Clunking when slowing down?

OzJavelin · 22-12-2006, 08:36 AM

This probably belongs in the "Transmission" forum .. but anyhow ..

Most often than not, when I slow down in the ute (AU 5.0L auto), just before I stop I get this "clunk" from the drivetrain. It feels like the transmission downshifting to first or something and it torque-loading the driveline. I'm not sure if the clunk comes from the transmission, driveshaft or diff? I've got under it and the uni's seem OK.

What's an easy way to check the diff ring/pinion lash? i.e. without pulling it apart?

Could it be the auto not shifting properly? It seems to function fine, shifts normal, doesn't flare (anymore than any other BTR) .. etc.

Any ideas/suggstions on diagnosing this?

Thanks,
Rod.

kennys · 22-12-2006, 09:41 AM

My au2 xr8 has done this since new. I have read the service history and ford has just written it off as a usual operation/usual noise. It hasn't seemed to get worse aslong as iv had the car. Yeah it is just when then box changes down into first.

JC · 22-12-2006, 12:45 PM

Mine does it too - also in reverse, so I know mine's not transmission. I think it's diff gears that now have some play in them, but will get it fixed only when I have no drive left! If yours is LSD, putting one rear wheel on grass and one on the road and stomping on the accelerator is supposed to help "Realign" the LSD clutches etc. I am yet to try this on mine.

Bill M · 22-12-2006, 05:39 PM

Just before you come to a stop slip it into neutral and see if it still does it.
BTR /ION tester did this to mine so I figure he knew what he was doing. Possibly valve body issues with the trans. I remember a statement by a dealer tech that Ford would look at it if the customer raises the issue. My trans seems to be the same as Kenny's as in clunking issues, still functions fine otherwise.
cheers
Bill.

**DJM83** · 23-12-2006, 05:57 PM

J.C your right i had mine looked at, it happens if there is some play in the 'meshing' of diff gears ive been told if you change the diff oil to something thicker and there is an additive u can add to the oil to keep it abit thicker, therefore reducing the effect slightly. But other then that everything else works fine. Or you can adjust your driving style as i have but it still happens

lil au3 · 29-12-2006, 06:45 PM

my au3 sedan does exactly this also. It's only done 90,000kms. I can't really work out where it is coming from but it's more noticable the more the car warms up. For the first 15min you can't notice it at all.

bonk182 · 29-12-2006, 07:13 PM

Its probably the diff gears also - it takes 15 minutes to warm up the diff oil - when its warmer the viscosity decreases and kinda becomes 'thinner'. Maybe thats why it doesnt clunk right away because the oil is cold.... maybe?

bodes-sh · 29-12-2006, 09:02 PM

^^although oil seems to get thinner as it warms up, according to the viscosity ratings it is supposed to get thicker...hence the oil bottles eg diff oil 80w/90...

RG · 29-12-2006, 09:12 PM

Mine does it too. Usually when slowing and turning making me suspect diff gears. I might try that realignment trick.

GK · 29-12-2006, 09:15 PM

Quote:

Originally Posted by bodes-sh

^^although oil seems to get thinner as it warms up, according to the viscosity ratings it is supposed to get thicker...hence the oil bottles eg diff oil 80w/90...

That's what I though!

Perhaps oils aint oils!

:

Sorry, couldn't resist that one!

GK

V8falcons · 29-12-2006, 10:49 PM

My old XR6 ute did this ,I changed OIL viscosity and it went away (almost anyway)cant remember what viscos to,(about 1 1/2 years ago) But a guy on the forums recomended it.I used an Oil stabiliser as well.and yes it still locked up nicely when needed.

mad40l · 27-08-2014, 10:03 AM

I have a xr6 AU doing the same thing clunking when slowing down to a stop mostly from speeds over 80kms its like kennys & ozjavelin.....

Any ideas iv had the auto serviced twice in 4 months ( gasket & filter ) both times and as recent as last week i thought that would get rid of the clunk but to no avail......

so im thinking it maybe uni joints will check them & also iv read about the ext housing bush going, although everyone said that causes the seal to fail, and touch would its prob the only au without a gearbox leak lol

im baffled any ideas its low kms car has just hit 88,000kms

Bill M · 27-08-2014, 01:34 PM

I still own mine and it now has 150 000km on the clock. Clunk has not gotten any worse but I did install a trans cooler a few years back. While still under warranty I remember the BTR/ION tech saying mine was borderline for valve body replacement.

Maka · 28-08-2014, 08:49 AM

Hi there & welcome to AFF, the above link might point you in the right direction -

http://fordforums.com.au/showthread....t=au+irs+clunk

cheers, Maka

Mainlube · 28-08-2014, 09:29 AM

Oil thins as it gets hotter (end of conversation)

However, with the higher rating on oils like 75w140 say the high end rating is 140 all this means is that the oil won't thin as much as an oil with a lower rating.

You guys need to look at a viscosity chart, 80w90 (I see above) is NOT a diff oil. 80w90 in cSt is SAE 30 engine oil thickness and SAE 30 is far too low for diff oil, even 150 cSt @ 40C which is SAE 40 still too low, must be 85w140 (320 cSt @ 40C mineral with no LSD) or (75w140 200 cSt @ 40C which is a diff oil with LSD.)

Your clunk Mainlube has had success in quietening to an acceptable level, diff and gearbox oil usually nails the shunt.

For the people with shunt, recheck what viscosity you put in, possibly the lighter gearbox oil and not diff oil.

PS. I'm not interested in what manufactures say, they just underestimated the load when changing down to a stop, it's just too light.

Holden don't get this shunt. (but I haven't seen light oils in diffs there either)

I persuade them to go 75w140.

Cheers

Steve

mik · 29-08-2014, 03:01 PM

The kick back is probably a combination of things, a bit of combined play in the driveline, but in my opinion a lot of it can probably be a bit bad manners from auto kicking back into gear, we used to get this back in 70s, v8s where a bit notorious for doing it, one of the things we used to do was lower the Idle speed a tad, which would kill some of the violent kick back in the auto as it was going back through the cogs, especially as you pulled up at the lights, back in those days you could adjust the kickdown if it was too harsh...... i dunno what the story is with these electronic autos.

Davehoos · 29-08-2014, 06:31 PM

old 3 speed gearbox would have a slow band apply for third to second and a over run sprag clutch for first gear.

half of my early BTR 4 speeds had engine braking on down shift and the others freewheeled. wasn't the box, behaved differently when swaped to another car.

old old diff didn't use calapsable spacer, It VL and skyline days we rebuild the diff with shims.often you could hear the original flange move and see the wear marks, the other thing was CV joints moving on the spline or pushing the grease away from the balls. often a trip on the hoist resetled stuff and noise disappeared.

My BF wagon often makes noises. with one piece alloy drive it transfers or amplifies other knocks. AU wagon was the same. Ive checked it at ever service and the small movement never got worse, I like to add grease but it probable don't need it.

I had thought some of the noise came from the hand brake and rear calipers. I replaced wheel bearings on works utes these also loose in the axle splines.non LSD. noises go away for some time after the job.

clutch pack LSD make all sorts of noises. doesn't mean there stuffed.

lot of the heavy machinery uses Sae 30 equivalent gear oil in the diffs.
with good old 80W/90 it took forever to drain out, this new stuff like lolly water. it might be equal to but its certainly not the same measure of viscocity.