Collapsible steering wheel boss

[MartinClan]

Can anyone recommend a collapsible steering wheel boss? There seem to be a few available. Raid seems to be highly advertised.

Cheers

Robin

[Patrick]

I just bought the MOMO one that goes with the steering wheel, I think it was around £40.

[AndyDane]

Vindi went a different route - they made the steering column itself collapsible cos the SVA bod wasn't happy with it's straight through angle - I have the original Beemer steering wheel so no idea if it's collapsible or not...

[MartinClan]

Originally Posted by AndyDane

Vindi went a different route - they made the steering column itself collapsible cos the SVA bod wasn't happy with it's straight through angle - I have the original Beemer steering wheel so no idea if it's collapsible or not...

Sounds interesting. What did they do to make the column collapsible?

[AndyDane]

basically (I'll take a pic tonight) cut a piece out of the straight shaft, welded it back in at a slight angle and then joined the 2 pieces with a flat plate - in an impact the plate buckles and the shaft is then in 2 pieces....

Andy

Just found it - SVA Failure point 12. steering column and shaft not designed to minimise upper column displacement in impact

[peterux]

Originally Posted by MartinClan

Can anyone recommend a collapsible steering wheel boss? There seem to be a few available. Raid seems to be highly advertised.

Cheers

Robin

I got one made by OMP.
Seems to be made OK, fitted fine, has the steering lock splines, has the bit for cancelling the indicators and is obviously collapsable because you can pull back the rubber surround to see inside.

Peter
My theory is that the BMW column is so well fixed at the top and bottom it just wouldn't move. Assuming you hit something hard enough that the rack moves the 1/2 inch bit of spindle that Marlin supply would just give up first and bend all over the place before the column even flintched. The rack is mounted to the chassis cross memember which is 4x4 inches so it ain't going to move much! The trouble is, they say you can't argue with the man in the white coat!

[AndyDane]

collapsible steering column a la vindicator

Andy

[peterux]

Thanks, Andy.
Certainly an interesting solution.

I'd be a little bit concerned about the strength of those welds under severe cornering, but I'm not a mechanical engineer, so not really qualified to comment.

[Simon]

For info, the Marlin Cabrio uses the Sierra steering column shaft that has a sliding section within the top part. Some production cars also have a collapsible section that resembles a cylindrical cage that is rotationally stiff but that collapses comparatively easily with the axial loading you’d get during a crash.

The problem I can see with the Vindicator design is that it doesn’t look that weak axially (where you need it to be for crash purposes) and I’d also be very worried about it fatiguing (and perish the thought) failing due to steering loads.

I work in the automotive engineering business and know that a lot of detailed design and analysis goes into getting the steering system both durable but able to collapse properly during a crash and I have not come across the Vindicator type of design before!