Rumbling noise.... possible auto gearbox issue???

[Whiskeyonesix]

Hi Guys,

Got a problem... I was going to post this in the driveline section, but I thought this might be a general AU issue...

When I'm driving, and I coast ( in gear ) I hear a rumbling noise from the underside of the car. Noise goes away if I accelerate or brake. No vibration at all.
Only noticable when driving (60 kph+), not if I'm just crawling through traffic.

I thought It might be the exhaust, but it's not a "knock" or anything like that, or maybe CV joint - but theres no noise when I turn the wheels so fairly unlikely..

I'm thinking maybe diff or gearbox? Car is upto 213,000 on its original gearbox, so it's probably about due to go...
I had the brake discs and pads changed all round about 3 weeks ago - noise started just after that.... any connection do you think? Mechanic who did them checked the car over, serviced it, and gave it a clean bill of health - nothing wrong with it back then...

I'm off work for the next couple of weeks so I'm going to start trolling around a couple of garages to see what they think - I just wondered i you guys could give me an idea first....

[GASXD]

Things to check would be wheel bearings, going around bends at speed does the pitch of the noise change, i.e side load?

Also, dry universal joints can do funny things at times and check your pinion bearing for play while your under there.

CV joints are in the rear of the IRS equiped AU's, so turning your front wheels would make no difference.

Good luck.

[mongrelEF]

Also try checking the brake pads are seated properly and not playing back against the pistons. Sticky slides can, in rare cases, cause a similar sound....

[mik]

tail shaft universal? is it possible something came loose? wheel nuts, disc caliper?

[GK]

Originally Posted by mik

tail shaft universal? is it possible something came loose? wheel nuts, disc caliper?

Tail shaft unis were my thoughts also. Reminds me, I've got 4 unis for the AUs. Must arrange to have them changed over.

GK

[rowan194]

Does the noise disappear if you switch to neutral while you're coasting?

Can you tell us roughly where you think the noise may be coming from, eg front or rear?

[Whiskeyonesix]

Rest easy Chaps, problem solved... for now.

Mongrels post about the brakes intrigued me, so before work this morning I jacked the car up, took the wheels off all round, took the brake pads out, put them back in, put the wheels back on and tightened up everything d*mn tight.

No noise now.... whatsoever. I still don't know if it was the brakes or maybe loose wheel nuts.
I think the Mechanic (who I WONT be using again - and only did, cos of the warrenty - which as we all know isnt worth the paper its printed on) just didn't tighten everything up properly.

Although I've changed brakes in the past myself and never heard a noise like that - although I've never done them on a Falcon before now....
Guess I chalk this one down to experience - and be thankful I didnt lose a wheel on the freeway or something!
Something to keep an eye on though...

[J.C.]

Excellent outcome.
Disappointed though that you had to do the job again ........yourself.
I recall a similar issue I had. 40000k service I think on EB sedan. Front wheel bearing repack. Brake calipers left loose ....... both sides. Lucky I picked the car up and not the wife. I pulled over immediately and investigated. Wheels full lock and tightened caliper mounting bolts.
Got home and rang the dealer expressing my disappointment.
I hope your issue is fixed and it was just poor workmanship on behalf of the mechanic. Maybe he was having a bad day.............

[Day-mow]

How do you change Uni joints? I also have a noise from that sound of my car.

[mongrelEF]

Good to hear it was an easy fix!
Did you happen to check if the caliper slides had been cleaned and greased? Hardly anyone ever does that; I've repaired so many sets of dragging brakes caused by no grease on those slides.......

[mongrelEF]

Originally Posted by Day-mow

How do you change Uni joints? I also have a noise from that sound of my car.

Hammer and pliers Actually from memory the unis on an AU are held in by circlips but it's been a while so don't quote me on that.

[Day-mow]

sweet. they're pretty cheap on fleabay so hopefully shops also their not to bad.i'll have a sus 2morro. do you need to plug up the trans? when you do it?

[Whiskeyonesix]

Good to hear it was an easy fix!
Did you happen to check if the caliper slides had been cleaned and greased? Hardly anyone ever does that; I've repaired so many sets of dragging brakes caused by no grease on those slides.......

Clean, but no grease.

I put a dab of grease on them, and will keep an ear out for an other odd noises....
to be honest, I think half of this is I've only had the car 5 months, and this is my first Falcon - so I'm very new to their habits... closest I've got in the past is my old 1.6 Ford Seirra, although this AU is more closer in spirit to the '80 Cortina I had...
Having said that, I've done 16,000kms in the thing in that time due to Work Relocation, bombing up and down the Kwinana freeway has surely taken its toll
I'm taking it on a road trip down to Balingup week after next, so we'll see how we go.

[mik]

Originally Posted by Day-mow

How do you change Uni joints? I also have a noise from that sound of my car.

if you have the aluminum tailshaft...... very carefully.

[Day-mow]

Originally Posted by mik

if you have the aluminum tailshaft...... very carefully.

yeah i have an XR6 so thats me.

[mongrelEF]

Yeah the trans will leak a bit when you take the tailshaft out so plug it. A cut-off front yoke works well for some reason but you can get away with a Gatorade bottle and a drip tray.
Also be aware the uni joint caps have loose needle rollers under them, so be careful not to drop them off, it's a real headache getting them back in!

[mik]

and imo it`s a good practice before removal to always make a mark on the tailshaft and the pinion so the shaft comes out and goes back in the same way, re balance issues..

[Day-mow]

Originally Posted by mik

and imo it`s a good practice before removal to always make a mark on the tailshaft and the pinion so the shaft comes out and goes back in the same way, re balance issues..

like this?

http://www.youtube.com/watch?v=QK-g9Uuc140

[mik]

i dunno if that`s an optical illusion but it seems to be movin around a bit, are you gettin vibes? if you leave it in neutral, hand brake off while it is safely secure on stands, see if you can get any up and down movement in the uni by holding the tailshaft close to the uni(should be none) turn it a little check again, you can check both ends, the way the shaft appears to be wobbling around i`d bet that uni is tired.

[Day-mow]

nah ive put it in wrong. cos it didnt vibe b4 i put the uni joints in,

[mik]

how did you go?

[Day-mow]

cars in a shop. somethings not right.