10 replies to this topic

[iSonic]

HI All,

 

I am building a pro-motive mini and I have to choose suspension... What is the best? Coil over? Just other dampers? And which then??? Could you share some experiences? 

 

I think I will be doing most of my kilomters on public roads and rarely on a circuit....

 

Meindert

[racerlike]

I'm running gaz coil overs as I went for a rear beam subframe.
They're firm that's for sure but because my build took 7 years I can't remember what a normal mini feels like.
I know a lot of folk advise against coilovers as being too harsh but I use mine on the road and I don't feel it ruins the ride at all.

[Aceslow]

I am running coil overs (spax kit). If your using your mini on public roads it should fine. I remember reading about the coil overs not having enough droop when using them on track.

[iSonic]

okey thanks! So there is no real advantage for coil overs? They are a lot more expensive...

[nicklouse]

If you have the standard suspension and plan on using the original shock mounts the coil overs are a waste of time. If you can position them correctly then it might be worth thinking about but I would use rubber donuts as they with compensate for a lighter load naturally. And some quality shocks.

A beam and coil overs on the rear is ok.

[Alan Carruthers]

You should see what Duds has to say as he has donuts and dampers up front and coilovers on the rear and seems his torque steer is under control.  Mine's not! 

 

I've got coilovers all round but clearly a whole load of reasons why it's pulling which might not be because of the shocks.  Would certainly agree with the last comment that a lot of coilovers retro fitted to the front of minis have issues as difficult to get them sitting at the right angle and in the right place unless you go wild with mods.

 

All the best, get some photos up!

 

A

[duds100]

First off, as Al says, gets some photos up! Would be great to see another build and also, strictly speaking, this part of the forum is for build threads only but it seems recently it has turned into a more of a Q&A area. However, there is no specific motorbike engine mini Q&A section so I think it is understandable why it is happening.

 

Please don`t be offended if you already know some/most/all of this, it`s just much easier to start from the beginning. Also, this is not gospel  - just what I have found/believe about mini suspension!

 

A sorted chassis setup & 'good' handling is the sum of many things. Wheel width and diameter determines what tyres you can use & therefore how much grip you can potentially create (=road holding). I say potentially, as tyres only give maximum grip when operating at their optimum temperature (ie warm) and a 13" wide tyre takes much more effort to heat up compared to a 165 section 10" tyre. 

 

This grip level also determines how much roll will be induced into the car. Which will determine how stiff you need your springs to be & form part of the reason why you may potentially look to run Anit-roll bars.

 

Anyway, you asked about springs & dampers so I will stop babbling on and try and answer your question!

 

A mini has a relatively small amount of suspension travel (bump/droop) which is why rubber cones work so well. The rubber cones have a progressive spring rate -  so they get 'stiffer' the more they are compressed which acts a bit like a built in bump stop. Usually the mini coilover kits have a fixed spring rate and, on the front, are mounted where the mini usually mounts just it's dampers. So the mini was not designed to have strut mounting point here. That doesn't mean it can`t be made to work, but what it does mean is that bolting on a coilover unit, esp with a fixed rate spring, will most probably not give you they same performance as a rubber cone setup can.

 

Rubber cones come is 3 grades of spring rate. 

1) Standard Dunlop OE Cones

2) Red dot (medium stiffness, fast road)

3) Yellow do (Hard stiffness, race)

 

I would suggest for a road car to use standard or red dot cones.  I previously used red dot and did not find them harsh at all & only a small step up from standard. Stay away from the yellow dots as they are very stiff. I have these fitted on the front and I only have 10mm bump and 35mm droop, & quite a firm ride.

 

So once you have your cones, you will need dampers. It all depends on budget really. What you need is a very quick reacting short stroke damper. Ideally you need to measure the bump and droop of your suspension & match this to a damper. However, if your mini is lowered a moderate amount, any of the off the shelf lowered version dampers will be fine. If it is standard height then just use a standard damper - simples! 

 

After that, suspension geometry, tyre pressures, corner weighting, & roll bars can be used to fine tune the handling or 'balance' of the car. 

Edited by duds100, 17 December 2015 - 10:56 AM.

[iSonic]

Thanks for your replies! Well I am building it mainly for on the road so I think coil overs are not the way to go. I was thinking of this kit: http://www.minispare...px|Back to shop together with red dot cones. Or are cheaper dampers also oke? The adjustable ride height is just to get weight distribution right, right??
 
I will see if I can post some pics, but currently it is just an (almost) empty shell. Next step is to decide on a roll cage or not.

Edited by iSonic, 22 December 2015 - 12:22 PM.

[iSonic]

Or this one http://www.minispare...r-classic-mini/ because of the solid looking bottom arms...

[Aceslow]

Hey Duds,

 

I am using this kit. My truck will be road use only. I am I going to see a noticeable difference in performance between these and rubber donuts?

 

I swapped to the coil overs for the convenience factor and cost.

 

https://www.minispar...sic/RSX519.aspx

[nicklouse]

The rear is ok but the front is just wrong and has always been wrong since the first kit was made.

The coil springs in the subframe is only marginally better but you don't have any travel.