Rebuild the rear differential

[Twilight]

My 250sx ran for 3 days, then today I went to drive it off the trailer and the drive shaft just spins and spins... sucks, but I figured with any project trike it needed to be done.

Manual says I take off the rear wheel, slide the axle out and then unbolt it.. lets hope its that easy! Are the gears still available? If not, anyone have extras, haha.

Atleast the 350x and the 250sx made the trip and ice fishing easier and fun!

[honda250sx]

You will need some special honda tools to do this job. Its not for the faint of heart.

I purchased the tools from a dealer that was going under. I wish I had a picture of them.

Good luck

[oscarmayer]

or he coudl send you his rear end and you fix it since you got the tools for a decently cheap price. ;) help a bro out mans! :D

[Twilight]

What kind of tools are they?

[oscarmayer]

:shiftyeyes: super secrete squirel tools :shiftyeyes:
he coudl tell ya, but then he has to kill ya. :twisted:

[Twilight]

Ohhh la la... So vice grips and a BFM is in order... hehe :naughty:

[oscarmayer]

hahaha that's funny right there! :lol:

[Twilight]

In all seriousness, I have been to so many mechanics that have the special tools being vicegrips and a blunt object.

I sure dont do it :)

[Twilight]

Okay, before I tackle it tomorrow I need to know.

When in neutral, the drive shaft moves when the wheels move, when i pop it into first gear it doesnt move. Would this be a gear or bearing? In the 5th gear it makes a bad noise.

[ScottZJ]

I made my own tool out of a pipe and large nut. I just welded them on and it worked great. I just took the diff to the hardware store and found a nut that would fit it perfect.

here is the nut you have to get out of the top part of the diff
http://www.fototime.com/{5951EDBC-08ED-49FE-872F-25F778D20877}/picture.JPG

Here is the part I made
http://www.fototime.com/{18FD2B3B-8129-4606-AA43-4026D8266F85}/picture.JPG

http://www.fototime.com/{4E35429A-856A-4855-AE1B-1AD602199671}/picture.JPG

here it is all tore apart
http://www.fototime.com/{D4A5320A-B650-4E7D-82DC-97322482BEA2}/picture.JPG

http://www.fototime.com/{B8EABB71-CA00-4E18-B4C8-EF25378B1FE9}/picture.JPG

http://www.fototime.com/{D3192E2D-5C18-4348-94BF-0C42D43EEA5D}/picture.JPG

http://www.fototime.com/{E372F76E-EED9-4C0F-B367-31BFDE13057E}/picture.JPG

[oscarmayer]

if youy can turn the wheels and the shaft turns, then it's not the differential. it's a good chance it's in the transfer case if where at that point I would start.

[Twilight]

Okay, I took the damn rubber boot off so I can see whats going on, this is what I can see.

Neutral, if I turn the rear wheels, the shaft turns. The trike will try and go forward.
1st gear, shaft turns wheel doesnt
2nd,3rd,4th... same
5th gear, shaft turns, differential makes a horrid noise, wheels dont move.

[honda250sx]

Scott thats a quick fix! What size nut for the rest of the DIY??? Nice job.

[oscarmayer]

welp, maybe the rear diff is bad then. does the driveshaft have a yoke between it and the rear diff or is there jsut a spline? (i forget on those years)

yea u may be lookin for a new rear diff. i seen them on ebay for liek $150-$200 working perfectly. may be easier to just by a working unit. then repair that one and save for later.

[honda250sx]

There is a u-joint in there.

[Twilight]

the splines and the u joint are good, no breaks. No splines missing or worn.

[Dirtcrasher]

Take it apart, see how bad it is and it's possible a kit can save it, aren't the kits about 70$??

The bad thing about repairing a diff thats shot is that all the journals where the shafts are pitted and corroded. You can see in Scotts pic how bad his journals are. You can shine them up with 400 and 600 grit cloth a bit but the surface will remain abrasive. And with every turn, it eats at your seal just a bit more.

The back of the pinion bearing also has a bearing which if that portion of the pinion shaft is worn or pitted, it will not ride within the bearing tightly and the tooth wear pattern can be affected because that back bearing supports the pinion shaft.

Then when the seal gets sloppy and water has a chance to get back in there again and the process starts all over again.

With the SX, ES and BReds, there are hub seals and a drive shaft boot to stop water and dirt at the first front, then the seals surrounding the 3 differential bearings is the next barrier. If any of these go bad, water eats the entire differential. I really try and avoid deep water with my SX, it's fun, but not fun finding excellant parts to fix it again.....

I must admit though, these are not rocket ships going hundreds and hundreds of miles and a quick rebuild may be just fine for plenty of people :beer

[honda250sx]

Be sure when you take this apart...DO NOT MIX UP THE SHIMS for the gears. Measure them and label them accordingly. You do not want to mix them up!

[Twilight]

DC- Just taking a quick look at mine today. i may be better buying a new one. The inside is straight rust and grit. I am wondering though, how come silicone, gasket paper and some other lovely ingredients dont work to keep water out. Do they get in by the axle shaft, or is there another way?

There is always a way to fix and make better on whats going on on the machines. So what place should I start?

If one of my gears is screwed, does honda still make the gears or am I SOL? Would a Trx differential work as far as anyone knows?

[Dirtcrasher]

DC- Just taking a quick look at mine today. i may be better buying a new one. The inside is straight rust and grit. I am wondering though, how come silicone, gasket paper and some other lovely ingredients dont work to keep water out. Do they get in by the axle shaft, or is there another way?

There is always a way to fix and make better on whats going on on the machines. So what place should I start?

If one of my gears is screwed, does honda still make the gears or am I SOL? Would a Trx differential work as far as anyone knows?


Jeff is SO right about the shims, Honda has like 12 different thickness's :lol:

You can't "fix" them, Honda did great! It's lack of maintenance that wears them past the service limit. I'll make an good analogy to a girl thats been with a bunch of a holes her whole life, then along comes Mr Nice Guy - Too bad, soo sad but she is too far gone at this point to FIX HER!!!!! :lol:

I try to find good parts and tear them down, file and stone every mating surface and seal them with silicone. Replace bearings, all seals and make sure every journal is nice and shiny. Grease every spline with super thick grease that water cannot penetrate. Then it's a good diff that you can maintain.....

Do a search about the TRX diff, I know the ES is the same but geared in a manner that you will lose top end speen running SX 22" tires.

[Twilight]

Thanks, Honda does great with all. I know all about human error and before i found manuals... lol I do a lot myself.

Good thing for me I have a photographic memory. As I tear it down I will fix and clean as I go. Right now I am having trouble with the rear axle, its not budging for some reason.

[Twilight]

Well, i am now debating what to do. One of my fellow Pilot owners has a parts bike in Illinois that he will get the diff off for me if I want it, he cant test it because he doesnt have a way to that he knows of.

attempt to fix... or try luck with another... dunno yet.

[Twilight]

Also I still dont understand why when I move the wheels in neutral it spins the driveshaft just fine, but when the engine is on and in gear it doesnt make the connection and only the driveshaft spins.

Can anyone shed light on this?

[Dirtcrasher]

Your post is somewhat confusing to me :D

The ring and pinion are a direct positive link PERIOD. No matter what the engine does or is doing unless something is stripped and grabbing "sometimes"

Now if the whole arse end were removed, and the engine was running even in neutral, the output shaft would spin due to friction, but you could stop it with a pair of pliers.

It's tough for me to explain ( It's been awhile for me....) but it has 2 one way clutches that slip in one direction and grab in the other. Thats why the kickers slip, the one way clutch in the centrifugal clutch (rt side) has worn out and slips.

The clutch in the flywheel side (lt side) allows the starter to drive over the engine in one direction and spin free in the other. If this clutch fails, the starter gears get chewed to hell....

Those axles seize up in the chuck splines from corrosion, the hubs seize too! and I think the SX axle comes out the right side, not the left.

Download the manual and make sure your going the right way there professor :lol: J/K

[Twilight]

Trust me I have checked the manual. I will try and be more scientific now.

Motor when placed in neutral I can lift the bike up and spin the rear tires and the shaft turns with no play or noise. Now, when I upshift into S1 gear, the driveshaft will spin, but the rear wheels stop and will NOT turn freely, they stutter forward in small increments of an inch or 1/2in. 2nd-4th gear will do the same. Now when I get into the 5th gear, there is a grinding noise in the differential.

So, my conclusion was the differential. Before I placed the engine into the SX frame I tested it and the output shaft spun hard and strong and couldnt be stopped by any of my means.

I have no tried reverse since right now all the cables for brakes have been removed.

Driveshaft spins from the engine in all gears... wheels dont budge more than an inch. So im guessing the differential is toast. Sun-Tues it worked fine, I loaded it up on the trailer, came home and she wouldnt drive off.

[oOGoFastOo]

Also I still dont understand why when I move the wheels in neutral it spins the driveshaft just fine, but when the engine is on and in gear it doesnt make the connection and only the driveshaft spins.

Can anyone shed light on this?

it could be the splines on the driveshaft that connect to the rear diff. are worn and when you turn the tires it puts reverse load on them causing them to grip and turn the driveshaft. But when the engine is turning the driveshaft it causes them to slip because thats the way they are worn kinda like a chain sproket when its worn out if that makes any sense? Just an idea.