where the welded rectangular area is, there is a square nut inside. Does this slide to the new position?

blueoval · 14-12-2008, 09:02 PM

In new position.

Pics of underside coming

blueoval · 14-12-2008, 09:20 PM

Diff now in new position

As you can see its in a far better position and seems to sit straighter.

Im going for a test drive now to see if there is any sign of vibration

blueoval · 14-12-2008, 09:34 PM

and the verdict is:

we have a winner!!! Took the car for a little drive up the main road, and what do ya know, no vibration, smooth as a baby's bum.

Im so relieved its not funny.

For anyone looking to do this mod, just be real careful where the upper trailing arm is positioned and check the position of the diff.

Thanks all who provided some critical clues to get this right for me. Very much appreciated.

GK · 14-12-2008, 11:51 PM

Another win for the forum.

Good job all.

GK

The Monty · 15-12-2008, 07:18 AM

So what diff gears did you come from, and whats it feel like now?

The Mighty Red · 15-12-2008, 08:12 AM

Nice works guys......

blueoval · 15-12-2008, 10:21 AM

Quote:

Originally Posted by The Monty

So what diff gears did you come from, and whats it feel like now?

Just a streetable 3.45 limited slip ratio. Nothing out of the ordinary.

Before, I believed I had a 2.92 or a 3.08 open wheel ratio. To put it mildly it was lethargic off the line. Ordinary grandpa takeoffs. Nothing to comment about really.

With the new diff in, well taking off is heaps better now, much more noticeable and responsive and way less lethargic in comparison. Its competative on take off now and the LSD is grippy as anything. A worthy investment if your after improved handling, grip and better acceleration.

RPM wise, its well behaved and sits at 1800-1900rpm @100km/h approx. in top gear.

Fuel wise Im yet to assess as Im still running on the same tank. Give it some time. But I doubt it will be significantly changed.

I have had a 3.45 LSD in my old EB XR8 for those that have known me that long and even in those days there was no real change in fuel economy if driving style doesnt change.

Hope that helps some out there who are in two minds on whether to take the plunge.

EDIT: btw, my motor is dead stock. exhaust is stock, and intake is stock. But this diff change has helped increase driving pleasure of a once ordinary experience.

fourl6 · 24-04-2009, 06:23 PM

Hey All... dont mind me thread mining... this thread might come in handy... im just wanting to confirm that a AU

Quote:

AU FORD 4.0L XR6 Differential Auto 98-02
Rear Diff Assembly, Solid ABS complete XR6 LSD. 3.9 Ratio.

will fit in my AU3 Forte Manual... i think it would be a nice upgrade from 3.08 single spinner... its just they make out like it'll only fit in a auto...

Cheers Cam

The Monty · 24-04-2009, 06:27 PM

Should be the same for auto and manuals. Mine was for a manual.
Beware if you go the 3.9's though, dont get me wrong, they rock big time, but they can get a bit noisy as 99% of them are old school ricer gears.
I would do the mod again first thing next car, even before an exhaust.

JC · 24-04-2009, 09:39 PM

Quote:

Originally Posted by cam.giles

Hey All... dont mind me thread mining... this thread might come in handy... im just wanting to confirm that a AU

will fit in my AU3 Forte Manual... i think it would be a nice upgrade from 3.08 single spinner... its just they make out like it'll only fit in a auto...

Cheers Cam

Talk to GK about 3.9s and manuals; I'm pretty sure he'd say if he had his time again he would only go 3.45s.

GK · 25-04-2009, 11:26 AM

Quote:

Originally Posted by JC

Talk to GK about 3.9s and manuals; I'm pretty sure he'd say if he had his time again he would only go 3.45s.

I informed you wrong when I mentioned 3:9s JC. I was talking about swapping my 3:9 for 3:45s. I actually have 3:7 gears. Sorry.

You're right of course on the matter of if I had my time again. I would have gone for 3:45 gears. The car doesn't rev out at much as I'd like, it appears to not work the best with the sweet spot of the engine. It just feels like I have to short shift all the time. I've noticed it lots when taking off quickish from the lights. I seem to have to change a little too quick.

I've heard that 3:7s with an auto are great, just the right ratio, but I think I'd prefer 3:45 with the T5 spread of ratios.

Just my opinion, but I think the 3:45 in manual guise would give a better result than I've got now.

As for economy, the 3:7s aren't bad. I get 400kms plus pretty easy and around 450 when I go gentle.

Your choice of course.

Cheers,

GK

The Monty · 25-04-2009, 11:45 AM

I have 3.9's and had my first decent drive in the auto, and returned 10.8L to the 100. Mountains included, 60 and 80 zones, but probs around 70 K's an hour average.

Ronza · 26-04-2009, 12:32 AM

Quote:

Originally Posted by cam.giles

Hey All... dont mind me thread mining... this thread might come in handy... im just wanting to confirm that a AU

will fit in my AU3 Forte Manual... i think it would be a nice upgrade from 3.08 single spinner... its just they make out like it'll only fit in a auto...

Cheers Cam

hey cam sounds familar like the diff i bidding on lol!!!

fourl6 · 26-04-2009, 09:52 PM

Quote:

Originally Posted by Ronza

hey cam sounds familar like the diff i bidding on lol!!!

ronza no... lol... if you end up getting it im getting some BA seats from the same bloke so could sort something out... ill let you have the diff... i should prob finish of my interior lol...

Ronza · 29-04-2009, 07:31 PM

HA HA well mate i missed out computer crashed at wrong times as it always does how you go???

fourl6 · 30-04-2009, 09:53 AM

Quote:

Originally Posted by Ronza

HA HA well mate i missed out computer crashed at wrong times as it always does how you go???

Quote:

The seller ended this listing early because the item is no longer available for sale.

they jibbed me :(