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Liam Nixon

Rear straight axle problems Honda foreman 450

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Hey, I had my rear differential started to clunk recently when turning sharply or going from forward to reverse, so after taking the right hub of and pulling it left as much as I could I could see the actual straight axle was worn down on the splines, I'm wondering if I should rebuild the diff or just replace the straight axle, when I pulled it through what looks like the front part of a bearing and 2 ball hearing fell out so I'm gonna have to open it up, but what is the the right kit for the job? it's a 98 with original straight axle and diff so should it be done?

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Probably going to need a new axle and ring gear.  The splines on both will wear and eventually strip out.

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4 hours ago, jeepwm69 said:

Probably going to need a new axle and ring gear.  The splines on both will wear and eventually strip out.

So I should get a straight axle, the pinion and pinion conversion gear, and bearings basically all around? Is that essentially what should be done? Man, that won't be cheap.

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2 hours ago, Liam Nixon said:

So I should get a straight axle, the pinion and pinion conversion gear, and bearings basically all around? Is that essentially what should be done? Man, that won't be cheap.

all of these models have nothing but straight axles !. parts list : a new axle, new ring gear, new pinion gear ( you have to buy the ring gear and pinion gear as sets ! ), all new rear differential bearings and seals. may as well look into rear hubs, the splines maybe stripped out on them ?.

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Take it apart and see what you find, order accordingly.

 

You can mix pinion and ring gears on the newer machines.  They are straight cut gears so you can buy the ring gear only and use your existing pinion gear if the ring gear is all you need. 

 

On the older machines like the 300's and 350D Foreman the gears were helical cut and had to be used in matched pairs. 

 

More than likely you'd need a ring gear, an axle shaft, and the left rear axle bearing that sits at the end of the tube right by the wheel.  Those are the common bad spots.

 

Again, tear it down and inspect everything.  Then see what parts you need to replace.

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2 minutes ago, jeepwm69 said:

Take it apart and see what you find, order accordingly.

 

You can mix pinion and ring gears on the newer machines.  They are straight cut gears so you can buy the ring gear only and use your existing pinion gear if the ring gear is all you need. 

 

On the older machines like the 300's and 350D Foreman the gears were helical cut and had to be used in matched pairs. 

 

More than likely you'd need a ring gear, an axle shaft, and the left rear axle bearing that sits at the end of the tube right by the wheel.  Those are the common bad spots.

 

Again, tear it down and inspect everything.  Then see what parts you need to replace.

sense when does honda sell the ring gear and pinion gear separate ?, i just looked on partzilla ( i wont buy from them now, they jacked their prices up even more ! ), they show the ring and pinion gears as a set, you can not buy just one or the other !. 

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14 minutes ago, jeepwm69 said:

Take it apart and see what you find, order accordingly.

 

You can mix pinion and ring gears on the newer machines.  They are straight cut gears so you can buy the ring gear only and use your existing pinion gear if the ring gear is all you need. 

 

On the older machines like the 300's and 350D Foreman the gears were helical cut and had to be used in matched pairs. 

 

More than likely you'd need a ring gear, an axle shaft, and the left rear axle bearing that sits at the end of the tube right by the wheel.  Those are the common bad spots.

 

Again, tear it down and inspect everything.  Then see what parts you need to replace.

After further investigation today the left rear bearing is absolutely toast, I am guessing it went bad long ago and then the wobble wore out the axle, but I slid the able out and quite a few ball bearings fell out so that and the axle need to get replaced at the very least, if not more.

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2 minutes ago, jeepwm69 said:

https://www.partzilla.com/catalog/honda/atv/2002/trx450fe-a-fourtrax-foreman-es/final-driven-gear

 

Ring gear is #9

 

Pinion gear is #8

 

And yeah, that left rear bearing goes and then water gets in there and rusts the splines between the ring gear and axle shaft.

thats a '08, his post ^^^, says 1998 ??. look up a 1998 rear set, then tell me you can buy the gears sep ?.

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what ever you buy from honda ??..DO NOT BUY IT FROM PARTZILLA !!..LOL.

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4 minutes ago, shadetree said:

thats a '08, his post ^^^, says 1998 ??. look up a 1998 rear set, then tell me you can buy the gears sep ?.

 

 

Yep, looks like 02-04 used different part numbers for the gear sets.  Same parts though. 

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Just now, jeepwm69 said:

 

 

Yep, looks like 02-04 used different part numbers for the gear sets.  Same parts though. 

they maybe the same parts ?, but you can not order for a 1998 sep !..lol. i dont do mixing year parts..but if later model parts will work ?, then sure..he might get by with it ?.

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Just now, shadetree said:

they maybe the same parts ?, but you can not order for a 1998 sep !..lol. i dont do mixing year parts..but if later model parts will work ?, then sure..he might get by with it ?.

 

I put the 450 ring gear out of powerstrokes old diff in an 07 500 diff.  Fit perfectly.  Ring gears are the same in all the 400/450/ 500's at least in the air cooled bikes. Can't say about the newer 500's

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2 minutes ago, jeepwm69 said:

 

I put the 450 ring gear out of powerstrokes old diff in an 07 500 diff.  Fit perfectly.  Ring gears are the same in all the 400/450/ 500's at least in the air cooled bikes. Can't say about the newer 500's

good info !. but..from my past work..most times the ring gear and pinion gear teeth wear as a set, i would wonder if its a good idea to mix and match sets ?, i always replace as a set..but this is me..lol.

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35 minutes ago, sled_22 said:

06 foreman footshift - trx500fm.

I was out driving this weekend and when going down the road from one parcel to the next i noticed my rear end clunked about 3 different times. each time separate. I was in higher gears, faster speeds, and lighter loads. Basically a constant throttle maintaining 15-25 mph cruising. One quick clunk, just enough to feel it, almost like a loss of power but definitely came from the rear end. When i was tooling around in the woods with and w/o 4wd i could never get it to replicate. It's almost like it needed a higher speed and light load to "clunk".

I'm wondering if i don't have the start of a wear issue. I haven't taken anything apart but wanted to do some research and get some insight before ripping apart the rear axle. maybe some known wear items to replace so i have parts ready to go while I have it apart to limit downtime.

Thanks,

Sled.

Sled__22 , I have stripped the splines on the axle #14 at the ring gear #9 and have also stripped the splines of the drive shaft and pinion coupler #5 in this pic image.pngand 

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Could be splines popping as Fish said.  Could be the ujoint slapping the inside of the swingarm if your swingarm bearings are worn.  Do you have a lift on the machine?

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9 minutes ago, jeepwm69 said:

Could be splines popping as Fish said.  Could be the ujoint slapping the inside of the swingarm if your swingarm bearings are worn.  Do you have a lift on the machine?

No lift. Machine is new to me, 2300 miles, 600 hours. I did a complete tear down and replaced 1st gear.

It does have 27" vampires and 26" IPTs in the front. New tires are in the works as I don't need that aggressive of a tire for a what I do but figured is relevant to define as there's probably extra stress on the rear end.

I'll probably get it on jack stands this week and see if i can't get the axle out and inspect those splines as I think that'll be the easiest to start.

I know the rear shocks are pretty soft and i'm sure the machine didn't get any love in the swingarm dept either so those will be checked as well.

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I would jack all 4 wheels off the ground and spin the rear tires by hand with the engine in gear ,   before tearing in to it 

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11 minutes ago, Fishfiles said:

I would jack all 4 wheels off the ground and spin the rear tires by hand with the engine in gear ,   before tearing in to it 

Out of curiosity, what's the advantage of having the front jacked up (electronic 4x4) as well as it being in gear (resistance to find slop)?

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Need to have all 4 tires the same diameter if you're going to run it in 4wd.  That's a big no-no to run different sized tires on a 4wd bike.


If you keep it in 2wd won't hurt anything.

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Posted (edited)
2 minutes ago, jeepwm69 said:

Need to have all 4 tires the same diameter if you're going to run it in 4wd.  That's a big no-no to run different sized tires on a 4wd bike.


If you keep it in 2wd won't hurt anything.

Yeah i know that. Rarely use 4wd unless needed up steep inclines right now. The tire heights are almost identical now being worn so much but that is the major reason to getting new tires on order.

Edited by sled_22
spelling

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2 hours ago, sled_22 said:

06 foreman footshift - trx500fm.

I was out driving this weekend and when going down the road from one parcel to the next i noticed my rear end clunked about 3 different times. each time separate. I was in higher gears, faster speeds, and lighter loads. Basically a constant throttle maintaining 15-25 mph cruising. One quick clunk, just enough to feel it, almost like a loss of power but definitely came from the rear end. When i was tooling around in the woods with and w/o 4wd i could never get it to replicate. It's almost like it needed a higher speed and light load to "clunk".

I'm wondering if i don't have the start of a wear issue. I haven't taken anything apart but wanted to do some research and get some insight before ripping apart the rear axle. maybe some known wear items to replace so i have parts ready to go while I have it apart to limit downtime.

Thanks,

Sled.

i don't know why the other mod's let you post in another members thread for a different reason ?, all your doing is confusing the OP and others, please start a thread on your atv problem in the utility section. but to answer your question ?, you need to tear the rear end down, and start looking for damaged bearings, ring and pinion gear teeth damage, collar damage, everything !. don't GUESS ?!..tear down, then look to see what all you need to replace ?..then order...WAIT for parts...fix it :-).

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19 minutes ago, shadetree said:

i don't know why the other mod's let you post in another members thread for a different reason ?, all your doing is confusing the OP and others, please start a thread on your atv problem in the utility section.

My apologies, I thought the OP had found the problem and in order to prevent a clutter of common posts about the same potential issue i replied here.

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3 hours ago, sled_22 said:

06 foreman footshift - trx500fm.

I was out driving this weekend and when going down the road from one parcel to the next i noticed my rear end clunked about 3 different times. each time separate. I was in higher gears, faster speeds, and lighter loads. Basically a constant throttle maintaining 15-25 mph cruising. One quick clunk, just enough to feel it, almost like a loss of power but definitely came from the rear end. When i was tooling around in the woods with and w/o 4wd i could never get it to replicate. It's almost like it needed a higher speed and light load to "clunk".

I'm wondering if i don't have the start of a wear issue. I haven't taken anything apart but wanted to do some research and get some insight before ripping apart the rear axle. maybe some known wear items to replace so i have parts ready to go while I have it apart to limit downtime.

Thanks,

Sled.

 

Well I tried moving Sled's post and replies to a new thread, and screwed it up. 

 

Sled, why don't you start a new thread, and we can reply to that.  I believe you are correct that the OP resolved the issue, or gave up on it.  No replies for a while.

 

That said, a new thread would likely show up on a google search and might help someone in the future.

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