Recently a customer of ours dropped off his Toyota Landcruiser 5 speed gearbox and transfer case that was noisy in 1st, 2nd and 3rd gear and was jumping out of low range in the transfer case.
We totally dismantled the complete assembly and put all main housings into the hotwash to remove all the years of dirt and grime to bring them back to like new condition.
The gearbox gear train was dismantled and hand washed and we inspected all the gears, syncro rings, gear selector hubs and the condition of the meshing dog teeth that hold the gear that is selected together.
We checked the inside splines of the main drive gear (shown above) to make sure there is no wear in the splines. We also checked the seal surface where the seal runs on that is installed in the housing between the gearbox and transfer case, which stops oil from moving from the gearbox into the transfer case or vice versa.
This gear is held in place by a lay shaft that runs through the middle and then on each side it has thrust washers and all this holds it in perfect alignment in the transfer case to ensure the correct gear mesh as to not produce any gear noise. We inspected the inside surface where the needle roller bearings run on for any excessive wear or pitting in the case hardened surface.
In this picture you can see the dog teeth that have a reverse cut on each side of the spline that matches and mates up the the same on each gear. These are checked for any wear, because if the spline has wear marks on these splines it will make the gearbox jump out of gear. So it’s a very important part of the rebuilding process to inspect all selector hubs as above and each gear in the gearbox and the high low gears in the transfer case.
We inspected the 3rd gear dog teeth to make sure that they have the complete unwarn reverse cut on each spline / dog tooth for a perfect match with the selector hub, to hold the 2 parts in mesh to stay in gear through acceleration and deceleration.
We also check for the correct clearance on the cone of the synchro ring to synchro cone.
The gearbox and transfer case is then re-assembled with all new bearings, needle rollers, thrust washers, seals and gaskets and all pre-loads set back to OEM specifications.
The Gearbox is now all back together, with the bearings on the cluster shaft having been found to be the cause of the noise and the dog teeth being warn on the high and low gears and selector hub, thus causing all the issues that the gearbox and transfer case came in for and all were replaced with new parts.
If you need a gearbox rebuild done, speak to us at NAE today!