First up is the driveshaft itself. The general Taylor Race arrangement is as follows...
Splined halfshaft into a tripod CV joint. That joint sits in a roughly inch thick housing, open on both ends. Torque is then transferred from the halfshaft, into the tripod by a spline, into the housing by direct contact, and then into the hub flange by the 6-bolt pattern. I don't like having 6 wired fasteners to take apart, and I don't like the open end on the tripod housing. As soon as you take it off, grease goes everywehre and you have to make sure other crap doesn't get in there.
I like the idea of sealing off one end of the housing, as shown above. It becomes a bit thicker, but by going to aluminum the total weight is considerably down. While bare aluminum likely wouldn't hold up to the Hertzian stress imposed by the tripod rollers... a thick, hard anodize or hardened steel sleeves might be up to the task.
Still haven't figured out a good solution to using less fasteners, and getting rid of safety wire while still having an easy positive stop on. I'll have to think about that.I'll add, I'd like to avoid cutting splines where possible. Expensive, and not always necessary.
I am thinking about something similar to the above for a diff housing carrier. I'd like to have an assembled, billet "diff box" that holds the suspension and differential. Placement of everything will require some creative packaging. This way however, the diff can pivot and rock back and forth on the bottom mount, allowing chain tension adjustment. By undoing the two long bolts, the whole diff can be rotated 90 degrees and then slid out from the left side. That large opening in the plates is longer than it is tall.
2 comments:
Tom,
Some drivetrain features I used in FSAE to avoid some of the same problems..
We used the TRE tulips in all 4 locations, solid one body construction and no bolts necessary. We had our outboard hubs broached to match the spline data given to us by TRE, since your CAD package shows the TRE diff, you could just use those tulips. We went a slightly different route inboard due to running a Salisbury, we turned the splines off, had new splines rolled on, then reheat treated. From getting both male and female splines cut, the cost isn't as expensive as you would think. We paid $50 per spline to get Moser to cut them for us.
As for an easy positive stop to keep the half shaft captive, we used the car geometry to make it impossible to come out. What I mean by this, is we designed the axle to sit horizontal at ride height, so it got longer in bump/droop but never shorter. As long as the length was never less than tulip-tulip distance, it was impossible for the axle to come out without taking off the upright. Is that simpler? Maybe maybe not, but we wanted the assurance of not dropping a half shaft out, and the upright was only one wheel nut and three bolts away from coming off anyway.
As for the diff mounting, we used a similar approach as your pivot, which was a circular bolt pattern non concentric with the differential. This allowed us to rotate the differential in fine increments to tension the chain as we saw fit.
Thanks for keeping up the blog, both it and superfasts make up for the lack of anything interesting on the FSAE forums.
-Radii
I'd do an eccentric housing as well. Two bolts with low torque can hold the thing because the frictional surface of the eccentric is so big.
It's the most elegant solution IMHO and doesn't have high wear or concentrated loads on any of the components.
Ben
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