When you engage 1st gear manually (I assume you mean Manual mode rather than Sport mode) it applies the Low/Reverse clutch, in addition to the Forward & Coast clutches. In ‘automatic’ mode (i.e. ‘D’) it relies on the Low Clutch sprag to hold 1st gear. Maybe the Low Clutch sprag has given up...

It lives in the big black plastic E-box under the bonnet, with the engine controller Phil

It’s never too late norseman! Stripping, cleaning, vacuum testing and Hydra-Testing the valve body assemblies is probably the most fun :) Phil

I've sent you a message :)

If you’re reasonably handy with a set of spanners there’s no reason that you can’t fix this yourself. Stripping, fixing and rebuilding the transmission is the easy bit. Getting the thing out of, and back into, the vehicle is by far the hardest part. People seem willing to tackle complex engine...

Well it’s certainly worth checking the fluid level, but I’m afraid it sounds like the axial needle roller bearing between the B-clutch hub & C-clutch drum has failed and allowed the input shaft to slide inside the B-clutch drum, splitting the O-ring which seals the A-clutch. When the fluid...

Does the transmission perform okay when it’s cold and then failsafe appears only once it has warmed up and then it reverts to working okay again once it has cooled down i.e. failsafe disappears? Or is the failsafe message there all the time? Is it definitely failing safe into 5th gear rather...

Early L322s used the New Venture Gear NV225 transfer box (i.e. petrol models to 2006MY and diesel models to 2007MY, both with 5-speed transmissions). This transfer box was unique to the Range Rover and wasn’t used in any other vehicle. Once the 6-speed transmission was introduced, all...

So this is a very early 6-speed model? I wonder if the output shaft spline has failed through fretting corrosion (they neglected to lubricate them at the factory). Does the park lock hold the vehicle with the handbrake off? Phil

This part of the connector stays attached to the metal bracket bolted to the top of the bellhousing so you will need to unbolt the bracket to access the pins for continuity testing. The half of the connector that is part of the vehicle wiring loom (shown in grey in the diagram below) twists...

Depends. Is it a 3.6 litre TDV8 (= ZF 6HP26/ZF Lifeguard Fluid 6) or a 4.4 litre TDV8 (= ZF 8HP70/ZF Lifeguard Fluid 8)? Phil

Or the output shaft spline has failed through fretting corrosion. Hopefully just your transfer box, though…

That diagram shows the straight-forward 5HP24 system from BMW. The circuit for the 6HP26 in the Disco 3 is a good deal more complicated :) Phil

I’m sure that you are already aware but, just in case, it might be worth highlighting that the BMW-engined petrol and diesel L322 final drives have a different ratio. M62 4.4 V8 = 3.727 (41T/11T) M57 3.0 TD6 = 4.100 (41T/10T) Phil

From JPAT: Shaft, Direct clutch hub and shaft 191mm long, JPAT p/n N224 29 04 = £93.75 +VAT Phil P.S. We should just keep in mind that we don't know for certain that this component has failed and caused the issue with 4th & 5th gears so I certainly wouldn't recommend shelling out for one...

I have an account with JPAT and I’m ordering some (ZF) parts from them tomorrow so I’ll ask them to quote for a 5L40-E direct clutch hub/shaft at the same time. Phil

Well that didn’t take a lot of persuading! Hopefully you will have received the repair manual(s) by now. 100% agree regarding the feeling you’ll have after fixing your own transmission – you’ll never worry about it again. Sonnax produce a large selection of replacement valves for the 5L40-E...

If you message me with your email address I can send you the official repair manual. The cheapest method of dealing with the piston seals is probably to use the Seal-e-Zee cones and freezing spray. https://www.hydratest.co.uk/transmission-tools Phil

If you’re capable of undertaking a manual gearbox conversion then you’re more than capable of re-manufacturing a 5L40-E transmission. Why don’t you rebuild your transmission yourself to ensure that, this time, it’s done properly? If you get the valve body assembly fitted with Sonnax valves this...

The bolt pattern for the E53’s NV125 transfer box is not the same as the NV225 (which was unique to the L322). I think, along with the electrical/electronic/control issues mentioned by holidaychicken, such a conversion would be extremely challenging. Phil