relative merits of different damper conversions?

[Willie]

Very impressive but it doesn't alter the fact that if you fit an anti roll bar to the standard Minor suspension it is greatly improved.

[Peetee]

if you fit an anti roll bar to the standard Minor suspension it is greatly improved

It does indeed. But what I have noticed is that it is easy to reach the limit of adhesion isomuchas the grip afforded by the tyres is less than the handling would suggest. Well on 145 tyres anyway!
Drive a standard 145 tyred Minor with an anti-roll bar and you soon understand the difference between 'handling' and 'roadholding'. Terms that are often confused in carspeak.

[Arnie]

The original geometry is set to provide optimum grip whilst the car is leaning into a bend.

Not so sure about that. Standard geometry on most mass produced cars is set up to understeer and be safely predictable. Optimum grip no. Of course a minor does produce a very nice 4 wheel drift at a fairly low speed so at least when you lose adhesion you can normally lift off and let it come back. On a modern car its masses of grip and then whoops you are backwards in a ditch when it lets go. Thats the thing to think about about improving a minors grip and roadholding you increase the speed of any loss of them, however the satisfaction of seeing a modern car get smaller in your rearview mirror is priceless.

[Peetee]

I've tried to simplify what is a very complex subject. By geometry I am referring to the angles and dimensions of the cars suspension components. The length of the shock absorber arm and the lower suspension arm is different to allow for the leaning and compressing of the susupension when cornering. because the lower arm is longer as the suspension compresses it effectively tilts the suspension leg inwards at the top. this tilting should more or less match the angle of roll and effectively maintain the legs correct angle.

Modern cars are set to understeer at the limit as a safety feature rather than an inherent weakness. Understeer is more desireable because, faced with a situation where the car is loosing grip, your average driver backs off the accelerator. As the car slows an increasing amount of force is applied through the front tyres and grip is restored. Had it been the rear wheels loosing traction then the decelleration would make the back wheels light and loss of grip would be even worse.

[Innovator]

if you fit an anti roll bar to the standard Minor suspension it is greatly improved

It does indeed. But what I have noticed is that it is easy to reach the limit of adhesion isomuchas the grip afforded by the tyres is less than the handling would suggest. Well on 145 tyres anyway!
Drive a standard 145 tyred Minor with an anti-roll bar and you soon understand the difference between 'handling' and 'roadholding'. Terms that are often confused in carspeak.

That is very interesting to read, very interesting! My experience of Minors is that if really pushed they understeer. What I havent analysed is if this is due to the front wheel going into too much negative camber or its an imbalance in under over steer.

I must take issue on another point made (see my next post) in that it was stated that when the car rolls the suspension is designed to camber the wheel in a negative angle direction and an ARB will stop this. Under roll most double wishbone suspension systems (of which the Minor is) the wheel will tend to go into positive camber. This is bad for grip. One of the main reasons an ARB is fitted is to restrict roll to control the outer tyre to keep it in reasonable camber.

What most people fail to realise is that a softer suspension (all other things equal) will give more mechanical grip than a stiff one. Therefore fitting an ARB decreases grip (all other things equal). The common time when this doesnt apply is when there is so much roll the outer wheel goes into massive positive camber.

So fitting a front ARB may reduce body roll and make the car feel sharper BUT it may well reduce actual maximum grip and make the car understeer more. The comment at the start of my post supports this!

I suspect and have always suspected that fittting an ARB to the front of a Minor will increase understeer and reduce ultimate grip. The car may feel sharper in the transients (when changing direction but I prefer to do this with dampers.) but ultimate grip is reduced.

John

[Innovator]

[quote="Peetee"]I've tried to simplify what is a very complex subject. By geometry I am referring to the angles and dimensions of the cars suspension components. The length of the shock absorber arm and the lower suspension arm is different to allow for the leaning and compressing of the susupension when cornering. because the lower arm is longer as the suspension compresses it effectively tilts the suspension leg inwards at the top. this tilting should more or less match the angle of roll and effectively maintain the legs correct angle.

quote]

That is correct, in bump the wheel will go more negative, but in roll the opposite is true. Unfortunately when cornering the roll is greater than the bump so the wheel goes into positive camber.

[Pyoor_Kate]

I would say that depends on the condition of your remaining rear spring. If it's still got the right sort of curve on it and is in pretty good shape then you can (and I did) get away with replacing one. The car still handled acceptably well.

However, my other spring went shortly after the first one and I ended up replacing that too - and the improvement in handling was then was quite marked.

Whilst I've no personal experience of the OB kit - over the last few years I've heard no positive experiences, but an awful lot of negatives. Obviously this is hearsay, and should be considered as such, but that's my personal comment on it. My beloved minor is likely to be the subject of the JLH upgrade as I've replaced the lever arm shockers a few times and am rather bored of the process. Whilst reconditioning them did, I'm sure, once produce a good quality item I suspect that they're now all getting a bit past it if you use the car regularly or on poor quality road surfaces. That, again, is personal opinion.

[bmcecosse]

Sadly the Minor suspension design does not put enough negative camber on the wheel during cornering - it just wasn't designed for that sort of motoring - and it was used with cross ply tyres. A considerable improvement is gained by putting a little negative camber on the front wheels along with increased castor angle - and slightly lowering the car. Additional damping is the most useful thing - and NOT an ARB - which only increases understeer on this car. It's a waste of money on a road-going Minor (different altogether if going racing!). The final limit is the wheel/tyre combination - you gets what you pays for!

[rcbowman]

Okay, one last question on this subject, just to make sure. For the moment I'm trying out the simple tele-damper conversion as described in the MMOC tech tips book. Among other things, this is easily reversible if I decide I don't like it.

One basic question, though: are the dampers used for this the same ones you order for the conversion kit (this one: http://morrisminorspares.co.uk/shop/pro ... ts_id=1129), or is it a different type?

[minor_hickup]

BMC, how exactly does one adjust the castor angle?

[IslipMinor]

Koni adjustable dampers all round. Front set to full 'hard' and rear set to full 'soft'. Front mount as the kit designed, but the rear was designed to use the inverted/reversed lower mountings and the original lever arm top mounts. Didn't like the angle and lack of damping factor, so made up a 'U' section across the boot floor, similar to the OB set-up. 9 years and 25,000 miles have shown no problems.

Polybushes have been fitted everywhere, and apart for the odd squeak, have been fine.

Anti-roll bars fitted front and rear, front castor increased by about 1°, camber around 0°/1° negative (spacing out the lower suspension arm to give the camber setting gives the additional castor at the same time - very convenient!).

The result is a very firm, but not harsh ride, a very positive 'turn in', little roll, exceptionally stable and altogether a thoroughly enjoyable experience!

[rcbowman]

Okay, one last question on this subject, just to make sure. For the moment I'm trying out the simple tele-damper conversion as described in the MMOC tech tips book. Among other things, this is easily reversible if I decide I don't like it.

One basic question, though: are the dampers used for this the same ones you order for the conversion kit (this one: http://morrisminorspares.co.uk/shop/pro ... ts_id=1129), or is it a different type?

anyone?

[IslipMinor]

BMC, how exactly does one adjust the castor angle?

Normally the castor angle is fixed as part of the design geometry. Increasing the castor will do two things, make the steering heavier at no/low speeds and increase the sharpness of the steering response.

As you lower a Minor, so the camber goes more positive - the top wishbone moves out more than the bottom until roughly when the top arm goes past the horizontal (not usable). To correct this and get even a small amount of negative camber means shimming out to the maximum that is possible, whilst still having a full nut length of thread on the eye bolt that goes through the chassis leg.

A 3mm shim out will either reduce positive or increase negative camber by 1°, and increases the castor by about the same amount. The reason is that the end of the wishbone is pushed out by 3mm, but is prevented from doing so by the tie rod, so moves slightly forward instead, thus increasing the castor. Win/win!!

Radial ply tyres need neutral or slight negative camber to work properly on the road. On the track just look at a current F1 car, and compare the camber with 5 years ago when they still used a cross-ply type construction. There is a distinct 'lean in' at the top of the radial ply tyres now in F1.

[minor_hickup]

Oh so castor is increased with camber...awesome!!

Oh and I know what you mean about racing cars, I've seen pics of some classic racers as well (raced recently) with incredible camber!

[IslipMinor]

so castor is increased with camber

Yes, on a Minor or any other car with a track control arm type bottom link, and a tie-bar to make up the other part of the 'wishbone'. If there is a full 'wishbone', such as a Sprite, Midget, MGB etc., then shimming out only affects the camber. Unless the shimming is more at the front than the back; in that case the castor will be changed as well!