Jump to content
Click here to contact our helpful office staff ×

saving weight


scooby dooby doo

Recommended Posts

I've been thinking of more ways to save weight that don't seem to be offered by caterham at the moment.

 

*arrowright*uprights

I've heard the the JW fireblade uses alloy uprights. no info on the website - any ideas anybody 🤔 I've heard suggestions of 200 quid a pair for alloy ones from somewhere, the std ones are listed at 250 EACH in my pricelist...

 

*arrowright*hubs

maybe not the rears (they need drive splines in them) but what about the fronts 🤔

 

*arrowright*calipers

the rear sierra things are heavy, spongy, have a sticky handbrake mech, wear pads unevenly. Hi-spec reckon they are a few months off doing a 2 pot rear caliper, in alloy, with an integral handbrake mechanism. thats a few kg off each side - 4kg in total 🤔 Looked very good at the autosport show.

 

*arrowright*disks

do the disks need to be vented 🤔 why not use solid disks (lighter) and more aggresive pads like the pagids. better than that - fit lightened disks like these here from fluke. any comments 🤔 looks like 2kg saving at the front corners and 1 at the rear - 6kg.

 

of course i've got the camcover (1kg), battery (3kg) and wiring (1kg) still do as well but that all adds up to a 15kg saving plus what ever is possible with the uprights...

 

 

HOOPY 500 kg R706KGU

Link to comment
Share on other sites

  • Replies 50
  • Created
  • Last Reply

Top Posters In This Topic

Brake calipers have got to be the most cost effective way forward, and Wilwood do some really light calipers. Solid disks should be adequate for 99% of drivers. What you could do is fit some temperature strips to your brakes and then give them a real thrashing. Once you know the maximum temperature that they reach, you could talk to some of the brake specialists about optimum disk size. A brake cooling duct would be a lot lighter than vented disks *smile*

 

*cool* 99,000 miles so far

Link to comment
Share on other sites

Thats why the pagids seem a good idea for pads. They are happy at much higher temps (i badly glazed some 1144s a couple of years back at the front on the vented/AP setup and the std rears). So solid disks seem like they should be adequate. Fluke say they'll ask for car details and usage and they're experienced with Westie's so should be able to help.

 

Presumably the Wilwoods won't be THAT much different from the AP 4 pots 🤔

 

 

 

HOOPY 500 kg R706KGU

Link to comment
Share on other sites

it takes energy to change the rate something is spinning in the same way it takes energy to change the speed its moving at.

 

so to go faster you make the car lighter. if you strip 10kg of a 7 it gets 2% lighter, so 2% quicker to accelerate (VERY crudley) so 0-60 goes from 5.0 sec to 4.9. Thats widelt optimistic for several reasons but will illustrate the point.

 

Now imagine the flywheel, its weight. we could remove our 10 kg from here as well. same effect (except that its less than 10kg to start with etc). But the flywheel gets spun from 1000rpm to 7000 rpm, back down to 5000 and up to 7000 rpm again.

 

now imagine a playground with one of those spinny round rides on it where you push on it to get it going and the kids love it (quite old fashioned - not seen one for a few years). it takes about a minute of hafrd pushing to get it up to speed, and yet its not actually going anywhere - its ROTATIONAL velocity. Alighter equivalent, eg a spinning top is easy to spin up as its lighter.

 

so back to our flywheel. I worked out once (long day at work) that from normal to lightened flywheel, saving about 3kg, would also give us a 0.1 sec advantage 0-60. so I've lost a third of the amount as above, but got the same effect. magic

 

other benefits are that i can change gear more quickly as the engine can frop from 7000 to 5000 quicker to let me get into 2nd. so i gain a bit more there.

 

here's the science bit...

when its spinning its not simple weight giving rise to simple inertia when its moving - we use the "2nd moment of inertia" instead. basically this takes into account that the weight on the edge has more effect than that near the middle. To demonstrate this sit on your office chair, spin it round and stick your arms and legs straight out. now pull them all in - you speed up. you "moment of inertia" went down as you had less mass away from the centre so you HAVE to spin up to keep your (angular) momentum up.

 

hope that akes sense. shout if it doesn't and i'll rework it a bit. Then if its proven helpful I'll send it into blatchat *smile*

 

HOOPY 500 kg R706KGU

 

Edited by - hoopy on 18 Jan 2003 23:53:35

Link to comment
Share on other sites

Well explained Hoopy, makes a lot of sense, thanks 😬 - just the thing for "Good Engineering Practices". I'm sure Barry will find a place for it. I don't think you need to alter it too much, the KISS Principal is best *cool*

Cheers,

Tony

 

Waiting for my BRG SV kit. 😬 Is there any other colour?

(Superior Version) - Still 10 weeks to go! Miscalculated - Bu**er

Link to comment
Share on other sites

The front hubs are alloy already. Well they have been since very early 90's at least. The race cars started cracking alloy hubs so they changed back to steel hubs in about 2000 but I'm pretty sure the road cars carried on with alloy hubs. The race cars have got a new design of alloy hubs this year but I haven't seen them yet, they come with a new stub axle and wheel bearing design.

 

The uprights are cast steel I think but they're fairly spindly and thin. I would think an alloy upright would need to be a lot more beefy so the weight saving would be marginal if anything.

 

Apart from this I agree. I've got the race rear brakes with alloy calipers (but no handbrake) and solid front disks.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...