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Old 05-12-2013, 09:11 PM   #18856
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Hey, I agree. Let's keep the bad science out of this thread. Are you reprimanding me for making this personal?????????

Was it not Sosidge who in essence said that I was full of crap????? Did I not apologize to him for a poorly worded post and explain that the conclusion he came to was not the what was intended?????

As far as Howardcano goes, wasn't he implying that I was stupid and that I needed to learn new things??????? Then, did he not lecture all of us on stuff most of us figured out our first year in the hobby?????

Both of my posts in reply to theirs was respectful and even apologetic in one instance. If you believe this was personal on my part, you've never seen me make something personal. I'm too old to give a crap about what you or anyone else thinks. I'm not making this personal here, just stating a fact. Go back and read my posts and theirs and see who was insulting whom.
Hey Granpa
I didn't read the whole threads and I no perfect myself..I am sorry about my bad...you being around racing for a long.. So just keep up the good work...
I still remember back in the TCS days In Seattle SIR were you there racing the mini classes...
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Old 05-13-2013, 12:28 AM   #18857
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QUOTE=howardcano;12145104]Please, always dispute and question! One should never blindly accept anything. There is plenty of information on the web regarding vehicle dynamics. Gather as much information as you can. I'll try to answer your questions, but you certainly shouldn't use only my input regarding the subject matter.
First let me thank you for your considered response. I should have included deceleration in my questions cause that is more appropriate to the question we were discussing. I do have a number of differences tho.

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If one end is raised and the other remains fixed in the height, then the CG is raised, and weight transfer is greater.
No, actually the correct answer is that the CG remains the same. It changes in relation to each end of the rod, but remains the same overall. It becomes lower in relation to the end that was raised and higher to the static end

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There will be no effect on the total weight transfer if the height of the CG remains constant.
Yes and No. Since the CG remains constant in the rod, the amount of weight transfer will be affected by the relation of each end of the rod to it's CG. It only has no effect if the CG and each end ore on the same plane.

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A higher CG gives more weight transfer because it has more leverage around the tire contact patch. This occurs regardless of the spring rate, or even with no springs at all (infinite spring rate)
First sentence true. Second not so sure. If it were true, we should be able to largely ignore springs, shocks , but i'll still consider changing that kind of stuff cause it seems to make a difference.

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If all other things are equal, then no. The total weight transfer is controlled by the CG location, wheelbase, track, and acceleration only.
I believe that the amount the car rolls or transfers weight to the outside wheels is influenced by considerably more than the above.

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My observation was for weight transfer only. As I mentioned above, we can use various adjustments to proportion the weight transfer between the tire patches, but the weight transfer will still occur in the same total amount.
Yeah, and that's why I told someone to raise his front ride to control the back end of his Mini if dropping the rear ride height did not do it. That was just one of several suggestions.

Maybe I'm just being obdurate here, but I still stand by my original statement that raising the front ride height reduce the steering sensitivity on corner turn in. I said i thought it was due to controlling the weight transfer to the front. Please note that we were fine tuning here and that we were trying to make a "good" mini into a better one. If your mini handles like all 4 wheels are going in different directions at the same time, just raising the front ride height isn't going to help much if any.
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Old 05-13-2013, 02:26 AM   #18858
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Originally Posted by Granpa View Post

[...]

My questions for longitudinal acceleration:

1. What sort of changes occur if you raise one end of the rod in relation to the other???? Or do any occur at all.

2. What happens if each end of the rod changes in height in relation to each other when ???? Does more weight transfer occur?????

3. If you can restrict the amount of upwards or downwards movement of each end of the rod, what effect will that have????? Spring rates

4. If the above do not affect the amount of weight transfer, why would a higher CG affect give more weight transfer???? For that matter,why would spring rates , shock oil etc. have any effect????

Lateral acceleration:

1. If one car rolls more in a corner than another, will there be more weight on the outside wheels than one that corners flatter?????

[...]
Rod analogy not quite good here. Rods don't have suspension which is what we're trying to work out how it works. But here's my 2c:

Longitudinal acceleration

1.changing the ride height of your car will have different loads on front/rear tires even at constant speed (or standstill) compared to the situation before changing anything. How? Well, it depends on which end of the car is higher and which is lower. But you knew that. And I think you know that there are other factors like droop and suspension travel which impact here. Acceleration/braking will change these resulting in car pitch (dive/squat) which in turn will
decide how much weight transfer can take place. In principle the more dive/squat possible, the more weight transfer. High ride heights together with high droop will increase dive and squat.

2. See above. The larger the difference, the larger the change.

3. Not directly an effect on weight transfer. Depends at what angle the movement takes place. If movement is restricted to say about 3 degrees about a 0 angle rest position (front and rear at same ride height) the weight transfer is less than say a movement of again 3 degrees about a rest position of 1 degree (say front lower than rear or viceversa - the lower end will be loaded more when movement - pitching in this case happens)

4. Because a higher CG has a longer arm to the fulcrum point about which the car rolls/pitches

Lateral acceleration:

1 Depends. Again, in principle the more a car leans, the more weight is transferred but keep in mind there may be a different loading start point depending on how the car is set up (ride height mainly). For two identical ride height setups and equal car mass, and identical CG position, if one car can lean more (for whatever reason), it will transfer more weight as it rolls more.

As you see, there are many details to take into account. I am sure you have more Mini driving experience than me, but I don't see the difference to TC driving. Most TC drivers here who drive minis find setting up their mini a breeze compared to a TC and I think that is because of the more involved, much finer subtleties of tuning a TC. Higher speeds are less forgiving with a bad setup too.

Lastly, I would agree with the guys at mini.net and mention that if you get the tires right, the rest you can make up for with good driving. At the very top of competitional racing maybe it's not enough, but remember the story of one aussie driver who won the championships and didn't even notice one of his shocks was shot.
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Last edited by niznai; 05-16-2013 at 07:02 AM.
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Old 05-13-2013, 04:23 AM   #18859
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Originally Posted by Granpa View Post
HC:"If one end is raised and the other remains fixed in the height, then the CG is raised, and weight transfer is greater."
GP:No, actually the correct answer is that the CG remains the same. It changes in relation to each end of the rod, but remains the same overall. It becomes lower in relation to the end that was raised and higher to the static end.
I think you may have worded this incorrectly, or misunderstood what I said. I am referring to the distance of the CG above ground. The location of the CG is always fixed in relation to the masses of the system (since it is determined by those), and I think that's what you are referring to. However, raising any of the masses relative to the ground while leaving others in the same location will always raise the CG in relation to the ground, and increase weight transfer.

Let's illustrate the situation using your analogy of a rod with weights on each end (which I think is a very useful model), like a dumbbell. We will assume that the rod is uniform along its length, and the weights are equal and symmetrical. We'll use an imaginary felt-tip ("Magic") marker to place an "X" at the location of the CG, which I think you will agree is located in the center of the rod, equidistant from each weight.

We place the dumbbell so that it is level, with the center of each weight, and therefore the CG, 1 inch above the ground. Now we raise one end so the center of the weight on this end is 2 inches above the ground, leaving the center of the other weight at 1 inch above the ground. Has the CG moved? Well, it is still at the location marked with an "X", so in this sense it has not moved. But the "X" is now 1.5 inches above ground, which I will call "higher".

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Originally Posted by Granpa View Post
HC:"A higher CG gives more weight transfer because it has more leverage around the tire contact patch. This occurs regardless of the spring rate, or even with no springs at all (infinite spring rate)"
GP:First sentence true. Second not so sure. If it were true, we should be able to largely ignore springs, shocks , but i'll still consider changing that kind of stuff cause it seems to make a difference.
If the second sentence were not true, then it would be impossible for a non-suspension car to traction roll. But they do. You've probably witnessed this yourself if you've watched old RC12E's on carpet, or go karts with big guys driving. (Or kids spilling their milk because their parents insisted on using tall, thin glasses, instead of short, fat ones. I'll never forgive my parents for not listening to my explanation: "The CG is too high"!)

As I stated, shocks and springs can change handling because they let us decide how we split the weight transfer between tire contact patches, not because they reduce it.

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Originally Posted by Granpa View Post
Maybe I'm just being obdurate here, but I still stand by my original statement that raising the front ride height reduce the steering sensitivity on corner turn in. I said i thought it was due to controlling the weight transfer to the front.
I have no arguments with this. Your key word here is "controlling". This is a different selection of word than in your post #18847, where you stated "I still maintain that raising the front ride height as stated in the first sentence of my post does reduce the amount of weight transfer to the front wheels." (Italics are mine.) That statement is the one I question.

On a different note, I have not felt at all that our conversation is "personal" in any way, and in either direction, and I have certainly not intended it as such. It seems like a calm, rational exchange of ideas.

Actually, your posts have been uniformly thoughtful and pleasant (even when you might have been tempted to be less cordial!) since I began reading this thread many months ago, and I have learned much from them.
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Last edited by howardcano; 05-13-2013 at 06:42 AM. Reason: Added dumbbell example.
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Old 05-13-2013, 10:07 AM   #18860
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Hey guys, enjoyed the discussion, but will sign off on it and let you have the last word. We need to return the thread to Mini guys cause we're off on a tangent here. If you want to continue via PMs, that's okay, but I'm not going to drive Jim (monkeyracing) with this stuff. I would guess that 99% of the guys who visit this thread wouldn't give a donkeys asshole for our discussion.

This however is Mini stuff. I have a lot of respect for Tony and his crew, but the they live in a different world. They do what I call "rich mans Mini" whereas the TCS racing I do here is just a fraction of the cost. When I go to a race now, I show up with 2 sets of tires, an extra set of springs, pit equipment and some extra parts and batteries. I'd imagine that it's not unusual for an Aussie mini racer to have more invested in his tires than he does in his car, including the electronics. No thanks, my pocket book, wife, stock broker all prefer the Spec tire rule.

So Niznai, to say that we should blindly follow Tony down the rat hole of open tires is not my choice. Been there, done that and never again. Almost got suckered into that trap just recently. I had gotten fed up with the constant tire thing so gave away almost all my tires. One of the smartest things I've ever done. So you ''tune'' with tires, I really don't want to spend that much on tires and inserts ever again.

We do have a race that I enter from time to time that has an open tire rule, but I've just decided I'm not buying a bunch if tires for it. If the ones I have don't work, I'll change the car until they do work.
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Old 05-13-2013, 02:37 PM   #18861
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Incorrect Bob... We pretty much use the same tyres at every meeting now and have for several years.
99% of the time it's Sweep 40's in front and Team Powers 36 or Pit SP in the rear. Thats what pretty much everyone at the recent Mini Nats ran.
Your vision of our 'boxes of tyres' is not really how it is...
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Old 05-13-2013, 03:01 PM   #18862
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Has anyone tried the M05 rally uprights for onroad? Just noticed it has a few more options the put upper and lower arm. Any thoughts?
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Old 05-13-2013, 03:15 PM   #18863
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Originally Posted by Granpa View Post
...I'm not going to drive Jim (monkeyracing) with this stuff.
Aw shucks. Now I have to join in. I actually found this discussion interesting. There's some great knowledge being exchanged. (Sorry if I've gotten under your skin at some point.) I was staying out of it because...
Quote:
...99% of the guys who visit this thread wouldn't give a donkeys asshole for our discussion.
I've become a big fan of shut up and drive lately. My car is cruder and faster than ever. I couldn't give a dingo's kidneys about the rest.

Quote:
I have a lot of respect for Tony and his crew, but the they live in a different world. They do what I call "rich mans Mini" whereas the TCS racing I do here is just a fraction of the cost.
There can be a bigger hit when you first start running open tire and "rich man's rules." That's partially made up for by never having to replace or mess with a motor and much more affordable aftermarket hop ups. With the way I and others I race with have been burning through S grips lately (We spec Tamiya) there's nothing in it. It's not worth running those 55mm gumballs, either. They're too damned small, especially with our spec 2200kv motor rule.

Quote:
So you ''tune'' with tires, I really don't want to spend that much on tires and inserts ever again.
Amen to that, brother. S grips and hard inserts all around. It's heaven.

We have a lot more in common than we do separating us. I just come off sounding like an a$$hole a lot of the time and, often to my detriment, I have an irresistible compulsion to play the role of devil's advocate. I can't leave a question unasked, even when the answer has apparently been found. I blame late nights, boredom and caffeine.
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Old 05-13-2013, 06:07 PM   #18864
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Incorrect Bob... We pretty much use the same tyres at every meeting now and have for several years.
+1
ive always used sweeps up front and either power 36, spice 28's or if really cold pit 24's on the rear

as for 60d tires hate them, especially when people use them just to be fast down the straight.


Quote:
Has anyone tried the M05 rally uprights for onroad? Just noticed it has a few more options the put upper and lower arm. Any thoughts?
yes have used the front and rear blocks from the rally. hard to say if it makes the lap times any quicker, just another tuning option to change the feel of corner exit and entry.

front knuckles tend to have less steering, steering link angle is higher and you will need to adjust the toe out as position is different.

rear blocks are quite good, currently swap and change between the 2 and 1 degree. and it allows you to keep a straight camber link. compared to running the std 1.5deg block which has a crazy angle.
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Old 05-13-2013, 07:15 PM   #18865
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Incorrect Bob... We pretty much use the same tyres at every meeting now and have for several years.
99% of the time it's Sweep 40's in front and Team Powers 36 or Pit SP in the rear. Thats what pretty much everyone at the recent Mini Nats ran.
Your vision of our 'boxes of tyres' is not really how it is...
Glad to hear it Tony. It's good that things have changed. I used to correspond with a couple of guys that ran your rules and they always had some new tire combo they were excited over.

Let me ask you though, has it always been this way or just recently? Don't most of the guys who've been around for awhile have sets of tires stashed, just in case? Now I have visions of tires sitting in a box or bag stuffed in a cabinet somewhere.

What happens if someone like Sorex comes out with a line of Mini tires???? Thas right!!!!!

Until then, have a great day and don't let anyone sit on your lunch.

Bob
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Old 05-13-2013, 08:04 PM   #18866
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We try any new ones, and usually go back to what we've been using.
Put it this way, the FAST guys do....they stick to what they know works.
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Old 05-13-2013, 09:06 PM   #18867
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We try any new ones, and usually go back to what we've been using.
Put it this way, the FAST guys do....they stick to what they know works.
I see your point, but the FAST guys here are always "tinkering". My cars have improved, driving hasn't, to the point my lap times are really close to what the FAST guys were running a few years ago. Wish they had stuck with what they knew works instead of messing around with stuff. Then I too could be one of the FAST guys, but I'm stuck here a half second or so a lap down cause they got faster.

My point----trying out the "new" tires can become expensive especially if they aren't as good as your old sets.
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Old 05-13-2013, 11:25 PM   #18868
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Hey guys, I'm thinking of running brushless in a mini this year, so what would be the prefered speedo and why?
Also, under acceleration the car pulls to one side, then as soon as I get off the gas it strightens up. What's the remedy to cure that?
Thanks in advance.
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Old 05-14-2013, 12:44 AM   #18869
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Originally Posted by 80'sracer View Post
Hey guys, I'm thinking of running brushless in a mini this year, so what would be the prefered speedo and why?
Also, under acceleration the car pulls to one side, then as soon as I get off the gas it strightens up. What's the remedy to cure that?
Thanks in advance.
Check the brushless rules before buying an ESC, some places restrict your choices.

Pulling to one side can be a couple of things. Diff could be too tight, which makes the car keep steering rather than straightening out. Standard steering setup (plastic posts) doesn't find centre reliably so upgrade to aluminium parts and the hi-torque servo saver. Your servo horn might be a bad fit on your servo. Also an assymetry or perhaps some binding in the the car, both sides of the car need to be setup the same and all parts need to move freely. Make sure you are running a little bit of droop rather than having the suspension pre-loaded.
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Old 05-14-2013, 01:42 AM   #18870
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It can also be a crap servo. Or a good one that has gone bad. It happens.

I think Granpa's point is their tire choice is limited to tamiya tire.

Not sure what it had to do with weight transfer.
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