Universal joints for steering column

[John Taylor]

I've got a bit of an issue with our steering column. The design of our car means the column has to turn 20 degrees through a universal joint. The problem is that I've found out the output shaft of a universal joint fluctuates 10% (for 20 degrees) about the input value twice per revolution. ie at 1000 rpm input, the output will fluctuate from 900 to 1100 rpm. I realise this can be solved by having a second universal joint correctly aligned, but is it necessary? A steering column is a very different usage to a high rpm machine shaft.

Anybody else had this problem? I've asked around and nobody knows for sure, and I'm concerned it may effect the handling.

John

[John Taylor]

I've got a bit of an issue with our steering column. The design of our car means the column has to turn 20 degrees through a universal joint. The problem is that I've found out the output shaft of a universal joint fluctuates 10% (for 20 degrees) about the input value twice per revolution. ie at 1000 rpm input, the output will fluctuate from 900 to 1100 rpm. I realise this can be solved by having a second universal joint correctly aligned, but is it necessary? A steering column is a very different usage to a high rpm machine shaft.

Anybody else had this problem? I've asked around and nobody knows for sure, and I'm concerned it may effect the handling.

John

[Foote]

This effect shouldn't be noticed. you probably don't even have two revolutions lock to lock, and you won't be able to tell. porsche's all used to have two u-joints improperly aligned in their steering column, doubling the inconstant velocity, and nobody seemed to notice.

[Ben Beacock]

We used 2 last year, and figured out the proper angle to place them to reduce the fluctuations. This year will be one u-joint to reduce weight and complications in mounting. Make sure the fluctuations are symmetrical left to right so that its not harder to turn one way or another.

Ben Beacock
Co-Manager
2004 Gryphon Racing - University of Guelph (http://www.soe.uoguelph.ca/uogracing)