On-track incident - Help with damage assessment

[KnifeySpoony]

I was involved in an incident at Sonoma yesterday, sustained some light damage to my left front wheel/wing. Video of incident and pics below. After the incident while driving back to the paddock, the steering wheel was turned slightly to the left (maybe 10 degrees?) to travel in a straight line. Looking at the front suspension after the incident, there was no play in the wheel/hub. Everything seemed tight. I don't see anything obviously bent. Steering arms looks straight, but there is a slightly shiny area on the front left arm (tried to photograph it). I don't know if this is just an irregular area in the casting, or if it is evidence of bent/stretched metal there. You can see from the video that the right front was hit as well, but only on the inside of the tire sidewall. Before driving home from the track, I adjusted the toe on the left front (just by feel, testing by driving up/down the paddock) until the car tracked straight. I had to turn the tie rod about 1.5 turns (pushing the steering arm outward (pushing the toe out on the left front, which I figured was necessary given the prior steering wheel position). Today I checked the toe with the steering wheel straight and there is 1/2" (12mm) of toe out. Previously the car was set for zero toe.

 

So I'm not sure what exactly was bent, or what I should replace. Should I just realign it and run as is? Or do I need to replace the steering arm(s)? Anything else that could've been damaged? The steering seems smooth but could the rack be damaged? There was a slight shimmy in the wheel at freeway speeds on the way home, speed dependent, felt like a tire slightly out of balance. The wheel itself is scuffed but looks straight though might not be. Or it could just be tires flat spotted.

 

Thanks!

 

 

 

 

[KnifeySpoony]

Oh also, eyeballing the distance between track rod end and brake disc on each side, I don't see an obvious difference, but I need to take wheels off and measure I guess. 

[aerobod - near CYYC]

Sorry to see your car has some damage.

I would say that if the toe is correct if you wind in the 1.5 turns on the track rod end again to where it was, that the steering rack may have moved sideways under the clamps and may just need repositioning, if your track rods look straight.

From a track day perspective I have found the Caterham can be pretty invisible to other drivers when helmeted and strapped in, especially when their seat is lowered to give helmet clearance. It can be out of sight below their window line. I normally only run in mandatory point-by groups when mixed in with other vehicles these days. The other issue is that they can also misjudge the rate the Caterham is slowing down when easing off the throttle, for corners that just require a lift for me, I've had a few cars get closer than they meant to because they didn't brake when they should have, followed by them getting into trouble due to being too fast into the corner. 

[Wrightpayne]

I'd check the 'bridge' on which the steering rack sits - these are prone to bending. Also the rack fixings - these may have been nudged along.

[Hampshire West AR]

This is why I like track days that have clear overtaking rules on straights on one side only and with the driver ahead indicating his or her intentions prior to any overtake happening.

Nick

[Roger Ford]

Agree with #4 - steering rack bridge is likely culprit if it's not the steering arm.

[KnifeySpoony]

Measured steering arms to discs - equidistant both sides. The rack does not appear to have slid within the mounts - at least I don't see any marks on the rack to indicate this. However we're talking just ~1.5mm of shift based on the amount of tie rod turns needed to make the car track straight. Looking at the steering rack "bridge" - the welds look ok, no obvious cracks. If it has bent, what is the solution? Just adjust the tie rods and go on with my day? 

 

I also noticed that the right lower wishbone appears to have flexed back enough to hit the paintwork during the hit to the right front tire. Is there any chance this could have bent the lower control arm bolt? It's not currently fouling, there looks to be a small gap. I never noticed the scratch before - I supposed it's possible it was there before. 

Pic below-

[Nigel Blandin]

Is it me, or does the chassis mount look a bit crumpled, like it's had a compression? 

[jody391]

Looks like just the weld slug to me.

But the wishbone from this shot looks like it has a bend/twist? or is it the angle of the shot?

[jody391]

There is probably enough deformation in the bushes when the hit occurred, and the front end squatting that its touched the body work?

[KnifeySpoony]

Wishbone is straight. I can put a straight edge on it to confirm. Any thoughts on a bent steering bridge? How to confirm and how to repair? 

[Roger Ford]

I believe the usual repair for bridges is simply to cut the old one off and weld a new one on, or as a field repair just bend it roughly straight. Not sure how to check it - ones I've bent have been very obviously so.

[Simon.Rogers]

Do check for a twist in the lower steering column.

You would be surprised how easy it is to twist it a little.

SO get it checked for alignment and you should be able to see if your corrections have missaligned the front wheels.

If the column has twisted then both wheels will have been offset to one side.  Then your alignment fix may be setting you running straight but toe missaligned.

Hope you follow.

[KnifeySpoony]

Do you mean the lower steering column itself has twisted? That seems odd based on where the forces are acting. 

I'm hearing from other sources as well that the bridge shifting/bending is a common situation and acts as a "fuse" in the system. If mine is only shifted a couple mm, it seems within acceptable tolerance to just realign and move on with my life? This all assuming the welds are ok? Or is that foolishly optimistic...

[KnifeySpoony]

I just a bubble level on the bridge and it is level/parallel with the lower front horizontal chassis tube. So it seems it's not actually bent. Maybe control arm chassis mount? I really wish something simple just broke, then I could replace and move on. It being a mystery is unpleasant...

[jody391]

Can you post up some more images? say from the underside showing the chassis etc

[Simon.Rogers]

Absolutely this is possible.

i have seen it happen first hand and it all happened with the driver just holding the steering wheel so tight as they went into the barrier!

I have also had two cars into the workshop with twisted lower shafts but have no knowledge of how it happened.

 

[KnifeySpoony]

Interesting, I never would have guessed. Is it easy to tell by looking? would it automatically require replacement?