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-   -   SVA requirements for steering column (http://www.haynes.co.uk/forums/showthread.php?t=464)

murpia 29th January 2008 01:03 PM

SVA requirements for steering column
 
What are the SVA requirements for the steering column?

Reason being I was thinking of fabricating my own column arrangement rather than using donor parts. I know it's supposed to be 'collapsable' but what does that mean in terms of load etc. required to collapse? And how far?

Regards, Ian

jabs 29th January 2008 01:31 PM

This from the SVA manual


Chris Gibbs 29th January 2008 01:37 PM

These pictures might help too







All in all I think it would be difficult to meet the requirements with a home made column, but nothing is impossible.

Cheers

Chris :)

murpia 29th January 2008 02:19 PM

Fig. 1 of the offset joints type was what I had in mind.

Is there a minimum angle or offset specified?

Thanks, Ian

Chris Gibbs 29th January 2008 02:50 PM

It's a minimum of 10 degrees, and as the SVA manual says "it is unlikely that joints of this type will work at angles above 30 degrees"

So it's between 10 and 30 degrees.

cheers

Chris :)

CurlyBen 31st January 2008 01:02 PM

One option might be to have the steering column as two tubes, one with an ID slightly greater than the OD of the other and drilling a hole through the pair and linking them with a shear pin of some kind. obviously you need to make sure it's not going to shear with steering forces! I've got an idea that would alleviate that problem but it starts making things too complicated. I think the above is essentially what's being done to the F750 car I work on, but we're buying it and I've yet to see it. We've also got a prop shaft at a hideous angle, probably over 30 degrees, and that's caused one failure so far! It'll also sap power and feel..

macdave69 31st January 2008 11:44 PM

Daft Question
But why would you want to build your own column, ?

colt_mivec 3rd February 2008 02:06 AM

Quote:

Originally Posted by macdave69 (Post 2996)
Daft Question
But why would you want to build your own column, ?

Depends on the build,What engine,Clearances etc.

You need to modify and change things to keep in the SVA regs but make it work for yourself and your build

macdave69 3rd February 2008 02:45 AM

Quote:

Originally Posted by colt_mivec (Post 3037)
Depends on the build,What engine,Clearances etc.

You need to modify and change things to keep in the SVA regs but make it work for yourself and your build

Nope still don't get it

Chris Gibbs 3rd February 2008 03:02 PM

I'd be wary of the shear pin idea to be honest, you could design it for normal steering loads but then it might fail under additional load such as kerbing or large pot holes.

If you were to design it with these loads in mind then you run the risk of it not shearing in an accident.

It's feasable to design your own steering column but given the inconvenience and possible SVA pitfalls I think you're better using a production car item.

cheers

Chris :)

CurlyBen 3rd February 2008 06:11 PM

I should probably have mentioned that the car the shear pin is being used in is a racing car, so shouldn't have to cope with pot holes or kerbing. There's ways to just let the shear pin take loads in the event of a crash but to be honest they'd be harder to implement than the other suggestions.

Bonzo 3rd February 2008 07:11 PM

Steering column
 
With the sheer variety of prodution steering columns available, it is a bit like trying to reinvent the wheel. :D

The first thing you are giong to loose is the steering lock. Your number one method of imobillisation for the SVA.

Personally I think that most production columns would be adaptable to cover most requirements. ;)

Although I understand where you are coming from with a view for track use.

The column I removed from the Volvo 850 is a peach.
All alloy 300-400mm of sliding spline, this connects to the rack via a couple of knuckle joints. :cool:

Ronnie :)

murpia 4th February 2008 01:28 PM

Quote:

Originally Posted by Bonzo (Post 3060)
The first thing you are giong to loose is the steering lock. Your number one method of imobillisation for the SVA.

I thought the ignition key itself was the primary SVA imobiliser, and that the steering lock, being operated by the key as well didn't count.

I.e. you need a second imobiliser method, independent of the key.

But, I may be wrong.

Regards, Ian

snapper 27th February 2008 12:00 AM

I have just been to SVA with a friends car ( first time pass) and the inspector was interested in the column and how it is fixed, i had asked him to explain as he wentr along so i could pick up tips for my car.
You need one mecanical and one elecronic means of immobalising the car, the mecanical one is the hardest because of the regs of not being able to start/stop the car etc so the ignition switch that also sets the mecanical immobalisor is by far the easiest option.

He was also keen that a motor manufacturer( the big car makers) had already had there columns approved and therefore he was happy to observe correct fitting of a known column.

To fit these, a Sierra column, to our cars usually means extending the column from the first UJ at the steering wheel end and as long as you support the column you can add further UJ's and compressable sections.
I have in total 2 UJ's changing the angle between 10 to 30 degs and 2 slidable joints with 1 crushable tube.

Also on his list of concerns was the strength of the steering support, this must be strong enough to prevent the column from being pushed forward or deflecting the steering wheel over 127mm right, left, up or down.

My current build which is not a Haynes needs the steering support hoop modified and i am using the original Ford Sierra steering support plate with the arms removed and two pieces of 3mm bar as support, that should do it.


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