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michvin
2007.10.01, 12:53 AM
I figured Iíll share what I learned, since many of us are struggling with the setup. If youíre an experienced racer, donít waste your time reading this. Itís pretty basic. It just came to me as revelation. A little of a background, so youíll have an idea of what I can know about mini-z (not much, but Iím learning). Been racing on regular basis for the last two years. Track is huge (never saw anything bigger) RCP, rough side up. Until recently, I was running all available classes (but NASCAR), which includes MR02 stock, MR015 Speck, F1 and AWD. None of the cars handled well ever.
Recently I become tired of this situation and decided to make at least one car handle. MR02 was chosen for this purpose. Disassembled it, rebuilt taking all regular precautions to avoid binding and to assure free movement in every part of the car. After some pretty sporadic tire changes combination that worked more or less was found. Result Ė 25-27 laps (Iím going to use this as a standard). Further tire changes yield no improvement and I was curios what else should be done to improve the car. The most annoying problem was that it understeered a little under acceleration and oversteered off-power. I went to look at the car and noticed that that if you push on the front of the car (with the body on) with the finger Ė the rear lifted in the air. In contrast, the rear was very soft. To make the car somewhat drivable I had to make the front very stiff to take away steering. That felt wrong: I never saw a real 1:1 car with such a difference.
Thatís when I first start thinking about front-to-rear balance. Fix took some time and involved changing front springs, front suspension travel limiters and rear shock adjustment. Finger test showed that front and rear reacted equally to pressure and that when I push on one side, the other stayed planted. Some obvious improvement (after tire selection, more below) was achieved (27 laps, consistent). The problem was cured almost completely, but the car felt edgy and I had to drive it carefuly. I started observing otherís cars and noticed that at least 70% of the cars have this problem (understeered under acceleration and oversteered off-power). Thatís why I decided to write this.
As I said, the car didnít feel well, especially when changing direction. Every steering wheel movement unsettled its balance and the car was quite difficult to drive. And the ultimate goal was stable and predictable car.
That make me think about right-left balance. Using finger as a testing tool again I pushed on the side of the carís body downwards. It was interesting to see how the front wheel opposite the pressure point was lifted in the air. It felt wrong, and it was wrong. I noticed that rear was soft compared to front in left-right direction. Changing the T-plate to hardest and making front a little softer gave the desired result Ė when pushed on one side the wheels were planted, only the body moved.
I always thought that the correct tire is 90% of the setup. I still think it is true, but apparently it was a mistake I made to try to fix the flaws of the suspension with tires.
So now as the suspension is fixed, to the tire selection. I hate this process. To make our life hard different manufacturers use completely arbitrary degrees of their own, so that PN 8 is harder than Kyosho 20. To make things even more interesting, thereís no consistency within the brand (PN/Kenon). Why in the world 15 front slicks provide WAY less traction than 25 radials from the same brand? I donít get it.
The only way to choose the right tire combination in a proper manner is to get all possible tires and to try all possible combinations.. Expensive, time consuming, boring. I started thinking about systematization of this process. And hereís how I did it. It worked for me, might not work for you.
There are slow and fast tires on each particular surface. I started with finding fastest rear tires; after all they transmit the power to the track. For this purpose I put hardest tire possible on the front and I didnít care about the steering Ė only straight speed. After finding best tire from what was available at the store, finding the front that will give the grip I want was easy Ė took only an hour (final setup below).
The car now is fast, predictable and I can put it where I want it to be on the track and it is easy to drive. Oh, since I started with laps as a measuring unit for the setup, hereís the number: with this car I did 30 laps in 2 heats out of 3 (I used different car for the third heat). Track record for this layout is 31.
Bottom line: if the car doesnít work Ė check the suspension operation.

Setup:
MR02 with 3010 board, Mclaren body with appropriate offset plastic wheels. PN speedy 07 motor with 8T pinion
Front:
15o PN slicks
1o knuckles, Alu, Kyosho.
Shortest travel limiters (most suspension travel)
Stock tie-rod.
Red Kyosho springs

Rear:
PN Alu multi length mount
Hard T-plate
PN Disk damper with softest springs
Stock Gear diff
20o Kyosho wide slicks

Hope you found it usefull

lfisminiz
2007.10.01, 04:32 PM
Excellent write up with good points. You hit the nail on the head with alot of your comments. ;) :)

michvin
2007.10.01, 11:25 PM
Excellent write up with good points. You hit the nail on the head with alot of your comments. ;) :)what were the ones i missed? Really interested to know :)

lfisminiz
2007.10.02, 08:12 PM
No i mean you hit pretty much all the good points. Ive been dealing with the same things as you have and it was very interesting reading. Good job. ;) :)

Programmers
2007.10.04, 12:44 AM
Thanks for this, VERY useful. I've recently encountered problems with my HFAY car that this topic will probably help me solve. So I was wondering:

You say you used the shortest suspension limiters for most travel. Why not use none?

I'm curious, I use none at the moment but my car doesn't handle so well. I've yet to learn what's 'causing certain things in particular areas.

bemoore
2007.10.04, 06:37 AM
You say you used the shortest suspension limiters for most travel. Why not use none?

I'm no expert at setting up a Mini Z, but in the 1:1 world of racing, you don't want the suspension to bottom out, and you don't want a tire hitting a fender. A suspension that bottoms out will cause handling problems. IMO, the proper suspension limiter would be the shortest one that keeps the tire from hitting the fender. And then, if you're bottoming out, you should use a stiffer spring. I have also heard of people putting shims in the front suspension to lower the car, but of course, this would reduce suspension travel, so you'd need to be racing on a very smooth surface.

michvin
2007.10.04, 09:43 AM
I'm no expert at setting up a Mini Z, but in the 1:1 world of racing, you don't want the suspension to bottom out, and you don't want a tire hitting a fender. A suspension that bottoms out will cause handling problems. IMO, the proper suspension limiter would be the shortest one that keeps the tire from hitting the fender. And then, if you're bottoming out, you should use a stiffer spring. I have also heard of people putting shims in the front suspension to lower the car, but of course, this would reduce suspension travel, so you'd need to be racing on a very smooth surface.
I'm not an expert either, but i'll agree. I never tried running without the limiters, but this IMO would have dual negative effect (assuming that body doesn't rub on the track when the front is compressed): You'll be in danger of rubbing the body with wheels and by allowing too much travel you provide too much traction to the front while braking by allowing more mass to be transfered. You can compensate for that by using tires with less grip, but that's exactly what you want to avoid - such a compensation. Another thing (that's a question, i don't know the answer): how the springs are kept centered on a kingpin without the limiter?

Programmers
2007.10.04, 12:42 PM
Yeah, after my question I decided to have a close look at the cars front end. Without the limiters, the suspension has about a whole mm of vertical play!! It also doesn't keep central (as you mentioned). So I put the shortest shim in.

I also followed the initial guide and applied pressure in the same places, and balanced the back out with the front. Now all my wheels stay planted too!!

Very cool thread, thanks again.

michvin
2007.10.04, 01:21 PM
No prob, i'm happy i got something right and could help. The ultimate test however would be the track and lap times.

Programmers
2007.10.04, 02:28 PM
Yeah, it'll be about no more than a week before I can test it on the RCP. It'll be an easy comparison. My car was very unstable out of corners before. Hopefully, it'll stay nice and flat now. My setup only slightly changed so if it causes me problems, I can change it back easy.

I'll also post any new findings or problems. :)

byebye
2007.10.04, 09:31 PM
One more thing to consider when adjusting the front suspension is how much compression is caused when the car is sitting flat? I mean is there a gap between the knuckle and the chassis? Let me take some pics to show what I mean.

Kris

michvin
2007.10.04, 09:35 PM
One more thing to consider when adjusting the front suspension is how much compression is caused when the car is sitting flat? I mean is there a gap between the knuckle and the chassis? Let me take some pics to show what I mean.

Krisyou mean spring so soft that it compresses, knuckle go up and the gap is between lower suspension arm and the knuckle? Is that what you mean?

byebye
2007.10.04, 09:38 PM
Okay well never mind :). I don't have any cars that do that. But basically the weight of the chassis and the softness and height of the spring can cause it to sit with a lot of play. This means that any bumps can cause it to unsetlle.

Good write up though. You can tell that you had to test and tune, test and tune until you found what was right for you.

Kris

byebye
2007.10.04, 09:41 PM
you mean spring so soft that it compresses, knuckle go up and the gap is between lower suspension arm and the knuckle? Is that what you mean?

Yes! The only way to fix this is shims and or new springs that are not of the "lowering" type.

I personally take my suspension limiters and cut them as short as possible. They act more as spring holders than limiters. I'd rather control travel with a stiffer spring and allow it to travel as much as needed.

On my VDSII car I run stock springs. On my points car/modified(used to be) I run a hard spring. The wider rear end of the VDSII means more push so I like to have soft springs up front for more steering. With the Mclaren I run stiffer springs so I get more push but of course it's not as fast as the VDSII so I don't need as much steering.

Kris

michvin
2007.10.04, 09:42 PM
Okay well never mind :). I don't have any cars that do that. But basically the weight of the chassis and the softness and height of the spring can cause it to sit with a lot of play. This means that any bumps can cause it to unsetlle.

Good write up though. You can tell that you had to test and tune, test and tune until you found what was right for you.

KrisThanks!
I think i see what you mean. No, my car doesn't have droop in the front. Is it neccesary and i'm missing something? I don't know...

byebye
2007.10.04, 09:43 PM
Thanks!
I think i see what you mean. No, my car doesn't have droop in the front. Is it neccesary and i'm missing something? I don't know...

No you really don't want that droop. I posted a fix above.

Kris

michvin
2007.10.04, 09:53 PM
Yes! The only way to fix this is shims and or new springs that are not of the "lowering" type.I try not to use springs that will not push the knuckle down till the end. I try to take as much slop out of the uspension as i can


I personally take my suspension limiters and cut them as short as possible. They act more as spring holders than limiters. I'd rather control travel with a stiffer spring and allow it to travel as much as needed.That's an interesting idea - i never thought of that. I'll defenitely try that if i'll ever need more travel than i have right now.

On my VDSII car I run stock springs. On my points car/modified(used to be) I run a hard spring. The wider rear end of the VDSII means more push so I like to have soft springs up front for more steering. With the Mclaren I run stiffer springs so I get more push but of course it's not as fast as the VDSII so I don't need as much steering.That's what i used to run: yellow springs to induce understeer. The point is that now i actually want more steering. The car handles so well that i want it to turn very sharp to cut lap times. We have a straight in our club three tiles wide (large tiles) I can actually (at full speed!), on purpose shift lanes. That's how good it is and it has huge amounts of steering

herman
2007.10.04, 11:01 PM
Without the limiters, the suspension has about a whole mm of vertical play!
i tried experimenting using the shortest limiter, without the shims (the small round plastic rings) and did see that there is more or less of a mm vertical play ... between the knuckle and chassis just as what byebye mentioned..

my theory is that each spring has a different load or springyness (is that even a word? but anyway) under compression... i figured, if they have a different load under compression (even though both of them are stock springs) wouldn't it be logical to let each spring be loaded or left to compress naturally by removing that shim - small plastic ring... this would enable the spring to be compressed naturally under a free load system depending on the front weight of the chassis...

this would also provide less wear because the spring isn't being compressed and would also help assist steering sensitivity (since the spring is under a free loaded system where it naturally compresses)... another thing that i thought would be beneficial is that there would be lesser resistance for the servo motor to center steering, because the springs aren't under compression...

just thinking out loud here... though it did help one of my cars center steering.. :D

michvin
2007.10.04, 11:17 PM
i tried experimenting using the shortest limiter, without the shims (the small round plastic rings) and did see that there is more or less of a mm vertical play ... between the knuckle and chassis just as what byebye mentioned..

my theory is that each spring has a different load or springyness (is that even a word? but anyway) under compression... i figured, if they have a different load under compression (even though both of them are stock springs) wouldn't it be logical to let each spring be loaded or left to compress naturally by removing that shim - small plastic ring... this would enable the spring to be compressed naturally under a free load system depending on the front weight of the chassis...

this would also provide less wear because the spring isn't being compressed and would also help assist steering sensitivity (since the spring is under a free loaded system where it naturally compresses)... another thing that i thought would be beneficial is that there would be lesser resistance for the servo motor to center steering, because the springs aren't under compression...

just thinking out loud here... though it did help one of my cars center steering.. :Dhow's the steering of this car under acceleration? Is this enough to remove the plastic washer to leave the spring free? I never tried that, sounds like it worth trying - will do this Sat. Good point about steering centering. Thanks for sharing

herman
2007.10.05, 01:18 AM
how's the steering of this car under acceleration? Is this enough to remove the plastic washer to leave the spring free? I never tried that, sounds like it worth trying - will do this Sat. Good point about steering centering. Thanks for sharing

steering under acceleration is ok... i would like to point out though that i don't race competitively... neither do i race (period)... sadly there's no track around here... what it did for one of my cars though was to help it center steering better... and i did feel that it was more sensitive to steering... dunno but it may be due to the springs as well since i changed it to softer springs...

actually removing the round plastic washer/ring while leaving the limiter in, is just enough (for my chassis) to have some droop a bit (is that what you call it?) having that small space between the knuckle and the suspension arm...

like what bye mentioned, the limiters act more like a spring holder... although i haven't tried cutting them shorter so they "They act more as spring holders than limiters"... probably one of these days...

let me know how it goes after you test it out... :D

michvin
2007.10.05, 01:51 PM
steering under acceleration is ok... i would like to point out though that i don't race competitively... neither do i race (period)... sadly there's no track around here... what it did for one of my cars though was to help it center steering better... and i did feel that it was more sensitive to steering... dunno but it may be due to the springs as well since i changed it to softer springs...

actually removing the round plastic washer/ring while leaving the limiter in, is just enough (for my chassis) to have some droop a bit (is that what you call it?) having that small space between the knuckle and the suspension arm...

like what bye mentioned, the limiters act more like a spring holder... although i haven't tried cutting them shorter so they "They act more as spring holders than limiters"... probably one of these days...

let me know how it goes after you test it out... :D
gonna test it tomorrow

herman
2007.10.15, 10:36 PM
wondering how'd it go?

michvin
2007.10.16, 12:36 AM
wondering how'd it go?Sorry for a delayed reply. I didn't like it. What's happening, is that our track is wide open with some very high speed turns. When the inner side of the chassis lifts off the pavement - it's fine, behaves just great. However when the chassis start to settle back after the turn, you can notice the "two-step" event - the undamped and then damped lowering of the chassis. The cars sort of shivers from side to side. Controlable, drivable - yes, but i prefer without it. I guess it's a matter of taste after all )

herman
2007.10.16, 05:44 AM
thanks for the reply... what surface were you running on? and what set up do you use now?

Programmers
2007.10.16, 06:47 AM
I finally got to test my cars on a big track:

As flat as they remained, it took from the articulation that let them handle smoothly and my cars kept spinning in the direction I was turning.

It turned out that the softer end helps my driving style.

michvin
2007.10.16, 09:40 AM
thanks for the reply... what surface were you running on? and what set up do you use now?
the very same setup i posted in the first post on rough side RCP. The track is worn out quite a bit, so it has a lot of traction. I will try even harder tires this weekend to get a little more speed.

michvin
2007.10.16, 09:41 AM
It turned out that the softer end helps my driving style.It doesn't have to be hard (actually how hard the car should be depends on the track/traction combination). And of course, the setup must suit your driving style.

anarchydude
2007.10.16, 09:53 AM
Just saw this thread now.. Great post!

I've been needing to do a re-evaluation on how I set up my cars and how I drive...

Tjay
2007.10.18, 04:23 PM
Thanks for sharing your idea! What's weird is we almost have the same set-up except I'm running the medium plate in the back. But everything else is the same. Even the body is the same :).

ruf
2007.10.19, 07:08 PM
Re: droop - I usually run a little droop. Calms the car down in transitions.

Re: suspension limiters - I run the shortest ones. Sometimes I cut 0.5-1mm off depending on how much uptravel I want. You don't want your suspension to bottom out, but it is better to bottom out your suspension and have the wheel still turning than have the wheel stroke through the suspension and lock up the tire on the headlight midcorner.

Honestly, I think most people pay too much attention to the front end of these cars. The front suspension design is pretty robust and consistent. Most problems start and finish at the rear suspension, imho.