Live or Dead spindle??

[Big D]

Hey everyone, thanks for your time.

We are currently trying to decide between a live axle setup (bearings in upright) on the front, or staying with the "dead" spindle (bearings in hub) we have now.

Maybe this is just like the 10"/13" wheel debate, with no right answer.

for the dead spindle I see as advantages:
- it's what we know
- disc is mouted to the back or the hub, and wheel is then spaced away from the caliper by the depth of the hub.
- possibility of smaller bearings?

for live spindle:
- we could be "cool" with uni-lug wheels http://fsae.com/groupee_common/emoticons/icon_cool.gif
- possible to make similar or same axles for rear
Disadvantages:
- heavier upright?
- harder to get nice bearing spacing?
- will need a spacer to get the wheel center away from the caliper

Anyways, I'd like to hear what everybody is running, and why you went with one system over another. Is there any reason to change if we have developed the one way over 3 cars already?

- Dan

[Big D]

Hey everyone, thanks for your time.

We are currently trying to decide between a live axle setup (bearings in upright) on the front, or staying with the "dead" spindle (bearings in hub) we have now.

Maybe this is just like the 10"/13" wheel debate, with no right answer.

for the dead spindle I see as advantages:
- it's what we know
- disc is mouted to the back or the hub, and wheel is then spaced away from the caliper by the depth of the hub.
- possibility of smaller bearings?

for live spindle:
- we could be "cool" with uni-lug wheels http://fsae.com/groupee_common/emoticons/icon_cool.gif
- possible to make similar or same axles for rear
Disadvantages:
- heavier upright?
- harder to get nice bearing spacing?
- will need a spacer to get the wheel center away from the caliper

Anyways, I'd like to hear what everybody is running, and why you went with one system over another. Is there any reason to change if we have developed the one way over 3 cars already?

- Dan

[Cement Legs]

Like you say 6 of one, half dozen of the other. I would think that the biggest factor would be how well you can justify your design in front of the judges. Second biggest factor is definitely coolness. Strongbad would understand.

-Trogdor keeps on burninating...

[fsae racer]

we base all of our design descisions on coolness, and from our experience, the judges do too. http://fsae.com/groupee_common/emoticons/icon_wink.gif Seriously though, you sound like your hitting on all of the major pro's and cons of each design. I think whatever wheels you choose to run will be your deciding factor, as they will typically cost more than any of the other components, especially in the rear where the wheels will dictate drivetrain design. Additionally, center lug wheels are certainly easier to design a live spindle for. I would say 4-5 lugs could be easy to design for either design, at least thats the way i see it.

[Big D]

Thanks for the replies, guys.

For right now, we are interested in making our own wheel centers. If that covers the coolness factor, then that still leaves the type of spindle open to discussion. I have become addicted to solidworks in the last little while, trying a bunch of different layouts, my goal is to strike a balance between low scrub radius, reasonable kingpin inclination, relatively wide bearing spacing, and having the wheel center line pass between the bearings.

So far live axle has allowed me to juggle all these variables with the least compromise.

Like I say, our last 3 cars have been 'dead' spindle, so I have been skeptical of the switch. If anybody has run one setup, and switched to the other, why did you do it?

[nick k]

We're switching from a live spindel for this year. This is due to the fact that we can keep costs down by using stock parts and keep the front and rear upright in the same castings. Since the rears need to have the bearing on the upright... the front's are going to have them as well.

[Big D]

Yours seems like some good reasoning.

just to clarify, by "live spindle" I am refering to the bearings in the upright, and "dead spindle" refers to the spindle welded/bonded/part of the upright.

there is also interest on my team for the same axle stubs all around, but we are likely doing the uprights in sheet or tubing fabricated style, so it is less of a concern to keep the same parts on all 4 corners.

[Patrick W. Crane]

We are going with the dead spindle so that we can keep the wheel centre line between the to races on the bearing... on the rear, since we don't have brakes on the hub, the upright is much closer to the wheel and the bearing can go in there...

my 2 cents

[Big D]

Patrick,
That's interesting, because that is exactlty the reason I am starting to sway towards live spindle. I suppose it depends on all kinds of things like wheel width/offset, scrub radius, or the amount of room your chosen caliper needs.
.... 6 of one, 1/2 dozen of another........

[Patrick W. Crane]

ya, had we gone with 7in tyres (possibility of an extra inch of backspacing) i would have gone the other way