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Post by Martin Young on Sept 29, 2008 12:17:43 GMT
The last two Sundays whilst the SLCC has been taking place (Well done to all who took part & by the sound of it roll on next year) I have been practicing at the track trying to find a half decent set up.
I have managed to find a good starting point on my Yokomo BD and Roberts Tamiya TA-05, however I am really struggling with Lucas’ car.
Lucas has a Tamiya Evo3 which lacks rear end grip when entering the corner, it is most noticeable when some speed is carried into the corner. It’s difficult to say but in my opinion the car is not over-steering but just lacks rear grip. I have tried lots of things but can’t seem to cure the loose rear end (The car not Lucas), another thing that doesn’t sound right is the squeal from the tyres as the car enters the faster corners.
The car is fitted:
- Front Diff
- Medium front roll bar (trying to loose some steering)
I run a ride height of 6mm all round
I have tried the following:
- Tyres Sorex 28R, Tamiya Type A’s, CS 27
- Droop I have tried increasing and reducing the rear droop.
- Various springs (Ended up with HPI Pink front, HPI Silver rear)
- Laying down the rear shocks (Helped but now I have a car with the front shocks stood right up and the rears laid right down, and I’m not sure that’s a good way forward)
I haven’t altered the roll centres or changed camber links at all as I don’t understand them much. Would putting spacers under the suspension mounts help? Any help or advise on the above would be appreciated, if not I guess Ebay may well be the answer!
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Post by lesbaldry on Sept 29, 2008 12:50:16 GMT
Martin Im not sure what adjustments that car has but it sounds like its a weight transfer proplem??..Bashley seems to like a lot of chassis uplift at the rear and some lads run a measured droop of as low as 2mm(with front 4mm) with a six mm ride hight allround .check too the toe out in turns(AKERMAN)..the more parallel the wheels when turned the more aggressive the steering will be possibly causing the car to hook off power?
This may sound strange but try it...if you have stiff front spings fitted to perhaps cure "the oversteer/hooking" but have the steering rate turned up to get round the tight corners?this can cause the car to "grab steer" ie slightly understeer on power and off power into fast bends but the use of max lock on slow bends/slow speed causes the tyres to dig in and flick the rear round...fit softer front springs and reduce the steering rates and let the chassis roll steer the car into the corner?!? Pinks/silvers are a good starting point, try putting the softer silvers on the front??
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Post by Mark Townsend on Sept 29, 2008 15:01:25 GMT
From your description it sounds fundamental rather than fine tuning and from experience a bad diff can ruin the handling of the car instantly. Check the tightness of both diffs. If the rear is loose you will lose the back end entering and have front wheel drive exiting corners. Like wise if the front is loose you'll have wild understeer and snap oversteer as you bury the throttle.
Make sure the thrust race has loads of black grease in there as well.
And like Les says, check the straightness on all the links for camber and toe angles.
Mark
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Post by lesbaldry on Sept 29, 2008 15:58:44 GMT
Yep nice one mark I had forgotten about the diff's ,Martins a experienced indoor racer so I hope he would,nt of missed the basics...some times we all do  Martin as you only live round the corner from me would you like me to give it a look over?...I am not racing this wed so I,ll be fooling with the toys "she goes out on wed,s whooopie" , any time after 7..just use side gate and bang on back door if im not allready in the garage |
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Post by Martin Young on Sept 29, 2008 16:01:41 GMT
Thanks for the advise Guy's.
Les, the steering rate is turned down quite low (set to around 85%), the Evo3 has always had a lot of steering so usually I've turned the steering rate down a little to compensate. I will try silvers on the front and see what happens. I will also check the Akerman but i'm not sure on the evo 3 it can be adjusted much.
If anyone could answer this question it would be appreciated, on the Tamiya steering blocks there are two sets of holes which set gives more steering? Looking at it from an geometry point of view the front holes will make the steering throw happen quicker as less movement is required for the same steering angle, will this also affect the Akerman? If so which set of holes will increase or decrease the akerman?
You are right Mark somewhere i'm missing something and this is a fundamental issue definately not fine tuning. I will rebuild both diffs before the next run and see how things improve.
Lucas uses the car indoors on a Wednesday and although the handling with a few set up changes is better, its still a little loose. The more we talk about this the more I would agree it probably the diff's.
Les thanks for the offer regarding the once over of the car, I will i'm sure at some point take you up on that. I will first strip it down rebuild the diff's make sure everythings pointing in the right direction.
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Post by Mark Townsend on Sept 29, 2008 18:32:25 GMT
Martin, i think the only Akerman change you can make is to move the pivot balls in one hole on the steering blocks. From memory the Evo 3 (nice car by the way I used to have a Surikarn edition and it was wicked) has a fixed carbon steering link you may be able to flip it over to give alternate akerman settings. On my 415 and 416 I run the pivot balls on the outer most hole on the steering blocks. Moving them inboard I found made the steering quicker but less mid to late corner. Best way is to stick the car on a set up board and look at the relative angles of the front wheels in both positions and see which one gives the best angles. Personally, sharper angle on the inside wheel. Second idea is to try it trackside and see which you prefer, takes a bit of time adjusting the trackrods again but it's only on the track you'll be able to feel the difference. If it's none of the above we'll talk roll centres. Woo hoo!  |
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Post by Chris N on Sept 29, 2008 20:09:03 GMT
 "From your description it sounds fundamental rather than fine tuning and from experience a bad diff can ruin the handling of the car instantly." Hmmm I didnt know this at all.. It makes me want to just give up and forget it. I think SHMCC should start a RC racing school with trying out setups etc.!
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Post by lesbaldry on Sept 30, 2008 7:27:00 GMT
Depending upon the central position and looking from the rear of the car, the further the steering /track rods sweep to wards the mounting points on the steering hubs the greater the toe out in turns will be (more Ackerman) And just to start another debate,what we falsely call Ackerman (easier to call) is really toe out in turns..akerman is very closely related but measured in a completely different way..."roughly speaking"Its to do with angle of the line drawn between the king pin position,steering hub arm pick up points towards the center of the rear diff...toe out in turns is what we adjust by moving the angle of the track rods in board..moving the pick up points on the steering hubs is the closest we get to ajusting true akerman  |
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Post by yellowshark on Sept 30, 2008 8:29:36 GMT
LOL Les I had never thought of it that way, but I guess it is toe out (or indeed "toe-in") in turns ;D Ackerman addresses the fact that in a turn your outside wheel travels a wider arc (shallower angle) than the inner wheel. IE at any given point it ensures that the turn in angle of the outer wheel is not as sharp as the inner wheel. If they were the same you would likely experience severe scrubbing of the inside tyre, creating excess wear and reducing the steering effectiveness. Now I know you are right in describing the geometry as being in relation to position to the rear axle and perhaps nothing to do with toe-in etc. Buit the end result is an angular difference between the two wheels in a turn and I have to say that I check mine on the setup board, using the toe guage and checking the wheel angles on full turn. And of course adjusting Ackerman on the Black one is easy and flexible  |
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Post by lesbaldry on Sept 30, 2008 8:44:00 GMT
I had to learn all this at collage...look it up it will confuse the hell out of you, it did and still does me ;D...Its surprising how many parts of the car and their angles are related and how they effect each other  Another thing that puzzles me is that as per full size set up/geometry is critical to performance as is ours and the same principals apply...how come we need massive amounts of rear toe to maintain traction..do full size race cars run this much??? |
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Post by issac on Sept 30, 2008 9:41:30 GMT
"Another thing that puzzles me is that as per full size set up/geometry is critical to performance as is ours and the same principals apply...how come we need massive amounts of rear toe to maintain traction..do full size race cars run this much??? "
just a thought but could it be that the rear wings on the full size cars give a lot more rear traction the one thing that cannot be scaled down is air.( plus their rear wings are adjustable)
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Post by lesbaldry on Sept 30, 2008 10:17:46 GMT
Here we go this should confuse things moving the steering hub track rod pick up points"normaly one of two holes" is the closest we come to adjusting true akerman...yes? Moving the steering arm track rod angles inboard(steering post/pivot adjustment) will have the same visual efect...Yes? But the speed of the increase of the "toe out in turns" effect will differ causing a different rotation/steering "feel " into a corner ...get your head round that one ;D...bugger more to worry the mind and play with ;D Tuning your set up is a black art and very hard to understand,the majority of the faster drivers do things by feel and experience,best guess really  ..its only the major teams at the worlds that have set up pit crews that do it 24/7 that DO know cheese from chocolate |
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Post by yellowshark on Sept 30, 2008 11:35:14 GMT
...how come we need massive amounts of rear toe to maintain traction..do full size race cars run this much??? Need to do a little research on that. I remeber working on a race Anglia back in the 60s, I do not recall the rear toe-in but I do recall prodigious amounts of rear negative camber. Quite possibly the fad at the time or the result of taking a very ordinary saloon car and pretending it was a race car! I just do not recall the rear suspension and axle arrangement on the car |
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Post by yellowshark on Sept 30, 2008 11:39:36 GMT
Here we go this should confuse things moving the steering hub track rod pick up points"normaly one of two holes" is the closest we come to adjusting true akerman...yes? Moving the steering arm track rod angles inboard(steering post/pivot adjustment) will have the same visual efect...Yes? But the speed of the increase of the "toe out in turns" effect will differ causing a different rotation/steering "feel " into a corner ...get your head round that one ;D...bugger more to worry the mind and play with ;D Dunno Les, I just move the black slidey thing on the Xray backwards and forwards ;D |
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Post by lesbaldry on Sept 30, 2008 11:41:58 GMT
...how come we need massive amounts of rear toe to maintain traction..do full size race cars run this much??? Need to do a little research on that. I remeber working on a race Anglia back in the 60s, I do not recall the rear toe-in but I do recall prodigious amounts of rear negative camber. Quite possibly the fad at the time or the result of taking a very ordinary saloon car and pretending it was a race car! I just do not recall the rear suspension and axle arrangement on the car that car had a full axel Pete,toe in on the rear can only be done with full independent rear suspension |
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Post by lesbaldry on Sept 30, 2008 11:47:52 GMT
Here we go this should confuse things moving the steering hub track rod pick up points"normaly one of two holes" is the closest we come to adjusting true akerman...yes? Moving the steering arm track rod angles inboard(steering post/pivot adjustment) will have the same visual efect...Yes? But the speed of the increase of the "toe out in turns" effect will differ causing a different rotation/steering "feel " into a corner ...get your head round that one ;D...bugger more to worry the mind and play with ;D Dunno Les, I just move the black slidey thing on the Xray backwards and forwards ;D Ha ha but you can do this easily on the 008...fit t/rod ends to inner hole and move inner post forward...your original position will have the same angle of appearence but will move the akerman point forward from the center of the rear diff slightly ...but the car will feel totaly different . |
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Post by TryHard on Sept 30, 2008 11:54:59 GMT
Part of the reason for the large amounts of rear toe?.... tyres widths.
On pretty much any car that runs real car that runs RWD, you'll have wider rears than front... This obviously aids with traction.
On a FWD car, rear toe is only really needed to keep the car tracking straight, and not required for traction.
However, I'll admit, that on a 4wd car you probably wouldn't come up with the same amount of toe we run... but in some respects that can be put down to scaling effects. We have a lot large power/weight ratio than a real size car.
Imagine if it was scalled up, your real car would have to be accelerating with a huge amount of grunt (electric motors; Max torque @ 0 rpm!) up too 300mph... see where I'm going? Even a veyron doesn't come close, and that has a fantasticly complex driveline and electronic trickery to keep everything in check... we have a belt, and a ball diff, plus your throttle finger!
As for ackerman settings, in my experience, the hub holes change the feel of the car (back for a smoother centre, forward for sharper), whilst adjusting the inner points changes the amount of steering (forward for more, back for less).
And I agree with les. If I wanted I could move the the whole steering link forward (on the holes, and the hubs). Whilst it may look the same, it would feel completely different...
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Post by lesbaldry on Sept 30, 2008 12:14:33 GMT
Genraly the more akerman "toe out in turns" the less agressive the steering responce...thats what works on the Cyclone,remove one of the post shims "angles the t/rods towards the back of the car inboard" calms the twichy steering with beter mid corner rotation(info from team hot bodies)....works on the 008 too!...as for those blue things..th,re just wierd ;D
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Post by lesbaldry on Sept 30, 2008 13:59:37 GMT
Lucas has a Tamiya Evo3 which lacks rear end grip when entering the corner, another thing that doesn’t sound right is the squeal from the tyres as the car enters the faster corners. Sorry Martin I have to ask,one or two experianced club members have made this misstake after a rebuild or with a new kit..are the "c" hubs on the correct side,good clue..does the car wonder at high speed and feel very twitchy?..if OK a small increase in castor will soften the steering into a corner!..say from 4 to 6 deg..if you have no other caster blocks jack up the leading mounts of the wishbones "kick up" this will increase the castor a little!and calm the steering some. Front shocks stood upright: can give more side bite off power and for me make the steering feel snatchy. shortening the upper camber link "if you can" will reduce steering quite dramaticaly too. thats it I,ve ran out of idears..good luck |
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Post by Martin Young on Sept 30, 2008 21:13:00 GMT
Thanks for the insight into the Akerman I think i've got a headache now! Wonder if taking a week of work may help ;D Have checked the C hubs and yes I'm glad to say they are the right way round. I think I'll try some kick up on the front and will bring the shock back inboard a little on the front, the camber links can also be shortened so another thing to try. Will have a play indoor tomorrow night and see if things improve. I will have to twist the bosses arm into racing this weekend to try a few more things out, although the weather looks yuk! Thanks |
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Post by Simon Crabb on Sept 30, 2008 22:55:33 GMT
Fascinating thread!
Wont kick up on the front encourage weight transfer to the front when off power, going into the corner, thus encouraging the rear to lighten and lose grip?
I'm no setup expert, I've learnt lots in this thread! Back in 'my day' we didn't have half these adjustments!
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Post by lesbaldry on Oct 1, 2008 6:51:01 GMT
Fascinating thread! Wont kick up on the front encourage weight transfer to the front when off power, going into the corner, thus encouraging the rear to lighten and loose grip theoretically yes,but i would imagine it to be more effective on a mod car doing Mach1 into a corner hard on the brakes??..the idea behind the kick up was to give Martins car more caster to help it understeer a little off power and to perhaps handle the Bashley bumps better making the car more forgiving for his lad to drive??...I,d love to get my hands on that car ,I do enjoy a chalange!..Mark T has had one of theses cars ,he,s the best person to give it the once over! |
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Post by Simon Crabb on Oct 1, 2008 10:29:51 GMT
Ahh, I get the theory, take the benefits of increased castor and ability to handle the bumps better, and don't worry about the perhaps increased weight transfer - you can always dial that out in a different way.
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Post by yellowshark on Oct 1, 2008 18:41:32 GMT
OK guys, so when do you use pro/anti squat and pro/anti dive rather than droop?
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Post by lesbaldry on Oct 2, 2008 7:00:16 GMT
OK guys, so when do you use pro/anti squat and pro/anti dive rather than droop? The only way to find out is to experiment with it Pete...BUT! as long as you have a good basic set up that works and the driver IS consistent.Trial and error can be fun and will tell you a lot about the car and a drivers style/feel for the car. A small change to a cars set up can have a dramatic effect on lap times,its not necessarily noticed by the driver until he checks his times,sometimes the car will feel slower "easier to drive" but be quicker!.Last weekend just spacing the rear hubs by rearward by 2mm completely change the rotation into a fast corner,from running 11th fastest (B final) to 7th fastest overall,and to chase down a top driver for 2/3 mins and think of passing him untill I had brain fade "whacked a barrier"..thats the differance small adjustments can make!!nearly 3/4 sec per lap Pro/squat/anti dive and kick up are explained quite well in the 008 set up book,they are not often played with and I would expect a lot of drivers just experiment with them on the day just to get the feel of the changes and to try and shave of a few tenths per lap...none of these are used instead of droop,droop is probably one the most important setting on a TC that is critical to stable handling. Someone of Craigs standard can read all he likes about another drivers preference with set up but it would not necessarily work for him or his chassis,the only way for a driver of his standard to move forward is to experiment with fine adjustments..but you may take two steps back to move one forward!!One definite step forward for Craig is to get the BL combo fitted ASAP,you wont have to worry about FDR,s and skimming,concentrate on set ups,the Cotswolds comes to my mind ;)LOL Fine tune your set up,worry about that extra bit of motor speed later "thats the very last thing I do on a test day!!" A fine example: Mark and Rob,two very quick drivers with exactly the same car,two completely different set ups Simon Crabb is a lovely driver to watch,smooth with very good lines,but he,s finding his pace is 3/4 of a lap off the faster drivers!no doubt there IS fustration.No one can help this guy with set up,only experimentation with fine adjustments will alow Simon to push harder and carry more speed that will gain that extra 0.5 sec or so a lap! and thats all it takes for him to be on the pace It astounds me when I hear a driver say "I never use the brakes" either he's scrubing speed of with the steering "poor set up???or he,s frightened to use them because of poor set up!!" or he,s not going fast enough ..watch top drivers they will stand a car on its nose with the brakes into some corners..At our track there is two places that for me DO need the use of barke,one or two others that need just a "dab" "if you are going fast enough with a good set up..One at the hair pin at the end of the dog leg and two down to the thermometer!!food for thought???  |
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Post by Simon Crabb on Oct 2, 2008 10:28:23 GMT
Yep, you're right Les, I've lots of things to try to attempt to go quicker. Inboard steering link position, top roll centres, wheelbases, diff adjustment, shock position. All of them I want to play with. One at a time! BUT! I do need some help, I don't always know what they're supposed to do!
And driving too, I must improve my braking/throttle technique.
Oh, and the other reason I'm not quick enough is my tight-fistedness, I never buy new tyres!
(Go on Pete n Craig, go Brushless! The opportunity cost of not doing so is immense, all that time you'll have to improve other areas!)
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Post by lesbaldry on Oct 2, 2008 11:41:37 GMT
Hopefully the winter fun days perhaps with 17.5,s will help people with set ups..easy to drive but fast enough to notice small changes to set up's and learn As for knowing what things do,none of us do exactly ;D..alter things and find out,trial and error It would be rather difficult to make a set up flow chart,drivers views of set up changes differ due to feel and driving style,some of the basic changes and effect are easily found on the web,but I find may be confusing to a new driver and send some off in the wrong direction...to be honest I tend to do things by feel and experience,best guess! I was ear wigging on the group of top drivers pitting next to us lot at the weekend and even they were arguing about what does what and how to go about a handling prob A good basic kit set up on a "GOOD" chassis with some minor adjustments to suit our track should see any driver with consistency to do say,18 laps in stock and 19 laps pro stock,the difference between fast/slow 18/19 laps is attention to detail with the build measurements,any faster after that is fine set up adjustments!..roll centers,shock oil and position,spring rate,droop,ride hight ect ect..but minor changes to suit you!!! Keiths Cyclone was built very well,I gave it the once over,he gave it a shake down run to settle things then I went over it with a fine tooth comb,adjusting things in a minor way..the difference was very noticeable(faster laps than other club members he nomaly looks up too) ...2nd in the B stock last weekend..not bad for a new,ish driver..Ian Newton Listened to advise and paid attention to detail ..stock "A"final for him..blimey |
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Post by yellowshark on Oct 2, 2008 12:41:59 GMT
Good answer Les, as usual I totally agree with "Someone of Craigs standard can read all he likes about another drivers preference with set up but it would not necessarily work for him or his chassis,the only way for a driver of his standard to move forward is to experiment with fine adjustments.." I wasn't after specifics, I was thinking more of the principle. The vast majority of adjustments are to do with controlling weight transfer from one perspective or another. As you say droop is one of the major adustments, arguably the most key in controlling pure front/rear transfer. Unlike eg ride height which whilst also contributing to this, modifies the COG too and will impact sideways weight transfer too. My question was addressing the principle of when would you use squat and dive adjustments to control front/rear transfer instead of droop - or as well as droop. If you like what do they give you that droop adjustment does not. EG ride height can impact transfer too but also gives you an advantage on a bumpy track or can give you an advantage on a smooth track by reducing sideways roll. Unless a track is real low grip my strategy is to keep ride height as low as reasonable and use droop and shock hardness and geometry to control weight transfer. So like many I too have never played around with squat and dive. Whilst I am more than happy to play around with it ;D and as you rightly say experimentation ultimately is the only way, I was trying to short cut and understand what I should expect to find,as a result of trying this out, that I would not find with modifying droop. Now from one perspective you have answered this in part, ie kickup (I think it was) also affects castor but squat I assume does not. So for example why should I play around with squat rather than front droop |
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Post by lesbaldry on Oct 2, 2008 12:50:59 GMT
Blimey Pete your in a bit deep there mate ...If I even tried to answer that lot I,d be talking oar supporting devices ;D...Botom line ..ain't got a clue  One thing for sure!..when you change somthing and the cars planted you will never forget it,regardless of cause "n" effect ...thats how I work things out |
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Post by TryHard on Oct 2, 2008 13:36:18 GMT
Personally, I've never bothered with Anti-squat (as I find there are other more easier methods to gaining rear grip, and I'm lazy) ... however Kick-up and anti-dive I do use, as these can also affect other aspects of the car in a positive manner. Kick-up I find good for bashley, simply as it gives better bump absorbtion (it effectively makes the front softer, helping weight transfer) and increases castor, which is useful for the on power steering. Also, on the way it's setup on the 416, I can lower the front roll centre slightly too (more front end). Anti-dive is good where heavy braking is required, as it helps to resist the front end shifting forward (like less droop, or a stiffer front spring), but it also helps initial steering as it reduces castor. So more suited for a track with a lot of hairpins.. Always worked well at the old Ashby track I found  So why change that over droop? As Les has said can be quite a fundamental adjustment, I tend to set and forget (5/4 at bashley, 6/5 at cotswolds)... unless I'm having a very big issue, I won't alter it. It's also, IMO, quite a coarse effect, as hitting a droop screw is quite a hard stop, unlike say a moving suspension compent (ok, not quite that simple, as the other end will compress onto it's springs at the same time, but hopefully you see what I mean). Personally, I run as little as I can get away with, and tune the rest of the car around it. Only place I can ever remember having to adjust the droop to suit the track was Southend, where we needed more rear droop into a tight chicane off the sweeper, simply as the car riding the outer droop screw into the turn, snapping round (i mentioned this to les last night). Running more droop ment that the car was resting on the screw round the sweeper, and allowed it too turn nicely into the chican, completely counterintuative (more droop to cure an oversteer issue!), but it worked... |
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"From your description it sounds fundamental rather than fine tuning and from experience a bad diff can ruin the handling of the car instantly."
