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Suspension Improvements Gr.a Rally Mini


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#1 M998S

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Posted 25 March 2020 - 01:38 PM

Hi all,

 

my name is Thomas. I am racing a Gr.A Rally Mini in the Austrian Rallye Championship. Here a video from the last season:

 

 

Sadly we had an accident at the end of the last season and now we are rebuilding the Mini. I want to use the situation to improve the handling of the car.

 

There are two things I dont like one thing is the very bad torque steer and the other thing is that the car gets very nervous on bumpy roads. I was using red spot rubber cones at the front and standard at the rear, GAZ shocks, minispares race anti roll bar at the rear and 6J13 Wheels.  

 

To get rid of the torque steer I want to use spherical jointed tie bars and lower arms. Furthermore I got the advice to set castor to 0, has anyone tried this or other ideas to reduce torque steer?

 

For the other problem I want to change to coilovers. I think that the rubber cones dont give the suspension enough room to work when the road is very bad. In my thoughts that shold be better with a coil spring. I have an old but little used Spax coilover set that I want to try. I have read that the rear springs of this set are too hard. Is there someone with expierience in using coilovers for rallying? Which spring rate is working?

 

Would be very happy if someone could help me with my questions.

 

best regards Thomas



#2 Chris1275gt

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Posted 25 March 2020 - 01:58 PM

I can't help you with your suspension questions but that is a top video and hats off to you!!!

#3 luismx123

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Posted 25 March 2020 - 02:12 PM

hey thomas, offtopic but where in austria are you located? Im from graz



#4 Quinlan minor

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Posted 25 March 2020 - 02:51 PM

Regarding torque steer: have a look at what these guys have done, particularly in the December edition of Mini Magazine.

 

 

http://www.vetechbusa.co.uk/news.html

 

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#5 M998S

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Posted 26 March 2020 - 08:35 AM

Chris1275GT thanks it is a lot of fun driving it :D

 

luismx123 I am from Engerwitzdorf near Linz in Upperaustria. I have done a lot of races in the Histo Cup Austria at the Red Bull Ring with my dark green/white Mini maybe you have seen it. https://api.histo-cu.../users/show/115

 

Quinlan Minor thats an interesting idea I have seen such a kit also from KAD https://kentautodeve...-wide-track-kit

but that would require longer drive shafts which will cost a fortune I think. Is there a Company that offers longer driveshafts?

 

 



#6 Quinlan minor

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Posted 26 March 2020 - 09:27 AM

Quinlan Minor thats an interesting idea I have seen such a kit also from KAD https://kentautodeve...-wide-track-kit

but that would require longer drive shafts which will cost a fortune I think. Is there a Company that offers longer driveshafts?

It'd be worth contacting

http://www.vetechbusa.co.uk/news.html

 

These guys are very knowledgeable and they've done all their development themselves.
 



#7 DeadSquare

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Posted 26 March 2020 - 09:45 AM

Before thinking of expensive cures, borrow a set of 5J rims with the same back-marks as a standard 4.5J rim.

 

The handling of a Mini on 4.5J is almost perfect;  anything over 5J just makes the handling worse, which outweighs any improvement in grip.

 

When competing, far too many people start with the engine.  Tyres, wheels, dampers and brakes should really come first.



#8 nicklouse

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Posted 26 March 2020 - 10:35 AM

Sounds like you have not really set the suspension up correctly.

 

Zero caster would not be good and would make things worse.



#9 Cooperman

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Posted 26 March 2020 - 10:58 AM

First of all, you DO NOT WANT coil springs on a rally car. Coil springs are only good for racing Minis when a very high initial spring rate is needed. On a rally car the coils will 'coil bind' and you will have a really big problem.

 

Now for the ideal settings for a tarmac rally car.

 

Set the ride height to standard height using Hi-lo's. This provides sufficient suspension travel for the sort of tarmac roads used on rallies. Use OE rubber cone springs or 'ed dot' ones as suplied by Mini Spares. Beware of the sub-standard cones supplied by other sales outlets.

 

On the front set 2.75 degs to 3.5 degs caster with 1.75 degrees negative camber. You must use rubber tie-bar bushes and it is best to use the competition lower arm bushes, again from Mini Spares. Set the toe-out to not more than 1 mm to 2 mm.

 

However, the key to Mini handling for rally cars are the rear suspension settings. You MUST have a toe-in of 2 mm to 3 mm on the rear with zero to -0.5 degrees negative camber. this can be achieved by either filing/shimming and welding a large washer onto the outer brackets, or using the adjustable ones. Beware the adjustable ones for rallying as they have been known to fail. Even the standard ones can split from the top where the bend is and I always weld in a small triangulat piece of 3 mm steel plate.

 

Set like this you should not get torque-steer, unless you are running an LSD. I have been reuuning and building raly Minis since 1961 and have never been able to get on with an LSD. 

 

Those settings are good for both tarmac and gravel rallying, although for gravel the suspension should be raised a bit, maybe 1 cm to 1.5 cm.

 

With regard to wheels, it depends on which tyres you are allowed. If you are running with approved E-marked road tyres, a 4.5" or 5" wheel is best. I run both on my 1964 historic Cooper 'S' with 10" wheels and Yoko A008 tyres, or if running forest tyres I use the 4.5". Make sure the datum offset of the wheels is as standard. If the wheels are spacered out, the handling will be compromised. Don't run 13" wheels because there is insufficient sidewall depth and that reduces the suspension compliance.

 

Lastly, don't set the dampers too stiff. I have driven some rally Minis where the owners  have set them to hard and the car will not keep the rubber on the ground. For very rough roads or gravel, back them off a bit so that the suspension can actually work.

 

I hope this helps. PM me if you wish.



#10 nicklouse

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Posted 26 March 2020 - 11:34 AM

did not see the coil over kit mentioned.

 

bin it sell it give it away. totally useless on a car that get used. Everything about them is wrong.

 

the read with the offset mounts.

 

the front coil angles.

 

totally unfit for purpose.



#11 M998S

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Posted 26 March 2020 - 01:48 PM

Can you please explain to me what the effect of "coil bind" on a car is?

 

I was running 2 degrees camber 4 degrees castor at the front and 1 degree rear camber. Toe out 1mm at front and 1mm toe in rear. Yes I have a LSD and I think this is the biggest reason of torque steer at my mini but I dont want to miss it because as you can see in my video in austrian rallies there are a lot corners with deep cuts and there the inner wheel would spin all the time... The electrical power steering helped living with the torque steer but didnt solve the problem.

 

The reason why I am using 13" tires with 6J13 Wheels is that 175/50 13 is the only Dimension where different rubber compounds are available (they dont need to be e marked I use extreme tires at the moment). I dont like all 4 tires with the same compound it is always difficult to bring the rear tires on temperature… I always use softer tires at the rear even on my curcuit car with the 10" dunlop slicks.

Do 175/50 13 fit on 5J wheels? The other cars in my class are using Michelin Rally Slicks so the Yoko A008 would not be very competitive although I like these tires I used them when I started racing Minis. 

 

Another reason for the wide track of my car is that a standard Mini doesnt fit in the ruts of the modern cars that is very uncomfortable… Dont you have this problem in England?

 

Cooperman did you tried spherical jointed tie bars and lower arms at one of your cars? I would expact a "stiffer" geometry would help against torque steer? I was using Standard bushes on the inside and poly of the outside of the tie rod and the competition lower arm bushes from Minispares.

 

My dampers are very soft compared to the curcuit car and since I added the anti roll bar at the rear I am at 0 clicks on the rear and I felt a bit more softer would have been better… Which dampers are you using?

 

What I didnt mentioned yet is that the cars in Gr.A in Austria have to have 840kg + 160kg crew so my car is very heavy for a mini that is also not positive for handling.

 

Nickelhouse 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...

 



#12 nicklouse

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Posted 26 March 2020 - 02:22 PM

Coil bind. The springs compress and touch each other so go solid.
This normally causes something to fail including springs explode. Not so common on coil over kits but common in the coil replacements for the rubbers(again not a replacement as they are not fit for purpose).

#13 nicklouse

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Posted 26 March 2020 - 02:23 PM

For the rest you will have to wait till I have finished driving teamst cars for the day.

#14 DeadSquare

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Posted 26 March 2020 - 02:27 PM

"Coil bind" is the result of a spring being so compressed that there is no gap between any of the coils.   It becomes a tube.

 

The space in a Mini subframe is not enough to get a coil spring with 'wire' of sufficient diameter in the coils to hold the car up, and leave enough gap between the coils to allow the top arm to have full travel.



#15 DeadSquare

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Posted 26 March 2020 - 02:34 PM

We don't have the problem of a Mini fitting in other people's ruts.  When a Mini is set up well it leads the field and all the other cars have to drive in its ruts

 

 

 

 

 

P.S.  You really shouldn't moan about driving in other car's ruts, until you have driven a "Dell Boy" Reliant.


Edited by DeadSquare, 26 March 2020 - 02:43 PM.





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