What about titanium?

[Automoda]

I used to be involved in recumbent bicycles a lot. I have one titanium model, one aluminum, and one chromoly model. I remember years ago talking to the manufacturer of the chromoly bike and he said that he could actually have the bike made in quantity in China from titanium for the SAME PRICE as he could have the frames made here in the US in chromoly steel tubing. Now, his brazing was beautiful and all and these were expensive bikes, but not outrageously so. In fact several builders did do exactly that. So of course that gets one to thinking....

 

About the only way to make a Seven lighter in any significant way would be to build it from Ti.

 

So what about cost? Well, if I can get a Birkin kit for lets say low 20K range with all of their new suspension etc, but a top-of-the-line Cat costs 65K, that leaves a lot of wiggle room. If someone was building Ti frames and leaving the engine to the buyer (I dont know how to spend 20K+ on a 4 naturally aspirated 4cyl... 3-5K seems plenty) I think they'd have quite the hot product. Imagine it with a bike engine or one of those light little V4s.

 

Ti is a bit more flexy-springy (I consider it part of my single-beam bike's suspension) but the 7's frame design is so triangulated I don't think it would flex at all. That stuff is TOUGH. Its lightness is amazing. The seven is just built from mostly 1 inch square tubing. I think its doable. Any thoughts?

[coffee break]

Chapman liked lightness but he also considered costliness. It occurs to me the drive train has the heaviest items. Loosing weight in these would have a bigger weight saving.

Now if we drivers could loose some mass.... :blush:

[Davemk1]

I'm a professional bicycle framebuilder by trade and have worked more than I care to admit over the years with titanium. It has some wonderful qualities but stiffness isn't one of them. In fact for a given diameter and wall of tube the Ti is about 30% more flexible than steel. The only real way to make this stiffness up would be to make the tube diameters larger. This isn't in most cases a deal breaker but in some places it could be more difficult to package the tube in the small area it needs to reside.

 

By far the bigger concern would be one of cost.........both in terms of the raw material cost and the much great amount of labor to cut, bend, clean and weld Ti as compared to steel. It goes through cuttings MUCH faster and takes much longer to cut and it needs to be welded in an oxygen free environment. This means purging both the inside and the outside of the tube with argon during all the welding. If this doesn't go well the joint can be very brittle and break without warning. Welding a bike frame is pretty simple but a Seven chassis is another level of PITA.

 

This doesn't even take into consideration the greater weld distortion one gets with Ti and the difficulty in making a straight chassis.

 

In the end one might be able to make a chassis that is about 25-30% lighter with Ti but at a great cost. How much can a steel Seven chassis weigh? Taking 25% off that might not be very cost effective and I think bolting lighter stuff to the chassis might be a more cost effective way to cut down the weight.

 

Just my 2 cents.

 

dave

[James A]

I do know that the 7 chassis can easily be lifted by two not very strong people, by that I mean me and my wife. The whole thing cannot weigh 80 pounds. I just don't see this as the place to focus as the car weighs 1260 pounds. I think the De Dion tube, gearbox, engine, and wheels are a better place to get weight out. In fact I think a little more triangulation (weight) would be a good thing for the S3 chassis.

[bigdog]

When I was working at a motorcycle dealer in South Dakota a few years ago. We saw a lot of people suffer from a sickness called brochure racing. Wherein a person buys a Yamaha R1, Said person will always come in the very next season and want the new R1 because a motorcycle magazine tester was able to get a 1/4 mile time that was .001 second faster than last years model. Boy did we make a lot of money off those guys. moot point for most of them as they were mostly crap riders or stunters/ showoffs that only did wheelies from a stop light.

 

Truth is. Most folks (that includes me) Don't have the ability to drive what we have to the level that the vehicle can attain. Especially on the street.

 

We must resist the temptation to chase numbers just for the sake of numbers. As the numbers game is always an expensive sport.

 

That 65k Cat when running the inflation numbers back to 1957 would have had the 1957 cat at $7800. It actually cost 1036 quid or $2900 which is 24k in 2012 dollars. That 65k cat is way over priced and should already be Ti at that price.

 

Of course this is just my opinion.

[dhubbard422]

In order to get both light and strong - carbon fiber would be a much better chassis material choice. But, the cost would be high for a well made carbon chassis. Personally, I like cheap and strong. And steel is easily repaired.

[WestTexasS2K]

I looked at doing Chrome Moly chassis. It triples the build time and doubles the material cost. It should save about 20 percent on weight on the chassis which is about 23 lbs for the Ultralite. I think that 23 lbs could be saved by a diet on my part. If I were racing for a championship and every once counted then it would be worth it maybe. IMO for street and occasional track duty mild steel is the best bang for the buck.

[CarMan]

For the record. The SCCA has a very strict weighting system for every vehicle. And after every race they weigh every car that finishes in the top 3 in class.

My Caterham has to weigh #1460 including driver.

My Best weight at the scales..... #1520

 

Believe me, Lightening the car is a waste of time. I am the problem. The easiest way to lighten the car is to lighten the driver, The fat bastard that I am. But I can't push the pasta away!

 

Also, the fastest way to quicker lap times is not some high zoot gadget or more powerful engine... It's driving lessons! A good driving school instructor can lop off seconds per lap...... and do it safely.

[Sean]

From all of the posts above, the logical conclusion is:

Good driving school instructors are made from titanium. They are strong, light, and tough, but flexy-springy, and cost a lot.

[S1Steve]

From all of the posts above, the logical conclusion is:

Good driving school instructors are made from titanium. They are strong, light, and tough, but flexy-springy, and cost a lot.

 

Sean , I agree with you... Well said !!!!