Advice: If you autocross a Caterham you might just want to inspect the fastenings at the front of the rear fenders.

[pethier]

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Advice:  If you autocross a Caterham you might just want to inspect the fastenings at the front of the rear fenders.

 

From 2008 until 2010, I autocrossed a 1979 Caterham 1600.  Had a lot of fun.  Must have hit dozens of cones in those seasons. Never sustained any appreciable damage to the car. I had then, and have now, absolutely no idea how the rear fenders were attached to the car.

 

A week ago, I took my 1991 1700 SuperSprint to its first autocross. Made 8 runs and hit several cones in the process.  No big deal.

 

Sunday, I took the 1991 Caterham 1700 SuperSprint out for its second autocross.  First run clean.  Smacked a couple my second attempt, but got a rerun for timing failure.  Second run faster, third run just a tic slower than the second.

 

Turned the wick up for the fourth run and ran just a bit too wide in the exit of a left-hander.  There were two cones in succession, and I hit them with the back fender.

 

Time was no improvement.  The Mustang driverwho had followed me came up to the car to thank me for getting him a rerun.  I asked if there was any damage to my fender.

 

"I could probably answer that if the fender was here."

 

I pulled my mirror down and was staring at a Yokohama tread pattern.

 

I got out of the car.  They entire fender was AWOL.  The Mustang pilot started taping up the wires.

 

"Be careful to keep your arm in the car your next run."

 

I decided the only run this car was making was to my trailer.  After I got the car strapped down, I went out on the course and retrieved my fender.  The worker told me the fender had flown high in the air.

 

SEE PIX

 

Upon examination, I believe several things had to align to come to this result.

 

The cones needed to be on the right side of the car.  The exhaust pipe is substantial, and its angle probably would have sliced the cones to the side, or at least absorbed the bulk of the impact energy.

 

The fastening of the front of the fender had to be pretty-lightweight.

 

There had to be two cones.

 

How I think it happened:

 

The first cone struck the fender and cracked it across the top.  This allowed the fender to pull out the forward fasteners, which were simple threaded pop rivets with no backing washers.  They left small round holes

 

 

The second cone struck the front of the flopping front half of the fender and pushed it into the spinning tire, which pulled the fender down.  Unfortunately, the crack at the top of the fender did not go all the way across, so the tire was able to rip the rear fasteners (nut-and-bolt combos with washers) out of the aluminum body.

 

I suspect the rear fenders on my 1979 car were anchored at the front better than on this 1991 car.  No idea if that is true or why they were different.

 

 

Damage at the rear is much worse than it probably would have been if the rear was secured with the same undersized fasteners used in the front.  Although the holes are very large, the rips in the  aluminum do not appear to extend beyond the area which will be covered with the new fender.

 

 

Ruined pieces:

 

The fiberglass fender itself.  Could be reconstructed by a competent fiberglass worker.  That's not me.

 

The taillight assembly did not survive being driven over by car.   The rubber base may still be workable, but that might be moot as it may not be a separate part.

 

The backup light was completely squashed.  I don't think I really NEED two backup lights, but we will see.

 

 

Parts that appear still usable:

 

The chromed metal stoneguard looks just fine.  Drill out the pop-rivets and put it on the new fender.

 

The piping/gasket looks like it can be cleaned up and installed again.

 

 

[panamericano]

Food for thought indeed.  Since Mad Max damaged his F1 car with a pylon 2 races ago, you may have discovered the fix for FIA's "track limits" problem.  F1 needs more cones!  A real, but slight, mechanical penalty for violating track limits.

 

Our region gives a trophy each year for the autocrosser that hits the most cones.  You might be in contention for a prize if your club does similar.  I prefer to leave the cones alone, but seem to find a couple a year.  This was my solution on the Birkin.

 

[pethier]

15 minutes ago, panamericano said:

Food for thought indeed.  Since Mad Max damaged his F1 car with a pylon 2 races ago, you may have discovered the fix for FIA's "track limits" problem.  F1 needs more cones!  A real, but slight, mechanical penalty for violating track limits.

 

Our region gives a trophy each year for the autocrosser that hits the most cones.  You might be in contention for a prize if your club does similar.  I prefer to leave the cones alone, but seem to find a couple a year.  This was my solution on the Birkin.

 

I have been noodling on that concept,

 

My first thought was to put a fake exhaust pipe on the right side.

 

Did you cut yours out of aluminum plate?

 

How is it fastened to the car?

 

One idea I had was a similar item held on by the bolts that hold the seat tracks.

[panamericano]

Aluminium yes.  As I recall, it's bolted into the lower frame tube.  Held up well and serves as a step for small children.

[pethier]

> Our region gives a trophy each year for the autocrosser that hits the most cones.  You might be in contention for a prize if your club does similar.

 

I am not in contention for hitting the most cones.  I may have hit four at this event.  None are recorded on the preliminary results.  1 or 2 would have been on the run that earned me a rerun (only a DNF will show if there is a timing error, cones hit on a rerun-earner are not carried over).  For reasons that elude me, the two cones I hit that ruined my fender are not recorded.  Perhaps they were not were not reported.  The finish marshal showed me a raised fist (the sign in our club for a clean run), and I yelled to her that I was certain I hit two.  The station captain may have been too busy radioing "hold the cars" to remember to report the cones.

 

There were a lot of people who hit a lot of cones at this event.  The highest total I noticed for any driver was 13 cones.

 

 

[11Budlite]

Sorry to hear about the incident and all the damage.  Besides adding a deflector to hopefully protect the fender, a lot of people use nylon attachment bolts for the rear fender to protect the aluminum skin in case of an incident. It doesn't help much with the fender but will prevent or reduce damage to the aluminum skin. The nylon bolts are available in most standard and metric sizes.

[pethier]

32 minutes ago, 11Budlite said:

Sorry to hear about the incident and all the damage.  Besides adding a deflector to hopefully protect the fender, a lot of people use nylon attachment bolts for the rear fender to protect the aluminum skin in case of an incident. It doesn't help much with the fender but will prevent or reduce damage to the aluminum skin. The nylon bolts are available in most standard and metric sizes.

Thanks!

[IamScotticus]

[pethier]

3 hours ago, IamScotticus said:

LOL.  I do tell my students, "Don't fear the cones; the cones should fear you."

 

I can't tell you how many cones I hit with my yellow Caterham.  Never a bit of damage.  I was totally stunned by the destruction last Sunday.  Well, this one was a kit.  I don't know if the Yellow one was factory-built, but I do know this FMB one was assembled by the owner.

[IamScotticus]

Perhaps the cones are softer on hotter days

[pethier]

 

 

 

Getting closer to a complete car.  The RR fender from the factory has all the mounting holes in different places.  Since the aluminum is messed up anyway, I will drill new holes in the body and use the factory holes in the fender.  Such fun.

Edited July 14 by pethier
hamfisted typing

[pethier]