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Discussion Starter #1
Is anyone out there making ultra light forged wishbones for the Elise? I've been looking for these for ages.

Cheers

Tony
 

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Discussion Starter #2
I guess not. Is no one else interested in this? Every 1lb you save in unsprung weight is worth 5lbs of sprung weight. If you can reduce the overall weight of your Elise you'll notice a massive difference in handling and acceleration.
 

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>>>I guess not. Is no one else interested in this? Every 1lb you save in unsprung weight is worth 5lbs of sprung weight. If you can reduce the overall weight of your Elise you'll notice a massive difference in handling and acceleration.<<<

Well there is a mutiplier effect but it has to do with rotating things. Lighter arms won't noticeably affect acceleration. But cutting weight from wheels/tires can pep things up a bit. Because they act like flywheels when they spin.

Sprung weight is stuff attached to the chassis more or less. Unsprung => the parts attached to the hub end of the suspension. Things like a-arms have an unsprung and a sprung component. Lowering unsprung weight helps the suspension to be able to control that mass and keep the rubber on the road while aiding ride quality.

I'm sure the a-arms could be made lighter, but there may be other areas to investigate first.
 

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Discussion Starter #4
It's the last thing I can do on mine. I've already got ultra light wheels and lighter brake discs. Stripped my car so much that I'm running out of places to lose weight. I even lost 10 kilos myself!! Looks like the last thing to come out will be the aircon and stereo system.

Have you weighed the wishbones? They bloody heavy....
 

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Damn Tony your right there is not much left to modify! Do you do your work yourself?
ARe the RS14 pads Ok on the street I thought they were more of a track pad?
 

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Tony you sure have done a lot to your Elise! I doubt that a forged aluminum a-arm part will ever show up for the car...since there would not be enough demand to cover the large set up cost and to tie up a huge forging machine. But fabricated light alloy or special steel or titanium piece could be produced by a local race shop using the steel stockers as a model. Maybe convert to an all rod end setup. Using aluminum rod ends, those are readily available. You could save some more brake weight if you converted Porsche's composite rotor to the Elise. It's way lighter than cast iron. Maybe it could be cut down in diameter a bit.
 

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Discussion Starter #7
James A said:
Damn Tony your right there is not much left to modify! Do you do your work yourself?
ARe the RS14 pads Ok on the street I thought they were more of a track pad?
I do some of the work myself but mainly done my a motorsports mechanic. The RS14s are fantastic and fine for the road. The only problem is they need to be quite hot to work really well. Oh, and they have a tendancy to squeel like a pig.
 

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Discussion Starter #8
Stan said:
Tony you sure have done a lot to your Elise! I doubt that a forged aluminum a-arm part will ever show up for the car...since there would not be enough demand to cover the large set up cost and to tie up a huge forging machine. But fabricated light alloy or special steel or titanium piece could be produced by a local race shop using the steel stockers as a model. Maybe convert to an all rod end setup. Using aluminum rod ends, those are readily available. You could save some more brake weight if you converted Porsche's composite rotor to the Elise. It's way lighter than cast iron. Maybe it could be cut down in diameter a bit.
They produced light weight wishbones for the S1 because of the race series but as there is no S2 race series, no wishbones. I am thinking of getting some made in Japan but it will cost BIG bucks...

As far as brakes go, the composite discs will be too powerful for the Elise. I can almost lockup now as it is. Maybe a light weight drive shaft would help. The main thing though is to reduce the centre of gravity, make it as low as possible. This is a mission of mine. At some point I'm gonna replace all the glass to plexi. Also want to house the battery lower down and remove the window mechanisms.

After that you're talking CF clams but this is MAJOR money and not worth it.
 

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>>>They produced light weight wishbones for the S1 because of the race series but as there is no S2 race series, no wishbones. I am thinking of getting some made in Japan but it will cost BIG bucks... <<<

That's what I'm suggesting...I'm sure those weren't forged though...the set up costs would make this prohibitive.

>>As far as brakes go, the composite discs will be too powerful for the Elise. I can almost lockup now as it is. Maybe a light weight drive shaft would help. The main thing though is to reduce the centre of gravity, make it as low as possible. This is a mission of mine. At some point I'm gonna replace all the glass to plexi. Also want to house the battery lower down and remove the window mechanisms. <<<

Yeah ditch the glass!! It's very heavy. That will lower the CG more than lightening a heavy part down low since the glass sits up so high. There may also be a way to get the motor to sit lower. That would certainly help the CG.

How much does your car weigh now and what do you think you can get it down to? Thanks.
 

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Discussion Starter #10
Stan said:
>>>They produced light weight wishbones for the S1 because of the race series but as there is no S2 race series, no wishbones. I am thinking of getting some made in Japan but it will cost BIG bucks... <<<

That's what I'm suggesting...I'm sure those weren't forged though...the set up costs would make this prohibitive.

>>As far as brakes go, the composite discs will be too powerful for the Elise. I can almost lockup now as it is. Maybe a light weight drive shaft would help. The main thing though is to reduce the centre of gravity, make it as low as possible. This is a mission of mine. At some point I'm gonna replace all the glass to plexi. Also want to house the battery lower down and remove the window mechanisms. <<<

Yeah ditch the glass!! It's very heavy. That will lower the CG more than lightening a heavy part down low since the glass sits up so high. There may also be a way to get the motor to sit lower. That would certainly help the CG.

How much does your car weigh now and what do you think you can get it down to? Thanks.
Maybe not forged but much lighter... http://secure.eliseparts.com/en-gb/p_54.html

No idea how much my car weighs my I know I can save another 20 kilos if I ditch all the aircon and the stereo system.

Either way, my car is MUCH lighter than the US model so I know you guys have lots to play with. You've also got more powerful engines so you can concentrate on weight reduction rather than engine mods.
 

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By the way have you changed over to a lighter battery? The drv batteries can be laid out flat and something like a Hawker PC-680 is only about 3 inches thick and weighs about 13 pounds. I'm sure there are lighter options too.

 

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Discussion Starter #12
If I get rid of the aircon and stereo, I will then get the lightweight battery. 20kgs.... very tempting, but HK summer is grueling without aircon. And getting stuck in traffic with no tunes sucks...
 

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Tony

if you have the cash for it you should try to find somebody who is experienced make such parts as the wishbones in titanium.

I know a guy who builds frames in titanium pipes for race bikes and most certainly he could also make Elise- whish bones in titanium. But first you have to find somebody who is able to calculate the equivalent minimal wall thickness required for the different material.

Perhaps Geary can help you, too.

Rüdiger
 

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tonyyoshi said:
I guess not. Is no one else interested in this? Every 1lb you save in unsprung weight is worth 5lbs of sprung weight. If you can reduce the overall weight of your Elise you'll notice a massive difference in handling and acceleration.
Hi Tony,
This is the classic confusion of the effects of unsprung weight and the effects of rotating weight.

Unsprung mass is anything that moves up and down when the suspension compresses or extends.

Rotating mass is anything that turns when the car is in motion.

The main effect of high unsprung weight is that more of an impulse gets applied to the chassis when the wheel hits a bump. A heavier mass requires a greater force to slow it down, and that force comes from the chassis. If the chassis is too light, then you'll bounce the whole chassis in the air. Therefore the heavier your unsprung mass is, the more mass you need in the chassis in order to be able to apply the forces to keep the wheels on the ground. The rule of thumb you quoted should be more precisely stated as "Removing 1 pound of unsprung mass will allow you to remove 5 pounds of mass from the chassis and retain the same ability to rack over bumps, assuming the suspension is re-tuned". The real benefits here are improved tracking over bumpy pavement and improved ride quality, unless you actually remove weight from the chassis.

Another important thing to know about unsprung mass is that suspension elements may not be fully "unsprung." Something that moves up and down the same distance as the wheel moves, is unsprung. Examples include the brakes, the wheel carrier, the wheel, and the tire. Other things move only a fraction of the distance that the wheel moves -- or like the control arms, they move as much at the wheel on one end but do not move at all at the other end. You do not count the full mass of those parts as unsprung. The fraction that counts as unsprung mass is calculated by breaking the part up into chunks and multiplying the motion ratio at that chunk times the mass of the chunk. If you do calculus, you can integrate. For a straight rod like a halfshaft, the unsprung mass would be half the actual mass. For a control arm which has more material at the inboard end, less than half would be unsprung mass.

Rotating mass is what buys you quicker acceleration and deceleration. It has no effect on handling, except to the extent that it is also unsprung mass. Rotating mass in the form of a wheel can affect acceleration and deceleration by up to a factor of two of its real mass. The factor of two comes from the fact that on a car moving at 50 MPH, a point on the tread of the tire is moving at 100MPH: 50MPH in a straight line with the rest of the car, plus 50MPH in a circle around the axis of the wheel. The most obvious place to see this is the point at the very top of the tire, where the motion around the axle is in the same direction as the motion of the car. Points on the tire and wheel that are closer to the axle don't get the full x2 multiplier. My estimate would be a x1.3-1.4 multiplier for a wheel, and a x1.9 multiplier for a tire.

A flywheel turns at a much higher rate than the wheels, although it is usually a smaller diameter. Therefore reducing the weight of the flywheel has a "rotating mass" effect which may have a multiplier greater than 2...it depends on the exact size and gear ratio (each gear will be different!).

Some other things to consider: If you use the wrong material or go too light, the control arm may fatigue and crack. Lightweight parts on bicycles carry a recommendation that they be replaced periodically (every 1-2 years usually) for that reason. Also, control arms are often designed to bend or break in order to save the attachment points or the frame from being damaged. That's an especially important point on the aluminum-framed Elise, because a bent frame or damaged attachment point cannot be repaired. So whoever makes the control arms has to really know what they are doing so that they don't make them too strong or too weak.

Is there really much weight to be saved there? How heavy are the factory control arms?
 

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Discussion Starter #16 (Edited)
You've got to remember the Elise is all about weight. It's been heavily bastardized over the years and is now very heavy, especially the Fed version. I've trimmed over 50 kilos (111lbs) off my car so far. Actually, maybe a bit more now. If you've ever driven a standard Elise next to a professionally stripped one, you'll know what I'm talking about. Forget about the flywheel, been there, done that. Now I have the lightweight one I have much freer revving. I'm not interested in top speed at all. It's all about acceleration and lateral ability.

As far as the weight of the wishbones go, take them all off at some point and weigh them. Then you'll know what I'm talking about. I would advise if you're gonna do it, then change all the bushes to Nylatron. No flex at all after that.

BTW, if you want an interesting article to read about a VERY expensive weight reduction session, read this: http://www.340r.net/technical/weight/weight.htm

Strip, strip and strip some more.....
 

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Hi Tony

Above I mentioned Geary (http://www.eliseparts.com )

He offers these wishbones for the S1 Elise:

They are still made in steel but look lighter than the OE wishbones you still have in your S 2.

Contact him perhaps he can help you, too.



BTW:
I saw that you got a very light titanium silencer.

Is it custom made for you and how much did you pay for it?
Please also inform about its silencing potential. Here in Germany we have severe problems with the police in case we are too noisy.

Cheers

Ruediger
 

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Discussion Starter #18
Hi Ruediger,

I asked Geary about the wishbones a year ago and they are not producing them. He only produced them for the S1 because there was an S1 race series.

The exhaust is not custom, it's Yoshimura. Saying that, they are made to order though. Cost? Thousands of US$....and VERY loud. No where near legal.

Cheers

Tony
 

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Hi Tony

Did you try to convince Geary that there may be a market for such low weight wishbones not only in Hong Kong?
The dimensions for all Elise-wishbones are not that different. Perhaps it may even be possible to modify S1 wishbones for your S2.(If you have an experienced welder to help you)

I already guessed your answer referring the titanium exhaust piping and muffler.

Thank you for replying

Ruediger

BTW
What did you do against oil starvation? You know that this might also be a problem for the k engine when being raced. ( high lateral acceleration )
 
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