ATC 250SX and 250ES Differential Rebuild Tutorial

[Flyingw]

Some of you have asked if I do a tutorial on rebuilding the differentials on you SX and ES. I have four differentials to rebuild so I will do a tutorial during one of them. I won't be starting this for a few days but I'm getting things together. Once I get rolling on this, please refrain from posting until I complete the tutorial so the information flows smoothly. Once it's complete, then please post your questions and comments so stand by.

[Flyingw]

Alright boys and girls. As promised I'm going to do this tutorial on rebuilding the differentials for the ES and SX.

First, lets look at the two types of kits available on Ebay.

The first kit is the economy kit. It comes with everything shown but when you compare the pics, you will see a huge difference between the economy kit and the All Balls kit.

Both kits come with:

Ring gear bearings (2)
Ring gear seals (2)
Pinion Needle bearing (1)
Pinion shaft bearing (1)
Propeller shaft water seal (1)

Now, look at the two pictures. Note the difference in the ring gear bearings and pinion shaft bearing. The economy kit comes with sealed precision bearings and the All Balls kit comes with open race bearings. Why is this important? Because the differential is a bath lubrication and having sealed bearings does not allow the oil to get to the bearings. This will eventually lead to epic failure.

The other difference is the propeller shaft water seal. The All Balls water seal is reinforced on the ID. The economy kits is not. These two major differences is why I don't buy the economy kits even if I'm just changing the ring gear bearings and seals.

[Flyingw]

Next, lets look at the tools you will need to disassemble and reassemble the differential. To do this job correctly, you will need the following:

Cold chisel (used to cut the propeller shaft water seal)
Ball peen hammer
Small punch (used to stake the pinion shaft bearing retaining ring during assembly)
Pinion shaft holding fixture (this is essential to lock the pinion shaft to remove and install the gear lock nut on the end of the pinion shaft)
60mm torks bit (used to remove and install the pinion shaft bearing retaining ring)
12mm socket
14mm socket
22mm socket
28mm socket
Foot pound torque wrench
Blind hole bearing puller with a 1/2 inch tip
1/2 inch drive impact
Modified blind hole bearing tip with a pinion shaft gear retaining nut welded to it. (This is used to pull the pinion shaft out of the case) A brass drift can be used in lieu of this but I'll explain this later.
Freezer (to freeze the bearings for installation)
Oven (to heat the case and pinion shaft for installation)
Dial indicator mounted to an adjustable arm with a magnetic base (used to check the gear backlash)
Feeler gage .012-.24 inch (for measuring the gap between the ring gear and ring gear stop)
Screwdriver (for prying the case apart)
17mm wrench (to remove the oil fill cap)
Split bearing tool (for removing the pinion shaft bearing from the pinion shaft)

As you can see, this is a pretty involved process. The pinion gear holding fixture is really a show stopper for most of you. No longer available from Honda I got lucky and found this one on Ebay. I bought a second one but Dave Little bought that one from me. Unless you have mad scientist fab skills and the tools to make something similar, you don't have any way of getting the nut off the end of the pinion shaft. Trying to jam the pinion shaft to remove the nut usually ends in breaking the gear on the end of the pinion shaft. Its hardened but that makes it brittle. In any case, the pinion shaft holding fixture is essential in rebuilding the differential.

Please hold any comments until I get completely through this tutorial. If you have questions along the way, shoot me a message. The next part to come is the disassembly which I'll get in to later today.

[Flyingw]

Disassembly

Begin disassembly by removing the two 14mm bolts and six 12mm bolts. Remove the oil fill cap and the 10mm drain bolt and set aside.

[Flyingw]

Disassembly Cont

Next, place a screwdriver in the slots on the side of the cover and pry the cover apart from the case. DO NOT put the screwdriver between the cover and the case as you will damage the sealing surface. Use the slots.

[Flyingw]

Disassembly Cont

Remove the shim from the ring gear and mark it "Right Side". Remove the ring gear from the case. Remove the other shim and mark it "Left Side". I put them in ziplock bags. Set the ring gear and shims aside. At this point you can remove the ring gear seals and bearings from the cover and case. Discard the old bearings and seals.

[Flyingw]

Disassembly Cont

Attach the pinion gear holding fixture to the differential and secure in a vice.

This is where I will lose a bunch of you because of the pinion gear holding fixture or lack of. If you are doing just the ring gear bearings and seals then stop here and reassemble in reverse order. I should also note that for guys who are so inclined, this fixture can be made pretty easily with an old propeller shaft and a little bit of 1/4 plate steel. Cut off about 1 1/2 of the differential end of the propeller. Bore a hole in the plate and weld the cut piece of the propeller shaft to the plate centering it up on the hole. Weld a piece of plate on it as shown about 2" long and about an inch high. There really many ways you could fabricate this tool. Remember the goal is to lock the pinion gear so the nut retaining the gear on the end of the pinion shaft can be removed and reinstalled but you will need an old propeller shaft to sacrifice to do that. It has the matching splines you need. I think I have an old unserviceable propeller shaft if someone wants to make one. Just cover shipping and you can have it.

[Flyingw]

Disassembly Cont

Remove the nut on the end of the pinion shaft. I use an impact with the 22mm socket. Set the nut aside and remove the differential from the holding fixture. Remove the gear from the end of the pinion shaft and set aside.

[Flyingw]

I really wish it would put the pictures in the order I upload them in but it does it randomly but you get the idea.

[Flyingw]

Disassembly Cont

Here is where I put the cover back on the case and mount it in a vice. Take a sharp chisel and place it on the edge of the propeller shaft water seal and using a hammer, cut the seals outer metal band to remove it. Be careful with the chisel so you don't damage the inside of the case.

[Flyingw]

Disassembly Cont

Insert the 60mm torks bit in to the pinion shaft bearing retaining ring. Put the 28mm socket on the impact and remove the retaining ring and set aside.

[Flyingw]

Disassembly Cont

Honda made a tool for removing the pinion shaft from the case but haven't found one so I made this. I took a blind hole bearing removal tip and welded a spare pinion shaft nut to it. It works very well.

Remove the pinion shaft from the case. The pinion shaft will come out of the case with the pinion shaft bearing on it.

[Flyingw]

Disassembly Cont

Now comes time to remove the infamous needle bearing. This bearing is the single most point of failure in these differentials. Replacing this bearing is key to preserving the life of these differentials.

Insert a 1/2" blind hole bearing removal tip in to the needle bearing and tighten the tip. Attach the slide hammer assembly and remove the needle bearing from the case and throw that thing in the trash.

[Flyingw]

Disassembly Cont

The last thing to the disassembly is removing the pinion shaft bearing from the pinion shaft. There is a shim under the bearing so don't lose it. Clamp the split bearing removal tool around the bottom of the bearing and under the bottom race and remove the bearing from the pinion shaft. Set the pinion shaft and shim aside and discard the bearing. As you can see, Honda used a three piece bearing. They did this so the bearing can be preloaded. Preloading is done to keep them from destroying themselves under heavy load. The replacement bearing is not a three piece but still has to be preloaded but I'll get in to that during assembly.

Next comes cleaning, inspection, and Painting

[jays375]

Wow!Awesome write up!

[Flyingw]

Thanks Jay but no posting until I'm done. Pm me if you have questions.

[Flyingw]

Going back to the pinion shaft holding fixture. I should have shown the backside of the fixture. With an end off the propeller shaft, If you attempt to make one, half of the splines will need to be removed to accommodate the wall thickness of the socket. See the pics and you will see what I mean. The ID of the non-spline portion of the fixture is 1.31inches. Pretty much all the splines have to be removed.

[Flyingw]

Cleaning, Inspection, and Painting

I'm going to pause here to talk about some of the other parts that make up your drive train. If you have your differential removed from the trike then you have your left axle tube removed along with the axle, and propeller shaft. Let's not neglect those parts. The rubber boot between the engine and swingarm is essential in keeping water out of the differential. SAY WHAT YOU SAY!!!!!! The seal on the top of the differential is NOT an oil seal. It's a water seal. This means if the rubber boot is torn in any way, that allows water in to the propeller shaft cavity of the swingarm where it begins to rot your propeller shaft. That water will eventually work it way past the water seal depending on the sealing surface of the propeller shaft. In the picture you will see five propeller shafts. Starting at the top, you will see a propeller shaft that had water intrusion past the water seal and in to the differential. Second from the top is a propeller shaft that had water in the propeller shaft cavity but the sealing surface of the propeller shaft was in good shape so the water seal was doing it job. These first two propeller shaft are typical. The third propeller shaft is one that was in great shape so I sent it in and had it Zinc plated. Same goes for the fourth propeller shaft. The bottom propeller shaft shows heavy pitting on the water seal end. If installed would not keep water out as the sealing surface is badly damaged.

The top two propeller shaft are salvageable. Soak them in something like Evapo-Rust for about a week. Rinse well and dry. No matter what condition they are in, I put several heavy coats of PTFE Dry Film lube on the propeller shafts before I install them. PTFE is a dry film Teflon lubricant and offers great long term protection. You could also paint them but mask off the sealing surface on the differential end. Anything you put on the propeller shaft is nothing but benefit and protection. If the sealing surface is badly damaged, find a replacement propeller shaft.

As I said, the rubber boot on the swingarm is a critical item. If its damaged, replace it. The SX boots are still available from Honda but the ES boots are discontinued but I'm pretty sure that SX boot will work on the ES in lieu of anything else. The molded angle of the boots is what drives the different part numbers.

I have seen some pretty corroded axles on the SX and ES trikes. This is due to water intrusion. If you axle is corroded, clean it up. Get a wallpaper pan and put a couple of inches of Evapo-Rust in the pan and soak it. Wire wheel will work too. Just get the corrosion off by whatever means you have available to you. Once the corrosion is off, paint it. Don't paint the splines but paint it with something to protect the metal. Remember, anything you put on the axle to protect it is all benefit.

This is also a good time to replace your swingarm pivot bearings and seals as well as the axle tube bearings and seals. The last item to look at is the sealing surface of the hubs. If the sealing surface of the hubs is damaged, water WILL get in especially when the trike is submerged. The ES and SX have a bad problem with water intrusion at the hubs especially in the 85 models. Honda made some design changes for the 86/87 models but the water intrusion problem persisted. When assembling the rear ends, apply a generous bead of silicone sealant at all joints.

[Flyingw]

Cleaning, Inspection, and Painting Cont

Lets look at the differentials and what happens when water gets in to the axle tubes as well as what happens when water gets in to the propeller shaft cavity and past the water seal. as you can see in the pics, corrosion ranges from mild to severe and if left unchecked will destroy your differential over time. If you swamp your trike, change the oil. Flush out the differential well and refill. Check your oil frequently and change it often. The pics speak for themselves.

[Flyingw]

Cleaning, Inspection, and Painting Cont

The differential I'm using for this tutorial is actually in pretty good shape. This is the one that still has the original paint on it. The other shown is one I already ran through the bead blaster but note the pitting on the outside of the case. Keep in mind that any topcoat has a service life and the topcoat on the stripped case was failing allowing water to corrode the outside of the differential case. Later today I'll get the black one blasted, washed, masked, and powder coated. For you guys who don't have a blast cabinet, wash the cases well. Get any corrosion off by whatever means you have and at very least, shoot the cases with spray paint to protect the metal. There are some areas you cannot paint but I'll illustrate those areas later so I'm going to pause here.

[Flyingw]

Cleaning, Inspection, and Painting Cont

See the pictures and note the areas I have masked. Whether you are spray painting or powder coating, these areas need to be masked as they are sealing surfaces. paint as required.

[Flyingw]

Cleaning, Inspection, and Painting Cont

The cases are out of the oven, masking tape removed, and all the sealing surfaces touched up with a fine scotch-brite pad on my air motor ready for assembly. I'm doing four differentials at the same time. I have two more in the oven right now baking. Tomorrow I'll get the other parts cleaned up and ready for assembly.

The Honda manual talks about some in-depth inspections but that's assuming you have all the special tools and jigs to do this but for you and me, the inspection boils down to looking for any obvious damage aside from corrosion such as damaged gears and cracks or breaks in the case and cover. I have seen some busted cases. Probably a heavy hand with a hammer trying to get the cover off of the case or perhaps high side of a rock. Who knows.

Now, it should be noted here that the ring and pinion gears were match machined during production so they are a mated pair and they should be kept that way if at all possible. That's not to say you can't mix and match ring and pinion gears but know that if you do, you may experience some anomalies such as varying levels of growling in the differential. Assuming you have the ring gear shimmed correctly, growling is more of a nuisance than anything and as the gears wear together the growling may quiet down over time. Setting backlash on mismatched gears is more critical than normal. During assembly I will talk more in-depth about the shimming and why its necessary.

[Flyingw]

Cleaning, Inspection, and Painting Cont

I am ready for assembly. The case, cover, and fill cap have been cleaned and painted. The pinion gear, pinion bearing locking ring, propeller shaft gear, and propeller shaft gear retaining nut have all been washed. The ring gear has been washed and I put it through the bead blaster to get the corrosion off the ID of the hub and washed again. I have a new drain plug and sealing washer but reusing the old one is ok too. All parts are clean, dry, and serviceable. The last thing I will do while the oven is heating up is run a tap through all the threaded holes.

[Flyingw]

Assembly

There is a sequence to the assembly. Heating and freezing parts and bearings is the easiest way to assemble. The fragile needle bearing at the end of the pinion shaft slips in to absolutely has to be installed using the heat and freeze method. That bearing can not be pounded in because even one blow of the hammer will destroy the bearing. Using the heat freeze method will allow the needle bearing to drop right in to the hole in most cases. If any persuasion is needed, I use the pinion shaft and a small soft blow mallet to do this.

Pinion Shaft Needle Bearing Installation

Warm the case, cover, and large pinion shaft bearing to 200deg for minutes

Caution!!! Heating the case will soften paint so be carful when handling the case if you have just painted it. Even PC will soften at 200deg wear cotton gloves when handling the parts. Grab the hot parts on the unpainted areas.

The needle bearing should be thoroughly frozen for at least 4-6 hours. I usually put the bearing kit in the freezer a couple days ahead of time. Go ahead and place the pinion shaft needle bearing on the end of the pinion shaft and leave both in the freezer until the case has warmed. This way the pinion shaft needle bearing and pinion shaft are already cold for installing the needle bearing. Once the pinion shaft needle bearing is installed, the next step will be to freeze the pinion shaft and heat the large pinion shaft bearing to install the large bearing on the pinion shaft so this gets things ready for that step.

When you place the case and cover in the oven, take the large pinion shaft bearing out of the kit and place it in the oven to heat up. This will be used in the next step. This is the large bearing with the small OD. The other two large bearings are for the ring gear. Those get frozen until ready to install.

The case has warmed and the pinion shaft needle bearing and pinion shaft are frozen..... READY!!! GO!!!!!
Pull the case out of the oven and lay horizontally on the bench. Pull the needle bearing and pinion shaft out of the freezer. Insert the needle bearing in to the hole. Leave the pinion shaft in the bearing while the bearing heats up. Leave the case sit horizontally throughout the entire heating process because if you up end it at any point, the needle bearing may fall out. Work quickly because the needle bearing will heat up fast once it comes in contact to the hot case. After a few minutes, remove the pinion shaft from the case and place it back in the freezer for the next step and place the case back in the oven horizontally.

Bearing installed...... I did have to use a little persuasion to get the bearing in. Some I've had just drop right in with no effort.

[Flyingw]

Assembly Cont

With the needle bearing installed in the case, the next step is to install the large bearing on the pinion shaft. The large bearing was placed in the oven in the last step and the pinion shaft is back in the freezer. When ready, pull the pinion shaft out of the freezer. place the shim on the pinion shaft. DO NOT TO FORGET TO DO THIS BEFORE THE BEARING GOES ON.

Remove the bearing from the oven and install it on the pinion shaft. Let it sit for about 10 minutes then place the pinion shaft back in the freezer. The case should already be back in the oven. The next step is to install the pinion shaft with the large bearing on it to the case. Case should be hot and the pinion shaft should be cold.

The bearing is installed. I should have let the pinion shaft sit in the freezer longer. I did have to use a little persuasion to get the bearing down the shaft but it on and back in the freezer.

[Flyingw]

Assembly Cont

Now is a good time to install the ring gear bearing in the cover. Pull the cover out of the oven and lay it on the bench bearing side up. Remove the bearing from the oven and install in the cover. Set aside and let cool. Install the seal and set aside.

Bearing and seal installed...

[Flyingw]

Assembly Cont

The next step is to install the pinion shaft in to the case. When ready, remove the case from the oven and the pinion shaft from the freezer. Insert the pinion shaft in to the case. You may have to help the large bearing slid in to place. Place the case back in the over to warm back up to install the last ring gear bearing. Install the left bearing and lLet the case cool to room temp. Install the left ring gear seal.

You can see how this is a drawn out process with heating and cooling parts but it is the most effective way to install everything without having to pound the snot out of the bearings to get them in.
Pinion shaft installed, Left ring gear bearing installed. Neither required any persuasion. They both dropped right in. Seal installed. Now I'll let it sit and cool to room temp. This took about two hours to accomplish.

Almost done!!!!!

The next step is to install the pinion shaft bearing lock ring, propeller shaft gear, propeller shaft gear retaining nut, and water seal.

[Flyingw]

Assembly Cont

Pressing on. I now put the differential in to the vice to install the pinion shaft bearing locking ring, propeller shaft gear, and propeller shaft gear lock nut. I place the cover loosely on the case so it clams evenly in the vice. Install the pinion shaft bearing locking ring and torque to 65-80 foot pounds. I usually over tighten the nut then loosen then torque to about 75lbs. Over tightening then loosening ensures everything is properly seated before final torqueing. Be sure to put a little grease on the locking nut threads before you install it. Install the locking nut and torque. Be sure you install the locking ring cupped side up. Take a small punch and stake the locking ring.

Next install the water seal. A little Scooby lube around the outside of the seal helps it in to place.

Place the differential back in the pinion holding fixture and clamp it in the vise. Place the propeller shaft gear on the end of the pinion shaft. The gear goes with the grooved end down. Install the nut and tighten to 72-87 foot pounds. I usually set my torque wrench at 80lbs.

[Flyingw]

Assembly Cont

Now its time to install the ring gear. Before I get in to that, the gap between the ring gear stopper and the ring gear should be checked. Place the cover with the case side up. Put the right shim on the ring gear hub and install it in to the cover. Using a feeler gage, check the gap between the ring gear stopper and ring gear. the gap should be between .012-.024in. This one checks out at .014in.

The next thing to check is the backlash. Since you are installing the same shims you took out, I really wouldn't get too deep in to this. The book says you should have a back lash of .003-.007in. Basically if you place the ring gear in the case with the left shim on the ring gear hub and you have just a tiny amount of backlash between the ring gear and pinion gear, you're good. Allot of slop between the two is a problem. Too much backlash will result in the contact profile being too small resulting it the gears tearing themselves up. Get in to the book and read about the backlash but that is written assuming you have everything necessary to check the backlash. Most guys don't. Just make sure you put the shims back on the side they came off of and you'll be ok.

[Flyingw]

Assembly Cont

The last step is to apply sealant to the cover and install the cover. Apply a generous bead of sealant around the sealing lip of the cover. I usually take a small artist brush and fay out some of the sealant to ensure good contact. Install the cover and install the cover bolts. Torque the 12mm bolts to 17-20 foot pounds and the 14mm bolts to 32-36 foot pounds. I use black sealant for SX and clear for ES differentials. Adding some anti-seize to the bolt threads is a good idea. When you tighten the cover down, there should be a good amount of squeeze out around the edges. Let the squeeze out dry before handling the differential otherwise you'll have it all over the place. Let it dry overnight and the squeeze out will peel right off. The very last thing to install is the drain bolt, sealing washer, and fill cap.

[Flyingw]

Well that's it. In all, about a 5 hour operation but that's with powder coating. Properly done, this diff will be good for another 25 years assuming the water intrusion issues are kept in check. When you install the differential, each joint should be sealed with sealant. Don't rely on Honda's orings to keep water out. I don't even install the orings anymore. Just a generous amount of sealant does the job. Feel free to post away. I have three more of these to do over the next few days so I'll be busy. I also have an SX to finish for a guy in Tulsa. Enjoy and good luck.

ATC 250 ES/SX Differential Rebuild Tutorial..... Complete

[wonderboy]

Oh my is that completed diff a thing of beauty! Seriously, seeing that thing all pretty on the outside and knowing it is perfect and brand new on the inside makes me happy...

This write-up is just awesome. I hope some day to do a write up 1/2 as good as this one. Thanks!

[trike savior]

awesome write up flyingw. you do some good work.

you had it easy LOL. I know you have done work for UPNATM and don't know if he ever told you, but I did the diff for his first bike. he said it had been apart for 25 years and he had lost one of the ring gear shims. took some work with dial gauge and some plasti gauge but I got it figured out. I had never seen it happen before, but one of the balls on the pinion bearing was actually dented. not like there was a chunk broke and missing, but actually looked dented. don't know how that happens to a solid steel ball but interesting none the less.

this write up will help a lot of people. awesome work.

[Dirtcrasher]

Excellent write up Jim!!

One thing I should mention. As water intrudes the axle and the drive shaft gets pitted; I would check with Harwal (who I use; They may be in Vermont with rubber coated seals.....) especially in the East coast for a seal with 1 or more probable, a 2mm smaller ID. Then a person can toss it in a lathe and remove .040 or .080 roughly to have a nice new surface for that pinion seal to run on.

And all you guys running shaft drives, check that diff oil often, make sure it's clean and that the breather hose is nice and high!!

[DohcBikes]

Thanks for a great writeup Flyingw! I was just wondering the other day how critical the backlash was on shaft driven trikes....great to get trusted input from a pro such as yourself.

[Dirtcrasher]

Thanks for a great writeup Flyingw! I was just wondering the other day how critical the backlash was on shaft driven trikes....great to get trusted input from a pro such as yourself.

It's that wear pattern that's so important. Some people even LOSE the shims and make it work, but severely ruins it's longevity. Honda has a bunch of part numbers for various shims. No, it isn't a Ford 9" or a Dana 60, but, it's just as important and if you start from scratch, you have to put blue marking on the ring and pinion and get it correct.

Again, IMHO, the biggest issue is water intrusion. And, if caught in time, your fine. But the people that neglect it and just keep playing in the mud and water that lose the gears themselves within time...........

[Flyingw]

DC, if I had it my way. I would have the sealing surfaces of the ring gear hub and propeller shaft reconditioned however, the ring gear hub and differential end of the propeller shafts are plated with a very thin layer of hard chrome. The hard chrome provides a durable long lasting finish suitable for sealing. This means those areas can not be machined without destroying the hard chrome. Thanks to the EPA, shops that used to provide hard chrome finishing are extremely hard to find and the ones that do hard chrome charge out of this world rates mainly because the cost of the process and maintaining the EPA license. Hard chrome is used in things like hydraulic actuator pistons, aircraft landing gear struts and so on. With all that said, all we can do is clean off the corrosion and reassemble with the hopes of getting an fluid tight seal.

Dohc, the backlash is very critical with any meshed gear assembly. The right angle (hypoid) type gear sets will prematurely wear the gears if the backlash is too tight and will destroy the gear teeth if the backlash is too loose so yes, the correct backlash is essential.

[Flyingw]

Prussian Blue is what is typically used to check the contact patterns on gear sets and as you said, Honda does have part numbers for different shims but that can get a little expensive. The procedures in the book are written basically for installing a new gear set and since each new mated gear set is different then having an assortment of shims would be required but for this exercise, reinstalling the same shims will usually preserve the shimming that was done when the differential was originally assembled assuming the differential has never been messed with. I took apart one differential a couple years ago. Someone had removed the ring gear and failed to install either of the shims. I tossed the whole thing in the trash. The teeth were completely destroyed.

[atc007]

As someone who's done more of these than I can remember. A+++++. Mine were mechanically sound. But they darn sure weren't these true works of art!! I don't have a blast cabinet,,,,,yet. Your work is next level all the way Jim. THREE days guys,,THREE days it took him to do this. THANK YOU sir. I was gonna say to about using a NEW vent hose,and routing it right up to the steering stem under the tank,but DC beat me to it. Without that,,water intrusion,and off we go. Also, I have seen two? or more of these Pop the side of the case right out at the pinion bearing,,not from a rock,,from so much garbage and metal grinding around in that small area. I will try and post pics sometime.. Just don't hold your breathe,,I may have junked all of them..This HAS to be moved up as a sticky!!!! WITH his carb tutorials!

[Flyingw]

I totally agree on the vent hose although on my SX, I put a short piece of hose and screwed a valve stem cap on it with a tiny breather hole in it. It will let air out but I don't swamp my trike but if were to, I'd pull that off and run a hose up.

[dougspcs]

As usual Jim your builds are like a great chick flick!!

Starts out as a love gone bad scene, it's old and broken, the beauty is gone and is there really any hope??

As the plot develops you see things get torn to pieces and worse than ever, surely this is the end of it forever right?..but wait!!!

Suddenly, seemly by accident but yet ever so intentionally it's love reborn, as beautiful, shiny and even stronger than ever!! Awwwww...

Sniff, sniff..

Or at least that is what I've heard!! :cool: Chick flicks..blah!!

But nice diff though..:drool:, I'll be heading your way with one this spring!!

[Flyingw]

Now that cracks me the hell up!!!!!

[Flyingw]

When you guys replace you rear axle tube bearings here's one thing that will get you in to trouble. When you are ready to assemble the rear end, there is one thing you need to be aware of. Before you do final assembly on the rear end and commit sealant to anything, dry fit everything. You can go ahead and mount the diff in the swingarm with sealant and bolt it down. Where you will encounter a problem is with the long axle tube. The bearings do NOT get driven all the way down. If you look on page 12-11 in the SX manual, you will see they callout a bearing driver. That bearing driver sets the depth of the bearings but they don't tell you what that depth is. If you drive the bearings all the way down, it shifts the axle to the right and prevents the right axle tube from flushing up against the swingarm flange by about 1/8". I drive the left axle tube bearings down to about 10mm from the edge of the axle tube flange. The seal is about 10mm thick. When everything is pulled down tight, it leaves about 2 threads exposed outside of the axle nut. After to dry fit everything, be sure the axle still rotates. If all is good then pull it back apart and seal all the joints and do your final assembly. The right axle tube that's inserted in the back of the brake panel does get its bearings driven all the way down so the snap ring can be inserted.

I have also had a couple of guys ask what sealant I use. Permatex Ultra Black. Let any squeeze out cure. If you wipe off the squeeze out while its wet, it WILL end up smeared all over you, the trike, and anything else you touch. Let it cure and it comes off nice and clean.

[acellr8]

Just wanted to thank Jim for this thread and for all the help on getting my 250ES back on the road. I amazed at the knowledge he has on these machines. Also, just wanted to say thanks for the newly rebuilt rear differential you built me. It is a work of art and truly looks Brand new, almost too nice to put on my trike.

Thanks again for the help and the new diff!! Much appreciated!! As you can tell I am excited it has arrived and can't wait to get it back together.

Regards,
Ed Rist

[Flyingw]

You guys are welcome. Let me know how it works when you get it installed.

[Jmoozy27]

Crap, I didn't mark the shims, broke everything down a week ago and I'm just reading this thread. A great one might I add.

[Flyingw]

If you read the manual, the allowed backlash is .018 which means there will be a tiny bit of movement of the pinion when its all assembled. If you have the shims switched, there will be allot of movement in the pinion. Pretty easy to figure out.

[Jmoozy27]

Roger that, thanks

[Flyingw]

In fact, you can just set the ring gear in the case mating it to the pinion and tell which shim offers the smallest movement of the pinion.

[3wheelnewb]

Awesome write up! Besides the fancy tools I followed this two by step and it worked great!