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CV joint

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zeeshan View Drop Down
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    Posted: Dec/19/2012 at 6:20am
What aspects should be kept in mind while designing the CV joint connecting the tyres to the shaft?
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Purduebaja View Drop Down
Welding Master
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Purduebaja Quote  Post ReplyReply Direct Link To This Post Posted: Dec/19/2012 at 7:24am
Are you guys making your own CV joint? You should ask cornell how easy that is to do right off the bat.

As far as designing custom half shafts goes it all depends on what shafts and joints you plan to use. Some have lower articulation and plunge limits than others. Also some plunge only on the inside while others plunge on both ends. For example in the past we used honda foreman joints with a custom shaft. This worked well until we increased our suspension travel to 12 inches which would have gone past the articulation limits of the inboard CV shafts.

If you are using an A arm or H arm rear suspension you can minimize plunge by lining up the virtual articulation point on the cv joint to be in line with the upper and lower ball joints or bushings. This is just a rule of thumb however. A better way is to estimate the articulation point by looking at and measuring the cv joint and putting it in your cad model. The difference in length between inner and outer joints at full bump and droop is your axle plunge.

Hope this helps.
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Soccerdan7 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Soccerdan7 Quote  Post ReplyReply Direct Link To This Post Posted: Dec/19/2012 at 10:21am
Originally posted by Purduebaja Purduebaja wrote:

Are you guys making your own CV joint? You should ask cornell how easy that is to do right off the bat.

Haha. Not easy at all. It was a fairly big senior design project and one of the harder parts to make fully custom (uprights, hubs, gearboxes, steering racks, brake rotors and calipers, etc are all easier to understand and design).

Our general design progression was something like this:

2005-2008: stock (fairly low angle) joints with maybe changing shaft length
2009: carbon driveshafts and heavily modified stock CVs, with custom spindles (we also has nice custom steel shafts this year too that many people are quick to point out we had to resort to at times)
2010: 2nd iteration of both carbon shafts and fancy steel ones, and first custom CVs (both sides plunging)
2011: nearly identical setup to 2010 with a few ounces shaved off and no more carbon
2012: hollow steel driveshafts with a new custom CV design where only one side plunged
2013: we'll see in April

It is a large undertaking and you will need to interface with the proprietary geometry of joint internals and have a very good understanding of Hertzian contact stresses and heat treatments as certain areas will see outrageously high localized contact stresses.
Danny

Cornell

(fall'07 - spring'12)
Former Captain / MEng / that guy with all the carbon
10 races, 7 top ten's, 2 overall wins
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