Need Advice - 400 Foreman front drive problem

[BigAxeJack 6]

Hi folks, thanks in advance for reading. I have a 1995 400 Foreman and the front propeller shaft is worn to the point of failure. 
 

I’ve seen used ones available and I plan to replace the shaft & drive collar. 
 

My question is: how bad do the splines on the front differential and transmission output shafts look? They are definitely more worn at the contact surfaces than at the “shoulders”. 

In your experience, would you R&R the propeller shaft and ride? Or would you look to replace the front diff (coupling or entire unit)? What about the tranny shaft?

 

I can provide more & better pictures if needed.

 

Thanks for looking!

[shadetree 5,869]

1 hour ago, BigAxeJack said:

Hi folks, thanks in advance for reading. I have a 1995 400 Foreman and the front propeller shaft is worn to the point of failure. 
 

I’ve seen used ones available and I plan to replace the shaft & drive collar. 
 

My question is: how bad do the splines on the front differential and transmission output shafts look? They are definitely more worn at the contact surfaces than at the “shoulders”. 

In your experience, would you R&R the propeller shaft and ride? Or would you look to replace the front diff (coupling or entire unit)? What about the tranny shaft?

 

I can provide more & better pictures if needed.

 

Thanks for looking!

front final shaft is shot, time to replace. may as well open up the front diff, have a look at the ring gear, and all the bearings. keep in mind, you should replace all 3 oil seals while you are rebuilding it. word of caution !, the final shaft, in order to replace it ?, the engine has to come out, engine split in order to replace the final shaft. replace that oil seal right there in the front cover also.

[shadetree 5,869]

little tip: the trx400fm and the early trx450S ( '98-'01  trx450S ) , both use the same front differentials.

[BigAxeJack 6]

16 hours ago, shadetree said:

front final shaft is shot, time to replace. may as well open up the front diff, have a look at the ring gear, and all the bearings. keep in mind, you should replace all 3 oil seals while you are rebuilding it. word of caution !, the final shaft, in order to replace it ?, the engine has to come out, engine split in order to replace the final shaft. replace that oil seal right there in the front cover also.

Copy that. Thanks for the wisdom!

 

Regarding the front diff, I’m assuming I’ll only need to replace that female splined coupling (and seals, bearings, etc) if the R&P are good. 
 

Regarding the final drive shaft, is the oil seal you refer to the one through which the front final passes? 

[BigAxeJack 6]

16 hours ago, shadetree said:

little tip: the trx400fm and the early trx450S ( '98-'01  trx450S ) , both use the same front differentials.

Thank you! These are the kind of tidbits that make a forum like this such a wealth of knowledge. Greatly appreciated!

[jeepwm69 7,611]

2 hours ago, BigAxeJack said:

Copy that. Thanks for the wisdom!

 

Regarding the front diff, I’m assuming I’ll only need to replace that female splined coupling (and seals, bearings, etc) if the R&P are good. 
 

Regarding the final drive shaft, is the oil seal you refer to the one through which the front final passes? 

 

Yes, that seal is under final shaft in the schematics.

[shadetree 5,869]

5 hours ago, BigAxeJack said:

Copy that. Thanks for the wisdom!

 

Regarding the front diff, I’m assuming I’ll only need to replace that female splined coupling (and seals, bearings, etc) if the R&P are good. 
 

Regarding the final drive shaft, is the oil seal you refer to the one through which the front final passes? 

yes, oil seal right there on front cover where the final shaft comes through. you do not have to pull the engine to replace this seal ?..but..you do have to pull engine, split it, in order to replace the final shaft.

[BigAxeJack 6]

Thanks again. 
 

I’ll be reading the manual and shopping for parts. 

[BigAxeJack 6]

On 4/17/2024 at 11:50 AM, jeepwm69 said:

 

Yes, that seal is under final shaft in the schematics.

I see two oil seals in that schematic. I will replace them both “while I’m in there”. 

[BigAxeJack 6]

On 4/17/2024 at 3:24 PM, shadetree said:

yes, oil seal right there on front cover where the final shaft comes through. you do not have to pull the engine to replace this seal ?..but..you do have to pull engine, split it, in order to replace the final shaft.

It look like quite the process to split the motor, like a full tear down, but I’m willing to try. What other preventative maintenance do you recommend while I have the case open? The machine runs and shifts well. 
 

I plan to get an engine gasket kit, assuming one is available. It looks like I need a special tool to pull the flywheel, but just basic tools for the rest. 
 

What advice can you gurus offer?

[jeepwm69 7,611]

3 hours ago, BigAxeJack said:

It look like quite the process to split the motor, like a full tear down, but I’m willing to try. What other preventative maintenance do you recommend while I have the case open? The machine runs and shifts well. 
 

I plan to get an engine gasket kit, assuming one is available. It looks like I need a special tool to pull the flywheel, but just basic tools for the rest. 
 

What advice can you gurus offer?

Timing chain while you’re in there. DID or OEM only. 
Clean the crap out of everything.

A cheap motion pro flywheel puller from Ebay will work fine.  3 jaw puller for the centrifugal clutch 

[shadetree 5,869]

2 minutes ago, jeepwm69 said:

Timing chain while you’re in there. DID or OEM only. 
Clean the crap out of everything.

A cheap motion pro flywheel puller from Ebay will work fine.  3 jaw puller for the centrifugal clutch 

you do know...they also sell a centrifugal clutch puller tool...right ?..lol. i use a large bolt, fine threads to pull my flywheels, then i use the correct clutch puller tool. some are larger than others.

[shadetree 5,869]

3 hours ago, BigAxeJack said:

It look like quite the process to split the motor, like a full tear down, but I’m willing to try. What other preventative maintenance do you recommend while I have the case open? The machine runs and shifts well. 
 

I plan to get an engine gasket kit, assuming one is available. It looks like I need a special tool to pull the flywheel, but just basic tools for the rest. 
 

What advice can you gurus offer?

advice is free...parts are not !..lol. first off, complete engine gasket kit. tube of yamabond ( for where there is no gaskets ONLY ! ). all engine oil seals, D.I.D. cam chain is what i install in all my builds. 3 qrts of atv oil, oil filter, spark plug. air filter. only spec tools you will need: valve spring compressor ( if you do not have one ? ). flywheel puller, centrifugal clutch puller tool. a seal puller ( but not really needed, but works easier than prying seals out with a screwdriver ). service manual for sure !!. have your camera ( cell phone ) on hand to take lots and lots of tear down pics, before, during, after. this way, if you get stumped?, you can always go back, look at pics to see where that thrust washer goes ?..lol. if it were me ? ( i know its not..lol )..i would replace the main crank bearings while you have it torn down, yes..its extra money, but i would do this now, and be worry free for a few more yrs !. a good metric socket set, brass hammer, pry bars, air compressor, air impact gun ( 1/2 ), deep impact sockets, you will need 27mm, 24mm, 22mm, here and there. you can never have enough impact sockets !. some cases, you will need a 30mm, 29mm, 28mm. these come in handy for the hub nuts. not needed, but handy..A PARTS WASHER !. this comes in very handy to rinse out the cases once you get it all part, yes..i go that extra mile when i build my engines. if you get stumped ?, we are always here to help !, myself..i also do phone support..lol.