Rear Final Gear box internal clunking noise.

[WhitefieldJim]

Hello All. Over this past weekend my 2017 Honda Pioneer 700-4 developed a very concerning clunking sound coming from inside the rear final gear box assembly while in drive or reverse. Luckily it happened on a gravel road, so we parked it and walked back for the truck & trailer. I haven't tried taking it apart yet, but it sounds like something came loose and is fouling the gears or maybe a gear lost a tooth or two.

Has anyone had a similar issue? Is it worth trying to rebuild myself, or possibly better to replace the entire assembly? Hondapartsking has a OEM replacement for $415 shipped to Maine.

Thanks,
Jim
Whitefield, Maine

 

[Montecresto]

Hey Jim, are you referring to the rear differential? Presumably you checked fluid level. How do you know for certain the noise is from that? Is it just when first engaging or as you’re rolling down the trail. I guess you’ll put it on stands when you get it back to the garage and test it out. I’ve not heard of this. Good luck and of course keep us posted...

And welcome to the club, though I see you’ve been a member over a year...😊

 

[Mudwing]

Hello All. Over this past weekend my 2017 Honda Pioneer 700-4 developed a very concerning clunking sound coming from inside the rear final gear box assembly while in drive or reverse. Luckily it happened on a gravel road, so we parked it and walked back for the truck & trailer. I haven't tried taking it apart yet, but it sounds like something came loose and is fouling the gears or maybe a gear lost a tooth or two.

Has anyone had a similar issue? Is it worth trying to rebuild myself, or possibly better to replace the entire assembly? Hondapartsking has a OEM replacement for $415 shipped to Maine.

Thanks,
Jim
Whitefield, Maine

I don’t have an issue or never had an issue but I would isolate and identify the problem for sure. Check the fluid level in the rear end and maybe jack the rear wheels off the ground and rotate in neutral to try and find the noise. As far as rebuild vs replace, once you pinpoint the problem I would disassemble, inspect and assess. The cost of parts vs time doing it might offset each other. 😉😎

 

[WhitefieldJim]

Thanks for responding Mudwing and Montecresto -
I did check the oil level and it was full, but did look kind of milky like it might have been contaminated with water. I haven't jacked it up yet to spin the wheels, but did push it down the road in neutral and it didn't seem to make the noise. It only made the clunking sound while under power, both neutral and reverse. I'm also pretty confident the noise is internal to the final drive gear assembly, which I believe is similar to a differential but slightly more simple since it is direct drive in the rear.

 

[WhitefieldJim]

One of my concerns with tearing the gear box apart is the likely need for Special Tools. I haven't found anything on YouTube specific to the Pioneer rear gear assembly yet, but there was video of a guy rebuilding a Honda atv with direct drive rear end, and he needed a special tool similar to an oversized socket to remove the spindle that he quoted cost around $100 just for the tool. And assuming some replacement parts are likely needed, I'm leaning towards swapping out the entire assembly, but of course would prefer not to if it might be something simple. I did also just order the Shop Manual earlier today, so am hopeful once it arrives I can get a better idea of which way to go. Thanks.

 

[snuffnwhisky]

It could be a cv axle making the noise. Drain the diff oil and look for metal.

 

[Mudwing]

Thanks for responding Mudwing and Montecresto -
I did check the oil level and it was full, but did look kind of milky like it might have been contaminated with water. I haven't jacked it up yet to spin the wheels, but did push it down the road in neutral and it didn't seem to make the noise. It only made the clunking sound while under power, both neutral and reverse. I'm also pretty confident the noise is internal to the final drive gear assembly, which I believe is similar to a differential but slightly more simple since it is direct drive in the rear.

If it’s milky and the level is above the threads then you had water infiltration. That may or may not be the problem. You are correct the final drive is not a differential so it is a bit simpler. If you think it’s the final gear drive then it might be but I would make sure before you disassemble or buy parts. If you get a video of the problem, post to YouTube and put link here. 😉😎

 

[906UP]

It could be a cv axle making the noise. Drain the diff oil and look for metal.

This^^^^^^^^, I lost a rear CV on the Donkey (P500) and you would've sworn I blew the rear gear. Not saying it isn't possible gear damage but I'd consider it unlikely, the CV's are definitely the weaker link. The rear gear is very simple, easily rebuild-able with normal hand tools although you may want a dial indicator to set the backlash. You can find el-cheapo versions at Harbor Freight that would be good enough to accomplish the task.

 

[WhitefieldJim]

Update! I now do NOT believe it is the final drive gear box causing the noise since more troubleshooting over the weekend. After jacking up the rear and running operation check, I'm fairly confident now that it is the connection where the drive shaft or prop shaft couples with the final drive box at the pinion joint. The pinion joint is where the disc for the brake is mounted. While I had the rear end jacked up, with a foot held on the brake, when putting the machine into gear the driveshaft would still spin. From the best I can tell from the parts diagrams, the prop shaft has a male end grooved with gears that inserts into the female pinion joint, that I assume has receiving gear grooves to match, which I believe should provide a solid connection. However, in my case that connection is not holding solid. It's gone from just making noise, to providing 0 torque to the rear end. I can't confirm 100% that I've assumed correct since I haven't actually pulled it apart yet. I'm hoping the shop manual I have coming in the mail will provide the tips I need to confirm and repair the problem efficiently. I know I'll likely have to take a bunch of stuff off to get to it, but like all of us, I'm just hoping to do it the quickest way so I can get back on the trails! If anyone has any tips to share on how best to replace the rear prop shaft and pinion joint, it will be greatly appreciated! Thanks to All!

 

[Montecresto]

I assume it’s out of warranty.....🤔

 

[WhitefieldJim]

It's a 2017, so I think it it is beyond warrantee?

 

[Montecresto]

It's a 2017, so I think it it is beyond warrantee?

Indeed if you didn’t buy the extended warranty. Good luck with this....🤞

 

[WhitefieldJim]

Thanks Montecresto, I never believed in the extended warrantees.. until now! 😂 I'm also guessing that since I swapped out the stock 25" tires for 27" that I would have likely been denied anyway. Everything I read leading up to my putting larger tires on told me 27" would be ok, but now I can't help but question the move, wondering if the extra torque required to turn the bigger tire was too much for the drive linkage? There was suggestion before that it could happen, so again I can't help but wonder if what happened with mine is proof?

 

[Montecresto]

Thanks Montecresto, I never believed in the extended warrantees.. until now! 😂 I'm also guessing that since I swapped out the stock 25" tires for 27" that I would have likely been denied anyway. Everything I read leading up to my putting larger tires on told me 27" would be ok, but now I can't help but question the move, wondering if the extra torque required to turn the bigger tire was too much for the drive linkage? There was suggestion before that it could happen, so again I can't help but wonder if what happened with mine is proof?

I suppose that’s possible. But most of us have gone to larger tires, and haven’t had such a problem. I would be more likely to believe that your unit had a defective part that failed...

But, I’ll be interested to see what you come up with.

I hope you get this repaired with the least inconvenience, down time and expense....👍

 

[WhitefieldJim]

Thanks for your support!! 👍