RC Car - What is the Difference Between a Dog Bone, Universal, and CVD?

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Dog Bones, Universals, CVD's

Comments: Hi, I really enjoyed your site, and all the info it contains. I have a question that I'd really like to know the answer for, and I'm asking you because you seem to know a whole lot about RC's. What are the differences (pros & cons) between a dogbone, a universal, a CVD, and which one is best?

Thanks for your time.

Response: A dogbone is the least efficient of the drives you mentioned. It consists of a swing shaft (dogbone) and an axle. The dogbone and axle are not actually joined with this setup. This causes two negative effects. First, there is potential for the dogbone to fall out if the suspension arm travels past its intended movement. Second, there is increased friction as the dogbone rubs at various angles the inside of the axle cup (the area where the dogbone inserts into the axle). All this makes the dogbone and axle setup the poorest choice for performance. Although, it is the cheapest.

A universal is a one piece drive shaft that connects the dogbone and axle into one piece. The movement is still possible between the two units through an x and y pivot where the axles are joined. This is a major advantage, especially on the front of a car where the joint must allow for up and down movement for the suspension as well as left and right movement for the steering. A universal joint cannot pop out in a crash and there is much less friction as compared to a dogbone and axle setup. This all makes a universal joint a far superior setup for a drive system.

A CVD (Constant Velocity Drive) works in much the same manner as a universal drive. The main difference is that the joint utilizes a ball joint system to reduce the friction between the shafts and to increase the effective travel range of the drive (allow for more steering or suspension travel). However, there is only a minimal difference. I personally would not scrap a good set of universals for CVD's. They are better but, I would wait until my universals were worn out before I purchased CVD's. Universal joints and CVD's both offer major advantages over a standard dogbone and axle setup.

One more note on drives. Universal joints and CVD's are very expensive as compared to a regular dogbone and axle setup. If you cannot afford to get universals or CVD's for the front and back of your car, it is far more advantageous to install them in the front end first. Once you can afford a second set, then you can install them into the rear end.

Let's take off a few tenths per lap,

"PRO"
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