Front end gear noise?

[Rustyferrious]

Hi All, my 2015 BX25D needed the seals replaced on the vertical stub shaft where the final drive connects. I also figured I'd replace the bearings and final drive seals since I would have it all apart and the BX has a little over 800 hours on it. There's a pretty good Utube video that shows how to do it so I ordered the parts needed. I picked up the parts and commenced the repair. Pulled the final drives off. Replaced the seals on the stub shafts. Then took the small bearing and large bevel gear off the final drive. Removed the two split ring retainers keeping the FD shaft from falling out and replaced the large bearing and the seal. I put it all back together, made sure everything lined up, all retaining rings in place. Small bearing is just slightly proud of the FD shaft, just like the original bearing was. I pulled/pressed the bearings off and on smoothly. No hammering. Everything seemed great going back together. large O-ring in place where the two halves of the FD bolt together. When I got the second drive back on I gave it a spin by hand and was surprised to hear some gear noise. Sounded like it was coming from the first drive on the right side. Like the bevel gears are not meshing smoothly. Not like they are grinding, but I'm thinking something is not as it should be. Tried adding the fluid back in but it didn't seem to make a difference. Definitely a growling gear noise. Like the two bevel gears are too close together, but there is no adjustment for that. The snap ring is in place on the stub shaft, otherwise the whole thing would just drop out. Everything looks ok except for the darn noise. Time to knock off for the day, but hoping someone might lead me in the right direction as to what the heck is the problem. Thanks for your help.

 

[Mike1955]

is that not normal for gears to produce a little noise? All the correct parts, went together perfectly by a good mechanic. I think it may be fine.

 

[rScotty]

OK, you sound like an experienced mechanic. You know that noise in a bevel gear is not right. I also see in your signature that you have a lot of accessories for your BX. If you will bear with me, I've got a couple of questions & maybe we can help each other out.

From my end, I am hoping you can advise beyond this repair since I am trying to help a friend who is interested in getting a small tractor,,,perhaps a used one. I like small tractors, and your model BX25D just happens to be one of several BX models we are considering.

We are talking about the front axle right? I just ask because in my mechanical experience saying the "final drive" sort of implies the rear axle. But your description makes it pretty clear that we are talking about the driven front drive axle on a 4wd. It has the differential in the middle, and tower bevel gear drives out at the each end to allow for steering while transmitting power to drive the right and left front stub axles and wheels.

And right off the bat I'm surprised that it needs anything to the front drive axle at 800 hours. Well maybe outer front axle seals...it's not uncommon for them to leak a little even when newish. Sometimes just changing from a light oil to a heavy gear lube will slow the leak to acceptable levels.

But do you any ideas if something caused the seals to fail? Did you buy it new? Did it haul a lot of heavy FEL loads in 4wd? And why replace the bearings as well as the seals? It is a much larger job. Were they worn? Was it making noise before or just leaking? As I'm sure you know, those bevel gear bearings are each one individually shimmed in the casting so that the bevel gear engagement is correct. That shimming is done at the factory using hardened machined shims in thousanth of an inch increments...All of which is why front axle mechanics are fanatical about being careful to identify and replace the bearing shims exactly as they came out.

Without going any farther, could those bearing shims be the problem? If they got out of order, we can set the bevel gears up correctly but it is a bit of a chore and requires some special tools. It's the sort of job you will probably have to do for yourself. I don't know of many shop mechanics with that skill set, patience, or tools to set up bevel gear engagement. But it can be done and I can help if necessary.
good luck,
rScotty

 

[Rustyferrious]

is that not normal for gears to produce a little noise? All the correct parts, went together perfectly by a good mechanic. I think it may be fine.

Mike, You may be correct. After spending the morning on the skeet field, I drained the fluid and removed the right side drive assembly, which is where I thought the noise was coming from. I spun the remaining drive and discovered that the noise wasn't coming from the right side, it was coming from the front differential. I never touched the differential so I feel pretty good about my repair work, but would like to confirm that the noise is "normal". If anyone has a minute to raise the front end of their BX and spin a front tire by hand with the engine off, do you hear anything? That would be greatly appreciated. Thanks.

 

[Rustyferrious]

OK, you sound like an experienced mechanic. You know that noise in a bevel gear is not right. I also see in your signature that you have a lot of accessories for your BX. If you will bear with me, I've got a couple of questions & maybe we can help each other out.

From my end, I am hoping you can advise beyond this repair since I am trying to help a friend who is interested in getting a small tractor,,,perhaps a used one. I like small tractors, and your model BX25D just happens to be one of several BX models we are considering.

We are talking about the front axle right? I just ask because in my mechanical experience saying the "final drive" sort of implies the rear axle. But your description makes it pretty clear that we are talking about the driven front drive axle on a 4wd. It has the differential in the middle, and tower bevel gear drives out at the each end to allow for steering while transmitting power to drive the right and left front stub axles and wheels.

And right off the bat I'm surprised that it needs anything to the front drive axle at 800 hours. Well maybe outer front axle seals...it's not uncommon for them to leak a little even when newish. Sometimes just changing from a light oil to a heavy gear lube will slow the leak to acceptable levels.

But do you any ideas if something caused the seals to fail? Did you buy it new? Did it haul a lot of heavy FEL loads in 4wd? And why replace the bearings as well as the seals? It is a much larger job. Were they worn? Was it making noise before or just leaking? As I'm sure you know, those bevel gear bearings are each one individually shimmed in the casting so that the bevel gear engagement is correct. That shimming is done at the factory using hardened machined shims in thousanth of an inch increments...All of which is why front axle mechanics are fanatical about being careful to identify and replace the bearing shims exactly as they came out.

Without going any farther, could those bearing shims be the problem? If they got out of order, we can set the bevel gears up correctly but it is a bit of a chore and requires some special tools. It's the sort of job you will probably have to do for yourself. I don't know of many shop mechanics with that skill set, patience, or tools to set up bevel gear engagement. But it can be done and I can help if necessary.
good luck,
rScotty

Hey Scotty,

1) Happy to give you my opinion on the BX25
2) Yes, front axle w/4WD
3) I was surprised that the seal on the stub shafts were both leaking. Enough to leave a donut size puddle on the floor after a couple days. This seal only comes into play for steering, there is no rotating powered shaft that it contacts. I thought it was odd that the seals limited to use only for steering would fail first. The outer seals at the very ends of the drive axles that seal the drive stub axle were not leaking at all. The bearings seemed to be in good shape too. It was probably not necessary to replace them, but the parts people at the dealer talked me into changing them while I had everything apart. It actually is not a big deal to do the swap them out. I had to spend a half hour building a plywood fixture to support the drive housing in my hydraulic press, and there are a few other tricks I learned the hard way, but the work itself takes about an hour each side start to finish once you know what you're doing and understand how the thing is put together. The first wheel took me a day, the second took less than an hour.
4) I do use the FEL a lot. I'm always hauling dirt, rocks, mulch, gravel, wood, machinery, block etc. over rough terrain. I live in CT on a wooded lot with a lot of ledge and almost the entire lot is sloped, very little flat space. I don't use the 4WD unless i'm clearing snow or on a slippery wet slope.
5) No shims in the drive units, there may indeed be shims in the differential, but I didn't touch that. The noise may be normal, see my reply to Mike above. I'm hoping someone will confirm this.

6) what would you like to know about the BX? I recently added a grapple to my attachment arsenal. I got rid of the front plow blade that I intended to use for clearing the driveway but the tractor is too light to power through deep snow, it just pushes itself in the direction you don't want to go. I acquired a 48" 2-stage blower for the garden tractor and that is what I use for clearing the driveway these days. The grapple does come in very handy for clearing brush and leaves. Forks are great for wood and pallets. I have a rear grader blade that works much better than the front blade for smoothing dirt or stone. The ripper blade for the back hoe works great. I have a little-used Land Pride post hole digger that is going up for sale. The BX has worked hard and I am very happy with it. I told my wife not to make me choose between her and the BX.....

If there is anything else you would like to know, ask away.

 

[Mike1955]

Mike, You may be correct. After spending the morning on the skeet field, I drained the fluid and removed the right side drive assembly, which is where I thought the noise was coming from. I spun the remaining drive and discovered that the noise wasn't coming from the right side, it was coming from the front differential. I never touched the differential so I feel pretty good about my repair work, but would like to confirm that the noise is "normal". If anyone has a minute to raise the front end of their BX and spin a front tire by hand with the engine off, do you hear anything? That would be greatly appreciated. Thanks.

Maybe some will. But you might have to expand your confidence and try it. You know how some gears are noisy and some are not depending on a whole lot of factors. I don’t blame you for being careful but it isn’t going to wreck your machine Good luck sir