Lower Wishbone Intrusion Protection on OMS

[andylaurence]

So, to summarise, do I need to do anything if I have anti-intrusion bars? My lower mount is on the floor inside the car.

[Clive Austin]

My reading is that you will be OK Andy - see the pic from the MSA attached to my earlier post.

C

[Radical]

Originally Posted by andylaurence

So, to summarise, do I need to do anything if I have anti-intrusion bars? My lower mount is on the floor inside the car.

If you have vertical chassis members for the anti-intrusion bars to act upon to prevent the intrusion if you see what I mean.

As it says in the earlier post and the new MSA newsletter, just consider what would happen if the pivot rose joint or bolt mounting broke, where could the wishbone leg go and what would stop it?

[andylaurence]

A couple of photos from mine. I have anti-intrusion bars on the lower wishbone (but not the top, which mounts outboard) restrained by three vertical bars and an alloy panel and the inboard lower wishbone mounts are about 20cm inside the driver compartment at a sharp angle and under my knees. If the bottom mount broke, the wishbone would rattle around but remain a good distance from my leg as the hole the wishbone passes through the alloy panel restricts up/down movement, subject to a little damage if the bottom mount broke. Where it could be a problem is if that alloy panel tore quite a lot so the wishbone moved vertically upwards enough to crush my legs or if the wheel was able to move vertically (it'd have to be pretty much under the car) such that the angle the wishbone passed through the alloy panel was great enough for the wishbone to spear my leg. Either way, this would be only my right leg - my left is too far away.

I'd appreciate comments on the chances of the above happening and whether the scrutineers would see my car as legal. I think it's pretty good.

[Clive Austin]

Yep - by my reading this would be OK according to the latest note from the MSA. It's a bit difficult to tell from the pic but is there a chance of the whole thing rotating and poking a sheared rose joint into your leg? If so, I'd be tempted to add a small "cup" or something around the rose joint to catch the end it it snapped. You look OK in current form though - although I'm not a scrute.

[Radical]

Looks fine to me Andy. The important part in the anti-intusion bar andvertical chassis members should be sufficient to show the reduction of the hazard that the MSA are worried about.

Most of the people on this thread such as the OMS do not have this anti-intrusion and therefore are exploring other forms of protection.

Intrinsically the lack of the bar on the upper wishbone appears to be a much lower probability of intrusion hazard such as to cause injury, the radical also does not have the bar on these.

Angus

PS, Off topic, but having the pivot point so far inside the car must produce some strange angles as the suspension moves?

PPS I agree with Clive, there could be a "hazard" of the broken end not so much intrusion but just rotating straight up into the leg, if you think about it this is a small scale example of the issue in the letter posted earlier that prompted the rule change (clarification) of the driver threading his legs through the suspension and mounts to get at the pedals ?

[minitici]

Angus - on your Radical the top wishbone mounts are not in the passenger footwell and are shielded by the chassis therefore the to wishbone has no need for an anti-intrusion bar.

[andylaurence]

Yes, rotation was my primary concern. I think I'll play it safe and plate it in somehow. Not sure how yet! I've no idea what it does to the angles having the pickup so far inboard. I can imagine a good amount of camber recovery in roll.

[Clive Austin]

Originally Posted by fergusd

I've changed design a little to run the shield under the bracing bar and around the vertical mounting post, haven't put the hole for the post into this yet but that is next when I get a minute and test fit this week on a couple of cars hopefully. Red crosses will be bolts, into the chassis and joining the front and rear parts together (not easy to see in the pic that this is 2 parts). Should be stronger, smaller and lighter.

How did it turn out in the end Fergus?

C

[steve88]

Well finally got round to getting the old girl out of the trailer and stripping the bodywork off . After five or six attempts on the templates , would have been fifteen or twenty if Clive had not supplied me his to work from, cheers for that mate , they now fit a treat. Hoping to get a bit of fabbing done this weekend after have cleared the 2 years worth of grass out since I last had the body off . First event Easter weekend so should have plenty of time. Famous last words .
Thanks to all for all your viewpoints and words of wisdom on this matter

Steve