Transfer Box Rebuild

Having rebuilt the gearbox, I’m now checking through the transfer box. Apart from weeping seals on the output shaft and a rattle from the high/low selector stick, I didn’t have any symptoms to worry about, but I’m glad I decided to check anyway.

I’m not sure if the output shaft’s rear bearing outer race slipped after the speedo housing was removed (the housing sets the preload on the bearing, adjusted by shims between the housing and transfer case), or whether things were already out of tolerance, but there was well over 1mm of end float and lateral play on the output shaft. I had already ordered a full set of bearings for the transfer box from Marshalls (my local LR franchised dealer), but on completion of the strip down, close inspection of the bearings revealed they are actually in very good condition. I’ll be reusing them and keeping the new bearings as spares for later use.

There was a lot of rust coloured sludge in the corners of the casing, and the 4wd selector rod had enough rust build up on its rear end that it seized as it was being removed. Thankfully, the shaft was repairable – they cost £80+VAT new! The transfer gear selector shaft is damaged beyond use, though. The rear end is fine, but the front end is very worn where it passes through the front of the 4wd housing, with a severe groove worn by the O-ring. Not only will this affect the seal of the O-ring, but it also allows the shaft and the lever to rattle. I have a new shaft coming from Dunsfold Land Rover, for just over £30 including VAT.

Also in that DLR order are a pack of new circlips and a thrust bearing for the output shaft – the existing circlip was found to be 40% absent, with the remaining section only just able to clip into its groove, and the thrust bearing is very slightly worn. I was concerned that the high ratio gear or output shaft itself was worn, as the end float when I checked it was just over 0.5mm (the Hanynes and LR manuals specify 0.15-0.2mm). However, the Haynes manual (I use it in the grarage and cross reference it to the LR manuals on my computer) did not include the essential information in the LR manual that the circlip should be pressed firmly down towards the gears while the end float is checked. The movement on the circlip is significant, and a re-check with the circlip pressed down resulted in 0.2mm float. With the new thrust bearing, the float should be comfortably within norms.

The rest of the components are good, so reassembly shouldn’t be too costly or time consuming once the new parts arrive. I have already rebuilt the 4wd housing with its new seal and O-rings, and refitted the front output shaft and drive flange.  I have also fitted a new seal to the back of the speedo housing, and all the transfer box parts have been cleaned. I think it will only take a few hours to completely reassemble the whole transmission, ready for installation in the vehicle.