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Suspension Improvements Gr.a Rally Mini


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#16 DeadSquare

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Posted 26 March 2020 - 02:53 PM

Part of the secret of a Mini's handling is the ratio of the track to the wheelbase.

 

A Pick-up, with a 4" longer wheelbase, handles better than a saloon.

 

Increasing the track moves the ratio in the wrong direction.

 

I could "left foot brake" a pick-up round bends in a way that I never mastered in a saloon.



#17 nicklouse

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Posted 26 March 2020 - 10:40 PM

Nicklouse can you explain me the difference why other cars use coilovers successfully and they dont work on a Mini? I am a bit confused about that...

Ok what other cars?

 

then maybe I can.



#18 M998S

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Posted 27 March 2020 - 09:21 AM

Thanks for your help and sorry for the amount of questions but I like to understand whats the reason for the advices you guys give to me ;D

 

I think the most similar suspension with coil springs compaired to the Mini is the MGTF which I heared have a good handling.

Here is an example Foto of the front subframe from a MGTF:

Attached File  subframe1.jpg   57.99K   2 downloads

 

DeadSquare I would love to see how you manage to be faster than the M-Sport Fiesta R5 in your Mini ;D

The Problem at our rallies is that the R5 cars come first then a lot of EVOs than the R2 and R3 cars then the class which I am competiting with BMWs, Fiestas, Golfs, Felicias... and then the historic cars. At latest the second time driving over the stage there is a lot of dirt and ruts from the AWD cars.

 

I havent driven a Pick-up but I heard that they are more balanced. I have seen a few racing minis especially the spaceframed ones with the rear wheels moved backwards. How do they manage this? Nicklhouse you are using Metro radius arms at the rear of your mini are those longer than the mini ones?



#19 nicklouse

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Posted 27 March 2020 - 11:48 AM

metro arms are the same length as Mini ones.

 

as you can see the frame above has been seriously modified to get the springs to fit. like wise you need to do some serious cutting and modifying of the mini subframe and body to get them in the right place.

 

like I said before all the spring kits available for the Mini are not fit for purpose. Unless the purpose is just to support a static car.

 

I will add some pictures and other bits later tonight.



#20 nicklouse

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Posted 28 March 2020 - 12:22 AM

ok the first thing that needs to be understood is the effect of inclining a spring. now by this we are talking about the angle of the spring to the input force not the actual angle. as suspension rotates about a point the angle changes.

cAyWAJn.jpg


now lets look at the mini front suspension

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what happens to the lower shock mount as the top arm moves. so the top mount needs moving inboard so you get a rising rate spring rate. that you do want as your base setup. 

 

adding ARB can also improve the rising spring rate but at the cost of the handling.

 

as to the coil springs to replace the rubbers in the subframe just dont go there

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ok back to coil overs.

 

oh these are track cars but the results are the same. see where the top shock mounts are. there is a very good reason they are where they are.

my own car

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and loads of others

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even at the back

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back to the front

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as the Mini was not designed to work with coil springs you have some serious work to do to get them to work with them.



#21 DeadSquare

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Posted 28 March 2020 - 08:00 AM

If you had included acknowledgements, there is almost enough work there for a PhD.



#22 nicklouse

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Posted 28 March 2020 - 11:11 AM



If you had included acknowledgements, there is almost enough work there for a PhD.

Funny you say that.

Attached File  855EF8A6-7BB6-4053-88E7-BB9C8EB6D23B.jpeg   28.25K   3 downloads



#23 nicklouse

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Posted 28 March 2020 - 12:16 PM

Ok now onto the other topic Torque steer. This can be reduced by having equal length drive shafts but it only fixes it when going in a straight line. Soon as the suspension is not at the same height left and right it will come back. 
 

most people who say they have torque steer actually just have a poor suspension set up.

 

with a rally car on surfaces with differing grip  you can also find the car moving all over the place as the LSD works. This is not torque steer. Just maybe the wrong LSD (or lack of one).

 

can you describe what is happening to give you the impression that you have torque steer issues?



#24 DeadSquare

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Posted 28 March 2020 - 12:28 PM

 



If you had included acknowledgements, there is almost enough work there for a PhD.

Funny you say that.

attachicon.gif 855EF8A6-7BB6-4053-88E7-BB9C8EB6D23B.jpeg

 

 

 

Congratulations !

 

Perhaps "It takes one to know one" holds good for Engineers..

 

If I had been able to understand Math, or even do sums, I wouldn't have chucked Southampton 1/2 way through the first term and become a self taught precision engineer.



#25 M998S

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Posted 28 March 2020 - 07:59 PM

Wow thanks for sharing this expierience with me :lol: I think I am understanding now what you are explaining to me. 

 

I made this sketch correct me if I am wrong, the second picture is the problem? Picture 3 is how it should look like?

 

Attached File  Dämpfer3.png   155.31K   7 downloads

 

 

I visited my Mini today and did some measuring.

 

With the Spax coilover Set the shock is standing vertical in the car.

 

Attached File  20200328_110044.jpg   39.68K   4 downloads

 

I could lean the shock at the top mounting about 15mm without cutting but that is probably not enough. With cutting Body and Frame there would be 50-70mm possible I think. How much did you move the upper mount? The front end of the car is already welded in place again after the accident but it is not repainted yet so if I want to do cutting I should do it now... have to think about it, way back to rubber cones would be difficult...

I want to use the minispares road anti roll bar at the front (I think the race is too hard for rally)

 

 

What about the rear I have seen that you are using coilovers on the rear which are standing vertical. Are the standard mounting points ok at the rear?

 

Regarding torque steer as an example I can feel it when shifting the car pulls from one side to another especially in corners but I think a good part of the pulling at the steering wheel when pushing the throttle in a corner is the LSD. I am usin the minispares road LSD https://www.minispar...|Back to search

 

 

 



#26 nicklouse

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Posted 28 March 2020 - 09:48 PM

almost right but but not. the situation in image 3 should be at MAX bump or the spring rate is getting softer as the arm moves up. hence the term rising rate.

 

also you arm line does not go through the ball joint pivot center of rotation.

 

anti roll bars just reduce grip and should only be used to balance the cars behaviour by reducing the grip available allowing the end it is attached to to slide. (first part of your video and the rear brokeaway on the corner.i was thinking way too stiff at the rear).

rear is nothing like the front as the suspension rotation is very different. yes the top should be slightly forward of the bottom but I dont have suspension movement like you. the rear can take coil overs better BUT what you have in the back will need different springs depending on the weight.

 

Torque steer ONLY pulls in ONE direction if it is pulling both ways it is NOT torque steer. so flat smooth road and boot it the car (any car) should only pull one way left or right NOT both. if it is pulling both ways then you have set up issues. corner weights must be done with the car at driving mass. so weights in the car in the foot wells and the seats (if you cant get the bodies in the seats) and with normal (1/2) fuel load. setting your cornerweights will also most likely need you to reset and adjust all the caster camber and Toe settings on the front.

 

ahhh the "good" old salsbury diff sorry Bin it they are crap.

 

something to watch

https://youtu.be/kJ0IY8yf0Z8

 



#27 mini13

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Posted 29 March 2020 - 09:55 AM

Some great info already posted, one point I didn't see covered, although I may have missed it....

What offset are your wheels? If they are the common 7mm ofset these are terrible for torque steer as the give a load of scrub radius. The std 13" mpi wheels have literally 1" less scrub radius.

As mentioned, if your running a an old plate or cam and pawl Ltd, these. Are terrible too, the modern diff are much better, but need to be set up right, also there's the atb type diff.

One other thought, there's a guy over here that rally a kad engined mini, kad did a wide track setup for this so the scrub radius can be kept sensible, with what you said about following over cars tracks, it may be worth looking into that.

#28 M998S

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Posted 29 March 2020 - 10:29 AM

I made another scetch considering your explaination:

Attached File  Dämpfer6.jpeg   22.78K   3 downloads

So this is how it should look like?

 

The part from the video with the rear brokeaway is mainly because I was a bit late with braking and used the handbrake to avoid a frontal crash ;D

I have fitted the minispares race front anti roll bar at my circuit car and my expierience with it is that the corner speed is higher with ARB. Is that because the ARB is transfering grip to the inner wheel?

 

We havent had the car counter weighted we had set it up left and right symmetrical. Maybe doing corner weight would also help improving the handling. I will keeping an eye on the steering wheel when the car is back on the road again.

 

I only klnow two different types of LSD for the Mini the ATB which is not working when one wheel is in the air and the salsbury are there other options?

 

 

That Metro in the video runs like on rails looks impressive!



#29 M998S

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Posted 29 March 2020 - 10:48 AM

I think I am using 6J13 wheels with 13mm offset +20mm spacers.

 

I had a look at the KAD widetrack kit but i costs a fortune and has not even driveshafts in the right length included... Do you have some pics how it looks like fitted on a Mini?



#30 nicklouse

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Posted 29 March 2020 - 11:08 AM

I think I am using 6J13 wheels with 13mm offset +20mm spacers.

I had a look at the KAD widetrack kit but i costs a fortune and has not even driveshafts in the right length included... Do you have some pics how it looks like fitted on a Mini?

The spacers are a big part of the problem as well.

it has made big (bad) changes to the scrub radius. Measurement 2. The bigger the number here the more bumps and changes in the surface effect the steering. Wanting to rip the steering wheel out of your hands. The cheapest improvement you can do is remove those spacers.

if you need the width then you need something like the KAD wide track kit.

i know having a track width the same as the other cars is very beneficial it has been something that has been done for years but you don’t just add spacers.

there are many good books out there about suspension have a google for Alan Staniforth he has a few good understandable books covering suspension and set up and more. He is also a person I spent much time talking suspension at Harewood Hill Climb and at his home/workshop.

Edit: the image of the effect of inclining the coil spring is from one of his books. Race and Rally car set up.

Edited by nicklouse, 29 March 2020 - 11:10 AM.





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