Bunch of naive guys assigned FSAE project

[carreshwell]

Hey Guys!
We have been assigned a project to design a FSAE car for next year. I am the part of the drivetrain team. Our team is not going to use a differential. I don't really know what that middle part is called to which both the half shafts are attached using CV joints. Could you guys help me figure out what that part is called and where can we buy that part. Btw we are using a chain drive system and CV joints.
I would really appreciate any help.

[MRT_Xii]

It is called Steel, or Aluminum if you are fancy and want it to be lighter...

No but seriously, if you are not using a differential, you will design what is called a ''spool'', essentially just a cylinder with attachment points for a sprocket and inner splines for your CVs. There are thousands of different CV joint types and sprocket types out there so there is no specific part you need to buy. Check out the Taylor racing site for a large catalogue of drivetrain parts.

Best of luck, and next time, try to research more before asking questions, this forum does not really appreciate handouts

[carreshwell]

Thanks!

[Carrington]

Since you are using a spool, you may want to also consider a simple solid axle setup. It'll be easier to build, and will probably turn out more reliable. Save the IRS for when you have a better understanding of basic kinematics. The rules don't require much suspension travel, so the chain drive should not pose any problems, even during body roll.

[Tom Wettenhall]

Does that mean the chain twists with body roll? Wouldn't that cause it to throw the chain?


Another, even simpler option is a quad bike type monoshock and swingarm arrangement. Given you generally want a very high rear roll stiffness for a spool car, (unweights the inside rear tyre in turns so it can't cause understeer) performance should be pretty sharp if you can keep the unsprung weight down and make it rigid enough.

[Carrington]

@Tom - Even if roll wasn't constrained, 1" of suspension travel still would not result in very much chain misalignment. I've been surprised how much chain misalignment still does not result in a thrown chain.

[Tom Wettenhall]

Fair enough. Saves quite a few parts too.

Are there any live axle cars out there apart from UNSW@ADFA? That's a nice car, and if you talk to them about it it's hard not to like their reasoning.

[mech5496]

Yeah, Uni at Buffallo, CalPolySlo and many many others I cannot recall right now have used (or still use live axles). BTW the ADFA car uses a DeDion rear axle and not a live axle setup (they still have a chassis mounted diff and CV's/halfshafts).

[Charles Kaneb]

1" up on one end and 1" down on the other of a 48" axle is a 2 1/2 degree chain misalignment angle. You'll be fine.

[Rex Chan]

Do you like the look of ours? Made of aluminium, and only 0.5kg. MUR 2012 Spool Driveline (with CV, rotor, sprocket carrier) (http://www.facebook.com/photo.php?fbid=10150996831663036&set=a.10150996828893036.429455.559588035&type=3)

We have a similar ones from 2010, and 2011 (both same design). High mileage (for an FSAE part), but we'll just call it well tested.

[Tom Wettenhall]

Dammit, again with the configuration naming! I'm familiar with the setup, but for some reason I still refer to it reflexively as a live axle. Apologies for the confusion.