centre diff that has been leaking for years and squeaky noise heard at 100km/h

[user2154]

With the squeaky noise that I have been ignoring for years starting to get uncomfortably louder and not wanting to be one of those broken down on the Auckland motorway I finally decided to investigate this problem.

I have had a leak from the seal when the centre driveshaft front CV mates to the centre diff for as long as I have owned the vehicle but it only drips (a tiny bit) if I park facing up hill so I have managed to get away with it now for many years now.

To get to the centre diff fill port requires removal of the CV heat shield which requires removal of the much larger chassis heat shield which requires removal of the exhaust mid section from the downpipe back, which requires removal of a skid plate. The only hard part about this is the exhaust removal just due to the corroded fasteners. This is comfortably achievable with the car on ramps at the front and a rubber mat to lie on.

By some miracle I managed to get all 6 of these bastards loose without rounding a nut. I sprayed them yesterday with CRC marine 66 and then again before removal.



There are two exhaust clamps about 1.5 metres down from the cats which are easy to remove. I managed to break 3 of the 4 nuts loose without rounding but one was fastened too tight so I could not get the socket onto it square. This one I rounded and had to cut it with a hacksaw and then smash it with a hammer and chisel but that only took about 20 minutes. Centre section of exhaust removed.

After that I had a look at the driveshaft centre bearing and after 300k km it has excessive play. Hopefully this is the source of the whining / squeaky noise I can hear only at 100km/h. Here is the play in the driveshaft.

http://vimeo.com/265934624

If I rotate the shaft a little there is a tiny tiny amount of play from the centre diff but I think this is normal. There doesn't seem to be any play from either the front or rear driveshaft CV but I have not yet removed the shaft from the vehicle.

front CV and leaky diff seal



rear CV



So I have ordered the new diff seal plus two new CV's and two boot kits, as well as the driveshaft bearing. The driveshaft bearing and CV boot kits are 034motorsports kits but I bought the lot from fcpeuro as I could not get the other parts from 034 (but I can get the 034 parts from fcpeuro).

So to remove the driveshaft you have to remove the entire exhaust so that has been done. It's a heavy bastard. Spray the rubber mounts with CRC 66 or some other lubricant from a can so you can easily lever them off with a screwdriver.

Upside down photo of my workshop for the last two days and the rest of the exhaust.



Next step is to remove the driveshaft but I think that can wait till next weekend or the one after that..

[sfkarl]

I have a B6 3.0 quattro and replaced the output flange seal at the rear of the trans a few weeks ago. Yes there is a lot of stuff to move out of the way but the job itself was pretty easy!
Only 100kms but going through the service history the seal had been noted as leaking some time ago. When I drained the transfer case where the center diff is there should have been around 900ml of gear fluid in there. There was about 250ml or so. Wasn't dry at least. After replacing the seal and filling the housing the drivetrain felt a lot smoother right away. There was a lurch between acceleration and engine braking (auto trans). However, after a few weeks the lurch returned disappointingly. Maybe not as bad, but not gone away either.

For the Quattro IV system I know there is a torsen center diff and an open front and rear diff with traction control operated through individual brake application. Because there is no electronic or active control of the center diff, (entirely mechanical) should there ever be tyre scrub on very tight turns? Can a torsen diff only compensate up to a point and then a bit of binding occur? Or should this never happen?

If I drive on tarmac carpark with steering on full lock (left or right it doesn't matter) it sounds to me like a binding diff. I don't know if this is normal and acceptable.

[user2154]

I also get the tyre scrub at full lock but from what I read online this is normal.

[user2154]

I drained my centre diff last weekend and replaced the seal. It only had about 200ml of oil left after about 10 years of leaking. For the centre diff fill and drain plugs you need m16 and m18 aluminium crush washers from the dealer for about 50c and 70c each.

Refilled both centre and rear diffs with Fuchs Sintopoid LS 75W 90 which is a full synthetic oil from BNT for about $40 a litre.

Bought a $15 oil pump from supercheap which fits a 1 litre bottle, works a treat.

[tjsmada]

squeaking less now i hope

[user2154]

Not back on the road yet, trying to get it all done before it gets too cold, maybe in another month...

I sent the driveshaft to ATL Balancing in Hamilton to have the u-joint replaced and shaft balanced, so I should get it back this week. I thought while I have it off I might as well do it as I never want to have to take it all off again.

I had removed the rear subframe as the welds were starting to rust, just surface rust but might as well take care of it now, so the diff came out also.  The front seam on the fuel tank was also starting to rust. Treated the rust on all of these and and painted it all with CRC zinc it black. Also removed all the heat shields and painted them with CRC bright zinc which has a metallic finish. While I was at it I painted the exterior of the boot tray with Rust-oleum flat black which is suitable for plastic.

I'm going to remove the driveshafts and maybe the rear trap arms and they will get the same treatment as long as the temperature doesn't drop below 10 degrees. I will see if I can paint the trap arms on the vehicle..

Installed subframe and diff today. Install rear subframe first then prop up the front of the diff on a bit of wood and lift the rear end up and over the subframe. There is just enough clearance to do it this way.

[user2154]

Received the driveshaft back last week and got it all installed on Saturday.



Staked in u joint replaced and shaft balanced by ATL Balancing and Driveline in Hamilton.



Rear wheel bearings on the way, might as well do it all while I'm in there. Going to patch up the paint on all the remaining suspension parts.

All the rubber bushings are still in great condition by the looks of it but I need to find a solution for the rubber boots on the heim joint end of the rear upper track arm.

[user2154]

Rear wheel bearings done, these should outlive the car. Had to buy a bearing removal / install tool kit but was able to sell it again on trademe for only a small loss.

I spent ages searching for the rubber boots for the rear control arm spherical joints but no luck with these so I bought two rear control arms on ebay for about NZD$130 delivered.

New CV boots and re-greased CV joints on the rear half shafts.

I found rear shocks for US$115 each plus $50 shipping from rockauto but didn't have the money on hand at the time to purchase and now the NZ dollar has dropped in value I will get pinged for GST + $50 customs fee at the border so unfortunately don't have the money for these right now so they will have to wait.

I lost the handbrake return spring from the right rear caliper! Lucky for me the spring for the right rear caliper is on ebay brand new genuine part, the left rear appears to be NLA, so I fricken hope it fits..

Everything here removed, stripped any damaged paint, painted and reinstalled just waiting on the few parts as above.

[user2154]

squeaking less now i hope

Unfortunately not! Back on the road now and the same noise is still there and still noticeable at 80 - 100km. It seems to be speed related and only when coasting not accelerating.

I will repack the front inner CV's at the end of the year and will see if that makes a difference.

Not sure what else it could be other than maybe outer front brake pad vibrating which I have had before with another set of brae pads when the retaining spring broke off one of the pads. But that was a lot louder and occurred at normal round town speeds, this noise is only at highway speeds and is actually very quiet. I can only hear it with the radio off.

[user2154]

Well I think I got the squeaky noise (it was more like a bag of coins noise). Replaced the grease in the front inner tripod CV's over the weekend, did not hear the noise today!

Used special GKN tripod CV grease, grease was US$40, shipping was US$50.. ouch

This is what the old grease looked like. The new grease doesn't run out like that.