View single post by Ron Earp
 Posted: 02-18-2007 11:30 am
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Ron Earp

Joined: 03-12-2005
Location: Cary, North Carolina USA
Posts: 339
We (Jeff Y, Jeffery R, Robert M, and myself) took the Jensen went out for a track testing session at VIR yesterday for a 2007 shake down.  This is the first track session that it has had in about nine months now and we had reasonably positive expectations.  It has a new engine and a much better level of prep than it had when it went out on track last June, so we figured we could run around in the Touring Lights club class to learn about the car.
First session out we were having some mixture problems with the Strombergs. The car was reluctant to take throttle and pull like it should, but I think we eventually got most of that sorted out. In the second session the car was running pretty well and would pull to our intended shift point for the test day, about 5500 to 6000 RPM.
I was able to make a few laps and start to get a feel for the handling of the car at about a 65-75% race pace. I’d say the handling was okay, nothing spectacular.  It had fantastic turn in though, I really liked that aspect of the car, but the cornering grip was difficult to feel out. If you turned in too sharply the tail would readily step out and it was definitely a step out that was out of proportion to tire grip; that is to say, it wasn’t tire related.  The rear end would also break away under increasing g cornering too, in a manner that was predictable but that happened far too early to be racable. I think the rear was far too “hard” and had trouble getting hooked up.  The front was better than the rear, but I didn’t have a good chance to push the front as the rear was limiting me.  Anyhow, these are things that can be solved with development and part of the fun of running a car.
About the fifth or sixth lap around during the second session we had a fairly heinous failure. I came out of Oak Tree, a sharp right hander, and started down the 4000’ straight.  There were no other cars around for about half a mile or so.  At about 70mph and just a little ways down the straight, I heard a tremendous BANG!!!!! There was dirt (what I thought was dirt at the time) and debris flying all around the car with a lot of vibrations coursing through the chassis. There were various noises clanking and clunking so I figured maybe it’d be a good time to pull off track.
I reached down to hit my cockpit electrical kill switch but it wasn’t there. A quick glance revealed that most of the drive tunnel that my kill switch and accusump were mounted to wasn’t there either, and my gear shift was poking out of the tunnel at a really strange angle. I managed to turn off all the switches on my electrical panel and get the car pointed left of track.
As soon as the car rolled across the track curbing I was up and out, it was still rolling a bit as I jumped from the cage (open top cars quick to get out of, a good thing!!!!). The car was leaking fluids out of three places and I could hear a heavy flow of liquid splashing on the ground that turned out to be fuel from the broken pump and line system.  The track was littered with pieces of metal, driveshaft, and exhaust system. I was a bit shaken up, no doubt.
To make a long story short it appears that the driveshaft broke. When it broke the car was moving and it was securely bolted to the differential, so of course it had to rotate. It beat the hell out of the transmission tunnel, broke the cross bar loop, and sheared off the exhaust system while turning itself into a 3” diameter metal facsimile of a snake.
The engine was spinning at about 5000 RPM when this happened so of course the transmission was being turned until I could shut off the engine. The output yoke of the transmission is a heavy u joint affair and it just about cut the center console in half while taking scattering shards of metal all through the cockpit. The accusump got deformed and vented oil making a nice shower.  Electrical switch was broken, and my MSD timing control was reduced in size by about a third. Tunnel is trashed and the carnage goes all the way back to the rear deck.
Once we got to looking underneath the car we could see that the transmission is missing some casing and the differential isn’t being a differential any more. The transmission is pulled away from the bell housing about an eighth of an inch, so bad things are going on there. The diff sounds like a box of rocks when turned and input flange wobbles around in a non-circular way.  Shifter structure is mostly gone, as is the transmission output flange, and some other bits back there.
Good news though – due to my last “bad” on track experience I was very protective of the motor! I don’t remember much about the bang and what happened right after, but I distinctly remember seeing 75psi on the oil pressure gauge as I flipped the power to the MSD off – so I’m sure the motor is okay!
I’ve learned a lot from this recent experience but need to think about what I’ve learned before I really know what my next move is going to be. I know I am very fortunate to have gotten out of this deal without a serious injury. Safe to say you won’t see the Jensen on track in the very near future though, unfortunately.