CV Boot Replacement Tricks

Modern ATVs use constant velocity (CV) joints on their drive shafts. These joints allow the rotating axles to change direction as the suspension goes up and down or the wheels steer left and right. They serve the same purpose as U joints did on older vehicles. CVs are more complicated and expensive to manufacture than U joints, but they provide a smoother transfer of power and they are normally longer lasting due to the rubber boot that protects the moving parts from water and dirt.  This is the same type of system used on front wheel drive automobiles.

The only maintenance required on them is to inspect the boots and replace them if they are torn or cracked.  Lately I have been replacing a lot of CV boots for people.  I think that the very cold (-30) weather that we had this past winter caused the boot to crack. 

The joints come in two styles, one has a fixed length and the other style can "plunge".  This plunging action allows the length of the axle to change slightly as the vehicle suspension moves.  The upper joint in this photo is a fixed length, the bottom green one is the plunge joint.  Most axles have a fixed length joint on the outboard end and a plunge joint on the inboard end.  

The fixed length joint pulls out of the wheel hub once the large nut on the end is removed.  The plunge joint that goes into the differential is a little trickier to remove.  It is held in place by a little spring clip on the end of the splined shaft.  Too remove the axle from the housing you push the axle all the way in as far as it will plunge, then quickly pull the axle out.  If you do it correctly the axle acts like a slide hammer and it will pop the shaft right out of the differential.

The first step to servicing the CVs is to get the old boots off.  The clamps holding them on come in several different styles.  On some of them it is easy to bend the tabs up to release them, on the stubborn ones I use a cutoff wheel to cut them.  

Once the boots are off you must take the joints apart to clean the old grease and any contamination out.

The above photo shows how a plunge type joint comes apart.  There is a wire snap ring the fits in a groove inside the mouth of the CV cup.  Pop that ring out with a small pick or screw driver and the cup will pull right off.  Once the cup is off there is an external snap ring on the end of the shaft that holds the center of the joint on.

The above photo shows a fixed length joint that has been removed from the shaft.  These are held on the shaft by a spring clip in a groove on the end of the shaft.  When the joint is together there is no access to this clip.  You must force the joint off the shaft over the top of the clip.

 

Here is the setup that I use to hold the shaft while I pound the joint off.  I have the shaft clamped in a couple of v blocks on the corner of my work bench.  The v blocks are sitting on top of a heavy counter weight from a tractor.  I use this as an anvil, the extra weight makes any pounding that you are going to do much more effective.

Once the axle is secured to something solid I used a large punch and a hammer to drive the center piece of the joint off the end of the shaft.

 

Carefully lay out the  parts in the order that you take them apart.  It is important to remember which side of each part goes on the shaft first.  The pieces are not quite symmetrical and they will only fit together one way.  Even the small snap ring that goes on the end has a inside and outside face.  Check out this older post for a description of how the snap ring goes and other CV tips.

 

After cleaning up the parts and inspecting everything it is time to reassemble.  I have been using boots from Moose with good success.  Their standard generic size boot will fit most machines and they also have custom size boots to fit just about any odd size machine.  Since I do a lot of these I purchased their fancy boot clamp tool.  It works a lot better than the free one that come with the replacement boots.  If you have very many to do it is worth it.

Here is the finished axle ready to go back into the machine.

Yamaha Grizzly Starter

A customer brought in a Yamaha Grizzly that would not start.  When the start button was pressed nothing happened, not even a click from the solenoid.  The battery voltage checked out ok so I tested the power going to the solenoid coil.  A little probing around with a volt meter showed that the solenoid coil was receiving the start signal, but was not working.  The solenoid would have to be replaced. 

After determining that the solenoid was bad I wanted to check out he rest of the system so I jumped the terminals on the solenoid with a screw driver.  This test (which they actually recommend in the Yamaha service manual) can tell you a lot about the condition of the start system.  There are three possible outcomes of this test.  The most common result is no sparks and no starter movement - means that the brushes are worn out or faulty.  The second result is medium sparks and the starter turns - indicates the starter is fine but the solenoid is faulty.  The last result is lots of sparks but no movement on the starter - indicates that the starter is drawing a high amperage but cannot turn.

I found the last result, lots of sparks but no movement.  The next step is to remove the starter and see what is going on.  The plastic body work on the right side needs to be removed and the air intake hose on the clutch cover.  The first photo shows my hand reaching in to loosen the bolts.

Here is the starter sitting on the work bench.  I make a few reference marks on the motor casing before taking it apart.  These marks make it easy to get the end caps back on in the proper order and in the correct rotation.

Here is the starter with the end caps off.  The magnets are broken and the pieces were jammed in tight and preventing the rotor from turning.  I am not sure why the magnets broke.  One possibility is that the faulty solenoid prevented the starter from operating and someone decided to tap on it to get it going.  On a starter with wore out brushes you can sometimes get it to by giving it a few taps to loosen up the stuck brushes.  A few light taps are ok, but maybe someone pounded on it very hard.

ATV Plastic Repair

Occasionally I have to repair the plastic body work on ATVs and snowmobiles.  In this case I had a cracked fender and a broken headlight mount.

Here is one of the broken headlight tabs.  Most of this plastic body work is impossible to glue.  It can be welded but that requires special equipment that most people don't have.

I have found that the best way to fix these problems is by stitching the parts back together with wire.  I drill a series of small holes and lace the parts up with stainless steel "safety" wire.  McMaster Carr has a large selection of stainless wire, I think that the wire I used here is .025".

Here is the repaired fender around the head light.  Notice that the wire is passed through each hole twice, this will hold the parts together more secure than a single wrap.

Taiwnese ATV

On of the ATVs that I own is an Arctic Cat 366.  I purchased it used this past fall, and it is now a few years old.  It has been an OK machine, it mostly gets used for running errands around town.  It is has independent suspension in the front and rear, a CVT (belt) type drive train with high low and reverse gear.  It is powered with a basic air cooled engine with a carburetor.  Overall I would rate it's performance high.  The only negatives with this machine are it's small size and the lack of EFI (fuel injection).

Recently I was reading an article in an ATV magazine about some of the new Taiwanese and Chinese machines that are starting to be sold in the US.  In on of the photos I notice that the machine offered by Kymeco looked very similar to my machine.  I looked underneath my machine and found this label on the frame.  It turns out that my machine was not made by Arctic Cat in Thief River Falls Minnesota, but was actually produced by Kwang Yang Motors in Taiwan (that is the parent company for Kymeco).

I knew that Arctic Cat has sourced engines from Suzuki for years (and Polaris has used engines from Fuji), but I was surprised to see that they sourced the whole vehicle from overseas.  It looks to me like the smaller basic machines offered by Arctic Cat come from Kymeco, but the larger machines in their line up are produced here.  I wonder how many of the other big manufacturers are getting machines from China?

ATV Throtle Cable Replacement

I had a Yamaha Grizzly in the shop with a bad throttle cable.  Whenever the temp dropped below freezing it would get stuck.  There was obviously some moisture in the cable somewhere.  When I checked it out I discovered that the jacket on the cable was broken in the middle and it would need to be replaced.

I removed some of the plastic body work and took the covers off the throttle control on the handle bar and the cable cover on the side of the throttle body.  To provide a little slack in the cable to remove it I opened up the throttle butterfly and stuck a screwdriver in there to hold it open.

Once there is a little slack in the cable it is a simple matter to twist the cable end around and slide it out of the slot.

The end on the handle bar comes apart in the same way.  Get some slack in the cable and twist it around so that it can lift out of the slot.  Once the cable ends are free the outside housing unscrews from each end.  When installing the new cable remember to adjust the cable free play and use the lock nut to hold it in place.

This last photo shows the old failed cable assemble and the new replacement.  There are two pieces of plastic tubing slipped over the cable housing to protect it from abrasion.  Where the two pieces meet in the middle the housing broke.  I don't understand why Yamaha made it this way?  If the outer tube was one piece it would avoid that kink in the middle.  When I installed the new one I put a few wraps of electrical tape around it to try and avoid this problem.

ATV Brake Bleeding How To

Most modern ATVs have hydraulic brakes that rarely need servicing, but once in a while I do have to work on them.  I have found that they can be stubborn to refill with fluid and bleed if the system has been opened up and all fluid drained out.  These photos show the brakes on a Yamaha Grizzly, but most machines work the same way.

After reassembling the system I connect a hand operated vacuum pump to the brake bleeder using a piece of clear tubing.

Fill up the reservoir with fluid, put a little vacuum on the bleeder, and slowly open the bleeder.

The vacuum will pull the brake fluid and any trapped air through the system.  The clear tubing will show the air bubbles escaping.  When the bubbles stop and there is only clean fluid coming out the brakes are properly bleed.

It is possible to bleed the brakes without the vacuum pump, using only the master cylinder to push the fluid through, but I have found that it can take a very long time.  The hand vacuum pump is an inexpensive tool that speeds up the process.

ATV Wheel Bearing Replacement

Wheel bearing replacement is a common job on ATVs.  This machine is a Yamaha Grizzly, but most machines are put together the same way.

Once you remove the wheel the first step is to remove the large nut that holds the hub on the axle.  On Yamaha machines the nut is locked in place by a small portion bent into a groove on the shaft.  I use an old screwdriver that I have ground down to match the groove to pry this spot out.

The easiest way to remove this nut is with an impact wrench.  If you do not have an impact wrench you need to find some way to keep the hub from turning.  One way to do this is to put a pry bar between the wheel studs.  Be sure to protect the threads on the studs with a short piece of rubber hose if you are going to pry on them.

Once the hub is off the spindle must be removed from the vehicle.  The ball joints (red arrows) and the steering tie rod (green arrow) need to be disconnected.  These are held in place with a nut on the end of a tapered shaft.

Remove the nut and pry or pound the ball joint loose.  If you are going to pound on the threaded end use something soft like a lead hammer to avoid wrecking the threads.  The other tool pictured is a ball joint fork, it is simple pounded in between the parts and the wedge shape drives them apart.

When you have the spindle on the workbench remove the clip that holds the bearing in place.  This one has holes in the ends that make it easier to get out. 

If you look close at these clips you will note that one side has sharp edges and the other side has edges that are rounded over.  (The top clip is sharp side up, bottom clip is round side up, it is more obvious in person than it is in the photo.)  These edges are a result of the way that the clips are stamped out when they are made.  When installing clips like this you should always put the sharp edge facing the direction that the clip is being pushed towards.  The sharp edge makes it less likely to slip.  In the case of these wheel bearings the sharp edge goes up.

To remove the old the old bearing I use a large hammer and a piece of pipe to pound the bearing out from the back side.  I do quite a few of these wheel bearings so I have made up a jig to hold the hub when I pound on it.  Make sure you have something solid to pound on.  I have an old cast iron weight from a tractor (about 75 lbs) that I put on my workbench.  In my old shop in Minnesota I had a large anvil to pound on.  If you don't have an anvil you may want to put your work on the floor.

Before you in install the new bearing you must make sure that the inside of the hub is clean.  Make sure there is no crud at the bottom of the bore or in the groove around the top.  Scrape or wire brush it out.

Heating the hub will cause it to expand and allow the bearing to go in much easier.  I use an electric heat gun, but a torch will also work. 

When installing the new bearing you can only push or pound on the outer race (green arrow).  If you apply any force (especially pounding) to the inner race or seal (red arrow) you will damage the bearing.    If you heated the hub up enough the bearing will drop in with only a few minor taps.

On this job I used a hammer to pound out the old bearing and tap in the new one. It may seem a little crude, but with care it works fine.  A hydraulic press could also be use to remove and install the bearings.  It would give a little more control, but the rules about protecting the inner race still hold true.  You must only push on the outer race.  An old bearing that has had the outside diameter ground down slightly makes a good tool for this job.  It can be used to press the new bearing in place and insure that the force is applied evenly.

Once the new bearing is seated all the way into the bore, install the clip to hold it in place.  Now the hub is ready to go back on the vehicle. 

Polaris Sportsman 500 ATV

I have my own vehicle in the shop today, a 2008 Polaris Sportsman ATV.  My wife was driving it a few weeks ago and she called me and said "something exploded, there is oil everywhere!"  This first photo shows what I found when I went to get her.  The oil reservoir had actually exploded.

These Polaris ATVs have a 4 stroke engine with a dry sump oil system.  Unlike a typical engine with an oil pan or sump on the bottom of the engine, these engine have a separate reservoir to hold the oil.  This allows the engine to be more compact and probably makes it easier to increase the ground clearance under the engine.  I think that it also helps with cooling the engine,  the oil reservoir has a large surface area to dissipate the heat in the oil. (There are probably more reasons than this to use a dry sump, but these seem like the obvious ones.)

I have seen this problem several times before on other peoples machines.  ATVs in the village make a lot of short trips in cold weather.  They do not get run long enough or hard enough for the oil to heat up.  This allows moisture to build up in the oil and the vent line on the reservoir gets plugged with frost and ice.  Once the vent is plugged the pressure builds up and blows the side of the tank off.  Polaris is aware of the problem and has tried to prevent this by putting a small slit in the vent line.  This slit in the rubber hose is supposed to stay closed during normal operation and open up if pressure builds in the line.  Unfortunately it seems like the blockage happens right at the tank and the pressure can not be relieved. 

Another potential problem with the moisture build up is the possibility of ice forming in the bottom of the tank when the vehicle is parked in the cold.  If enough ice forms it can block off the oil supply line to the engine.  This of coarse leads to an oil starved engine and all kinds of problems if the operator is not aware of the situation.

This photo shows the new tank and the original.  It is interesting how the whole side of the tank exploded.  This is the same way that I have seen other ones fail.  I am surprised that the tank doesn't simply split open?

To try and avoid future problems I have decided to insulate the tank to help the oil heat up better in cold weather. 

I cut up an old camping type sleep pad to cover the sides.  I am using DOW 732 silicone to glue the closed cell foam to the tank.  732 is great stuff, I use it for everything.

 Here is the completed tank ready to install. 

Corroded Wire

I had a Honda ATV in the shop today that had a charging problem.  It took a while, but I eventually tracked it down to a corroded wire going to the voltage regulator. 

ATVs around here operate in a salt water environment and it leads to a lot of corrosion problems.  The voltage regulator on this machine is mounted under the rear fender near the tire.  It routinely gets sprayed with water and mud  in this location.  It appears that the insulation on the wire was cracked where the wire bent sharply going into the plug.  The cracked insulation let the salt water get in and corrode the wire.

It was a simple job to fix.  I trimmed out the bad section of wire and soldered in a new piece.  When finished I made sure to seal it up well.  I like to wrap connections like this with electrical tape and coat them with "Liquid Electric Tape."  In this case I was out of the Liquid Tape so I used tape a coating of RTV silicone.  Adhesive shrink tubing also works well, but you must have the type with adhesive inside.  The cheaper kind without the adhesive does not work as well.

Honda Rincon 680

Today I have a 2007 Honda Rincon 680 in the shop.  This is supposed to be one of Honda's biggest and best ATV's.  It has a big fuel injected engine, independent suspension, and an automatic transmission.  The transmission is an actual automatic with a fluid torque converter and computer controlled solenoid shift valves.  It is just like a mini automotive transmission.  I can't imagine what it must have cost to engineer that thing!

The engine on this model is kind of odd.  The basic Hondas use a simple air cooled engine with pushrod operated valves and a cam down low in the block.  Other manufacturers high performance machines have overhead chain driven cams that operate the valves or rocker arms directly.  One the Rincon Honda decided to put a chain driven cam halfway up the cylinder and use short pushrods to move the rocker arms. It's not an "overhead" cam, it's an "along side" cam?  I guess they had to have a cool chain driven cam but just couldn't give up their traditional pushrods?



This particular machine was in my shop about 18 months ago.  Back then the machine had around 2000 miles.  The problem was that it would start and run fine at idle, but when you revved it up it just would not go.  It acted like it couldn't breath.  I checked everything out and discovered that the lobes on the cam had wore down so far that the valves hardly opened.  Everything else checked out ok.  I eventually came to the uneasy conclusion that the cam shaft must have been defective (not heat treated properly?) and it simply wore out.  I replaced the cam and everything worked fine.

Now the machine has around 4000 miles on it and it is running the same way.  I have not tore the motor apart yet, but at this point I am assuming that the cam is bad again.  Before I open up the motor I figured I should check the oil pressure.  The only place that you can access the oil system is at a small bolt with a sealing washer under it.  You are supposed to use your Honda factory authorized pressure tester with a banjo bolt fitting on it to connect to this port.

I don't have the Honda pressure tester tool so I had to improvise.  I had a few odd banjo fittings that I have collected from other machines, but they are all to big.  I made a banjo fitting out of a left over scrap of HDPE.  I also had to drill out a standard bolt to turn it into a "banjo" bolt.  In the photo you can see these two items next to a manufactured banjo fitting that is just a little bit to big.  The homemade fitting worked great, but the 1/4" hose that I stuck on the hose barb with no clamp blew off.  Turns out the machine has lots of oil pressure and a good pump.  It made a big mess in the few seconds that it took for me to turn the thing off.

Does anybody have an idea why this machine is wearing out cam shafts?

Honda Foreman

This is the same machine that I started on last week.  I have had a lot of interruptions, but I finally got the head off the engine.  I didn't find any big surprises, the piston was a little scuffed up on the skirt and everything was covered with a lot of stinky black carbon.  The scuffed piston is normal for a machine that has been abused and the carbon is a result of all the oil that is being burned.

I think I will just give it a basic top end overhaul: piston, rings, valve seals, head gasket, and hone the cylinder.  It should be less than $100 for parts and only a few hours of labour.  I still need to investigate why it overheated.  I'll check out the electric fan wiring system and temp sensor.  I'd be willing to bet it's all working fine and the real problem was that the owner let the kids take the machine out moose hunting.  Who knows what teenage boys did to it when they were out in the country?

In the photo you can see my homemade valve spring "tool".  It is a piece of 1/2" EMT (electrical conduit) with a cutout on the end.   The other end has a block of wood that you can push on.  I clamp the head down to the workbench, push on the block of wood with my shoulder, and reach in the cutout on the tubing to remove the spring keepers.  There are nice manufactured tools for doing this job, but they all seem to be made for automotive engines and are too big for the small engines that I work on.  If anyone knows a good source I'd like to hear about it.

Polaris 400 Sportsman

I had a Polaris 400 ATV in the shop today for a simple starter rope replacement.  This is a basic job that only takes 1/2 hour (if you don't let the recoil spring get away from you).

I generally like Polaris products and think that they are put together pretty good.  One thing that I think they do foolishly though is the recoil starters.  Most manufacturers make a simple cover over the pulley with a open drain hole in the bottom.  This keeps most of the crud out and allows any water that gets in to drain out.

Polaris makes a cover that is supposed to be sealed up water tight.  It never works out that way and a little water always makes its way in.  Without an open drain in the bottom the water stays inside and everything ends up a rusty mess.

That is how I found this one.  Everything still worked under the cover, but it was wet and rusty.  I had to spend a little extra time cleaning things up before I put it back together.

Yamaha 550 Grizzly

This machine is only 6 month old and still under warranty. Normally the owner could just take the machine back to the dealer and get it fixed up for free.   Unfortunately it costs several hundred dollars to put it on a plane and fly it back to the dealership.   I end up working on new machines like this frequently.

This is the same machine that I talked about in a previous post.   One of the bolts that holds the clutch pilot bearing support came out and flew around inside the clutch cover.  The belt was destroyed and the clutch faces were severally chewed up.  I talked to the dealership where the machine was purchased and they agreed to send me the new parts for free.  The owner is going to have to cover my labor cost, but at least they got the parts.

When putting the secondary clutch back on you need to tighten the nut to 70 ft lbs.  That is an easy amount of torque to achieve with a long wrench, but it is almost impossible to hold the clutch from turning.  I made a special tool to hold the clutch.  I used an old 1 7/16" end wrench to make a special spanner wrench.  I drilled two holes in it and put two short 1/4" bolts through the holes to line up with the holes in the clutch.  It may not look pretty but it worked great.

Polaris 500

Today I actually have my own four wheeler in the shop.  When I was driving fast on the beach this morning the drive belt broke.

It is a simple thing to fix, 10 bolts to take the cover off and there it is.  Unfortunately I did not have a spare belt here and I had to call the dealer in Nome to get a new one.

C.O.

Arctic Cat ATV

Today I worked on an Arctic Cat ATV. The owner towed it down to my place and I actually worked on it outside since the weather was ok and the shop had other things in it.

When I got the vehicle none of the electric system was working. The battery checked out fine at 12.4 volts. A modern ATV like this has about 6 fuses and they all check out good. I finally traced the problem down to a corroded wire leading to the ignition switch. The wire actually corroded away and broke off right where it went into the plug for the switch.

Once I located the problem it was a simple job to solder a new wire between the plug and the main wire harness.

C.O.