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moosetestbestanden
June 8th, 2008, 08:02 PM
Just got off the phone w/ Stokes. It seems he broke his driveshaft in a major way at Buttonwillow today. I'm heading over to the shop w/ a camera tomorrow to give it a look. More to follow so stay tuned.

Roll a 7
June 8th, 2008, 08:14 PM
Does he have some sort of hoop for protection? That could be a nasty event in a 7.

magnusfeuer
June 8th, 2008, 08:41 PM
I am guessing here, but I think that ignition retarding (or killing) during upshift and throttle blip during downshift will save him a lot of equipment.

If I understand things correctly, today his drive train takes the full shock of a revving engine when he goes into next gear with throttle applied. His slicks ensures that the wheels do not spin, which would lessen the load on all the parts between the wheels and the engine.

He will probably need a new ECU that can handle shift strategies and two micro switches on each side of his shifter. When the shifter is pulled or pushed, one of the switches closes, telling the ECU what is going on.

/Magnus F.

Roll a 7
June 8th, 2008, 08:54 PM
Another website described it as a U joint or driveshaft failure. Apparently the driveshaft ended up in the passenger compartment. There is also a possibility that the sequential Quaiffe trans is toast. Not a great weekend.....

moosetestbestanden
June 8th, 2008, 10:21 PM
I am guessing here, but I think that ignition retarding (or killing) during upshift and throttle blip during downshift will save him a lot of equipment.

Yeah, he mentioned that in our conversation. I'll take some pics if the car is still there tomorrow. He didn't have a good weekend.

Elv15
June 9th, 2008, 07:58 AM
Thats bad news. I'm assuming Jon is ok?

I suspect it would have been worse if the driveshaft ended up in the drivers side!! :eek: :eek: :eek:

moosetestbestanden
June 9th, 2008, 06:50 PM
Well, as promised, see attachments. The lack of intrusion into the driver's side is likely either completely luck or perhaps due to the fact that Jon has an aluminum / honeycomb 'floor strengthener' (for lack of a better term, visible in the driver's side pic) under his foamed seat. Also note that the foam seat was between his leg and the failure zone, additionally helping cushion and preventing what could have been a very nasty injury, particularly had the car been right hand drive.

It's Jon's opinion (and mine) that the U-joint failed, which caused all subsequent damage. Jury's out on the gearbox internals (some swarf was found) but the case is cracked for sure and the frame damage is particularly apparent in the tunnel view shot, that shows how the frame member almost completely separated at the braze joint. Both lower horizontal frame mambers have to be replaced and personally I'd braze in a few extra verticals, or a hoop, for good measure if the car were mine.

I'm starting a thread over on BC to see if this type of thing is of any interest to anybody over there to see if anyone there has input. Magnus' theory seems plausible to me and so I wonder if CC's new R500 w/ the sequential option has any similar type cutout.

Edit: Hey Woody, do you guys have any of those hoops left, or know where I can get one for a Caterham?:D(not really kidding)

2nd edit: It happened during a change down at the I-5 hairpin at Buttonwillow. They were running clockwise.

Doug Liedblad
June 9th, 2008, 07:01 PM
We should all consider something like this.

Not my car, I captured the photo from some website. Probably in the UK but I don't recall.

I'm also not sure it's enough. Better if the hoop is fixed rather than just clamped in place.

Doug

moosetestbestanden
June 9th, 2008, 07:05 PM
That's Woody's hoop, as shown on their website.

slomove
June 9th, 2008, 07:26 PM
.....It happened during a change down at the I-5 hairpin at Buttonwillow.

That means the car and consequently the drive-shaft were still moving/turning pretty slow (and torque high which would explain the problem). I am just trying to imagine the carnage if that happened at a high-speed shift-down. But it may be hard to even design a hoop that can contain a flailing drive-shaft at high speed. The forces must be quite substantial....Another reason for a carbon fiber drive-shaft that would probably disintegrate in such an incident.

Gert

moosetestbestanden
June 9th, 2008, 08:05 PM
That means the car and consequently the drive-shaft were still moving/turning pretty slow

Not necessarily. Jon coasted all the way down I5, through Cotton Corners, around Grapevine and stopped off-track just before Club Corner. See Buttonwillow's track map #1 at

Buttonwillow Raceway (http://www.buttonwillowraceway.com/)

Their website doesn't pass URLs through to a browser so click through Track Maps then on Race #1 to see how far he went.

rlingren
June 10th, 2008, 07:58 AM
Hi Guys
As we know Jon has more hp and torque than all of us and does more
track days also. I wonder if that was the original drive shaft and
U joint ? In a competition situation that would / should be changed every
x races, season ? It makes sense that a very high spec car
should be fettled, (I love that word) more often than a street / track car.
I think that Jon's drive train has seen at least several times more extreme use than anyone I know of. There might be a formula hp / torque , slicks contact patch, track hours = wear factor.
My point is the wear factor of most of us is well below that of Jon's.
My experience is that the joint will make cracking and grinding noises
before it fails. I think a simple wiggle of the drive shaft should
find the problem before it becomes catastrophic.
Even with a drive shaft hoop you want to catch it before it fails.
Rod

ps I sold the Birkin and bought a formula vee to play with and am building Rod's old 7 with one of Williams Esslinger motors and a Miata IRS.

magnusfeuer
June 10th, 2008, 08:24 AM
Rod,

Jon, according to himself, has about the same HP as me (~250 at the crank). It seems like his Atlantic head cannot come into its right until it hits an RPM which is above what his (and my) stock Ranger crank can take (7800 briefly).

This means that we both run CSR 260 range power (and probably torque) on what I believe is the same drive train bits (apart from the rear suspension). If there were failing CSR axles and bearings at a rate that Jon has seen, Caterham's offices would surely have been torched by now.

A blatchat poster asked if the clutch plate was sprung (the little springs integrated into the center part of the plate). These would lessen the shocks as well, just as they are designed to.

/Magnus F.

moosetestbestanden
June 10th, 2008, 12:57 PM
I wonder if that was the original drive shaft and U joint ?

Jon replaced the driveshaft & U joints before the start of this year, when the gearbox arrived. Perhaps they weren't well lubed - that I don't know.

Edit: I don't know about the clutch but I will ask.

Roll a 7
June 10th, 2008, 02:50 PM
Per Jon: The U joint apparently came from an AH Sprite, or something similar. It may not have been up to the job... The rear end of the trans was severely battered/damaged and will going to TX for some work. Jon is undamaged, luckily!