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Skye_Rover

Member Since: 30 Aug 2013
Location: Skye
Posts: 85

1998 Defender 110 300 Tdi CSW Cairns Blue

300Tdi gearbox crossmember rust

Sorry all if the following information is a repeat of anything else on this forum; I had a look around and couldn't find anything specifically like this. I thought that it might be of some use to those keeping their Defenders for a few years yet.

The history of this is that I have had my 300Tdi CSW 110" for many years now, and it still looks good underneath after 16 years of use from the factory. Just recently, I have had cause to worry about shudder from cold on pullaway in lower gears (high range only) which required me to investigate a few obvious points before delving further into the chassis bushes. So the gearbox required removal, so that I could investigate the clutch and flywheel. I knew that I was in for a "treat" when I couldn't remove the gearbox crossmember, even after jacking the chassis rails apart. To be precise, all of this was accompanied by a lot of cracking sounds....

The following two shots show what was revealed on the main chassis rails behind the crossmember flanges. First the RH rail, which didn't look too bad;

Then the LH rail, which looked a lot worse....;

Although the crossmember flanges didn't look too bad, there was a fair amount of the flaked rust from the main chassis rails attached to the back of them. Once I had cleaned the chassis rails off, the following horrors were revealed. First the "better" RH rail;

And then the LH rail, which was clearly suffering from lack of metal in all of the usual places;

To put these photos into context, the chassis otherwise looks fine on this vehicle. If you didn't have to drop the gearbox out of the way, you would never know about any of this. Which is all the more worrying, especially if you happen to have a serious frontal collision - these weak points are just under the footwells

More's the point, I would have argued blue in the face with any insurance company that suggested that my Defender was anything less than 100%, which I now see to be a fallacy. I reckon I have seen most things on Series LR's and Defenders, but this has come as a shock on a cherished vehicle like this one. I believe, and I stand to be corrected, that the arrangement of the enormous tabs on the end of the gearbox crossmember was deleted again for the TD5 (welded-on brackets), and only came about with the R380/LT230Q combination for the 300Tdi. So it probably only affects those vehicles in the mid to late 1990's (I have never seen this type of problem on earlier Defenders).

The resolution of the problem began with the removal of the whole area of steel (or most of it) where the crossmember tab bears against it, then replacement with new (and thicker steel) properly let into the side of the chassis (but not too thick on the steel, as the crossmember has to go back between the rails

)

I hope that this will encourage people to have a look for trouble on their Defenders, before trouble finds them. I caught mine just in time, another 12 months and things could have been a bit flexible under the cab. Roads? Where we're going, we don't need roads.

31st Aug 2013 11:10pm

GUM97

Member Since: 05 Feb 2012
Location: Cheshire
Posts: 3555

1997 Defender 90 300 Tdi HT Stornoway Grey

Nice write up

An engine to TDi for!
"Land Rover- Proudly turning drivers into mechanics since 1948"

1st Sep 2013 8:41am

Lou Sparts

Member Since: 15 Apr 2012
Location: Kent
Posts: 1501

2005 Defender 90 Td5 XS CSW Zambezi Silver

Similar things happen behind the rear shock upper mounts too, worth a look there too. 2005 Td5 90 XS

Steve

1st Sep 2013 5:18pm

Retroanaconda

Member Since: 04 Jan 2012
Location: Scotland
Posts: 2557

Yep, I guarantee you every Defender on the road with a gearbox crossmember that attaches like that (the 200Tdi style one on a 110 I took apart was the same) which hasn't had it sorted will be the same underneath. MOT man can't fail it for something he can't see.

Lou is correct re. the shock mounts. I had this issue with my 90 (see here). Haven't dared take the gearbox crossmember off yet!

1st Sep 2013 5:40pm

Skye_Rover

Member Since: 30 Aug 2013
Location: Skye
Posts: 85

AFAIK, the shock mounts on mine are OK. I had a go at rust-proofing the rear of the chassis in 2004 (the rear crossmember was solid but looking like it was about to rust) with a combination of rust-converter, POR15, and underbody Waxoyl sprayed everywhere aft of the crossmember near the transmission brake. Now you have got me worried, though.....

Tomorrow sees the refit of the bits around the gearboxes, and putting the front-end back together (timing belt changed), plus a few "extras" like sorting out the winch solenoid (renew) in the F/N/S wing, maybe a few suspension polybushes, offer-up the body-stiffeners (AKA rock sliders) to keep the SW body from self-destructing at the C-post every time I hit a pothole (which is every 10yards on Skye). And now an inspection of the rear shock mounting areas, which I did paint and treat behind in 2004, but sage advice is sage advice!

Having got the gearbox crossmember fitted this afternoon, I was surprised how easily it slid up into place between the chassis rails. I reckon I added 0.5mm of steel to the rail thickness on both sides, yet the whole thing seemed quite loose. Perhaps the jacking of the rails to get the xmember out was not all elastic deflection

Roads? Where we're going, we don't need roads.

1st Sep 2013 11:12pm

Skye_Rover

Member Since: 30 Aug 2013
Location: Skye
Posts: 85

All clear on the rear shock mounts. A bit scabby around the paintwork, but the Waxoyl seems to be holding the corrosion at bay. Definitely needs to go on the maintenance schedule, along with the bulk of the chassis rails. I did a fair bit of topping-up the wax around the vehicle this afternoon, but clearly it isn't going to last forever. The best policy, if I had time last year, would have been to strip, convert the rust, and paint in a decent chassis paint. The wax has not really got a good hold on the exterior of the rails, so tends to flake back off in time.

I had a good session on the radiator pack, which gets a regular dose of wax, as this seems prone to rotting around the outside framework. Having said that, the radiator matrix is going to be the first thing to require a change; common to most modern radiators, the fins are just falling off the flues with corrosion after 5 years, so it will need consideration for replacement in the Spring. Roads? Where we're going, we don't need roads.

2nd Sep 2013 11:40pm

WarPig

Member Since: 05 Dec 2009
Location: Sheffield
Posts: 1748

1996 Defender 110 300 Tdi USW Bonatti Grey

Richards Chassis sell galvanised gear box cross members if that needs replacing.

3rd Sep 2013 12:57am

Skye_Rover

Member Since: 30 Aug 2013
Location: Skye
Posts: 85

The gearbox xmember was a bit scabby on the tabs where they had touched the chassis, but having cleaned and painted them, then smothered the whole lot in grease, I don't think there will be a problem.

One day, but not now, I want to go over to a decent galvanised chassis from someone like Richards. I did a re-chassis on my 109" back in 1990, that was one of the first few Steve Walker chassis in heavy duty steel, leaf spring mounts, dripping with heavy zinc. He drove it down to me personally, having got a trailer load of these things to deliver in Dec_90, pulling with an SD1 2.4Diesel, and the snow just starting to fall at 10:00pm as he set off to deliver the rest from the Midlands. Now, that's what I call dedication! Roads? Where we're going, we don't need roads.

3rd Sep 2013 3:24pm

GUM97

Member Since: 05 Feb 2012
Location: Cheshire
Posts: 3555

WarPig wrote:
Richards Chassis sell galvanised gear box cross members if that needs replacing.

I've got one of those, sitting between the chassis rails, on my Richards galvanised chassis

An engine to TDi for!
"Land Rover- Proudly turning drivers into mechanics since 1948"

3rd Sep 2013 5:49pm

Skye_Rover

Member Since: 30 Aug 2013
Location: Skye
Posts: 85

The test-drive this evening has proven the Defender to be driving and handling so much better than of recent. It's back to the way it used to be a couple of years ago. Allowing for the improved driveability from the powertrain, I'm still a bit perplexed by the way that the suspension seems to have tightened-up; so far, none of the bushes has been replaced (as scheduled for yesterday), yet the vehicle seems to be handling far better. I'm wondering if this is just a bit of imagination, or has the chassis welding improved the stiffness under cornering? Thinking laterally from that, was the clutch judder partly down to flex in the gearbox mounting at the chassis itself? Seems a bit unlikely, but the sea-change in the behaviour of this 110" CSW is unexplainable just from the clutch change and new gearbox rubbers (all previous components were in good order, loads of life left in them, and comparable on spring-rates with the new bits going in). Roads? Where we're going, we don't need roads.

4th Sep 2013 12:07am

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