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Jensen Healey Race Car Update Feb 2007  Rating:  Rating
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 Posted: 02-18-2007 11:30 am
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Ron Earp
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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.






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 Posted: 02-18-2007 01:44 pm
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jcdean
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Holy Cow!

Looks like a grenade went off under the car.  You sir, are a fortunate man.  Do you think that welded spider came apart on you?  Would love to hear how this turns out.  Probably take you a bit to get it sorted out on just what happened, but for now I am very grateful you are OK.  I see a driveshaft hoop in your future.

Joey

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 Posted: 02-18-2007 01:55 pm
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Ron Earp
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It actually had the metal plate that bolts across the tranny tunnel - but it was blown out and not found. While not a drive shaft loop it is stout and we figured might do the job, it didn't.

No, the welded spider gears didn't have anything to do with this. When those let go, which is really rare, it just turns the differential open and generally breaks it, but that is about it. They still turn okay. We're not sure what caused this mess but I think it is either the transmission locking up which preciptated the driveshaft failure, or the driveshaft itself.

I think it was the driveshaft but can't be sure at this point. This driveshaft came with the transmission I bought from CA a couple years ago. I don't know the origin, but driveshafts that mate a five speed to a four speed rear end must be fabricated for the job since that wasn't a factory part or combination. I imagine this one was just not up to the job.

Ron

Last edited on 02-18-2007 01:58 pm by Ron Earp

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 Posted: 02-18-2007 02:42 pm
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Judson Manning
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Again Ron, I'd like to convey my most sincere condolences.  I've been there with my JH in Solo I, and the fact is we're forced to do all the missionary work the 240Z and Miata guys don't have to do.

Had it been just one of the u-joints snapping, the 'anti-pole-vault' plate probably would have been enough.  The shaft itself failing points to one end locking, and knowing the 5sp can be fragile, my money is on a transmission failure.

Of course the irony here is the one-piece drive-shaft you have is supposed to be more reliable than the original two-piece shaft.  Even if your shaft was 'custom' to fit the early 'small' 4sp differential flange (late 4sp have the 'bigger' 5sp flange), I would think the failure would have been at the flange or the u-joint.

There was no way you could have seen this coming, but the most important thing is you are OK!

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 Posted: 02-18-2007 06:17 pm
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Ron Earp
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Thanks Judson, much appreciated. I've got some more pictures I'll get up later in the week, and, we do have a video of the JH running around on track through NASCAR bend at VIR. I should have posted this in the transmission area because I think you are correct in that it might be a tranny failure. Until we get it off the trailer and really look it over I won't know, and I'm not that inclined to look at it just right now....

R

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 Posted: 02-19-2007 07:54 pm
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edward_davis
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Yowza!  I'm glad you're OK, too!  Fixing the car is part of the fun, after all, but fixing yourself really shouldn't have to be part of the game.  I'll be curious to hear how it all turns out.

I'm sure we're all looking forward to seeing the video of her flying high before the driveshaft failure, too.

Edward

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 Posted: 02-20-2007 05:44 pm
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Joel
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Ron - Glad you are ok!  Damn.

I see you're looking for a tranny from another post.  I have a 5spd with rear end and i think the drive shaft as well.  I wasn't really looking to sell it (it's always good to have spares!) but if you're looking for one let me know - I might be persuaded.

Joel

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 Posted: 02-20-2007 06:15 pm
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Ron Earp
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Excellent Joel, PM sent. My buddy at the track took some video and she's out there, but I never got time to hook up in car. I'll get the video from Jeff and see if I can upload it.  Looks cool, and it is on the same lap the explosion took place as well.

R

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 Posted: 02-20-2007 06:23 pm
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Joel
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As an aside - from you pics it looks like where the tranny tunnel meets the rear ledge you might have had some welding done.  I noticed on my car that there is a small 'tear' in the same place.  I was going to weld it and then put a 'T' shaped piece of 1/8" steel over it and weld that on too. 

Sorry for the thread hijack! 

Got your PM - let me 'tink about it a bit and get back to you.  I'm still looking for the other 1/2 of the air intake box!


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 Posted: 02-20-2007 07:49 pm
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Ron Earp
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Nah, there wasn't any welding done or anything funny there BEFORE the accident - but afterwards it has that big crease and valley there. I think that is from the upper links on the differential pulling downward on the chassis because they mount right about there in the car.

One thing I didn't know about until yesterday in looking at the car on the trailer is that the driver's side is bulged out too against the seat. The driveshaft tried to come out that side too and there is a big bulge all the way from the shifter area to the end of the tunnel, about a 4 inch outward protrusion.

What a mess. All of that will have to be cut out of a donor car and welded into this car. Or, made from sheet steel, one or the other.

Ron

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 Posted: 02-20-2007 11:22 pm
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Jim DeClerck
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Ron, 

Looking at the photo from the front of the car I can see what appear to be inlets for brake cooling ducts under the front bumper.  Did I get that right? 

Also there doesn't seem to be an air dam fitted under the front end.  If that's correct, is it because of the rules regarding modifications or is it something that is not really needed to control lift at high speed?  I have considered fitting one to my road car but now I'm hesitating.

I had some body restoration done on my car, including new front floors.  The shop owner recommended welding on a reinforcing plate to solidly connect the top rear of the tunnel to the rear shelf.  He said it's common for that joint to crack if not reinforced.

Sorry about the driveline failure and I hope it can be sorted out without too much grief.  Lucky you, to be able to walk away from that one.  Best wishes for a speedy recovery of #38 and a safer outing next time.



 

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 Posted: 02-20-2007 11:41 pm
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Ron Earp
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Yes, each front rotor has a two duct inlet that goes to two 3" tubes. One tube goes to the rotor and has a hat around the rotor (off in the picture for work) and the other goes directly to the caliper itself.

The car will have a spolier, if it ever races, but I do not think you need one for road use. A road car would have many other things that would affect handling that could be worked on first before I'd worry too much about lift. If fact, at road car speeds you should not experience any lift of any effect. I didn't notice any at about 110-115, which is is fast as this car has gone at Roebling Road (test day from last year, not a race). Judson has more experience this than I, but I think he'll agree. I don't think it is needed from a lift standpoint on the race car either, but I do think it will be needed to clean up the airflow on an otherwise very aero dirty car.

Thanks for the wishes, I hope to do better next time out!



Last edited on 02-21-2007 12:44 am by Ron Earp

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 Posted: 02-21-2007 06:55 pm
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Jim DeClerck
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Ron,

  Thanks for the great photo of the brake cooling set-up.  Regarding the spoiler, should I presume that the value of cleaning up the aerodynamics is a resulting reduction of aerodynamic drag and therefore a reduction in the power (and fuel) required to propel the car at higher speeds, say above 60 mph?

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 Posted: 02-21-2007 08:19 pm
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Ron Earp
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Sure, if you clean it up it'll definitely help with drag, fuel consumption, and will help acceleration some tiny amount.

Drag is proportional to the square of speed as far as I remember. But, I had a nifty chart of where drag got to be an issue with a fairly dirty test car and for those cruising under 65-70mph it isnt such a big deal as far as horsepower consumed. But, push the speeds into the 90-100mph range it certainly is an issue on a race car where everyone is using aero mods to get a tiny edge. Add to the fact we have a very dirty convertible compared to the coupes in the class and we'll need all we can get.

Some of the tracks we're spending (or will have to if we're going competitive) a fair amount of time in the 115-135mph range. The average speed around the track might only be around 80mph, but there is a lot below, and a lot above that average.

Also planned for the car was ducting behind the radiator to direct air out and help reduce drag (actually very important), various aero pieces to seal cracks etc. in the front end, an under tray, and a front splitter/spoiler. You'll notice the windshield angle is already raked back quite a bit more than a standard Jensen Healey. In that picture the car is much higher than it ended up in final form with more suspension changes.



Last edited on 02-21-2007 08:19 pm by Ron Earp

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 Posted: 02-22-2007 11:26 am
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edward_davis
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So I suppose that with the windscreen raked back, you can't fit a hardtop to clean up the aero profile of the car?  I know from my personal experience (but with no numbers to back it up) that my JH drives much better on the freeway with the hardtop on than with the top down or with the soft top up.

Looking at the windscreen and roll-cage setup you have, though, I don't think you could modify a hardtop to fit.

I suppose you could always make an aluminum tonneau, though.

Edward

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 Posted: 02-22-2007 01:14 pm
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Ron Earp
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We were futzing with the hard top at Judson's place. If I redo the cage for a hard top, which would be absolutely necessary, we can make a hard top fit pretty easily. The window can go back up, or we can cut the bottom off the top to squeeze her on there. I'd probably go the latter route if I went to the trouble to squeeze every last bit of advantage out.

Aero is important and a hard top would help out I think. Too bad I didn't think about that two years ago!

Ron

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 Posted: 02-28-2007 03:44 am
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LambandAndy
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Ron,

Since you seem to be travelling from NC to Atlanta, I know where there are two JH's sitting on the side of the road (for well over a year that I know of) near Toccoa, GA (yes, they are still there).

One is a MK 2 that has no engine/gearbox that the guy might sell reasonably if you need donor parts.

I can give you the guy's name and number but I will no longer deal with him.

Andy.

Attachment: 100_2216w.jpg (Downloaded 367 times)

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 Posted: 02-28-2007 07:19 pm
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Ron Earp
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Thanks Andy, I'll bear it in mind. I think the fellow that posted one in NC must have disappeared off the board.

Were those two cars up for sale for some large sum of money in the last couple of years? I swear I saw a similar picture way back.  Sounds like he wants too much money for them. A nice yellow JH with five speed that was running, good hard top, etc. just sold for $4500 in the NW, so those two heaps he has there aren't worth too much at all.

Ron

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 Posted: 03-22-2007 12:31 am
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smcmanus
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J-H Christ! 

Thank God or the deity of choice that you are OK!  That is quite the malfunction. 

Peace be with you

Steve

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 Posted: 03-23-2007 12:18 pm
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Ron Earp
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That is what I thought too!!!!

Right now the car is on ice as the racing season has started and I've got to get my race on - thus I'm racing out 260Z. This 260Z has been a race car since 1990 and is well developed, and hence fast and drivable and most importantly does not have a tendancy to try and kill the owner!

Once I get my garage built I'll put the Jensen back out and repair the damage and make sure it is track worthy. I'll have another go at it, but it'll be a few months before I start to rebuild it.

I do know this - it'll probably go back together with a 4 speed! So I am going to need to find one of those to purchase, and I do need a good 4 speed rear end. Feel free to email me if you've got some of this for sale. The driveshaft I'm going to have made and plan to have a high dollar/strong drive shaft made too - don't want to see anything like that again.

Ron

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