23 replies to this topic

[CPC]

Hi

 

I have searched but with no real answers.

 

Over winter i am looking to completey overhall my tired suspension and im running 13x7 wheels with 175/50/13 tyres ( yes i know smaller wheels would be better!).  My suspension is very hard and you can barely bounce the car at all

 

What would you say is the most suitable fast road type setup for the above? i have a budget around £600 all in for the parts if needed

 

Thanks

Chris

[Cooperman]

The 175 width tyres don't like any negative camber, so set as follows:

 

Front:   1 mm to 1.5 mm toe-out

             Zero to 0.5 degrees negative camber

             3 to 3.5 degrees caster

 

Rear:    1 mm to 1.5 mm toe-in

             Zero to 0.25 degrees negative camber

 

Ride height: Standard to +1 cm higher than standard

 

Dampers:   Slightly soft to compensate for the loss of suspension caused by the low profile of the tyre walls.

 

That will be a reasonable compromise and should give the 'not quite so slow' (no such thing as a 'fast road Mini') road Mini a good 'feel' when driving

[Midas Mk1]

I concur.

 

Spax  lowered  dampers all round, hi lo's, quality camber brackets at the rear (adjustable), 1.5deg arms at the front, adjustable tie rods. Setup for fast road this is ace with 13's.

 

A definite improvement for the road once professionally setup. Ive done over 15k  with this setup, whilst also having my 12" car with the same components (abeit protechs)

 

Edited by Midas Mk1, 23 September 2014 - 10:55 AM.

[Cooperman]

Have a read of this. It is quite helpful and confirms what many of us have found when setting up suspension for different applications.

 

   

 

Some interesting information on wheel/tyre options for Mini's from Keith Calver's Minispares blog below:-

 

"There are a number of things that need serious consideration no matter which wheel/tyre combination you decide to go for. First and foremost is suspension and steering component condition.

The original 10-inch combination is relatively 'forgiving' - masking slight component wear simply because it has relatively low leverage effects and dynamics as a whole. This encompasses everything affected by wheel/tyre weight and profile and the grip afforded by the tyre contact patch on the road. Wheel/tyre weight affects damper performance - their ability to keep the tyre in contact with the road surface the main issue. It also affects acceleration and deceleration generated by the 'flywheel effect' and steering by the 'gyroscope' effect. Tyre profile affects ride, comfort, handling and grip. All these conspire to exaggerate any shortcomings in the suspension and steering components. Slightly worn swivel pins, top arm bearings, bottom arm and tie-rod bushes, track-rod ends, steering rack, and wheel bearings will become very worn in a very short space of time. Tired dampers will not be able to keep the wheel/tyre in contact with the road. This can be dangerous - it will adversely affect safety, as you are completely reliant on those four small tyre contact patches whatever you do in a car. If the tyre isn't in contact with the road surface, you can't steer, stop, or go. As outlined earlier - a situation made very much more difficult in a Mini (or any front-wheel drive car) as it's all going on at the same end at the same time. Lower profile tyres have less flexible tyre walls - affecting ride quality (making it bumpier), and less compliant (will follow all ripples, bumps and cracks in the road surface). Although it has to be said that a number of modern sports cars have huge wheel/tyre set-ups to not only increase grip - the larger over-all circumference 'bridges' some bumps/holes, thus 'smoothing' the ride out by reducing/eliminating some of the smaller bumps.

Wider tyres will usually increase grip that will apply greater leverage against all the suspension locating bushes and bearings. Any that are worn will cause the increased leverage to push and pull the suspension into unwanted positions/angles. The result is a wayward car that doesn't handle well - seemingly developing a mind of it's own at inopportune moments if not all the time. The more grip the tyre develops, the easier it is for it to overcome the baking capability of the set-up on your car - the extra leverage applied by the bigger over-all diameter worsening the situation. Up-rated dampers are a must. The standard items are barely capable of dealing with the standard set-up when brand new (a nod in the direction of 'comfort' by the OE manufacturers) let alone when worn. Bigger wheels/tyres means more (un-sprung) weight to control when encountering road surface imperfections (bumps/pot-holes). The barest minimum should be 20% up-rated standard-type dampers. Personally I would only recommend starting at Kayaba 'Gas-A-Just' dampers (my current preferred type for cost/performance and fit), if not going to one of the adjustable sports types. The message here then is to make sure your whole suspension is in first class condition before contemplating the change. This is an ideal opportunity to fit up-rated components if worn bushes need replacing. Up-rated bushes offer greater resilience in both wear and movement, which will help provide greater suspension location and control when a bigger wheel/tyre combination is fitted. Essential to maintain the good 'handling' aspects believed to be endowed by the Mini's original design. And make sure your braking system is capable of dealing with your wheel/tyre choice."

 

"13-inch combinations. The 13-inch wheel/tyre combination brings out the worst in everything Mini suspension and brakes orientated - but to many the aesthetics far out-weigh all other considerations. And there are many considerations. Those who believe they are fitting this combination for increased grip and handling capability on a road car need to think again. Most of the 13-inch tyres are manufactured for heavier cars. This means a harder tyre compound is used. A Mini simply doesn't get the tyre up to its proper operating temperature, so the increase in grip originally hoped for doesn't materialize or isn't maximised. Wayward handling (unless suitable suspension set-up has been applied), heavy wayward steering, and exaggerated bump-steer are further consequences. These are caused by the offsets employed, necessary to get suspension clearance. 13-inchers are generally wider than standard rims, so the wheels are made with the greater portion of the extra width applied to the outside of the wheel, effectively pushing the wheel further out away from the car. This causes a greater leverage to be applied to the already poor bump-steer geometry of the Mini. The wider tyre needs different geometry settings to ensure the full footprint is road-surface bound as the lower, stiffer side-wall does not distort as easily as the 10-inch tyre types. Excessive camber - positive or negative - will cause the tyre to loose contact with the road surface when cornering or with extreme steering in-puts. This then causes the tyre to follow any deviations in road surface. The offset dimensions employed can also mean wheel spacer shims are required in certain combinations to gain clearance, and even the steering rack may need replacing with the one used on the Sportpack cars - and these are definitely not cheap, costing in excess of £100. These have built in lock-stops to reduce the turning circle to prevent the tyre scrubbing the inside of the rear of the inner front arch. Again, the types and styles are legion, so doing a comprehensive and accurate whose needs what is impossible in a few pages. The increased footprint increases drag - responsible for reduced top speed, reduced acceleration, increased fuel consumption (all neatly illustrated by the difference in performance figures between the Sportpack cars and the 12-inch shod variants, the 13-inchers suffering 6mph slower top speed and 0.6 seconds slower 0-60 with less mpg). This larger footprint-induced grip/drag increase will help with braking, but only if the brakes are equal to the task. The wheel diameter also gives a greater ('longer') leverage working against the brakes. The combined larger footprint and greater leverage means fitting 13-inchers to a drum-braked Mini is an absolute no-no. They simply over-come the applied friction capability of the shoes.Disc brakes are a must. Even the 7.5-inch S type discs are a little marginal in my opinion/experience unless steps are taken to maximise their performance envelope. The 13-inch combination is a good deal heavier in most instances than the standard set-up so up-rated dampers are an absolute must."

The full article:-

https://www.minispar...gory/Tyres.aspx

 

 

"

 

[MaxAndPaddy]

Interesting reading, does that suggest that the later Sports and Sportpack models which came with 13"ers from the factory have different steering racks / geometry?

[cal844]

Interesting reading, does that suggest that the later Sports and Sportpack models which came with 13"ers from the factory have different steering racks / geometry?

Indeed

[MaxAndPaddy]

 

Interesting reading, does that suggest that the later Sports and Sportpack models which came with 13"ers from the factory have different steering racks / geometry?

Indeed

 

 

Well that's one for the "things i didn't know before today" list 

[cal844]

Every day is a school day! Im still learning and ive been building minis for 6 years

[Cooperman]

I'm still learning and I've been working on Minis since 1961  . Particularly I like engine & suspension work. I do not like gearbox work at all, although I do it (under duress!). Bodywork is OK and I am quite good at sheet-metal work, but I don't really enjoy it. I can only paint in cellulose as I don't have spray-booth facilities.

[Badboytunes]

We have 7x13 and have full coilover set up. Nice ride and the handling is pretty good.

[CPC]

Ok, before i go a spent a fair amount of money what do you think of my planned setup?

 

Was thinking Minispares red dot cones, KYB gas-a-just dampers and the camber/tracking kit ( new tie rods, lower arms and bushes?)

 

Should that all work together alright?.

 

Was quite tempted by the Minitastic fast road springs however

[skoughi]

Im setting mine up for 13s but only because I live on a rock in the middle of the north sea and we're not awash with a range of second hand 12"wheels and tyres and the 13s with nearly new tyres were offered to me cheap! With many thanks to Cooper man for advice and settings im nearly finished rebuilding my suspension, I've just bought a set of green spot rubber cones(I believe these are standard ones) but nearly bought the smooth ride ones and will be using spax adjustable shocks which will probably be on the softest settings to hopefully overcome the lack of flexible sidewalls on the tyres. Im already thinking about getting 12s once I get her on the road!

[tom1]

Ok lots of good advice here, when setting up your suspension, would I be right in thinking front then rear?  Ride height first,I would guess, then what order would you do rest ?

[Spider]

Every day is a school day! Im still learning and ive been building minis for 6 years

 

While I've not been at it nearly as long as Cooperman, even after 38 years tinking with them, I'm still learning.

 

Gee, now I read that, maybe after 38 years it's time to move on!

[A-Cell]

Single most important parameter for 12 and 13 inch wheels on Mini to get geometry ideal is the ride height. The height was raised in orde to get a better compromise between bump and rebound travel and the camber/ castor angles about the straight ahead. So a spacer was introduced into the knuckle joint with the introduction of 12in wheels, and the knuckle joint with a built in spacer introduced from 1990. http://www.minispare...|Back to search
Lowering the ride height by inference compromises both the handling and the ride characteristics.