Outer Limits 4x4 Board

After rd 2 Ozrock lm of the opion that treated hollow axles would be heaps stronger than solid axles whatta ya recon bearing in mind that the surface are on a hollow tube is stronger tha solid straight away ie tail shaft.

There's potential for weight savings, but not increased strength.

There's not usually room to make axles bigger diameter as hub bearings dictate the room avialable. Manufacture would get a lot trickier.

It is also quite advantageous to have some torsional give in an axle to cushion shock loads. Making them bigger reduces this.

I've gotta have a hunt for it but I found a article on hollow vs Solid linkages (not quite the same I know ) and hollow only wins because of large weight loss's for a small loss of strength not by being actually stronger.

hope thats somewhat relevant.

Simon

pretty sure high end drag cars use gun drilled axles as in top fuel and door slammers and the like there would be a reason that they use them,I personally don't think that it would be weight related.

tuf045 wrote:pretty sure high end drag cars use gun drilled axles as in top fuel and door slammers and the like there would be a reason that they use them,I personally don't think that it would be weight related.

When you're pulling 5G off the mark, weight becomes a priority.

I thought that gundrilling axles is more of a speedway practice. Not only getting the sprung weight down but also overall weight down. I have heard that the rule of thumb is gundrilling a 3rd of overall diameter only loses about 5%loss in torsional strength.

Most of the "torque strength" (what's the correct term? torsional rigidity?) is in the outside part of the shaft - the solid centre adds little strength.

As noted, hollow shafts give away less in strength than they gain through weight reduction. The reduced weight also reduces the rotational moment of inertia, which is probably something the drag boys are interested in - less torque to spin up the axle shafts.

A hollow shaft is more susceptible to dings - any discontinuity in the surface becomes a weak point. A solid shaft will typically suffer less from an equivalent hit, so is less likely to fail as a result.

You don't get anything for nothing.

Correct, high end drag cars do use gun drilled axles, usually because they are 40 or 44 spline, which is huge.
Gun drilling them reduces the sprung weight, but doesn't reduce the effort required to turn them, as the weight removed is from the centre, so isn't really centrifical weight.
As a rule of thumb, remove 100lb's from a proper drag car, and you will gain aprox 1 tenth over the 1/4.
Remove 10lb's of rotating weight (conrods, pistons, crank, cam, gaers and shafts in the gearbox, tailshaft, pinion, crownwheel, axles, brakes etc) will give similar gains.
But actually, if the weight is removed from the outside of the rotating circle, it is worth more than if it were from the centre, as the centre doesn't really move as much.

Drilled axles reduces UNsprung weight not sprung weight. Less unsprung weight is of great benefit to the handling of a vehicle so it's usefull in all forms of motor sport. Also remembering that the majority of motor sports that do this are driving vehicles less than a ton. I don't see a benefit in drilling axles for 4Wd comp stuff.
Dan

Hollow cylindrical beams are stronger than solid beams, when used as a beam (lengthwise). However when in torsion (all axles), I'm not sure if they would be stronger, I think they would be slightly weaker infact. (I really don't feel like calculating it). As far as fatigue failure goes, you would want solid, so long term = solid.

Personally I wouldn't bother unless your building a promotional or show rig to demonstrate technology, and/or your ideas/talents.

Highway-Star wrote:Hollow cylindrical beams are stronger than solid beams, when used as a beam (lengthwise).

No they're not.
If both solid and hollow are the same diameter, then the solid is stronger.

Ruffy wrote:Drilled axles reduces UNsprung weight not sprung weight.

Either way, it does not make a great deal of difference to a drag car, except for overall weight reduction.