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Rally Car Suspension


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#1 Moggy.

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Posted 06 April 2021 - 07:54 PM

Thinking of changing my sprint spec mini to tarmac rallying. It runs Swiftune engine, Mk6 lsd, dog box
I’m interested in the relative merits of suspension/wheel diameters. Obviously I’d change cwp to suit wheel diameter.
Obviously I can get proper moulded tarmac tyres in 13”.
I’m particularly interested in the rear suspension. Is there much advantage in a beam axle and/or turrets to run good coil overs and get longer travel?

#2 yeti21586

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Posted 07 April 2021 - 11:13 AM

what does the rule book say about beam axle etc? and suspension changes



#3 MiniMadRacer

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Posted 07 April 2021 - 11:39 AM

Doing Qtr Mile ovals on dirt, I ran coil overs on the back fed up into the roll cage rear legs and an alloy beam axle. The tyre pressures and springs and dampers were all set to give minimum bounce of the rear wheels. Car runs an alloy boot floor and a fibre glass boot lid, so weighs little to nothing at the rear end. Suspension is all set up to control the rear end bounce rather than grip as such. Even the pretrol tank was a max of 2 gals capacity. Rear light panels are cut out alloyed over as are the panels making up the rear doors if a Mini had any rear doors. But as said above depends what your rules are for Rallying

 

Front suspension is STD mini plus decent adjustable dampers, as the front bar a fibreglass front weight pretty much as per a STD mini.

 

I run 13" tyres that I bought second hand of F3 fronts (slicks) that I hand cut a thread into...

 

Was never going to beat the big boys, but scared a few :-)



#4 nicklouse

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Posted 07 April 2021 - 06:12 PM

Thinking of changing my sprint spec mini to tarmac rallying. It runs Swiftune engine, Mk6 lsd, dog box
I’m interested in the relative merits of suspension/wheel diameters. Obviously I’d change cwp to suit wheel diameter.
Obviously I can get proper moulded tarmac tyres in 13”.
I’m particularly interested in the rear suspension. Is there much advantage in a beam axle and/or turrets to run good coil overs and get longer travel?

It all depends by what you mean by Beam.

 

one has less weight but works like a subframe.

 

the other keeps the wheels at the set angle to the surface and is not change by body roll.

 

but both need turret mods and proper shocks without the stupid offset mounts. Not to mention correct sized mounts.



#5 Moggy.

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Posted 07 April 2021 - 06:21 PM

what does the rule book say about beam axle etc? and suspension changes


I can run whatever. I’m not in historic classes etc

#6 Moggy.

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Posted 07 April 2021 - 06:30 PM


Thinking of changing my sprint spec mini to tarmac rallying. It runs Swiftune engine, Mk6 lsd, dog box
I’m interested in the relative merits of suspension/wheel diameters. Obviously I’d change cwp to suit wheel diameter.
Obviously I can get proper moulded tarmac tyres in 13”.
I’m particularly interested in the rear suspension. Is there much advantage in a beam axle and/or turrets to run good coil overs and get longer travel?

It all depends by what you mean by Beam.

one has less weight but works like a subframe.

the other keeps the wheels at the set angle to the surface and is not change by body roll.

but both need turret mods and proper shocks without the stupid offset mounts. Not to mention correct sized mounts.

Good question. I’m not a mini expert by any means. The car has excellent handling right now (properly set geometry/corner weighted etc). But it’s very low, very hard and has minimal travel.

I’m not aware of the different types of beam axles. I was thinking of a solid beam to replace the front of the subframe and hang the trailing arms from without having to support and control the springs/cones. I can see various people sell them with a wide range of prices.

I wouldn’t run the small offset pin coil over shocks. I would turret it properly and run shocks with a 1/2 bottom mount onto the arms.

Thanks for the response

#7 nicklouse

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Posted 07 April 2021 - 06:36 PM

 

 

Thinking of changing my sprint spec mini to tarmac rallying. It runs Swiftune engine, Mk6 lsd, dog box
I’m interested in the relative merits of suspension/wheel diameters. Obviously I’d change cwp to suit wheel diameter.
Obviously I can get proper moulded tarmac tyres in 13”.
I’m particularly interested in the rear suspension. Is there much advantage in a beam axle and/or turrets to run good coil overs and get longer travel?

It all depends by what you mean by Beam.

one has less weight but works like a subframe.

the other keeps the wheels at the set angle to the surface and is not change by body roll.

but both need turret mods and proper shocks without the stupid offset mounts. Not to mention correct sized mounts.

Good question. I’m not a mini expert by any means. The car has excellent handling right now (properly set geometry/corner weighted etc). But it’s very low, very hard and has minimal travel.

I’m not aware of the different types of beam axles. I was thinking of a solid beam to replace the front of the subframe and hang the trailing arms from without having to support and control the springs/cones. I can see various people sell them with a wide range of prices.

I wouldn’t run the small offset pin coil over shocks. I would turret it properly and run shocks with a 1/2 bottom mount onto the arms.

Thanks for the response

 

That is not really a Beam axel then.

 

so you are looking at  a subframe replacement. Points to note. The standard shock mounts on the stub axel bend and fail. The top mounts are not up to it. The coil over kits sold are poor as they use offset mounts that put side loads into the shock.

 

for a tarmac car I don’t think I would go coils.



#8 Moggy.

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Posted 07 April 2021 - 06:48 PM


Thinking of changing my sprint spec mini to tarmac rallying. It runs Swiftune engine, Mk6 lsd, dog box
I’m interested in the relative merits of suspension/wheel diameters. Obviously I’d change cwp to suit wheel diameter.
Obviously I can get proper moulded tarmac tyres in 13”.
I’m particularly interested in the rear suspension. Is there much advantage in a beam axle and/or turrets to run good coil overs and get longer travel?

It all depends by what you mean by Beam.

one has less weight but works like a subframe.

the other keeps the wheels at the set angle to the surface and is not change by body roll.

but both need turret mods and proper shocks without the stupid offset mounts. Not to mention correct sized mounts.
Good question. I’m not a mini expert by any means. The car has excellent handling right now (properly set geometry/corner weighted etc). But it’s very low, very hard and has minimal travel.

I’m not aware of the different types of beam axles. I was thinking of a solid beam to replace the front of the subframe and hang the trailing arms from without having to support and control the springs/cones. I can see various people sell them with a wide range of prices.

I wouldn’t run the small offset pin coil over shocks. I would turret it properly and run shocks with a 1/2 bottom mount onto the arms.

Thanks for the response
That is not really a Beam axel then.

so you are looking at a subframe replacement. Points to note. The standard shock mounts on the stub axel bend and fail. The top mounts are not up to it. The coil over kits sold are poor as they use offset mounts that put side loads into the shock.

for a tarmac car I don’t think I would go coils.

What about the KAD arms? They look like they do one designed with a half inch pin.

I would fabricate proper turrets and use quality motorsport spec dampers.

#9 nicklouse

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Posted 07 April 2021 - 07:02 PM

 

 


What about the KAD arms? They look like they do one designed with a half inch pin.

I would fabricate proper turrets and use quality motorsport spec dampers.

 

Well they do do the stub axels on their own. 
 

you also need to consider your track. Keeping it standard? Or changing it. You can’t do that with standard pattern arms. 
 

I would work with what you have already got just raise the suspension and fit suitable skid plates. Easy to do with a rear subframe.



#10 Avtovaz

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Posted 07 April 2021 - 07:17 PM

Oh hello Moggy ;) i see you made it here! Glad you did. ;)



#11 Moggy.

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Posted 07 April 2021 - 07:29 PM

Oh hello Moggy ;) i see you made it here! Glad you did. ;)


Hello mate! This one might not end up on proflex like our last rally cars......but the engine, transmission and weight are spot on, just need to work out the best suspension options.....I’m no mini expert!

#12 Avtovaz

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Posted 07 April 2021 - 07:37 PM

 

Oh hello Moggy ;) i see you made it here! Glad you did. ;)


Hello mate! This one might not end up on proflex like our last rally cars......but the engine, transmission and weight are spot on, just need to work out the best suspension options.....I’m no mini expert!

 

 

the wheels are lighter for me to swap thats the main thing for me ;) 



#13 Moggy.

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Posted 07 April 2021 - 07:57 PM


Oh hello Moggy ;) i see you made it here! Glad you did. ;)

Hello mate! This one might not end up on proflex like our last rally cars......but the engine, transmission and weight are spot on, just need to work out the best suspension options.....I’m no mini expert!

the wheels are lighter for me to swap thats the main thing for me ;)

Lol.....spoiling you!




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