Why polish your CVs? 

These are almost new. Nuff said?

Polishing will give you longer life and hopefully allow for more CV joint travel before they start to click, bind, and break.

This CV star came off a 1980 Vanagon. Notice the normal wear marks on the left side and the pitting in the center of the picture. Depending on the degree of the pitting you may or may not be able to polish it out. This one is probably better off as a spare.

Note: This page outlines the process of polishing CVs by hand. While free hand polishing is frequently used by off roaders it could introduce uniformity errors. A dedicated CV machine would be the best way to polish CVs. If you do choose to polish them by hand then one way to check your races for uniformity is to paint the races with machinist dye and temporarily install them on the vehicle and rotate the tires by hand. In any case, proceed at your own risk!

The Tools:

Here's the tools I used. The die grinder is a $20 cheapie that has come in very handy over the years. The two cartridge kits were bought from Summit Racing. I purchased the two kits initially to port and polish a few cylinder heads. The left kit contains a bunch of smaller rolls and 2 mandrels for about $25. The right kit contains larger rolls, 2 flapper wheels, 2 stones and 4 buffing brushes for about $35. A less expensive way is to just buy a couple mandrels and some sanding rolls with various grit surfaces (80 and 120 grit). 

Another very important lesson I learned is to watch your grinder speed and watch for wobbles in the mandrel. The mandrels are relatively thin and can bend. At higher speeds it is enough to break off the end of the steel mandrel at which point it will become a projectile and if your are lucky it will only hit your chest.  Important: Always wear a face shield and safety glasses. Also use a set of gloves because the sanding rolls do tend to come apart and will hit your fingers.

Before you proceed:

When you remove your axles always mark them so you know which side they were on and which way they spin. After use, they will have a natural twist to them. If you put them on backwards, they will easily un-twist the opposite way and could break from fatigue. (The same thing goes for torsion bars)

Also, CVs are machined to a very close tolerance and the moving parts on used CVs will develop their own wear pattern depending on fluctuations in those tolerances. When you take an old CV apart keep track of the direction it rotates on the vehicle, it's location, the exact rotation (clocking) of each part and the location of each ball. Put them back together in the exact same way they came apart unless you have good reason not to. Some people will flip (rotate) worn CVs so that they will run backwards and wear on the other side of the race. 

Polishing the CV:

Here is an almost finished polishing job. I used two different cartridge rolls - an 80 and a 120. (You may want to just use the 120 roll) What I have found to be the easiest way is to first clean up the surface in the very center where the cage rubs (#1). Then I went around the CV and took the edge off the curved surface at the top and bottom of the CV ball race (#2). The reason I recommend doing that is so that when you polish the race surface the sanding cartridge will be less likely to catch on the sharp edge and shred your roll. Then lightly radius the edges of the races (#3). The final step is to polish out the race surface and make sure the edges are still radiused (#4).  Please note that the race surface on the outer cage is not round. It is an arch so only remove as much material as it takes to get a smooth surface. Also work slowly so that you don't overheat the race and take away the surface hardening.

How do the CVs go back together?

This is very important. Look at the picture to the right. The surface on the inner star where the races are far apart  line up with the outer carrier where the races are close together. It is easy to put them together wrong in which case you may have a hard time getting them back apart. The outer carrier may be machined smaller on one side. The smaller side is bolted towards the bell. If the outer carrier just has a slot machined in it, then put that towards the bell. The flat/smooth part of the inner star faces the retaining clip. The chamfer on the inner star splines goes on the inside. 

Once you put it all back together, everything should move smoothly. Any surface rust or grit will cause binding. 

Remember to mount the CVs on the axle so they rotate in the original direction, unless you have a good reason to do otherwise.

Chamfer on star (#1) is on inside. Smaller part of carrier (#2) is on outside of axle assembly towards flanges The ball cage may have two distinct edges. The side with the flat edge goes towards the flange. If there's a groove on the outer carrier, then that is typically placed toward the flanges.

What kind of grease should I use on CV joints?

CJ joints are under severely high stress and require special grease if you want them to live a full life. Wheel bearing grease will NOT work ... Don't even try! Moly Sulfide based grease is good for most applications. For race use or possibly even long high speed trips at high CV angles, consider using a special racing grease so you don't overheat your CVs and axles. Belray CV grease for use in a grease  gun can be bought at McKenzie's or Kartek. Redline makes a good synthetic CV grease called CV-2 with red moly. It can be bought at www.summitracing.com  Part # RED-80402.  A grease gun with a needle attachment helps put the grease into the cavities. Be careful, some of the greases contain lead so wear gloves and don't get it on your clothes. I don't think you want that stuff to get into your septic system or your body.