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OK, so I've closed up my first radiator duct, resulting in a DNF, at the Cat Majors (Road America) on Sunday. Maybe that makes me part of the club, but I was none too pleased, especially given the late start time and the long drive home. And no, it wasn't bump drafting. Video below:

https://youtu.be/TXmsVzGTFu4

Shame on me for not checking my temp gauge until after I got shoved off the road a bit later, which maybe would have meant I pitted and lost 30 seconds, instead of DNF, but either way the race was done for me.

So here's my question... why, in 30 years, hasn't the SRF community come up with a solution? I can think of several that would be fairly trivial to implement. As a newbie in the class, it seems like an odd "design feature", that minor contact can DNF you (or at least ruin your race).

Larry, do you have the center pin in? A lot of people no longer use it for that reason. That didn't look like enough contact to cause an issue.

No center pin.

Hey Larry. The short answer is yes, there is a solution. Drop me a note at dennystripling at gmail.
BTW, your incident was much worse for this issue than bump drafting due to the tire contact as opposed to contact with the rear frame member. Been there, done that.

This may be what Denny is referring to, but here goes anyway...

At the point the two radiator mounting struts pass through the chassis tube, most guys do not use the forward mounting nuts; they use the rear (shocks side) nuts only. In a relatively minor impact, this allows the entire radiator/baffle "front porch" assembly to rotate up a couple of inches. This has saved me a wrecked radiator on at least one occasion.

If anyone else has some ideas on this, please share.

Bob - ditto

I received several emails about this so I figured I'd just post the info here for posterity.

IMO there are two primary impacts that close up the nose. I'll address both and how to avoid them. This is timely information, imo, with Daytona being the site of the Runoffs.

Number 1 (less common): The "he missed a shift and I popped his rear frame member dead center, WTH?!?" or "I have no clue how to bump draft apparently, WTH?" event. This one is usually from a dead center impact when the lower frame rail of the car in front impacts the "z" strut that keeps the belly pan separated from the radiator support. What happens is that the strut is firmly attached at both ends so the frame impact bends it significantly in the middle, folding the belly pan up and/or pulling the radiator down. The end result is a closed up (partially at least) radiator opening that can also lead to Number 2 (pun intended) below.

A fix for Number 1: Don't bolt the bottom of the z strut to the belly pan. I discovered a while back that if you rivet it in place (I recommend steel), a significant impact to the strut will snap the rivet and the strut will just be pushed back into the radiator opening. This actually increases the opening rather than closing it. In a severe case it can lead to dragging of the pan under braking but it's better than closing that sucker up and ending your day (or motor). A tip is to check the rivet from time to time as it can drag and be worn down on the bottom. If this happens it can lose its integrity and be easier to pop out when you least desire it.

Number 2 (more common) in the next post.

Number 2, more common and IMO more dangerous. While this can be a symptom of Number 1 above, I believe it's more often caused by an off-center impact, usually due to the encroachment of an evil Goodyear at or near the center of the nose. What happens in this instance is that the impact force is directed more downward than laterally. Shoving the nose 'under' a spinning tire is a great example. When the nose is pushed down by the tire it quite often has a nasty habit of 'clipping' itself underneath the vertical lip on the belly pan. This is the lip that faces upward towards the radiator. The nose is pushed down and the wheel contact simultaneously crushes the lip down and backward. This is a nasty cocktail as the timing almost always seems to coincide such that the nose is behind the lip when it happens. The lip clips the nose into the belly pan, and a minute or so later poof, coolant on the track, Bob's your uncle and you're asking "when's my Gen3 upgrade again?". While less common, flexion in a frontal impact (no downward force) can snap the nose down and into the 'clip' as well which is why both removing the front pin and support (Robert's post) and eliminating the front stanchion nuts (Bob's post) are also potentially good ideas.

*The* fix for Number 2 (and often the dead motor result of number 1): I have verified with Mr. Davies (thank you to Tony at SEI for making me aware of this initially!) that it is now legal to 'roll' the lip on the belly pan flat. This is a simple fix that I believe fixes a large portion of these types of woes. With the lip folded flat back towards the radiator, there is nothing left to 'clip' the nose down and in most cases it will just pop right back up with nothing more than a big ol' black mark from the offending tire as proof of the incident. In an extreme case you can still fold part of the belly pan back on the nose and close it up, but with the added strengthening of the front 1/2" or so of the pan (now with the lip folded back, effectively doubling the thickness) I think that's a very unlikely scenario.

As always, YMMV.

Happy hopefully-not-overheating-due-to-subpar-bump-drafting-or-that-dude-slow-shifting-to-5th-when-I-was-underneath-his-cowling...ing!

RacerX

Thanks, Denny.

Racer X wrote: *The* fix for Number 2 (and often the dead motor result of number 1): I have verified with Mr. Davies (thank you to Tony at SEI for making me aware of this initially!) that it is now legal to 'roll' the lip on the belly pan flat. This is a simple fix that I believe fixes a large portion of these types of woes. With the lip folded flat back towards the radiator, there is nothing left to 'clip' the nose down and in most cases it will just pop right back up with nothing more than a big ol' black mark from the offending tire as proof of the incident. In an extreme case you can still fold part of the belly pan back on the nose and close it up, but with the added strengthening of the front 1/2" or so of the pan (now with the lip folded back, effectively doubling the thickness) I think that's a very unlikely scenario.

I love this idea. I'm gonna do that and go out next weekend at Pocono and pop some dude to see how well it works! (That oughta make a few guys think twice before passing me on Long Pond Straight.)

Thanks for passing that along, Denny. (And thanks to Mike Davies for proclaiming it legal.)