Troy-Bilt Bronco Lawn Tractor Transmission Squeaky, Hot.

TylerFrankel1 · Jul 27, 2020

Hello Everyone! I'm making another post on the old Troy-Bilt Bronco Lawn Tractor I acquired earlier this year, saved from the scrap. It's a 13aj609g766 2005 mode. At first I was having drive belt issues, slipping, etc. I believe I have fixed it, everything's been incident free for a while. I replaced both belts, 2 idlers, and sanded on all the non-idler pulleys (the ones where grip is important) to remove glaze. I also set up the vari-drive mounts with nuts and bolts instead of the pitiful metal screws that were holding it in place before. It's been pulling great, no slipping for a while now even after long use. I've since replaced the deck with a good used one, installed headlights, re-painted the unit, replaced the muffler, essentially restoring it. The brakes work better after some adjustment. The steering got a new bushing. It's been pretty good.

Only one thing... a couple times after a long day of mowing, I hear a squeak coming from the transaxle area that starts getting worse as time goes on. When this happens, I can tell there is a great deal of rolling resistance compared to normal. When I mow, I drive around my neighborhood on the tractor and cut various yards. I put the mower in neutral down hills to get around faster. Normally I'll fly down hills reaching almost 20 MPH. When the squeaking starts, I barely pick up speed down hills and lose momentum quickly. The transmission assembly also gets hot to the touch. Obviously I'm missing lubrication somewhere. I'm betting the bushings inside are worn after 15 years, and I don't know a ton about metal properties, but I wonder if brass expands significantly when heating, causing this. Anyway, I'd love to pack the transmission with fresh grease, but of course, these cheap transaxles have no fitting. I also can't get the wheels off to replace bushings because the wheels are rusted on badly. I know you can take the axle off with the wheels still on, but you can't slide the bushings on and off with the wheels on... I'm probably going to invest in an air hammer and hope that helps. Before I do this, does anyone have experience with this and know better what's happening or a better way to deal with the issue? Thanks

TylerFrankel1 · Aug 4, 2020

I dug a bit further online and gathered some information. Went and checked my transaxle - there's about a 1/8 inch play/slop on the left axle and a small amount on the right. Clearly, my bushings are shot. I work at a small engine repair shop and the other day I put new belts in the exact same type of tractor (13aj609g766) and I noticed that transmission was FAR quieter and had no slop. So, mine's worn out. I'm gonna get those wheels off with oxygen and acetylene, take the transaxle apart and see if the bushings can be replaced or if she's too far gone (shaft digging into the housing). If its that bad, I'm looking at 350 for a trans. It honestly isn't worth it, but it is, because I already did so much to the thing (all the stuff I mentioned above). Oh well...
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Forgot to hit post and then I went and took out the trans and took it apart. Sure enough, the outer bushings were worn razor thin and the top case is chewed up on the left. I'm attaching some pics, you can see on the right side there's a 'lip' that goes all the way around the top case but on the left it's worn away. Do y'all know if it'll work if I just replace the bushings or will I have to replace the top case? Anyway, I'm gonna probably just try bushing first regardless. Worst case I'm out ~20. If I have issues after that I'll buy a top case but that's another ~70. There was a bunch of metal shavings underneath the differential shaft/main axle, and theres scores on the differentail shaft/axle on the left side where it was grinding on something (probably because of the bushings being bad) but they aren't nearly deep enough to compromise the axle. One of the seals was completely gone, chewed away. Also some light rusting in some areas, weird. If I take the differential/main axle out it has a lot of play but I think that's normal for a differential. I've seen pictures of new ones with slop like that. So, hopefully a thorough cleaning of the casing and gears, with new bushings and seals and grease, will save this thing.

Good Side of Top Case (Right)