LT77 Gearbox Failure: Part Two
Gary Stretton reports as the experts at Ashcroft Transmissions rebuild our LT77 gearbox
Following a strip down last month, Ashcroft Transmissions rebuild the LT77 gearbox
In part one last month, we followed the stripdown of an LT77 gearbox that had suffered sudden failure of the first motion shaft and lay shaft due to a lack of oil. Stripping the gearbox took Ashcroft Transmissions just 30 minutes. Rebuilding takes just an hour or so thanks to Ashcroft Transmission’s experience and expertise.
Before starting a rebuild it’s essential to understand the patterns of wear and the reason why the gearbox failed. To Gary at Ashcrofts, who is rebuilding our box here, this means assessing every component and replacing any that are suspect. Equally, if a component is within tolerance and is otherwise good, it will be re-used. Items such as the synchro hub slippers will be re-used because, currently, the metal used to manufacture aftermarket replacements is considered too soft. It’s insider knowledge such as this that makes the difference between prolonged gearbox life and early failure. Tricks such as leaving the reverse lever pivot arm on the centre plate, unless it’s damaged, makes a build so much easier. And applying to parts during the build ensures initial lubrication, with a more generous application on completion. It’s also important to prevent dust and dirt ingress, and to work cleanly.
Gearbox rebuilds are a specialist job, so this guide shows how the professionals recondition a unit. If you have the technical knowledge and facilities to do the job yourself, the guide provides illustration and tips. After the dismantled gearbox parts have been stripped, cleaned and assessed, refer again to our dismantling guide in Part one of this series (LRM July issue), and the Land Rover workshop manual and parts catalogue in conjunction with this Part Two guide to understand the component sequences and assemblies for your LT77.
Specifications differ on LT77 variants, so components such as circlips, slippers and spacers may vary according to suffix, or may not be fitted at all. The key to rebuilding an LT77 is in having suitable tools available to aid careful and correct assembly without damaging any internal components. Ashcroft Transmissions have an array of bespoke tools to make reconditioning as efficient and thorough as possible.