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Craig Powers
23-12-09, 21:57
A thread has just been started about how to measure the roll resistance of a Monoshock front end, presumably on a Force. I don't want to hijack the topic before its has been answered, so I've started an different thread instead.

*******

The Forces seem to have a VERY stiff front end and it is normal to see them lifting the inside front wheel. This is counter to the technical books which suggest that weight transfer to the outside wheel leads to less overall grip. However there isn't much you can do about weight transfer, the faster you corner the more you get.

What interests me is the apparently large difference in front vs. rear roll resistance of the Forces.

Having seen Messrs Hemmingway and others in action, the Force cars work VERY well. But why?

Craig Powers

bill chaplin
23-12-09, 23:04
A thread has just been started about how to measure the roll resistance of a Monoshock front end, presumably on a Force. I don't want to hijack the topic before its has been answered, so I've started an different thread instead.

*******

The Forces seem to have a VERY stiff front end and it is normal to see them lifting the inside front wheel. This is counter to the technical books which suggest that weight transfer to the outside wheel leads to less overall grip. However there isn't much you can do about weight transfer, the faster you corner the more you get.

What interests me is the apparently large difference in front vs. rear roll resistance of the Forces.

Having seen Messrs Hemmingway and others in action, the Force cars work VERY well. But why?

Craig Powers

Strange that ??? must be Somerset luck ! And thanks for your kind comments earlier Craig

dennis.doyle
02-01-10, 15:43
I think the answer is "a chair" - sidecars (& trikes) aren't allowed 4 wheels whereas racing cars must have 4.

Given that, perhaps it's best to make the best of a bad job, ensure that the useful (outer) front wheel is always on the outside of the bend & the useless (inner) one is not contributing any drag?

Alternatively, perhaps it is just the Somerset luck (& possibly cider).

redturner37
02-01-10, 20:09
I think the answer is "a chair" - sidecars (& trikes) aren't allowed 4 wheels whereas racing cars must have 4.

Wrong Dennis, sidecar outfits and 3 wheelers can have 4 wheels, provided that......................................

Craig Powers
02-01-10, 20:15
I think the answer is "a chair" - sidecars (& trikes) aren't allowed 4 wheels whereas racing cars must have 4.

Given that, perhaps it's best to make the best of a bad job, ensure that the useful (outer) front wheel is always on the outside of the bend & the useless (inner) one is not contributing any drag?

Alternatively, perhaps it is just the Somerset luck (& possibly cider).

OK lets also talk about other Monoshock hillclimb / sprint cars...
Goulds, Predator & Raptor.

I have been looking at Youtube footage of the Raptor at Kames. As I understand it the Raptor is a monoshock without any Belvilles, so rigid in roll.

There was no evidence of the front wheel lifting even through the tight fast corners of Kames. I assume front / rear roll resistance is more closely matched than on the Forces. That's more like I would expect....

...but as we said, the Forces are very fast. 52 secs for an 1100cc at Harewood is testimony to that.

stevie m
02-01-10, 22:38
I think in the latest version of Competition Car Suspension there's a section on "monoshock design" with the mathematics to work it all out.Allan Staniforth and Ian Scott got credited by the SAE for their work on this type of suspension system.I'm pretty sure,IMHO that radial tyres help monoshock suspension no end but I may be wrong:confused:

wight jr
03-01-10, 12:14
just a little bit of three wheeling, mainly on bumps.

Double G
03-01-10, 13:03
The Force is very soft at the rear to give good traction and has no rear roll control. So as the car rolls it picks up a front wheel.

Now that traction control has been banned in F1 most cars are running much softer at the rear. We see the same thing particularly the McLarens.

dennis.doyle
03-01-10, 19:04
just a little bit of three wheeling, mainly on bumps.

Yes, but that bend looks neither bumpy nor spectaculary cambered.

Whilst what GG says is a good rationale for running a stiff front it still doesn't get over the objection that once one wheel has left the ground no further weight transfer at that end is possible, so you shouldn't really be doing it.

However, the times you & the Force's do suggest we should all be doing it.

So, I stick to my guess that with your (as close as possible) "infinite" front roll stiffness setup (no belvilles) you treat it as a sidecar, but one where the steered wheel is always on the outside of a bend.

What I don't like about my guess is that such vehicles should have great difficulty turning into steeply cambered, bumpy haripins, e.g. Baitings Dam. The recieved wisdom there was to disconnect the front ARB in order to negotiate the bends.

Are Forces/Predators/Raptors happier at fast, flat, open stuff or slow, bumpy, tight stuff?

To summarise: None of this makes any sense, so, in all probablity, it is actually some form of black magic:)

Major Mallock
03-01-10, 21:19
The object of all suspension and that includes ARB's is to manage balance front to rear and control the slip angle of the tyre, front particularly. If the car front inside wheel is in the air, it does not matter as long as the tyre stays upright and max grip on the road, AND there is no understeer or oversteer. You also need very very good shocks because stiff ends patter! Incidently even if the inside wheel is in the air, you can still get weight transfer, it just adds to the torsional forces in the chassis reacting from the rear axle.
Maybe I am just a believer in the preachings of Staniforth. For Hillclimb, keep the springs as soft as possible -stiffer at the front for grip at the rear - and try to keep both front wheels on the ground and the inside one contributing even a little.

But Dennis is right its a black art. (nice to hear from you again Dennis - Happy New year to you -you to Craig)

Craig Powers
03-01-10, 22:43
If the car front inside wheel is in the air, it does not matter as long as the tyre stays upright and max grip on the road,

I guess this is where I get very confused due to the large amounts of static negative camber used for radials. Without any roll I fail to see where the camber change comes from to bring the (front) wheel vertical. I assume that radials don't really need to run vertical to generate max grip, and hence donít need the camber change. There WILL be camber change once the car is on three wheels, but you have to have enough grip in the first place to get into the situation! I think that most of the monoshock cars run radials.

Back to crossply's, which many of us run. I reckon that camber control is much more important here, to keep the outside / loaded wheel as vertical as possible, as Major Mallock says. Nearly all texts suggest that the grip of tyre falls off as it takes more load, i.e. as weight transfer increases, so 4 wheels on the deck should be better than 3.

You also need very very good shocks because stiff ends patter!

Yes, although the monshock springing can still be quite soft even with huge roll resistance. The beauty of monoshock is that it is easier separate out roll from normal suspension travel. Other than that I don't really see the benefits (except for minor weight savings).

Also an A/R bar is easy and quick to adjust or even to disconnect. Not so with monoshock.

What I canít quite get my head around is the reaction of a monoshock car when the car rides a curb.

Maybe I am just a believer in the preachings of Staniforth. For Hillclimb, keep the springs as soft as possible -stiffer at the front for grip at the rear - and try to keep both front wheels on the ground and the inside one contributing even a little.

Yes, all sounds good, and is the same in most respected texts, not just Staniís.

Happy New year to you -you to Craig)

Happy New Year Phil. Thanks for the work done to date, and Iíll be in touch re: the A/R bar calculations.

Craig

griffiths_l
05-01-10, 21:42
Hi Craig,

I have also been somewhat confused about the working of a monoshock. Having worked through the Gould weight transfer equations in Stani's book for both my peugoet when I had that and now the Hornet, I could not understand how very high roll resistance at the front would do anything other than transfer weight to the outer front during cornering. With an infinatly stiff front end this effect would be very large, overloading the front outer tyre and hence understeer!

I had a conversation about this with Steve Owen and was informed that its not as clear cut as roll being 100% seperate to pitch. When data logged you get movement of the monoshock even in a pure roll condition. I have however yet to get my head around how this plays a part!

Problem is anyone who knows how they work keeps stum.

yobdab
05-01-10, 22:21
If you have not already done so can I suggest that you study a copy of a Dallara manual. Any modern year will do. You can download one, 2002 from the BRSCC F3 website the address of which is the obvious.

Hopefully it will become a little clearer. According to how the rocker is set up the roll resistance can go from 200% of the oneside stiffness to 100% to infinite at the three points of the corner, or turn in, mid point and exit.

Playing around with the degree and point of these transitions can change the handling characteristic through the corner and thus enhance turn in and traction out.

megari
05-01-10, 22:30
I am very much a novice at trying to understand this stuff but what grabbed my attention in Staniforth was the description that on corner entry a monoshock will push the inner wheel down rather than lift it as with an ARB. So if the roll resistance is not set so hard as to lift the inner for too long maybe that negates the lifting downside? Not smart enough to calculate if this is a real effect though :mad:

wight jr
09-01-10, 12:43
Richard 2t4t has updated (http://electricracing.dnsalias.com/Raptor.htm) there are lots of pics at kames into and around the corners so you can see how the car is on load. allso the is string on the side pods, engine cover, rear wing and tub, just so that i could check the air flow..

wight jr
24-01-10, 20:31
and its rear end

wight jr
24-01-10, 20:47
another picture of the front rocker. and a picture of the engine installation, its well low..

SteveSlowboy
24-01-10, 23:10
Graeme, What the f%$£ is the raptor doing on it's side like that! Is this space saving or some weird and wonderful roll-centre calculations gone wrong? lol

wight jr
25-01-10, 10:08
It was just to get another view for a photo or 2.............

Craig Powers
25-01-10, 12:27
Graeme, what engine type & capacity is the car? (I'm assuming it is a 'Busa.)

wight jr
25-01-10, 12:37
ye Busa 1600, but we have mounted the engine on tube frames so bike engine options are easy to do with out having to upset too much. The tub has a lot of hard points on its rear end so car engines and the likes can be a option i you get fed up with the bike engine!!!

Double G
26-01-10, 00:12
The back end looks very clever...is that some form of damped roll control?

wight jr
26-01-10, 10:00
its pitch control, undampened...

wight jr
26-01-10, 10:08
http://electricracing.dnsalias.com/ER%20gallery%201/Raptor/Raptor%20Build/index.html
is up dated with more Pictures of the Raptor with its body off. thankyou Mr 2t4t...

dennis.doyle
26-01-10, 14:15
its pitch control, undampened...

Is the cross-wise tube between the rockers a hydraulic ram then? I could see it raising the rear ride height as it was pressurised.

wight jr
26-01-10, 15:19
nope ..........

team knifedge
26-01-10, 15:28
probably contains a lightweight spring, with the bumpstop then controlling ride height a higher speed ?

CNHSS1
26-01-10, 15:33
i assume its a spring that doesnt come into play in roll, but only in large bump such as hard launch or high speed extra DF from the rear wing? if so, whats the extra rate as a percentage of the coilover rate? is it a small 'helper' or a big increase?
car looks stunning :cool:

DaveK
26-01-10, 15:35
Dennis

As aero takes effect and pushes the back of the car down, the tube compresses until it hit the bump rubber, this effectively raises the rear spring rate for ride height control, but allows the rear whhels to still have bump travel, if you look at the forces , goulds etc you will see they all have a variation, also know as a third spring .

Dave

dennis.doyle
26-01-10, 17:25
Dennis

As aero takes effect and pushes the back of the car down, the tube compresses until it hit the bump rubber, this effectively raises the rear spring rate for ride height control, but allows the rear whhels to still have bump travel, if you look at the forces , goulds etc you will see they all have a variation, also know as a third spring .

Dave

A third spring makes a lot of sense, but if it were just a spring I'd expect to see just a spring, yet it looks telescopic & has a gaiter. I'm probably wrong but still feel there is more to it than that.

If it had been a ram though, perhaps we could have enjoyed seeing the Raptor dancing to the start line?

CNHSS1
26-01-10, 17:42
If it had been a ram though, perhaps we could have enjoyed seeing the Raptor dancing to the start line?

this sort of thing? :D

not 'active ride', more 'Pimp my ride'...

dennis.doyle
26-01-10, 18:26
Yes & no.

I was wondering if the Raptor had "active ride" but I was going into orbit imagining those pimped up thingies if you had good design intentions but got the feedback/delay calculations a bit wrong.

Double G
26-01-10, 23:19
No-one takes anything seriously any more....

CNHSS1
26-01-10, 23:38
apologies chaps:o

Filmstar
27-01-10, 09:53
I went to a lecture given by David Gould at Warwick University a few years ago and his thoughts on design of a hillclimb racing car were :-

The limit on weight transfer allowance is the torsional stiffness of the chassis.
Anti squat does not help performance in limiting pitch.
Chassis problems show up more in the dry than the wet.
Centre of pressure (downforce) to be under the centre of gravity.
Does not think side pods work with the 40mm ride height limit.
Racing cars are basically three wheelers when cornering.
Front of the car should be extremely stiff in roll, and relatively compliant in bump.
The front should have limited movement.
No droop on the front suspension.
Pre load is a good thing on the front suspension.
Load up the front tyres.
Understeer can be caused by too little or too much front load.
Monoshock movement 2.5mm in roll.
GR55 1g of downforce at 100mph.
Roll at the rear controlled at the front.
Rear to be compliant.
Keep polar movement to a minimum.

The interesting one to me was "racing cars are basically three wheelers" he explained this further by a three legged stool is stable whatever the floor is like and a three wheeled car is likewise stable on uneven hillclimb tracks with lots of camber etc. The additional benefit is that the front outside wheel has more load on it which increases the temperature and grip - an aside he said hillclimb cars never get enough heat in the tyres.
(This is confirmed by my experience as I have found that my tyres only get a core temperature get in excess of 40 deg C on rare occasions,this is hardly a heat cycle for a racing tyre which only really starts to work at 80 deg C.)

A monoshock is the easy way to fit the design philosophy of Gould as it ticks most of the above boxes, interesting the torsional stiffness of the GR55 is in excess of 20,000 ft/lbs per degree - if your car is below 2,500 ft/lbs per degree you will have problems with the first of Goulds design issues as the chassis flex is the control in roll.

GG I hope this is serious enough for you.

wight jr
27-01-10, 11:28
that about sums it up.............

wight jr
27-01-10, 11:59
[QUOTE=dennis.doyle;32569]A third spring makes a lot of sense, but if it were just a spring I'd expect to see just a spring, yet it looks telescopic & has a gaiter. I'm probably wrong but still feel there is more to it than that.

with this car being light you need to stop the wings from digging the car into the ground,(the car can double its weight @ quite a low speed) yet have complient suspention , so the car can move around at low speed and when the wings come into play the pitch control bump rubber keeps the car at a decent ride hight, the front has the same idea but because its a mono shocker its control is with a bump rubber on the damper

Craig Powers
27-01-10, 12:01
Excellent post Filmstar. Illuminating.

redturner37
27-01-10, 14:41
Excellent post Filmstar. Illuminating.
Illuminating, thats his halo glowing.....

dennis.doyle
27-01-10, 17:31
Just like to say thanks for taking the time & having the patience to respond to the questions, guesses & speculations.

Double G
27-01-10, 22:00
GG I hope this is serious enough for you

Absolutely...:p

CNHSS1
28-01-10, 10:43
Anti squat does not help performance in limiting pitch.
.

superb reply Filmstar, very very informative :cool:
i have a question re the anti squat point, my understanding is that pitch is nose high, tail low situation on launch and hard acceleration generally, and doesnt refer to roll (such as experienced whilst cornering) at all. If my assumption is correct, is Gould suggesting that work to introduce 'anti squat' geometry into the rear suspension (generally raising of forward lower wishbone mounting on rear wishbones) isnt worth doing?

hope my Q makes sense (does in my head :o)

cheers
CNH

wight jr
28-01-10, 11:00
A cars pitch is its angle too the road, the down side of anti squat is when you come off throttle it can ineffect lower the rear end,

Filmstar
28-01-10, 11:53
The simple answer as I see it is -yes- I agree with your comment.

There is currently a spat going on in Racecar Engineering between Danny Nowlan (creator of ChassisSim) and Mark Ortiz over the effect of anti squat I don't know if it's available on the net but it is in March 2009 and September 2009 if you get the articles they will certainly cure any insomnia you may have and test your maths.

BigYin
28-01-10, 12:24
superb reply Filmstar, very very informative :cool:
i have a question re the anti squat point, my understanding is that pitch is nose high, tail low situation on launch and hard acceleration generally, and doesnt refer to roll (such as experienced whilst cornering) at all. If my assumption is correct, is Gould suggesting that work to introduce 'anti squat' geometry into the rear suspension (generally raising of forward lower wishbone mounting on rear wishbones) isnt worth doing?

hope my Q makes sense (does in my head :o)

cheers
CNH

This should explain the basic terms of vehicle orientation: http://en.wikipedia.org/wiki/Flight_dynamics

What's more the pictures even move!

CNHSS1
28-01-10, 12:29
Filmstar
yep, have read them with interest although does seem to have become a bit of a slanging match

BigYin
yes that was my understanding of the dynamics, so pitch is fore and aft and not allied to roll in the example used.

GWJ
i assume that your 'aero loading' bumpstop device helps to stop the car squatting excessively so the normal geometry anti squat methods arent needed or used?

Filmstar
28-01-10, 12:55
Movement in pitch due to acceleration seems very small as you will see from Nolan's article the pitch movement of the F3 car from the data logger is only approx 1mm, my uneducated view is that when you look at the moment on a single seater the weight transfer is not that great due to the low centre of gravity. With such small movements it may be Gould's view is that the movement is small in comparison with the large aero movements due to there being 1g of downforce at only 100mph, which I would guess is 10 or 20 times the movement due to acceleration, therefore say you have 20% anti squat the effect is extremely small by comparison to the aero.

I agree with your comments over the spat between Nowlan and Ortiz, I must say the finer details go above my pay grade.

I think GWJ rubber bump stop acts in principle just as any third spring would - but no doubt he will confirm that - and I bet Massa wishes Brawn used a rubber one rather than a conventional coil spring.

CNHSS1
28-01-10, 13:12
ah, that makes sense. Im applying principles to a car 650kg+ rather than a featherweight single seater, and squat has been an issue which adding anti squat geometry changes did help, so was confused as to why DG thought it was of little value.

in my case its not just the finer points...

Craig Powers
28-01-10, 14:33
Filmstar,

Did David Gould discuss tyre types and their characteristics during his presentation?

I am interested in applying some of these ideas to my OMS 1100 but realise that most of the monoshock cars are running radials with significant static negative camber. I am running cross plys with very little camber. For 2010 I am trying to manage camber change via A/R bars but had been worried about excessive transient weight transfer at the front and its impact on understeer.

The educated opinion (front stiff in roll, rear soft) coincides with Steve Owen’s advice to me. He advocates stiffening up the front and dropping the rear to as soft as possible. OMSs don’t run A/R bars as standard so this can only be done with the springs. Like DG, Steve Owen's advice is likely to relate mainly to the hills because this is where he concentrates his efforts. I do a mixture of both hills and sprints, so will probably end up with a compromise.

Craig Powers
OMS2000m ZZR1100

wight jr
28-01-10, 15:36
only problem with doing that with just springs is you dont end up getting the pitch change, fit a very stiff ARB

Filmstar
28-01-10, 15:37
Simple answer is no he didn't - excuse the pun but tyres and the use thereof is a bit of a black art.
The easy one of his comments which I think is worthwhile looking at is the zero droop, this in effect adds roll resistance to the car set up as you are obviously trying to pick up the inside unsprung weight.

wight jr
28-01-10, 15:41
aswell as having the leading front wheel loaded with out having to wait for the chassis too lean over.

Filmstar
28-01-10, 17:39
Craig, one thing to do before you radically change the set up is to check the torsional stiffness of your OMS, I think there was a reason for that to be the first thing Gould talked about and it was that it you don't have a super stiff chassis that type of set up wont work.
Am I correct that the 2000M is a space frame, if so it is unlikely to get anywhere near the torsional stiffness of the Goulds and his 2,500 ft/lbs per degree was for a normal racing car not necessarily one with such a highly stressed set up.
The limit on weight transfer being determined by the chassis not the designed set up, in other words your chassis will twist before the ARBs are working correctly.

I would start with the easy to do (and undo) items first and alter things progressively. Putting stiffer springs on alters the handling bump as well as roll whereas a monoshock separates bump from roll as you know. Limiting the droop increases the roll resistance and does not affect the handling in bump.

Yobdab, who has forgotten more about racing cars than most of us know, commented elsewhere on this Forum about monoshocks stated that the Dallara was so stiff that the front ARB could control the rear of the car without this stiffness it won't work.

Mike.

Radical
28-01-10, 21:49
Craig, one thing to do before you radically change the set up is to check the torsional stiffness of your OMS, .

You beat me to it, The flex in the chassis would remove the theoretical advantages.

Craig Powers
28-01-10, 22:38
Craig, one thing to do before you radically change the set up is to check the torsional stiffness of your OMS, ...in other words your chassis will twist before the ARBs are working correctly.


Don't worry gents, I wasn't trying to stiffen that car by anything like that degree. I am aware of the limitations of a S/F chassis compared to a carbon tub, and also aware that other things will flex if you push the car hard enough e.g wishbones.

I am merely trying to deal with the front roll that is obvious from head-on photos taken at Harewood last year. My concern is camber control in roll.

My initial thoughts are to add ARBs front are rear and drop the springing to give conventional wheel freqs in the 160~180cpm region front and 135~150cpm rear. Mine are currently much higher (front > 200cpm).

When I started thinking in earnest about weight transfer and relative front/rear roll resistances, that is when I started the thread about monoshocks, which has been very interesting. It's been excellent that so many knowledgeable people have contributed.

I'm still uncertain how my experiments will go with the ARBs but I will probably keep the springs rates as they are for the moment. I can always disconnect the ARBs and I will know that the car works. It handled fairly well in 2009.

Regards,
Craig Powers

Filmstar
29-01-10, 09:26
That's why I suggested a first move at limiting droop to nil it can be achieved by putting a stop on your bellcrank and gives you the unsprung weight as anti roll resistance.

SteveSlowboy
29-01-10, 10:02
Craig,

I agree with Filmstar about limiting droop - I've done this on my SF2 (which appears to have almost identical front suspension layout to the 2000M) and the zero droop I'm running has improved things. Admittedly, this is in conjunction with the GWR designed bellcranks (giving a bit of rising rate) and specially built Nitrons that were specc'd to suit.

Steve

Double G
29-01-10, 11:32
A zero doop set-up on a spaceframe chassis will work really well. It was one of the tricks on my Westfield that no-one bothered copying - mainly becuase you don't get there by fitting shiny expensive new parts so it obviously can't be important....:)

DaveK
29-01-10, 11:58
GG

Some quick Caterhams i know of also use this same feature, but as mentioned if you cannot see it then people don't know to copy :D

wight jr
29-01-10, 12:14
you just need too watch cars as they get jacked up................

Filmstar
29-01-10, 14:15
There you have it Craig, GWJ, Dave K, Double G, SteveSlowboy and me all agreeing on something now that's a first! so get your thinking cap on and work out how to get zero droop on your OMS with out altering bellcrank position and off you go for lots BTDBTDBTD's in 2010.
If it works thank us otherwise it was one of the others idea not mine!

SteveSlowboy
29-01-10, 15:39
Craig - or cross GWR's hand with some silver and procure a set of his modified bellcranks...

For info, before I got the Nitrons fitted, I turned up a couple of spacers for the top spring seats so that I could run zero-droop with the old (original) AVO dampers.

Craig Powers
29-01-10, 18:11
This thread has been a real eye opener because it has contradicted much of the stuff Iíve read and believed over the years. The previous wisdom was that 4 wheels on the track will always give more grip than 3 wheels. Also that excessive (transient) weight transfer at the front car generally causes understeer / reduced grip as the tyre load is increased.

Perhaps all the stuff in the books is still true for car on a smooth track with tyres up to temperature, but clearly we are playing a different game in hillclimbs.

A common phrase is Ďall things being equalí and it is a hypothetical tool that we all mentally use when comparing one situation with another.

My realisation is that we canít compare a hillclimb car with a circuit car because tyre performance is very much different, because tyre temperatures are very much different. So Filmstarís advice from DG about using the weight transfer to load the tyre to increase its temperature is an eye opener. I'll treat my technical books with caution from now on.

That said I will tread this path with care. I wonít be stiffening the front with a super strong ARB. A mild ARB and zero / minimal droop seems a good way to go (at first).

The zero droop approach to aid weight transfer strikes a chord with me. A friend who drags bikes uses the technique, of a fashion. He straps the front forks right down with rachet straps so that the front is lifting dead weight as he launches off the line. Itís interesting how these techniques get used in different guises.

Thanks to all who contributed in this thread. Iím looking forward to digesting and understanding this topic over the next 20 years.

The thread isn't dead yet....keep the info flowing!

Craig Powers, OMS2000m ZZR1100

wight jr
29-01-10, 18:24
one thing that has not been adressed is driving style, 1 driver could be having under stear and another might not, the amount of drivers that iv seen braking for a corner then see that they have slowed too much and give throttle a wee jab just before turn in, a nice way to unload the front tyres......................

CNHSS1
29-01-10, 18:27
Great thread :) ive learnt loads, cheers.
would agree with what you say re all the books and info, but i think a post earlier hit the nail on the head re tyre temps, even though we are using soft rubber, its rarely up to an optimum temp even by the end of the run (really only relying on the semi-cured nature of the compound). The methods mentioned by GWJ, Filmstar etc are ways of getting around that and adding more tyre temp than would otherwise naturally be available in the time allowed. I think should we do a longer hillclimb, such as they do in Ireland or France, Czech rep, Italy etc, where the tyre temps were possible, maybe the tweaks mentioned either wouldnt be necessary or at least not to the same degree.
keep up the good work you clever types:cool:

AshM
29-01-10, 18:33
Think of it as the current flavour of the month. At some point someone will come along, talented, deep pockets, plenty of testing and rewrite the rule book with a new setup on how cars grip/handle/perform etc.

Everyone else will follow along and that will be the new flavour.

Good chance it will be different to what we have today.

Filmstar
29-01-10, 19:24
A simple fundamental of car set up is the more compliant a car is the easier it is to drive, and as a driver you become more confident in the car and go faster. This I think was the basic premise of Allan Staniforth, and in his books the normal set up is relatively soft on bump/wheel frequency and firm in roll which leads to a car that is compliant and easy to drive. To a certain extent any books/engineer authors are not going to give away trade secrets 'cos they cost an awful lot of money to acquire, such books are biased towards racing rather than our niche sport with its own problems to overcome.

Most teams will agree that the stiffer the car the faster you go overall but and it's a big but you've got to have the talent to drive a car which is harder to drive and I for one will dream that I have that talent but in reality know otherwise.
GWJ can set the car up in that manner and drive the dam thing fast, the rest of us can only try to be that good.

John Village said that when he sells a car it is set up as per the book and although the car could have won championships the purchaser does not get the benefit of hours of testing he and his drivers carried out - so be warned when buying from a professional outfit.

The zero droop idea was used by certain teams in F3 in the mid 1980's but no one talked about it at the time as it was giving an advantage away to the opposition, it has seeped out over the years to now be widely used.

wight jr
29-01-10, 19:30
i remember David Grace saying to me, get the car too 90% but know and drive it at 100%

Devon Chard
29-01-10, 20:30
And you did!!!:D:D:D

Hemsport
29-01-10, 20:31
Many a true word spoken in gest. :D

johnbull
30-01-10, 00:28
But would the zero droop theory even apply for circuit racing ?

We did both last season and will be doing both again this season so we really need to find the good set up for both with as few changes as possible.

We have always used the ARB up front on circuits but not on the hills, using the argument that a bit of roll may make the car react slower but it also gives more grip.

The previous car which we built ourselves was a space frame job which used to twist like a piece of chewing gum but it was glued to the road and impossible to spin. This new one has a CF tub and has never inspired the same sort of confidence in my son who drives it. In fact it is only after a year of racing it that he is finally getting the sort of times he got with the old car.

whimsy
01-02-10, 12:10
Just for info - Mark Ortiz's Feb 2010 chassis newsletter has an excellent piece about running suspension with droop limitation.

To subscribe - contact Mark on markortizauto@windstream.net

The works Pilbeam MP82 - and some others - ran with adjustable tie rods intended to limit front suspension droop. I didn't use it on mine but maybe Paul Ranson can throw some light on how well it worked?

Andy

Andy

PumaWestie
02-02-10, 21:20
A zero doop set-up on a spaceframe chassis will work really well. It was one of the tricks on my Westfield that no-one bothered copying - mainly becuase you don't get there by fitting shiny expensive new parts so it obviously can't be important....:)

Is that what you think? Most knew but thought you were mad! :p If you think non-one knew about yours because they couldnt see it, how do you know we didnt have it? :rolleyes:

AshM
02-02-10, 22:20
There wasn't much we missed !

AshM
02-02-10, 22:58
Or that much worth copying !






(said with tongue in cheek)

Double G
03-02-10, 16:54
Charminggg....:p

Joshua
28-05-10, 21:20
Craig,

Since a few months have gone by since all the above was discussed, have you tried any of the suggested setups this year? Any improvements re. handling?

This year I am slowly moving to the "UK" setup as you can call it and things seem to be improving as we had an overall win last Sunday braking the hill record.

Its the orange car at 1:55. As you can see from the video our road surfaces are unique to say the least!!! Some of you may recognize the red car before mine which is a reynard cosworth and used to belong to Terry Holmes in the UK.

http://www.youtube.com/watch?v=raPSMC545zI

carl talbot
29-05-10, 11:28
superb result .
Never mind the 'unique road surface'
I really like the unique driver safety features in the form of 'people barriers'
:eek:

kevham
29-05-10, 12:49
Ignore this post - I didn't read the whole thread.

redturner37
29-05-10, 13:17
superb result .
Never mind the 'unique road surface'
I really like the unique driver safety features in the form of 'people barriers'
:eek: and it looked like most of the population were there.........

Joshua
29-05-10, 13:20
and it looked like most of the population were there.........

At least they make the walls softer!!

There was deinately quite a turnout of spectators........most I've ever seen at a local hill climb!

Craig Powers
29-05-10, 13:23
Craig,

Since a few months have gone by since all the above was discussed, have you tried any of the suggested setups this year? Any improvements re. handling?



Front & Rear A/R bars have been fitted. The work was done by Phil Major (Major Mallock on this forum). Phil made a trial bar for the front that we both reckoned would be a bit too stiff. The bar runs across the car between the front chassis rails and is shorter than the width the tub, and the shortness of the bar makes it torsionally very stiff. Nevertheless I decided to give it a try on the basis of this thread i.e. stiff front end, promote weight transfer, get the front tyres working.

Once I had dialled in a bit of rear A/R bar to neutralise the understeer, I found that I could push the car harder than last year. The car is a bit twitchy but handles fast corners better. The car is different to drive and I am still learning.

So far I have been out 5 times and despite various tech problems the car has gone well, with 3 Fastest Time of Days at lesser clubbie meetings.

One feature of the handling is that the car will JUST lift the inside front when pushed hard. See photos from 3-Sisters & Aintree sprints.

Craig

Joshua
29-05-10, 13:30
Thanks for the update. Very useful info.

So with just the stiff front A/R you had understeer but cured it by using a rear A/R aswell??

Rescue Dude
29-05-10, 13:45
I really like the unique driver safety features in the form of 'people barriers'
:eek:

It doesn't look particularly safe does it. :eek:

Craig Powers
29-05-10, 13:45
Thanks for the update. Very useful info.

So with just the stiff front A/R you had understeer but cured it by using a rear A/R aswell??

Yes, the first time out was at Harewood Practice. I was experimenting with various permutations : no A/R bars (a reference point, same as last year); front A/R only, then front + rear. I had very limited numbers of runs but arrived at a set-up that felt OK.

Front only A/R bar had fairly serious understeer exiting Farmhouse bend. Some rear A/R cured this.

3-Sisters was a better trial because I had more runs. Stiffened the rear bar a bit more and modified my tyres pressures, taking 1 psi out of the fronts to make them 13.5psi Front & 13psi Rear. I have continued with this set up ever since.

Aintree gave me an effortless personal best but I had to retire after 1 run due to an oil leak. I am confident that I would have improved more later in the day because the car was in the sweet spot. The car is totally different to last year.

I took 1.5 secs off last yearís PB at Oliverís Mount and was able to lean on the car much more through the top section.

I am running the same type of x-ply Avons as last year with same camber. About ľ to Ĺ deg neg on the front, zero on the rear.

Craig Powers
29-05-10, 14:13
To put the recent thread activity in context...

The original topic of this thread was why Monoshocks Work so Well, with very stiff front roll resistance, often cornering on 3 wheels.

I do not have a Monoshock but felt that such lessons could be applied to my car by making the front stiff with an A/R bar. My car is a an 1100cc OMS2000m spaceframe with independent coil damper suspension on all 4 corners. I fitted front & rear A/R bars as part of the winter mods. The thread has been re-opened with Joshua asking how my car is handling with the ARBs.

...just to put in in context....

darcia1
29-05-10, 16:57
To put the recent thread activity in context...

The original topic of this thread was why Monoshocks Work so Well, with very stiff front roll resistance, often cornering on 3 wheels.

I do not have a Monoshock but felt that such lessons could be applied to my car by making the front stiff with an A/R bar. My car is a an 1100cc OMS2000m spaceframe with independent coil damper suspension on all 4 corners. I fitted front & rear A/R bars as part of the winter mods. The thread has been re-opened with Joshua asking how my car is handling with the ARBs.

...just to put in in context....

Craig as always with uphillracers this is an extremely useful thread. with different views and ideas from around the world well done... darren

Joshua
29-05-10, 18:50
Very interesting stuff. Our next event here in Malta is a non championship race so I hope to try a few of these things then plus I am really excited to see how I am going to fit a 3rd spring (progressive bump stop) to my car to try it out. Like that I should be able to soften the initial rear springing even further before it rests on the bump stop.

At the moment the main priority is getting the engine ready since I had to pull it all out after last Sundays event. No problems at all but needed to pull it out to re-uild it with lots of new bits to obtain the reliability we need for circuit racing...rods, pistons, valves, springs ,buckets, retainers etc. since last time we went circuit racing the engine dropped an exhaust valve.

Hopefully I will have the engine ready in time to make some of these suspension adjustments in order to try them out at the next non championship event in 3 weeks time. Already designing that 3rd bumpstop in my head!!