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Old 08-07-2003, 21:28   #1 (permalink)
gondwana
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AU V8 - driveline clunk...

hello all

I'm new to this forum...

I've just bought a low km (40km) 1999 AU Fairmont V8 car ... my first V8!

I've had the auto serviced and oil cooler added (at auto specialist) as well as 40km check (at different dealer to one I bought it off) and they raised no issues with car - I asked a bout a few things.

One thing was there seems to be a driveline clunk when going into gear at standstill and also as you accelerate up to highway speed and then off throttle slightly you can feel the drivetrain 'unload' (best way I can describe it). My older EF auto (6) did not behave like this. Ford dealer does not really want to go there ... reckons he does not know enough about drivetrain issues...

The car has lsd .... and has had oil in diff replaced with better Castrol oil (was not noisy before - just wanted to know it had been done)

I have read in recent auto mag where they reviewed and XR8 of same year that this was something that you could expect from them ...

would welcome any comments from people that have a few more clues than me...

thanks

Jerome from Gondwanaland
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Old 08-08-2003, 05:10   #2 (permalink)
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Re: AU V8 - driveline clunk...

Did the fairmont have IRS std? If yours is IRS, the clunk will be backlash in the LSD hemisphere, a little in crown wheel and pinion, and a little more in the half shafts. The first two are an easy fix. Series two ran better? (different, anyway) half shafts. It is easy to check exactly where the problem is.
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Old 08-08-2003, 08:36   #3 (permalink)
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Re: Re: AU V8 - driveline clunk...

Quote:
Originally Posted by WBT56
Did the fairmont have IRS std? If yours is IRS, the clunk will be backlash in the LSD hemisphere, a little in crown wheel and pinion, and a little more in the half shafts. The first two are an easy fix. Series two ran better? (different, anyway) half shafts. It is easy to check exactly where the problem is.
WBT56, I've noticed by your postings you seem to have a bit of know how on gearbox/diff issues. My question/s to you is, how to fix the diff? What can be done? Who can you recommend in Melbourne?
I own a s1 AUXR8 (man) and yes, I too have the "nop, it's within spec, world famous CLUNKING diff" I've tried oil changes and still same. As my car is out of Ford warranty now I'd like to fix this annoying problem once and for all. Everyone knows about it (everyone accept dealer), but nobody knows how to or who can fix it.
Sorry to hijak your thread Jerome, oh, and welcome aboard.
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Old 08-08-2003, 16:35   #4 (permalink)
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Re: AU V8 - driveline clunk...

Jerome,

The best thing to do would be get the car up on a hoist or up on stands and check the uni's etc.
Put the handbrake on and in neutral, see how much play is in the crown wheel and pinion, by turning the tailshaft. If there is a fair bit of play, you take it to a diff shop and get it shimmed up.

Personally, I wouldnt worry about it, unless its really pi$$ing you off.
Mine diff clunks and winds etc, but i really cant be stuffed with getting it done a 4th time, so it will stay.

One other thing ive noticed with EL's and AU's, when you are slowing down, coming to a stop, when the ecu drops the auto back into 1st, you generally get a bit of a clunk.
Funny enough, in two cars i've seen increasing the line pressure (trans module) makes it clunk less, although you would think it would make it slightly worse , but the next problem becomes a bit more noticable with increased line pressure:

When you are at highway speeds and back off, and you say you feel the drive line unload, its probably due to the ecu not releasing the torque converter lockup at exactly the right time, it might be letting go a little bit too late, so you are feeling it when it unlocks.
There is not a great deal you can do about that, unless the problem is being amplified through the drivetrain due to dodgey uni's or play in the diff.
You should also see the same thing at around 60km/h manually holding in 3rd, when you accelerate very slightly, you will feel the torque converter lock up, and rpm's dont increase dramatically, this is more noticable when going up a slight incline.
If you then back off, you will feel it unlock, which sort of pulls the car back for 1/2 sec or so, then frees up again.
Its pretty normal, due to the "computer torque control"
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Old 08-08-2003, 17:38   #5 (permalink)
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Thanks for great replies folks

My Fairmont doesn't have IRS but it does sound like I'm just experiencing a bit more of the not so great (at times) Ford engineering.... :-(

I thought the electric windows in the AU would be better than the crappy ones I had in my EF ... seems not though from what the dealer tells me... :-(

Already had Ford NZ cough up for new radiator as it failed at such a low mileage....

I'll have a look at the diff a bit more and see how bad the play is - its just annoying at the moment. The local Ford dealer is very helpful but doesn't own up to any diff problems! - ha. When the diff oil was changed they put in the recommended (Shell?) oil and the grumble out of the diff was unbelieveable! (wife rubbed it in that I had asked them to change the oil!) ... so they then used the Castrol (safax?) oil that is their recommended oil for IRS models which they said had more of a 'diff problem' .... things are now quiet again.

you can see the car here:
http://homepage.mac.com/gondwana/PhotoAlbum65.html

the wheels, front brake upgrade and exhaust mods were on the car when I got it - certainly makes a great sound (esp when in power mode in auto) and such a different car from my EF 6.

thanks for your help folks

regards

Jerome from Gondwanaland
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Old 08-08-2003, 18:26   #6 (permalink)
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Re: AU V8 - driveline clunk...

Jerome,

Nice car,
Are you planning on lowering it a bit?

The AU radiators are a common probem, they all start leaking at a fairly early age.
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Old 08-08-2003, 23:21   #7 (permalink)
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thanks for reply ....

wonder how long the replacement radiators last!

funny you should ask about the height .... not really been able to find out much about it other than it looks higher than normal to me ...

local Ford dealer thought it looked standard but it rides firmer than normal Fairmonts - but lower tyres will do that anyway I expect. He wondered if it had an XR package fitted but that doesn't seem right as they are all much lower.

I gather that when new the 17" tyre option was only fitted with a suspension package as well - and photos I've seen of these Ford modified ones look like they are riding a little higher... not really sure.

It drives very well compared to my EF but is a bit rough over bumps and can imagine things will only get worse the lower you go so it might stay the way it is as my wife gets to drive it every day ... I have to use a train each day! :-(

regards

Jerome from Gondwanaland
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Old 08-10-2003, 01:36   #8 (permalink)
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Re: Re: Re: AU V8 - driveline clunk...

Quote:
Originally Posted by Red-i
I own a s1 AUXR8 (man) and yes, I too have the "nop, it's within spec, world famous CLUNKING diff" I've tried oil changes
Is it a power on/ power off clunk, a going round corners clunk, or both? Is it worse hot or cold, or no different? What oil is in the diff? ( If it has that evil SAF-XA in it, the going around corners clunk should have nearly disappeared.) They can be easily fixed.
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Old 08-10-2003, 02:32   #9 (permalink)
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Re: AU V8 - driveline clunk...

It's power on/off clunk. Hot or cold it's still there. Have tried Shell, Castrol and currently Penrite diff oils and various additives.
Clunks when:
Shift to 1st and bring clutch up to drive off.
Shift to 2nd from 1st while driving (slightly less of a noise) and couple of jerks from the driveline.
Shifting from 3rd to 2nd slowing down/entering a corner.
Get's worse with a near empty fuel load (with a full tank clunking/thump sound is almost unoticable).
I know you can drive around a bit more carefully and not hear any clunks, but I don't like to be thinking of exactly when/how/where I shift gears. Apart from this, I really like the car.
What diff oil and additive do you reccomend (part no.'s if possible please) Do you think my diff is rooted or is it fixable? You seem to know a bit more than the Ford dealer.
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Old 08-10-2003, 14:45   #10 (permalink)
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Re: AU V8 - driveline clunk...

To test where the backlash is, (easier on a hoist) jack up the back wheels, car in neutral, park brake off. Hold one back wheel, (or the inner stub axle on an IRS), and rotate the other back wheel (or stub) until the play is taken up. This isolates the hemisphere. At this point, get a second person to rotate the pinion flange back and forth, while you continue to hold the hemi locked. This shows how much play you have in the crown wheel and pinion. On live rear axle, hold one wheel and rock the other to the extent of the travel. This shows play in hemisphere and axle splines. On IRS, do this with the inner stubs to determine hemi backlash, and check half shafts independantly for half shaft backlash. Power on/ power off clunk will usually be in the hemisphere and half shafts. I use Shell LS 90 with no additives. Noise is probably worse with low fuel as it provides a barrier to noise entering the boot area. If the play is in the half shafts, then they need attention. If it is in the diff, it is easily fixable. Synthetic or synthetic base oils mask the problem by disabling the LSD to some extent, and running these oils will often quieten or silence completely the clack/clack going around corners without fixing the underlying problem of incorrect internal tolerances these diffs have. They will not help power on/ power off noises though.
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