Lighter Caterham

[breezy7]

Caterham is working on a 50-60kg lighter chassis. http://www.autoexpress.co.uk/caterham/super-7/95020/caterham-seven-could-get-even-lighter-with-new-bike-tech-chassis

[powderbrake]

Not knowing what butted tubing is, I looked it up on Reynolds website. I could not see the pictures for some unknown reason, but it is an interesting process.

 

http://www.reynoldstechnology.biz/faqs/495-2/

[Sean]

Auto Express made some kind of error here. The butted tubing is expected to shave around 5.5 kg according to all the other sources of this story that I have seen (The chassis weighs around 55kg, so losing 50-60kg from that would be... difficult).

[supersportsp]

Yes, it was forecast to be a 10% weight reduction in the chassis. As noted above, the chassis barely weighs 55kg now.

[breezy7]

I misread the article thinking they were talking about a 50-60kg reduction in chassis weight. From the article :”Caterham claims around 10% of the car’s weight could be cut if the chassis was to be put into production. That means between 50kg and 60kg would be slashed from the Seven’s already tiny overall weight.”

[Sean]

I misread the article thinking they were talking about a 50-60kg reduction in chassis weight. From the article :”Caterham claims around 10% of the car’s weight could be cut if the chassis was to be put into production. That means between 50kg and 60kg would be slashed from the Seven’s already tiny overall weight.”

 

You read it correctly, but author Jonathan Burnjust wrote it incorrectly.

If you search using the terms "caterham" and "reynolds", the results provide many other sources writing on the same story, which got the numbers correct.

 

Seems to me like a lot of cash to save 5.5 kg. One can save twice that much weight for a bit over 300 bucks by ditching the Banner battery for a Ballistic Evo2 16 cell LiFEPO4 battery or similar.

[escondidoron]

 

Seems to me like a lot of cash to save 5.5 kg.

 

Or just have the driver go on a diet.

 

Last year I had the flu and lost 12 pounds (~5 kilos). My wife commented that my weight loss was the best performance improvement that my Seven will ever get.

[Davemk1]

Powder Brake - Butted tubing was first developed for the bicycle business a very long time ago. The outside diameter of the tube remains constant so the tube looks 'normal' but the wall thickness is greater at the ends and thinner in the middle.

 

The thinner middle section (where the stress is low) saves weight and the thicker ends keep the strength where needed. One of the issues one sees when you weld tubes together is that the welded area, due to the heat used during joining, becomes weaker and the added wall thickness is used to keep the strength up in that highly stressed area.

 

So just like with a bike frame butted tubes can cut weight while not lowering the strength or having a significant effect on stiffness. All good stuff.

 

I think the difficult thing for Caterham will be that they will go from using 20' long mill runs of tubing that they just cut to length to having a specific tube for each and every section of the space frame. Managing this inventory and all the SKU's will no doubt be a challenge.

 

I've had a 25 year relationship with the tubing company Reynolds (through the high end bike biz) and know that they can offer cut-to-size services and this might make the whole thing that much easier for Caterham to deal with on the production floor. They could in effect have Reynolds deliver a tube set in a crate with all the tubes needed for a chassis cut to length and mitered at the ends as need be so that Cat would just load the tubes into the jig and start welding. This would no doubt cost an arm and a leg up front but drastically cut down on labor cost in cutting tubes to fit into the jig.

 

I expect to see Reynolds offering special titanium tubes this summer for the upcoming ultra light Ariel Atom. They should be able to cut chassis weight by about 30% compared to the steel they are using but I expect cost to double or more. Ti ain't cheap.

 

dave

[Road Ready]

You read it correctly, but author Jonathan Burnjust wrote it incorrectly.

If you search using the terms "caterham" and "reynolds", the results provide many other sources writing on the same story, which got the numbers correct.

 

Seems to me like a lot of cash to save 5.5 kg. One can save twice that much weight for a bit over 300 bucks by ditching the Banner battery for a Ballistic Evo2 16 cell LiFEPO4 battery or similar.

 

I may be in the market for the right battery for my car. The one I have is way smaller than the space available and I have unresolved starting issues. i've been told that a bigger battery might help. What Banner battery do you have and where do I find one?

[Bonjo2]

I thought back in the early 90's that a seven would be even more amazing if built by the bicycle industry. Back then the Specialized M2 or the high end Reynold's steel customs, or the Lightspeed titanium. This really only makes sense if you're running a motor, drivetrain, wheels with as much effort in weight loss.... Spend $400 more per custom wheel, then a lighter flywheel etc... Carbon fiber springs?

 

Having ridden custom butted framed bikes, I can say there is a lot the seven community could adapt with regard flex and forward motion control. But, we've no ultra lightweight motor, less the snow machine/sportbike...

[Sean]

I may be in the market for the right battery for my car. The one I have is way smaller than the space available and I have unresolved starting issues. i've been told that a bigger battery might help. What Banner battery do you have and where do I find one?

 

Banner is the brand of battery that Caterham typically supply with the 7. I have never had one. I have read that the Banner weighs around 32 lbs. ready-to-use. I use an Odyssey PC625, which is just over 13 lbs., and the EVO2 is under 4 lbs. Each of these brands use a different type of technology, so are difficult to compare, but all three are well-proven in our application, depending on your operating environment. I am not at all an expert in this field, but have learned a few pointers here and there.

[Blokko]

I ran one of these on my Caterham - it might solve one of your issues (but might create another in the process). AGM batteries (sometimes, incorrectly, referred to as Gel batteries) offer better cranking capacity than the equivalent lead acid battery, which might help with your start up. These types of battery are typically smaller than a Banner, so it won't sort your spacing issue. You might be able to get a new bracket though.

 

The thing to watch with AGM batteries is that once flat they are toast. There are differing opinions as to whether they can be charged. The best bet is to remove any parasitic load when parked up (immobiliser / alarm) - an FIA cut-off is ideal. With no load they do not lose charge - I once left my car for almost 6 months and it fired up first time.

[Blokko]

Back on topic. I've spoken to a few people who have owned or driven bike-engine 7's - the ultimate light-weight sevening experience. Meant to give a very different experience on the track compared to a normal 7.