363 replies to this topic

[GeorgeBC]

I new some one would comment on that and if i was aloud to have a guess who you would of made my top 5

[VIX]

LOL,

guess I should have expected this....

So, having built and raced some of the very fastest Elise based race cars around the world, I obviously know nothing about ARB's?

OK, O great experts, show me the cars with these wonder setups on them, along with their laptimes so we can all fawn over them.

I'll start:

Snett 300 1:57
Brands Indy 0:47
Cadwell 1:31
Donington 1:08

or perhaps some further afield:

Bathurst 2:15
Wakefield Park 0:59
Eastern creek 1:33
Philip Island 1:56

so, show us what you have?

Fcuk me Elmo, if they're that good I'll 'ave to get one on me Foc-arse!

[Spitfire Engineering]

Consider this,

Makes little odds what steel is used to make an arb , for a given size/gauge they will have almost identical 'stiffness'

So,unless you change the pivot points, etc, one man's 1" Arb will be much are same as another...

Adding blades, etc is all well and good, but do you really need that level of adjustability and at what cost in both money and life?

I am also not a fan or rear Arb's, all they do is make the backend snappy at the limits, and really compromise traction buy unloading the inside rear, (and then some would sugest you have to have an lsd ).

Typically, a 1" Arb is man enough for 99% of users, although forma road car, it's somewhat OTT

Actually, I had Mike Pilbeam run the test on the 1" EP bar (which, if you remember we first developed on my car way back when), and we found that the flat plates at the end twisted causing a falling rate and also depleting the overall rate of the bar. This is why the Pilbeam one can be made lighter but achieve the same rate, as the end plates are a better design and don't twist. Interestingly enough, what we arrived at back then as being the correct rate for a 750kg race Exige on A048's was near as damn it identical to what Mike calculated the ideal rate to be.

"The Pilbeam one can be made lighter but achive the same rate"
You seem to be claiming the EP design was so poor the ends distort Chris? It certainly would not have been part of the design criteria.

You cannot claim (I hope) the Pilbeam is ligher than the CF bar for the same reason?
The reason it is lighter in this comparison is that it less stiff.

[Spitfire Engineering]

Winstar is right - the grade of steel isnt the factor in sizing an ARB to get a specific rate. the main thing is the OD of the tube or bar (given that the other factors are determined by the fit in the car)

the OD is so important as its function in the stiffness v displacement graph is to the fourth power. So go up a few mm and the stiffness increases immensely. the ID makes less difference as the function is OD^4 - ID^4..

this means you can make a bar hollow and have little effect on the stiffness - but you do make it more responsive.

the question isnt "is stiff rate better than a soft rate" the question is "is the rate "right". Grip is destroyed by tyre contact patch load variations and so much of the work we do in defining set-up parameters and testing is around controlling this - this is the driver for getting the rates "right".

my point here isnt to haggle over which bar is better than another but to explain that the springs, bar and dampers need to be well-matched to work together. They also need to be set at a rate that suits the use the car gets, the tyres, the driver etc etc.

there are very good rules of thumb that help us work on the proportion of stiffness that comes from an ARB - both front and back. if Scuffers has had problems with a rear bar then it is likely that the bar was not well-suited to the car set-up.

our set-up suits some people because they buy into the dynamics philosophy i have explained on here - for others they like another approach and thats fine. Money is certainly a factor and the kit we sell isnt the cheapest, partly because we provide 2 bars with all the fittings rather than one!



cheers

Simon

Its all very well buying into a design philosophy but that doesn't necessarily help absolute performance. One thing I have learnt in racing is you need to be prepared to ditch your own ideas, no matter how bright they may have first appeared, otherwise you can get awfully bogged down by them.

I think Simon said DYNAMICS philosophy Chris.

However, for the first time in years I find myself agreeing with you totaly.

……...One thing I have learnt in racing is you need to be prepared to ditch your own ideas, no matter how bright they may have first appeared, otherwise you can get awfully bogged down by them.

[Korkey]

Hello to the origional poster. Some polite questions for you. What makes you think that you have reached the limits of your standard set up? Have you done back to back laps and found that your times are consistent and feel that you can still go faster? And way before you go down the road of chassis tuning have you tried a change of tyre choice or width for example? I see people here festooning their cars with add-ons of many types. I would be very happy to put my almost standard chassis set up stage 2 Turbo against any of these road cars and see just how quick they are or are not. Unless you are going to run the car on a very heavily slanted towards track focus then there is sod all point adding this stuff to your street car............unless you just like the look of it. I like Scuffers. I will not put him on an ignore list..............He KNOWS what he is talking about. Keep your money in your pocket and just enjoy your car. Most so called "improvements" are useless on the road and of very minimal use on the track. Learn how to drive a kart very very fast and then drive a VX. You will be blisteringly quick I assure you. Regards. Korkey

[cnrandall]

Consider this,

Makes little odds what steel is used to make an arb , for a given size/gauge they will have almost identical 'stiffness'

So,unless you change the pivot points, etc, one man's 1" Arb will be much are same as another...

Adding blades, etc is all well and good, but do you really need that level of adjustability and at what cost in both money and life?

I am also not a fan or rear Arb's, all they do is make the backend snappy at the limits, and really compromise traction buy unloading the inside rear, (and then some would sugest you have to have an lsd ).

Typically, a 1" Arb is man enough for 99% of users, although forma road car, it's somewhat OTT

Actually, I had Mike Pilbeam run the test on the 1" EP bar (which, if you remember we first developed on my car way back when), and we found that the flat plates at the end twisted causing a falling rate and also depleting the overall rate of the bar. This is why the Pilbeam one can be made lighter but achieve the same rate, as the end plates are a better design and don't twist. Interestingly enough, what we arrived at back then as being the correct rate for a 750kg race Exige on A048's was near as damn it identical to what Mike calculated the ideal rate to be.

"The Pilbeam one can be made lighter but achive the same rate"
You seem to be claiming the EP design was so poor the ends distort Chris? It certainly would not have been part of the design criteria.

You cannot claim (I hope) the Pilbeam is ligher than the CF bar for the same reason?
The reason it is lighter in this comparison is that it less stiff.

The ends of the EP bar do distort, we tested it. Ages ago, I had Geary make me up a 1" bar to test and we found that it worked well and for quite some time it was exclusive to Hofmann's (they used to be all painted red too to differentiate themselves from the normal EP ones). Geary decided to start selling them on his main site so I started talking to Mike Pilbeam and gave him a set of criteria for a roll bar and sent him an EP bar to run some tests on. On the EP 1" bar you only really use the softest setting on 99% of cars, anything harder is only useful for slicks etc, so I asked for a better range of adjustment (softer and harder than the softest 1" bar setting) and better quality (kept having fitment and finish issues with the 1" bar). Mike found that the EP bar had flex in the fixing brackets so the actual rate was somewhat less than you would expect from a 1" bar and also that the rate was falling because of the flex. The bar you see on his site and mine was what we started using, not sure how different this was from what he sold before he did the testing TBO. I still actually have a 1" bar on my own race car and it works just fine although one day when I'm feeling flush I'll swap it out for a pilbeam!

The CF car is nicely made and I don't expect it suffers from any flex or fitment issues. I just feel its a bit overcomplicated for the purpose and I'm not a massive fan of the idea of blades on cars with lots of roll (although I'm sure you have done the maths and most likely fine).

At the end of the day, car setup is all about getting the nut behind the wheel confident in the car so there will always be differing opinions. For example, Steve A went some 2 seconds a lap faster with the CF bar so its clearly the right setup for him. If you have a pro driver on board you will never find that sort of time in a bar, and you can talk more in absolute terms but for us mere mortals its all about driver confidence.

[2deano5]

Hello to the origional poster.

Some polite questions for you.
What makes you think that you have reached the limits of your standard set up?
Have you done back to back laps and found that your times are consistent and feel that you can still go faster?
And way before you go down the road of chassis tuning have you tried a change of tyre choice or width for example?

I see people here festooning their cars with add-ons of many types.
I would be very happy to put my almost standard chassis set up stage 2 Turbo against any of these road cars and see just how quick they are or are not.

Unless you are going to run the car on a very heavily slanted towards track focus then there is sod all point adding this stuff to your street car............unless you just like the look of it.

I like Scuffers. I will not put him on an ignore list..............He KNOWS what he is talking about.

Keep your money in your pocket and just enjoy your car.

Most so called "improvements" are useless on the road and of very minimal use on the track.
Learn how to drive a kart very very fast and then drive a VX. You will be blisteringly quick I assure you.

Regards.
Korkey

Deep down I know the above is right Korkey and I two enjoy Scuffers posts even if he does come across a bit blunt but I still can't help myslf buying Shiny bits

Deano

[Korkey]

hello Deano. Buying the shiny bits is fine. And I quite like some of them also. But let's get it in perspective. As the OP says his car is a bit worn now. So what about this. He is also a track driver. So go to a track where he can put in consistent times. Take note of the times and conditions. Rain would also be a good thing. Then renew all the bushing maybe shocks etc with standard equipment. Then repeat the above. If the times are faster then he is heading in the right way. Do not destroy the road car for the sake of making it a track car. Even with standard equipment you can do some adjustments. You can also play with wheel rim width. The standard mono tube shocks can be fitted with rising and faling abutments. Giving the ability to trim the cars stance for rake. The castor, camber and toe can all be adjusted. Some weight reduction is not too difficult. The people who put this car together where not idiots where they? This will without doubt be more beneficial than bolting on some steel bars. Korkey.

[chris_uk]

Tbh, id put money on betting 90% of everyone who does trackdays could improve their laptimes just by sitting in a better seating position. To me thats the first and possibly most important aspect of a driver and machines connection.

[Korkey]

Chris. Spot on. I have built my own seat and raised the floor mounted gearshift unit by some 100mm at the front end. Retaining it's origional position at the rear. This brings the gear shift to exactly where I want it in relation to the steering wheel. Further to this I have a shift movement reducer on the gear box which I have designed that also reduces the side to side shift distance. So my gear shifts are small and very fast. Korkey.

[cnrandall]

TOTALLY agree on the seat. not just the position but the way it grips onto you. Its very important to be held by the seat so you aren't clinging to the steering wheel. Feeling the car at the limit is like reading braille... needs to be done with a light touch.

[chris_uk]

I was always taught that you should be 100% held in the seat by the seat and harness. Your arms and legs should NOT ever be used to support your body moving, you feet are there to operate pedals not hold you up, same goes for your arms. Id personally always prefer to be sat as high as reasonably practicable as to not effect COG too much but to me visibility is just as important as sitting propperly.

[Spitfire Engineering]

Consider this,

Makes little odds what steel is used to make an arb , for a given size/gauge they will have almost identical 'stiffness'

So,unless you change the pivot points, etc, one man's 1" Arb will be much are same as another...

Adding blades, etc is all well and good, but do you really need that level of adjustability and at what cost in both money and life?

I am also not a fan or rear Arb's, all they do is make the backend snappy at the limits, and really compromise traction buy unloading the inside rear, (and then some would sugest you have to have an lsd ).

Typically, a 1" Arb is man enough for 99% of users, although forma road car, it's somewhat OTT

Actually, I had Mike Pilbeam run the test on the 1" EP bar (which, if you remember we first developed on my car way back when), and we found that the flat plates at the end twisted causing a falling rate and also depleting the overall rate of the bar. This is why the Pilbeam one can be made lighter but achieve the same rate, as the end plates are a better design and don't twist. Interestingly enough, what we arrived at back then as being the correct rate for a 750kg race Exige on A048's was near as damn it identical to what Mike calculated the ideal rate to be.

"The Pilbeam one can be made lighter but achive the same rate"
You seem to be claiming the EP design was so poor the ends distort Chris? It certainly would not have been part of the design criteria.

You cannot claim (I hope) the Pilbeam is ligher than the CF bar for the same reason?
The reason it is lighter in this comparison is that it less stiff.

The ends of the EP bar do distort, we tested it. Ages ago, I had Geary make me up a 1" bar to test and we found that it worked well and for quite some time it was exclusive to Hofmann's (they used to be all painted red too to differentiate themselves from the normal EP ones). Geary decided to start selling them on his main site so I started talking to Mike Pilbeam and gave him a set of criteria for a roll bar and sent him an EP bar to run some tests on. On the EP 1" bar you only really use the softest setting on 99% of cars, anything harder is only useful for slicks etc, so I asked for a better range of adjustment (softer and harder than the softest 1" bar setting) and better quality (kept having fitment and finish issues with the 1" bar). Mike found that the EP bar had flex in the fixing brackets so the actual rate was somewhat less than you would expect from a 1" bar and also that the rate was falling because of the flex. The bar you see on his site and mine was what we started using, not sure how different this was from what he sold before he did the testing TBO. I still actually have a 1" bar on my own race car and it works just fine although one day when I'm feeling flush I'll swap it out for a pilbeam!

The CF car is nicely made and I don't expect it suffers from any flex or fitment issues. I just feel its a bit overcomplicated for the purpose and I'm not a massive fan of the idea of blades on cars with lots of roll (although I'm sure you have done the maths and most likely fine).

At the end of the day, car setup is all about getting the nut behind the wheel confident in the car so there will always be differing opinions. For example, Steve A went some 2 seconds a lap faster with the CF bar so its clearly the right setup for him. If you have a pro driver on board you will never find that sort of time in a bar, and you can talk more in absolute terms but for us mere mortals its all about driver confidence.

Interesting stuff, thanks Chris.
You have met Simon of course so the maths goes without saying as that is what he really does, usually at the top end. If I go out with him for the day I'm usually out of my depth by the time we hit the bypass.
The blade of course does not take the full load (or should not do) it just trims the rate of the entire assembly, but to match the curves of the two individual components and then in combination so they work in harmony takes quite a bit of maths.
There is no life to a blade, if it is correctly designed to the application and manufactured to spec it should never fail no matter how rough or to what range of movement the suspension is subjected to.
The real beauty for me is it takes 10 seconds to adjust and in increments almost unnoticeable so you can stop every circuit or even every 100m and tweak before everything gets cold.


I say cold, no doubt Simon will appear to tell us the tyre temperature drops as soon as you stop working it, so by the time you get back to the pits you have little useful information.

Pffff

[Spitfire Engineering]

hello Deano.
Buying the shiny bits is fine. And I quite like some of them also.
But let's get it in perspective.

As the OP says his car is a bit worn now.
So what about this.
He is also a track driver. So go to a track where he can put in consistent times.
Take note of the times and conditions. Rain would also be a good thing.
Then renew all the bushing maybe shocks etc with standard equipment. Then repeat the above. If the times are faster then he is heading in the right way.
Do not destroy the road car for the sake of making it a track car.

Even with standard equipment you can do some adjustments.
You can also play with wheel rim width. The standard mono tube shocks can be fitted with rising and faling abutments.
Giving the ability to trim the cars stance for rake.
The castor, camber and toe can all be adjusted.
Some weight reduction is not too difficult.

The people who put this car together where not idiots where they?
This will without doubt be more beneficial than bolting on some steel bars.

Korkey.

I'm not sure if anyone has suggested just bolting on some steel bars, if so it certainly was not from CF, it was explained in some length that the setup is a combination of ARB, damper valving, springs etc.
Rather interesting, you mention the standard setup as supplied by Lotus, the CF puts the springing quite close to standard.
Have you ever tried one by the way? not a challenge just a question.

[SteveA]

At the end of the day, car setup is all about getting the nut behind the wheel confident in the car so there will always be differing opinions. For example, Steve A went some 2 seconds a lap faster with the CF bar so its clearly the right setup for him. If you have a pro driver on board you will never find that sort of time in a bar, and you can talk more in absolute terms but for us mere mortals its all about driver confidence.

Hit the nail on the head there

I put the time found down to the fact I was more confident in the setup. The old setup was a bit soft and due to this I didn't feel like I could push it any more than I was. I'm sure a professional racing driver would have gotten 90%+ of the time I found even on the old setup but as you say this setup suits me and allows me to push harder without feeling I'm pushing too far.

[cnrandall]

Interesting stuff, thanks Chris.
You have met Simon of course so the maths goes without saying as that is what he really does, usually at the top end. If I go out with him for the day I'm usually out of my depth by the time we hit the bypass.
The blade of course does not take the full load (or should not do) it just trims the rate of the entire assembly, but to match the curves of the two individual components and then in combination so they work in harmony takes quite a bit of maths.
There is no life to a blade, if it is correctly designed to the application and manufactured to spec it should never fail no matter how rough or to what range of movement the suspension is subjected to.
The real beauty for me is it takes 10 seconds to adjust and in increments almost unnoticeable so you can stop every circuit or even every 100m and tweak before everything gets cold.


I say cold, no doubt Simon will appear to tell us the tyre temperature drops as soon as you stop working it, so by the time you get back to the pits you have little useful information.

Pffff

I have every respect for Simon's work, clearly a very bright guy. My Maths is terrible so I take the other approach which is lots of track testing, essentially educated trial and error (which is still very hard to beat if the driver knows his onions). Taking the practical approach, I struggle to see how the blade setup would give a linear distortion and rate at high angularity. Would be interesting to model it and see the results, I might be completely wrong. The CF kit does look nicely made and i'm sure the lifespan is fantastic. Its the rear bar that I struggle with as I've tried them on a number of occasions and find they load up the tyre to aggressively and don't allow it to reach its full grip limit. Maybe it responds to different driving style?

[Nikov]

I have Hofmanns Nitrons and a Plans adjustable ARB. I'll be changing to the Cornering Force setup soon. Maybe Simon would like to data log the before and after so there can be a real world comparison not just hearsay?

Edited by Nikov, 14 March 2013 - 11:49 AM.

[techieboy]

Sacrilege. That's not the .org way. We don't deal in facts here. We only deal in subjective feelings and levels of bling (please Simon, change the colour of the ARB's ).

[chris_uk]

Change it to chrome! Lol

[Nikov]

Sacrilege. That's not the .org way. We don't deal in facts here. We only deal in subjective feelings and levels of bling (please Simon, change the colour of the ARB's ).

I know what was I thinking? Perhaps best if I disappear into the ether again