Ride height of F3 etc cars

[andy97]

Originally Posted by MikeBz

Re: 2 litre K-series: Only exists in BTCC spec (and a special Caterham variant) which is substantially (almost totally) non-standard. You wouldn't want to try to run a K-series to mono spec (even if you could live with the power deficit).

Not relevant to the ride height discussion but, if alloy blocks were allowed in Mono. you could run a standard K Series engine in Mono 1800 or, depending on which variant of K Series and its power, in Mono 1600. Might provide an opportunity to do something different.

[Bob Pearson]

Diz, my understanding of it all is that all events are under the rules of the MSA and so 40mm minimum ride height unless special dispensation is sought from the MSA ( presumably on safety grounds ) as Uk F3, ARP F3 and all forms of FR ( not 1700 ) have done.

[schomosport]

I'm a bit intrigued by this safety thing..... I'm more than happy to accept that running single seaters at heights for which they were not designed is not going to result in optimum laptimes. But is anyone seriously suggesting that this suddenly destabilises the car to a level that it becomes dangerous?

What happens when we raise the car 20mm - roll centres change, CoG changes, chassis geometry changes, ratio of aerodynamic forces above/beneath the car changes, if the shockers are left alone then expect to run out of droop sooner than you might like. Probably some other things as well, I'm no chassis expert. The only one of those that I can see that might lead to a dangerous chassis condition (sudden, unexpected instability) is the shocker one. Maybe also aerodynamics - we can read that one of the leading manufacturer's himself admits it took time to understand the effects of aerodynamics on pitch sensitivity. But again, that was associated more with 'user friendliness' than with chronic instability.

Now lets look for the parallel with some other racing series, particularly those that involve running modified saloons. The worlds hatchback manufacturers spend umpteen millions on developing cars that will have acceptably safe handling characteristics. Sometimes a bit of a beast gets through e.g. Pug205 and we all rejoice. Send this assortment of cars racing though and what does everyone do - develop them like mad to get rid of those 'safe' characteristics in order to kill the dreaded understeer. So the cars are lowered, fitted with uprated springs and dampers, huge rear anti-roll bars, etc. We may also nobble the rear brakes so as to reduce instability under braking. The end result is a car with a huge lift-off oversteer characteristic. Now tell me all those radical changes, probably carried out with little regard to the theory of chassis design is 'safer' than using the cars as they were designed in the first instance!

So we have a contradiction: single seater pilots are demanding to retain design ride heights on safety grounds, every other series willfully compromises design ride height and the hell with safety although the aim is the same in both cases - optimum lap times.

To those series who have managed to get dispensations for running at sub 40mm, by whatever means, then well done to you. But if you have obtained it by using safety arguements then sorry, those arguments are full of holes.

From the point of view of Mono, running at design ride height will reduce lap times for the front runners (bigger accident when you have one) and increase the differential between the very quick cars/drivers and the slower ones. I quite understand why some want it, but don't tell me it will improve safety 'cos it won't.

[Bob Pearson]

I cannot disagree with a word you have said Schomo. You notice I did use the word "presumably" in my post, as I can't imagine how else it is done. I did ask BARC some years ago how we "got away with it", they simply replied " special dispensation". You can imagine, that I certainly wasn't going to rock the boat and so risk it being withdrawn by questioning it.
If you Mono guys were setting out to get dispensation, what arguement could you use other than the rather fragile safety one.

[MikeBz]

Originally Posted by schomosport

But is anyone seriously suggesting that this suddenly destabilises the car to a level that it becomes dangerous?

Not half as dangerous as running the car in it's design condition on a wet track

Originally Posted by schomosport

if the shockers are left alone then expect to run out of droop sooner than you might like

I thought that, like flared trousers and mullets, zero-droop was something became trendy from time to time. Maybe not on the rear...

My guess would be that the main effect is aero, and that assuming you work on the setup (usual spring/damper/rollbar/camber/castor/toe stuff) the overall result will simply be a bit less grip.

Mike

[Larry J-Croft]

I am stuck right in the middle of this debate, having just taken over a TOMs F3, which I don't feel has ever been properly sorted to run at 40mm (sorry spawny). One part of me would like to get it back to its design condition as any baseline for handling adjustment will be far easier and the old setup sheets I have will really be relevant. However, the other half disaagrees. The ease of movement argument is a good one - I am often at meetings on my own and just don't need the extra hassle. More importantly, I am out to have fun with other cars of similar performance. Currently the 40mm rule seems to help facilitate the level racing of a wide range of single seaters. The alternative would be even more Mono classes, Mono 2000 old and new (and wouldn't the debate about the age cut off be fun!). The fact is that quite a few Dallaras etc do run succesfully at 40mm albiet not at their full potential.

LJC

[Steve Wilkinson]

Originally Posted by MikeBz

I've never seen this rule checked or policed at a speed event. I've seen/heard plenty of cars scraping the ground though... It wouldn't be that hard to do at least a cursory check, just have a 'regulation' 40mm block that you have to drive over either in the scrutineering bay (if there is one) or on the entrance to the course. It's plain daft to have rules which can have a significant effect on performance which are rarely policed (and therefore regularly flouted).

It appears to be just one demon scrute North of the Border who brings his ride height stick with him to events and feels he must enforce the rule. He was told in no uncertain terms where to stick it when he only checked the single seaters. That's when the Westfield drivers got found out!

I have seen him in operation at Knockhill and Doune; however he had to admit defeat at Doune as there was no approved level area available when a car failed in the paddock.

[Larry J-Croft]

Some years ago I helped set up the Sprint at the airfield at Boscombe Down. Although quite low, there were quite a few domed runway marker lights (les than 15mm). We set the course away from them where possible but it wasn't always feasible. However imagine our surprise when a particularly low Aston Martin managed to kock a hole in his sump on one during the convoy run! Apart from delaying the event while we cleared it up we were also subject to severe complaints from the owner until the 40mm rule was pointed out to him. I was really glad of the rule that day!!

[SpawnyWhippet]

Originally Posted by Larry J-Croft

I am stuck right in the middle of this debate, having just taken over a TOMs F3, which I don't feel has ever been properly sorted to run at 40mm (sorry spawny).

Don't need to apologise, you are running Andy Webb's setup, not mine. I left a pretty good setup in the wall at Llandow! When I raced the car at Mallory (more of a shakedown than a race), it was comfortably doing 46 sec laps with wildly wrong gearing, sticking throttle, dodgy clutch and oil leaking onto the rears. It was happy taking Gerards flat, with only a confidence lift to put weight onto the front end. The car was running high downforce at the rear, low at the front and was pretty stable. However, it ran out of revs on the exit of Gerards and went down the following straight on the rev limiter, plus I had to freewheel round the hairpin. I reckon theres an easy 2 secs more in the car in its current spec when those things are properly sorted.

[andoiwebb]

yes, my set up was fl -4 deg, fr -2 deg, rl -2 deg, rr - 5 deg camber, not forgeting jammed in 3rd and 4th gears only and so much air in the front brakes that only the rears worked (probably didn't help the whippet / wall incident). i came 7th at silverstone national with 1 min lap times (same as my old fully functional ex steve maxted fvl - no slouch), so i also reckon there's another 2 seconds or so for mr LJC to get out of it.............. providing you do actually manage to get the thing to the start line larry, dermot did have to tow me to get me there. hopefully you will, and i see no reason why the car shouldn't have the pace to annoy the likes of the dawe / harrison dallaras.

[Larry J-Croft]

Thanks guys - so no pressure for a result then!!!

[THR]

i do think that cars are designed for a certain height..
but they will still work at a higher height.

areo is of course designed for the 15mm front height.. but raise it up and it will still work, but an amount less.......
rememeber when the F1 guys lifted the front wing 50mm? Huge losses..

anyway.. the scrutineers.... they check the end plates on the front wings... at 40mm.. and the front of the tub..
you cant really run the wing lower than 40mm cos it hits everything.
in hill climbing u cant run anything on the car less that 40mm cos there would be no floor left! bumps and hills and the softish suspension.

surely in circuit racing... if you have a dead aero car... the more important thing is to keep it level... to the ground.. to gain max areo effect... ifs thats wot u want.

people to me... dont adjust the whole height of the car.. i bet if u move every pick up point on the whole car then the car will still handle.,............ seems to me, most people just make the push rods higher.. and that wont really work! you change all the roll centres, dive and acceleration characteristics etc....
most cars, i know our F3 car (currently up for sale...) could be raised like this for a bit of engineering work... and would still go round corners really well!!
you would need........... longer push rods.. 4 off.. 16 slihglty new tub joints... and i think it really would handle lovely
if u made them yourself.. max cost £100 or.. £100 + time if u employed somoene (like me).

[SpawnyWhippet]

Originally Posted by Larry J-Croft

Thanks guys - so no pressure for a result then!!!

No pressure for a man of your calibre, you will be showing the Harrisons a clean set of rear wings in no time...

[SpawnyWhippet]

Originally Posted by THR

i do think that cars are designed for a certain height..
but they will still work at a higher height.

most cars, i know our F3 car could be raised like this for a bit of engineering work... and would still go round corners really well!!
you would need........... longer push rods.. 4 off.. 16 slihglty new tub joints... and i think it really would handle lovely
if u made them yourself.. max cost £100 or.. £100 + time if u employed somoene (like me).

I think as we discussed earlier in the thread, the cars will go round the track, but at best you will lose a few seconds per min. The new tub joints (I guess you mean for the suspension pickups?) will only work on some chassis. My old F3 TOM's (Now LJC's TOM's) had inset pickups and the suspension could not easily be relocated. Hence running at 40mm destroyed the suspension geometry, the car looked like it was going over a jump with the wheels at full droop all the time. Comparing the times at a shakedown at Snetterton to when the car was running at 15mm in British F3, we lost 8 secs per lap, albeit also on old tyres and a slower driver.

[Lola]

I dont know what the problem is? The cars run ok at 40mm. Yes maybe not at their optimum setup but TO THE RULES enforced in the given championship. Engineer a car to run within these guide lines , not change the rules to suit the car. My Reynard 883 apears to go ok. A mono 2000 win and podium places back that up.
Just need to soften up your suspension, fit the front push rods on the rear and make a pair of new fronts. ..... and a few other tweeks lol

[SpawnyWhippet]

I understand your point, Monsieur Bennett, but modern, stiffer chassis are less forgiving than yours. All 3 of the cars I ran in Mono suffered to some extent from this, but the FVL & FVJ I used occaisonally just absorbed ride height changes in their stride. I know you're going to say, 'well get one of those then!' but I would rather run a modern carbon tub than spaceframe or aluminium. I think if the accident I had at Llandow was in a FVL, I would have been lucky to walk away.

[Lola]

The 883 is a carbon tub f3

[Bob Pearson]

I maybe the odd one out here, but I suspect at least Andy is on the same wavelength, but to me, carrying a car with a known handling deficiency detracts from the pleasure of driving it. I feel that the better a car is handling the more I will " try " and vice versa. Simply accepting that it goes O K like this doesn't seem the right way to go. Strangely enough this leads to my one objection to the BARC Renault rules which do not allow ratio changes. Coming out of corners with the wrong revs on will give me the same dissatisfaction of driving with a 40mm induced handling problem.
Going back to what THR said, if it was as easy as moving the suspension clevis's then it would be no problem. To do it on a FR would need largish chassis modifications at the front. At the back it would require machining of the Hewland casing which would partly off set the problem.

[SpawnyWhippet]

Originally Posted by Lola

The 883 is a carbon tub f3

Oops!
I thought carbon tubs in F3 were only on later cars! Have you driven much this year, Lee?
Re Bobs point, just knowing that my cars handling is deliberately compromised by red tape irritates me.

[MikeBz]

Originally Posted by Andydickens

Oops!
I thought carbon tubs in F3 were only on later cars!

Surprising isn't it! There's an excellent repository of such information here (click on the Manufacturers link).

Mike

[Lola]

Only two races this year. A 3rd place on the Silverstone Gp circuit and a crash at Mallory (my fault).
Hope to do more next year if funds allow but transponder updates (rip off )etc dont help