Low Range Thudding

[aaron_2000]

Realised an issue with the Touareg today, it's the 2011 3.0 TDI 240, in normal gearing it drie fine, no issues at all. Put it in low range and it thuds hard when moving, even worse in reverse. It doesn't do it at all in high range, but it does it no matter what in low range. Tyres aren't the greatest, soon to be replaced, but that wouldn't explain why it's only a low range issue?

[Hereward]

Does engagement of low range also fully lock the centre/rear differential?

Thud only when turning, or driving in a straight line?

What surface are you driving on in low range?

[aaron_2000]

Hereward said:

Does engagement of low range also fully lock the centre/rear differential?

Thud only when turning, or driving in a straight line?

What surface are you driving on in low range?

You can put it in low range, then lock the centre diff then lock the rear diff, it thuds when driving straight or turning and this was first noticed on some Dales tarmac backroads.

[rallycross]

Likely to be the prop shaft bearing common on these although you would also hear this in normal driving.

There is a place in Feltham that does the repairs on these for a very reasonable amount you get a fully recon prop shaft and it’s not a big job for a local garage to remove yours and send off Then replace ( less than 2 hrs).

Link below to them last time charged me around £200 which is a lot better than VW £600.

http://www.propshaft-services.co.uk

[aaron_2000]

rallycross said:

Likely to be the prop shaft bearing common on these although you would also hear this in normal driving.

There is a place in Feltham that does the repairs on these for a very reasonable amount you get a fully recon prop shaft and it’s not a big job for a local garage to remove yours and send off Then replace ( less than 2 hrs).

Link below to them last time charged me around £200 which is a lot better than VW £600.

http://www.propshaft-services.co.uk

Thanks, bookmarked them. It's odd that it doesn't do it in anything other than low range. Only recently was it inspected and that didn't show anything up. Pretty sure it was some form of commercial vehicle when new though.

[InitialDave]

I don't know where you are in the country, but if it is prop related, MJC Engineering in Leicester did a custom prop job for one of my cars at a good price, worth asking for a quote if it's something they can assist with.

[Hereward]

aaron_2000 said:

Hereward said:

Does engagement of low range also fully lock the centre/rear differential?

Thud only when turning, or driving in a straight line?

What surface are you driving on in low range?

You can put it in low range, then lock the centre diff then lock the rear diff, it thuds when driving straight or turning and this was first noticed on some Dales tarmac backroads.

Hard to diagnose without me actually being there. If diffs are locking automatically, or fully locked, it's normal to experience thuds and bangs, especially if driving on high-grip surfaces (which isn't recommended), or if there is a tyre rolling radius difference between axles.

An OBD scan may pick up a problem with the transfer case or diffs.

[GreenV8S]

In low range I assume you'd get more engine rotation for a given amount of travel in the final drive so I expect any backlash will be more apparent. That might be apparent if you can get somebody under the car while you load the transmission in forward and reverse.

I also wonder whether there may be backlash within the hi/low range mechanism. The ones I've seen have a separate gear cluster and selector. It's not unknown for people to break reverse gear by abusing it and the low range gear train could be damaged similarly (knocking bearings out of shape, breaking housings etc).

[Mr2Mike]

aaron_2000 said:

You can put it in low range, then lock the centre diff then lock the rear diff, it thuds when driving straight or turning and this was first noticed on some Dales tarmac backroads.

Are you saying it thuds in low range without any of the diffs locked? Is it regular, e.g. linked to wheel speed?

[aaron_2000]

Been out and checked it in all the modes. Doesn't actually do it in just low range, centre diff locked and low range it does it a bit, rear diff and centre diff locked and low range it does it a lot.

[E-bmw]

And as above, with diffs unlocked?

[Mr2Mike]

aaron_2000 said:

Been out and checked it in all the modes. Doesn't actually do it in just low range, centre diff locked and low range it does it a bit, rear diff and centre diff locked and low range it does it a lot.

With either or both of the diffs locked the thudding noise would be expected when driving on a grippy surface like tarmac. This puts the transmission under a LOT of stress, do not do this. Diff locks should be used only for low traction surfaces.

If it's doing it in low range with neither of the diffs locked, then you have an actual problem.

[E-bmw]

^^^^ Wot 'e said.

Which is why I asked.

[aaron_2000]

Mr2Mike said:

aaron_2000 said:

Been out and checked it in all the modes. Doesn't actually do it in just low range, centre diff locked and low range it does it a bit, rear diff and centre diff locked and low range it does it a lot.

With either or both of the diffs locked the thudding noise would be expected when driving on a grippy surface like tarmac. This puts the transmission under a LOT of stress, do not do this. Diff locks should be used only for low traction surfaces.

If it's doing it in low range with neither of the diffs locked, then you have an actual problem.

Thanks for clearing that up, seems to be no issue then thankfully.