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Post by oldtimeracer on May 20, 2009 9:17:18 GMT
For some time now chassis flex and the ability to change it has been (or at least seems to be) one of the more popular chassis tuning options.
How good is it though?
I often wonder exactly how much our chassis actually does flex and whether it is a good thing or not.
We used to run very stiff chassis in the days of carbon tubs etc and did not seem to have too many problems so is it really necessary.
In my own little world it would seem that a stiff chassis would make the tyres and suspension work better and as they should do. Surely having a flexible chassis negates some of the reaction in the way the suspension works and the tyres hold the tarmac.
Are we not just introducing "controlled tweak" by allowing the chassis to flex?
Does flex actually just mask a poor handling car?
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Post by Simon Crabb on May 20, 2009 9:50:29 GMT
Back in the day when we ran solid chassis with little flex they went all right - for BACK THEN!
You put one of those cars on the track now, and unless you're particularly skilled with the thumbs, you'll have a slower car?
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Post by oldtimeracer on May 20, 2009 10:24:44 GMT
Back in the day when we ran solid chassis with little flex they went all right - for BACK THEN! You put one of those cars on the track now, and unless you're particularly skilled with the thumbs, you'll have a slower car? Is that true though? In all kinds of motorsport the object is to stiffen the chassis to make the suspension work better and yet we are the opposite. I can appreciate that a flexible chassis could be easier to drive but is it really the way to get it to be the quickest? Does a flexible chassis just mask the fact we are not able to set up the suspension etc properly? |
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Post by mattsedgley on May 20, 2009 10:37:20 GMT
does anyone have an old stiff car we can try this out with?
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Post by TryHard on May 20, 2009 10:52:46 GMT
it's a complex issue.... There's no point in adding flex for the sake of it... it need to be done in a controlled manner, such as that it's a positive infulence on the cars performance. Now my take on it is thus... the systems we use on our little cars are, by and large, particularly unrefined, when compared to the full scale counterparts. As such, and Ian you hit on it, that we could use very stiff chassis, and they would still be made to work, but the shocks, suspension etc would have to be absolutely 100% spot on, otherwise, the car will be very tricky to drive, and inconsistent. Now, for the most of us, these cars travel fast... and the loads on them are comparably a fair bit higher than we realise. Don't forget we also have no direct connection with the how the car is behaving on track, bar a visual confirmation. There's no seat of the pants feel a full size car has...(maybe we need to develop fly by wire bum feedback  Having the chassis flex is a good way to help numb the reactions, as well has having the positive benifit of improving grip and traction. Like I said at the start though, just adding flex for the hell of it is not a good idea. Try flexing your car in different ways (logitudinally, laterally, torsionally) and you'll find in behaves very differently. Longitundinally, most of the cars are very stiff, with little to no flex... this aids the forwad motion, as the car doesn't want to fold up on itself... Torsionally however, most are pretty flexiable... it's this that aids the grip and so forth of the car. This difference in flex is due to that wonderful material Carbon Fibre, which unlike aluminium or steel, can have it's properties orientated to suit the application. If you were to make an aluminum chassis plate, it would flex the same in all directions. By changing the directions of the fibres (which are Unidirectional's below the woven top surface), the chassis plates and top decks can be made to flex the way we want. Also the design of the car can be made to aid this... Take the 416 for example (yes I know, but it's what I drive  ), it's whole concept is about creating equal flex side to side. All the screws to mount components on the chassis are either on the centre line, or equi-distant from it (bar one, the outer servo mounting screw). It also has the servo rasied off the chassis plate to stop it influencing the flex. All of these little things add up to a car that uses it's flex to aid grip and traction, yet at the same retain good response to adjustability (you can still feel other changes to the car). It's something a lot of other manufacturers are cottoning in on, that flex is good, BUT only when used in a controlled way. Regards Ed |
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Post by Martin Young on May 20, 2009 10:54:22 GMT
does anyone have an old stiff car we can try this out with? Lucas's Evo3 is very stiff the bottom chassis plate is 3.1mm thick! I think the stiffness in the chassis narrows the window for a good set up (especially outside anyway). A softer chassis is easier IMO to set up (remember the problem setting up Lucas' car when i first started running outside). Indoors is again IMO is slightly different a stiffer chassis plate will help and ultimately I think quicker. |
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Post by lesbaldry on May 20, 2009 11:23:25 GMT
Having an indepth chat to a top driver..to much flex (chassis torque) is detrimental in mod but desirable in the stock classes..one car that shall remain nameless is next to useless in mod but is superb in stocks and another nameless car was the opposite. Introducing and useing flex adjustment is another personal feel to the drive and can or can not work on some tracks.example Sam uses a stiffer top deck than me with basicaly the same "other " settings..yes I know he's quicker than me but I didnt like the feel. I agree with Simon,there is no way the old TC3 or Losi xxx could keep up with any of our present cars. Is flex masking poor set up?..dunno  .. |
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hedge
In the Chicane
Posts: 13 
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Post by hedge on May 20, 2009 11:52:43 GMT
Race Foams, indoors and your chassis setup is solid, thick upper and lower chassis and extra hard suspension components.
Use this setup outdoors rubber tyres on tarmac and no matter what you try and do the car will not perform as well. The manufacturers and team drivers test all this stuff to destruction. So while its a blind leap of faith for most of us, there are hard facts behind it.
Paul
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Post by oldtimeracer on May 20, 2009 12:13:02 GMT
OK so I don't disagree with any of the comments here. I can understand that a flexible chassis will be easier to drive/set up than a stiff one.
Will a flexible chassis hide perhaps a poorly set up suspension. Maybe. But this will also help those who have neither the time or experience (or finances?) to get that set up spot on. I know I am probably one of those anyway.
Ed makes a valid and very important point about having equal flex. I am not sure how you check that to be honest. It must make a difference and can be altered surely by not having your weight distribution spot on, steering servos bolted tightly to one side will certainly change the characteristics. I wonder if sometimes over tightening of battery straps could change it as well.
Logic dictates that a solid chassis should be the way forward so all suspension etc mounted to it will perform equally. I guess we all know that may not be the ideal as Ed says. You would have to be spot on with settings to get the same performance maybe.
Equal flex would I assume also depend on having your suspension spot on equal in all respects otherwise different characteristics will emerge around different corners.
I guess we are back to making sure all settings/mountings are equal before you start to allow the flex to work properly.
Les I am not sure you are right about the older chassis cars not working as well as the ones we have now. I bet there is little in it if the truth is known. We have seen major improvements in motors/cells/tyres etc which all have contributed to faster lap times etc but I do wonder how an "older" chassis car would be. Better dig out the TC3 and have a go I suppose.
Oh sorry, yes I can maybe understand in mod that the new cars are better but not so sure about the stock classes.
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Post by lesbaldry on May 20, 2009 12:54:25 GMT
It would be fun to try an "oldie" again..dig one out Ian.
Chassi flex..hmmm dont know much about it "a dark sience"..for me a top main deck is the tool/adjustment I use to better my corner speed..the rear deck for rear end grip.
But what should we do...Run a stiff car with soft susspention or a flexi car with stiff susspention...advantages/disadvantages any one know??
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Post by oldtimeracer on May 20, 2009 13:24:32 GMT
I don't know what the right thing to do is Les. I was hoping an "expert" could help me ;D
I will try one of the "old" cars and see just what it's like. Wouldnt it be pants if it was really good! ;D ;D
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Post by lesbaldry on May 20, 2009 13:47:56 GMT
Food for thought.......when the TC3 and Losi xxx (both very stiff carbon tub cars) came out we used to butcher the chassis with a dremel to make them look like a string vest to give flex...and went faster.just after that the first true "sandwich" type chassis/ top deck cars apeared... hmmm I would imagine diagonal "equal" flex would be hard to get right for any maker due to the cells,motor and servo positons,besides my way of thinking is that perfect diagonal flex (central to the car) might not be the correct way to go due to weight transfer? ..just a guess says he(spotting the MI4 inclined top deck) |
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Post by oldtimeracer on May 20, 2009 14:03:25 GMT
The "new" Mi4 is being advertised as having "Symmetrical chassis flex"
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Post by gwesty on May 20, 2009 15:05:13 GMT
that was one of the areas that schumacher wanted to concentrate on as the 3.5 isnt good with a mod motor but its awesome with stock motors ! due to un even flex ( the car would tie its self in knots ) symmetrical flex is very important to chassis handling .
the tub chassis were a good design but the flex was too wide (width of the chassis) , newer cars have thin top decks to control flex .
flex in the chassis in normally used to give the impression that the car has more "lateral" grip !
yes the car will be easier to drive but too much flex the car will srub too much
hth glenn
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Post by yellowshark on May 20, 2009 17:24:49 GMT
Back in the day when we ran solid chassis with little flex they went all right - for BACK THEN! You put one of those cars on the track now, and unless you're particularly skilled with the thumbs, you'll have a slower car? Is that true though? In all kinds of motorsport the object is to stiffen the chassis to make the suspension work better and yet we are the opposite. Yeah as I have posted before Ian that has always flumoxed me. Coming from a motorsport background my natural tendency was to go stiff. Les will enjoy this  but the Xray T2 came within a whisker of the dustbin after 3 months of frustration of not being able to get a driveable setup - partly because it was too stiff and partly because the T2 was not a car for a newbie, its setup window/sweet spot was just too narrow for a beginner. |
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Post by yellowshark on May 20, 2009 17:36:50 GMT
does anyone have an old stiff car we can try this out with? Indoors is again IMO is slightly different a stiffer chassis plate will help and ultimately I think quicker. I would say you are right Ian. The main difference between the EU and USA Xrays model, ie asphalt vs carpet , is that the USA model has a a thicker stiffer chassis plate, stiffer A_arms/ rear uprights/steering blocks, and I think a stiffer top deck. |
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Post by yellowshark on May 20, 2009 17:43:49 GMT
Stiffening the chassis, and shocks, worked well for us at Cotswolds last year. I must say though that trying it with the 008 on other tracks, including Bashley has not. Predominantly negative effect and neutral at Bedworth where I did think it would be positive.
Caveat: if one had the time to persevere, rather than a one off Saturday practice, maybe some other complementary adjustments would make it work - on the right track.
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Post by lesbaldry on May 21, 2009 6:49:09 GMT
[/quote] Les will enjoy this but the Xray T2 came within a whisker of the dustbin .[/quote] Ha ha ......so did my early Cyclone "black version" when it used to explode spools if you kissed somthing hard. |
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Post by Matt Haskell on May 21, 2009 9:36:58 GMT
Tell me about it Les, its the Black version i am running, and the spool sucks!
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Post by lesbaldry on May 21, 2009 10:42:33 GMT
Tell me about it Les, its the Black version i am running, and the spool sucks! Sorry off subjuct a bit here. The only thing to do Matt is fit the worlds spool (lighter than the TC multi spool/one way) and fit the heavy duty or TC drive shafts..dont use the worlds cvd's,there good but wear more compared to the TC shafts..plus you can fit a heat shrink type gaiter to TC's to keep the grease in,stops the pin from comming out too should the grub screw come loose.my fronts lasted a season with a grease gaiter fitted!!..it helps a "little" bit with "chatter" too when they are well greased. |
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Post by yellowshark on May 21, 2009 11:59:46 GMT
Tell me about it Les, its the Black version i am running, and the spool sucks! it helps a "little" bit with "chatter" too when they are well greased. So do XRAY ESCs. LOL I couldn't resist that one |
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Post by lesbaldry on May 21, 2009 12:50:53 GMT
it helps a "little" bit with "chatter" too when they are well greased. So do XRAY ESCs. LOL I couldn't resist that one Re fitting of Xray ESC shafts to Cyclone I never did get round to mesuring your shaft at Aldershot...Will have Micrometer in pit box for next time we meet ;D |
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Post by yellowshark on May 21, 2009 18:32:11 GMT
A tad over 10 inches last time I measured it Les but I am a bit older now |
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Post by lesbaldry on May 21, 2009 19:13:28 GMT
A tad over 10 inches last time I measured it Les but I am a bit older now Blimey ....but you aint got big feet? |
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Post by martinchallis on May 25, 2009 19:38:51 GMT
i swear manufactures go in circles, years back yokomo were making chassis with flex dampers on what resembled the top deck...
everyone was screaming that flex was a good thing, then they made the tc3 and stiffness was the new trend,
were back to flex! and i need a new car!
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Post by lesbaldry on May 25, 2009 20:07:34 GMT
i swear manufactures go in circles, years back yokomo were making chassis with flex dampers on what resembled the top deck... everyone was screaming that flex was a good thing, then they made the tc3 and stiffness was the new trend, were back to flex! and i need a new car! Exactly right ...we are a load of sheep really ;D...somthing pops up and off we go like a load of headless chickens following the "latest" new trend. Ive got to have it in case I get left behind  ..we are all guilty  ...thats racing ;D Take the Worlds for example...X,W and Z cars were in the finals..."dont for get in mod format"...are these chassis the best for the club man in "stock" classes...probably not but it gives us peace of mind to run one flex or no flex..lol |
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), it's whole concept is about creating equal flex side to side. All the screws to mount components on the chassis are either on the centre line, or equi-distant from it (bar one, the outer servo mounting screw). It also has the servo rasied off the chassis plate to stop it influencing the flex. All of these little things add up to a car that uses it's flex to aid grip and traction, yet at the same retain good response to adjustability (you can still feel other changes to the car). It's something a lot of other manufacturers are cottoning in on, that flex is good, BUT only when used in a controlled way. 
..
but the Xray T2 came within a whisker of the dustbin after 3 months of frustration of not being able to get a driveable setup - partly because it was too stiff and partly because the T2 was not a car for a newbie, its setup window/sweet spot was just too narrow for a beginner.
..we are all guilty 
...thats racing ;D