This is what I know about CV joints in a nut shell. The information is mixed from first hand experience, shop talk, rumor, myth, legend, and books/ magazines. I will make sure to specify where the information came from.


Type I is a Bug, Type II is a bus, Type III are the square back and fast back, Type IV are the 411 & 412, Type 181 is the Thing. All VW's.


Back in the day I was killing 1 or 2 Type I boxes a year with my 2 liter "stump puller". I could grab used boxes out of Bugs or Type III for a direct replacement. The CV's where a bolt on match. Diameter and width where the same. However, I never took the CV's apart so I don't know about the size of the balls. They may very well be different. In the full size community, there was never any talk of improvement by trading your Type I CV's for Type III's. The next step up was Type II. I finally moved up to the Type II box and never changed the travel limiters on the arms. I never benefited from the additional angularity, but I bought my last box! Never had a Type I or II CV fail with either tranny.


Type II are a little bigger OD than the Type I, but have the same splines.
The stock Type I, and III stock axles are the same length of 16.25". The stock Type II axles are 18.75". You get the extra length for extra travel. You know that of course, but I feel I should write this down for the newbie too.


TypeII CV's are the same diameter as the Type IV. Type IV is the preferred of the small axle CV's because it is wider and stronger than the Type II. The type 181 Thing uses Type IV, and the stub axle fits in a Bug. This is a good way to go with other buggies. The 930 CV is the smallest of the larger axle CV. 934 and 935 are the biggest out of the box


Shop talk: Polishing the cage will make the CV last longer, and you gain angularity. In my opinion, the first set you polish will fail. Just like the first head you polished cost you HP. This is an art I'm sure. Race preped CV's are polished by a guy that polishes CV's all the time. When you de-bur, clearance and radius the cage, your CV is now "Race-Preped"
The cool part is this: When you buy new CV's they are stiff. When you clean old CV's and reassemble them they are loose. When you buy new CV's, and discard the new cage, then re-assemble them with "race preped" cages, they feel just like used/ just serviced CV's.
Legend: Prep your CV's by polishing the cages, and replacing the balls with a smaller diameter ball. I have heard it, but I don't know the two most crucial parts of the story. The size of the smaller ball, and where do you get them. If any of you know, add it to the post. It could help the right guy.


Axles: The shoulder of the axle will push on the center race and crak or deform your CV cage in off road racing. I have never used the Sway-a-way axle, and have never lost a CV, but I don't own a race car. The after market axle will slide on the splines and give you the little extra slip, that makes your CV assembly complete.
desertkarts