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190E with mid corner push on Tarmac rally setup


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#1 MatsNorway

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Posted 11 July 2014 - 08:38

A friend of mine is asking about how he can give his car more steering up front when he is mid corner. Now it goes into understeer. He has Proflex 3way dampers up front and some two way at the rear. Polyester bushings all around. 2.5L 16V motor

 

My suggestion was Toe out but i am no expert.

 

Edit: His diff is at 4,45:1 and might be as high as 75% lock. Unknown brand. Surely that is the main problem? But i doubt he got much else. Any suggestions to make the mid corner push less severe?

 

1901198_10153903815690183_183411273_n.jp


Edited by MatsNorway, 11 July 2014 - 08:59.


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#2 gruntguru

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Posted 11 July 2014 - 23:32

Damping rates will have more effect on corner entry. Same for diff preload.

 

Mid-corner handling is usually mostly about roll stiffness. To reduce push either:

 

Stiffen the rear with more ARB, more spring or higher roll centre or -

Soften the front with less ARB, less spring or lower roll centre.

 

There are also an infinite number of minor fiddles including toe, caster (increase), camber (decrease), tyre pressures (small increments either way might improve front grip)


Edited by gruntguru, 11 July 2014 - 23:32.


#3 Lee Nicolle

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Posted 12 July 2014 - 00:26

By that pic some stiffer front springs will help. It goes against basics but when the car is 'falling over' it will push like a pig!. Then bars and tyre pressures. Plus driving style too. Sometimes you have to be more agressive and [very gently] flick it in and set it up in an oversteer stance. And just lock the diff. It is positive unlike a LSD which never does the same thing twice! Though if it is a pure road car you will have to live with it. Burnt clutches and oil are all part of that!



#4 gruntguru

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Posted 12 July 2014 - 06:41

Yes, it might be on the front bump stops - that will make it push.

 

If so, I would still try tightening the rear first (assuming it isn't lifting any wheels yet) or perhaps removing the bump stops initially as a quick test.

 

Lee - because he has said "mid corner" push, I assume it turns in OK. If so, adjustments to driving style (flicking) are just a band aid.


Edited by gruntguru, 12 July 2014 - 06:54.


#5 Lee Nicolle

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Posted 13 July 2014 - 02:27

Yes, it might be on the front bump stops - that will make it push.

 

If so, I would still try tightening the rear first (assuming it isn't lifting any wheels yet) or perhaps removing the bump stops initially as a quick test.

 

Lee - because he has said "mid corner" push, I assume it turns in OK. If so, adjustments to driving style (flicking) are just a band aid.

It may be too. But it is rolling more in the front than the rear = instant push. Quite possibly to stiff rear and defenitly too soft front. The inside rear is near off the ground



#6 gruntguru

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Posted 13 July 2014 - 23:35

The photo is not "mid-corner"BTW. More like entry under brakes. No such thing as "more roll at one end than the other" (unless you have a very floppy chassis).



#7 MatsNorway

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Posted 14 July 2014 - 06:25

The car looks softer than reality due to the angle the picture has been taken in.



#8 Fat Boy

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Posted 15 July 2014 - 20:28

One cannot just give you a 'magic bullet'. Car setups are more than just a random application of 'Rule of Thumb' principles. The proper answer could be a list of chassis setting changes or as simple as 'Drive the car correctly'. Any advice anyone can possibly tell you with the information provided is worth almost as much as you've paid for it.



#9 Canuck

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Posted 16 July 2014 - 02:12

What? You can't diagnose a complex physics problem with a single photograph and a few lines of background? Pffft. Some tuner you are.

#10 Kelpiecross

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Posted 17 July 2014 - 13:26

The car looks pretty good to me as it is. Clearly generating a lot of cornering force (even on a damp road) and doesn't seem to be understeering much at all.

Edited by Kelpiecross, 17 July 2014 - 13:30.


#11 MatsNorway

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Posted 17 July 2014 - 19:49

Sure you might need some more info, video or numbers to get exact Fatboy but general rule of thumb is a thing for a reason. As one does not start adjusting bump steer if the car pushes in mid corner.. (just an example)

 

RC cars are adjusted entirely on "feel" while reality is that it is all hand to visual.. guessing.. And they have every setup option in the book.. and they do have a start here guide..

 

http://cosmobomb.com...set-up_book.pdf

Page 54.  Have a look and feel free to comment on it.

 

Another one

http://users.telenet.be/elvo/

 

There might be some video in the future.



#12 gruntguru

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Posted 17 July 2014 - 23:42

The car looks pretty good to me as it is. Clearly generating a lot of cornering force (even on a damp road) and doesn't seem to be understeering much at all.

It isn't. The photo looks like corner entry under brakes (or at least transition off the brakes)


Edited by gruntguru, 17 July 2014 - 23:45.


#13 Kelpiecross

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Posted 18 July 2014 - 06:39

If by "It isn't" you mean that it is not generating much cornering force - the car is rolling heavily to the point where the inside front tyre is almost off the ground and the rear tyre appears to be distorted sideways - both things tending to usually indicate the presence of sideways acting inertial force I would have thought.

#14 gruntguru

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Posted 19 July 2014 - 04:36

It isn't understeering.

 

Not surprising - the complaint is "mid-corner understeer".



#15 Kneifzange

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Posted 20 July 2014 - 15:03

What´s with the effect of the tyres?
The story as follows:
I drove two identical cars on a proofing ground with high torque output a the rear: Tesla Model S
The only difference between the two cars had been the tyres.
The manoveur was driven in a corner which became tighter and tighter to provoke the driver to some "saving" action by either turn the steering wheel or brake OR apply torque.
The "good" Tesla ModelS steered into the corner by applying the high torque at the rear wheels.
The "bad" Model S understeered out of the corner and was only to catch by steering wheel action.

The technicians at Tesla confirmed that both cars had the same software in the EPS.

Thus: there are tyres matching very good to a car (and reverse).
Just my 2cents.

Cheers!
Michael

#16 Greg Locock

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Posted 20 July 2014 - 22:22

I'll take a punt that the 'bad' tires had a higher tire load sensitivity than the 'good' tires.  But of course we'll never know,



#17 rms

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Posted 21 July 2014 - 09:13

One cannot just give you a 'magic bullet'. Car setups are more than just a random application of 'Rule of Thumb' principles. The proper answer could be a list of chassis setting changes or as simple as 'Drive the car correctly'. Any advice anyone can possibly tell you with the information provided is worth almost as much as you've paid for it.

 

A bit hard to generate lateral G's when you are on a straight bit of road ......... get rid of the "Scandinavian Flick"  as a starter !!!!!!!!



#18 MatsNorway

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Posted 21 July 2014 - 13:12

https://www.facebook...&type=2

remember to push "HD"


Edited by MatsNorway, 21 July 2014 - 13:16.


#19 gruntguru

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Posted 22 July 2014 - 00:56

It doesn't have what I would call "white knuckle" understeer. I bet he would be happy witth a bit more rear anti roll bar or better still a higher rear roll centre.



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#20 MatsNorway

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Posted 22 July 2014 - 06:51

So it looks not bad i guess. Fresh Co pilot btw.



#21 MatsNorway

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Posted 25 August 2014 - 18:29

Lots of action! Wet track.


Edited by MatsNorway, 25 August 2014 - 18:29.