Hello, I have an '84 850b dozer. I started it up yesterday to do some work and I found out I have some technical difficulties. I have uploaded a video to youtube so you can see the issue. Basically it lurches big time in reverse and a tiny bit going forward. Here is this video -> http://youtu.be/75C-5qhE7tg Thanks for your input!
Looks to me like you're losing your charge pressure. Have you changed the transmission filters and checked the fluid is up to level, clean, and not full of air bubbles? Could be lots of things, these are early hydrostats with lots of gadgets moving oil around.
Looks like the right side is the culprit, I have only worked on a few ( to many ). Get a book and start with filter inspection and pressures, each side should be separate, do all test on each then compare, good luck,