ausmini
https://www.ausmini.com/forums/

Extending the track of a mini. Questions obout handling.
https://www.ausmini.com/forums/viewtopic.php?f=2&t=28152		 Page 1 of 2
Author:  clubmn [ Fri Feb 16, 2007 7:59 am ]
Post subject:  Extending the track of a mini. Questions obout handling.
Wide wheels/ offset wheels, spacer drums, spacer discs; are all made to extend the track on a mini hoping to give it better response on the road or the track (maybe looks also). But what is the best combo, Is extra wider better? A local mini shop told me its not.... Can any1 add anything?
Author:  EST-071 [ Fri Feb 16, 2007 8:39 am ]
Post subject: 
The wider you make it creates more stress on your wheel bearings, Not a good thing when you are doing 100km/h and one lets go.
Cheers Pete
Author:  Mike_Byron [ Fri Feb 16, 2007 8:58 am ]
Post subject: 
Okay a sensible answer is that there is a world of difference between the handling of a Morris 850 on the original skinny wheels and a Cooper S (or any mini for that matter) on five inch wide alloy wheels and 165 radial tyres.

Spacer discs are illegal in most states of Australia so the only real way to achive a wider track is to use the spacer drums (and the brakes that were designed to be used with them). Discs already have the wider track.

Alloy wheels (been a long time since I have seen widened steel wheels being used) come with a different offsets so that you can have clearance inside the wheel arch without the wheels protruding past the body line and needing flairs. The other offsets are designed for cars that have the spacer drums and the flairs. They would foul the inside of the wheel arch if fitted to a mini with skinny brake drums.

On the subject of bearings - modern tapered bearings are available for all mini applications and these take the load of sensible widened track very adequately.
Author:  smac [ Fri Feb 16, 2007 9:00 am ]
Post subject: 
This is the second reference I have seen in the last couple of days with regard to bearings 'letting go'. The race boys use ridiculously high outset, and their wheels aren't falling off. Has anyone ever heard first hand of a bearing 'collapsing', 'failing' or any other 'ing' due to high offset? I'm a bit dubious about the whole thing actually - will high offset put additional pressure in the bearing? Maybe, but does that necessarily translate into a significant shortening of it's lifespan? First-hand, comparitive evidence only accepted :)
Author:  Harley [ Fri Feb 16, 2007 9:08 am ]
Post subject: 
smac wrote:
The race boys use ridiculously high outset, and their wheels aren't falling off. :)


That's because the ones with stupid offsets don't use mini suspension at the rear.
They replace the subframe with a lighter trailing arm setup.

As for the fronts, just change the bearings every couple of races.
:D
Author:  clubmn [ Fri Feb 16, 2007 9:14 am ]
Post subject:  mm1275
Not the answer im after.... The question is, is it better to have a wider track and what is to wide on a mini?

and why do
smac wrote:
The race boys

have such a wide track, how does it benefit their cars.
Author:  Mike_Byron [ Fri Feb 16, 2007 9:33 am ]
Post subject: 
Okay I thought I sort of answered that.
Quote:
Not the answer im after.... The question is, is it better to have a wider track and what is to wide on a mini?

and why do
smac wrote:
The race boys

have such a wide track, how does it benefit their cars.


The race boys do it because the more track width and tread that they have on the track the greater the grip and traction, particularly with slick racing tyres and grippy machined radial tyres. As with most competition, those with the greatest advantage have the best chance of winning and some go to great lengths to have best advantage.

To a point the same translates onto road cars androad driving although extreme wide tyres and extended track reduces wet weather driving abilites.

As for the bearing letting go - all front wheel drive cars have an increased load on the front wheel bearings. every car model has its archiles heel and wheel bearing failure is a particular problem with race going Subaru WRX's and I have seen a couple of spectacular in race failures.

I have also seen the damage done by bearing failures in mini front wheel hubs of both drum and disc type but I cannot say it was done by wide wheels - mostly by wear and neglect. Bearings do wear and fail.
Author:  DOZ [ Fri Feb 16, 2007 10:10 am ]
Post subject:  Re: mm1275
clubmn wrote:
Not the answer im after.... The question is, is it better to have a wider track and what is to wide on a mini?

and why do
smac wrote:
The race boys

have such a wide track, how does it benefit their cars.


It obviously doesn't when they are lapping at only 1 sec faster than a good Nb which would be at least 100kgs heavier!

Don't believe me, check this race result from Amaroo, Greig is driving an Nb historic and came 3rd in a SUPER MINI race. look at the lap time ! http://www.natsoft.com.au/cgi-bin/resul ... ARDC.P12.Y

Ok, I agree that Grieg is a good driver but so are most of the people on that list and I know the HP wouldn't be giving any advantage with the weight difference.

Without getting into the technicalities, an increase in track width should result in more grip to a point but as the scrub radius is increased grip is lost. Finding that balance point is the challenge I guess.

The best combo IMO would be the biggest tread width you can fit without increasing the track by more than a couple of inches, unless you redesign the suspension to suit of course.

Regards

Daniel
Author:  smac [ Fri Feb 16, 2007 10:22 am ]
Post subject: 
Don't misunderestimate (sorry, joke from work) the benefit of increased track (when compared to wheelbase) for turn-in.
Also, not sure greater scrub-radius necessarily means grib is lost?
Author:  DOZ [ Fri Feb 16, 2007 10:55 am ]
Post subject: 
smac wrote:
Also, not sure greater scrub-radius necessarily means grib is lost?


Grip is lost and also straight line stability is lost. Even bonneville cars are designed with scrub radius in mind even though they only go straight.

In a corner the wheelbase changes length more (with a higher scrub radius) and this affects the slip angles and ackerman angle. Not realising the errors the usual response is to adjust toe/caster to correct this geometry flaw which aids turn in but affects braking and straight line speed.

On the straight the wheel has more force over the steering control and can result in vibration/shimmy or increased torque steer as well as tramlining.

If the suspension is designed properly in the first place it won't be an issue but the question clubmn is asking I'm sure is based around std components and IMO increasing track too much by wheel offset isn't a good idea.

Regards Daniel
Author:  Mokesta [ Fri Feb 16, 2007 11:51 am ]
Post subject:  Re: mm1275
[quote="DOZ]Without getting into the technicalities, an increase in track width should result in more grip to a point but as the scrub radius is increased grip is lost. Finding that balance point is the challenge I guess.
[/quote]

^^^ What he said (someone has read Milliken). Increased track width is beneficial in that it reduces the left to right weight shift in corners. Another way of doing this is to lower the centre of gravity of the car. The benefit is real but not so great that other factors can be ignored.

When it comes to making a race car go fast, the fastest car often has a less than technically optimal solution that gives the driver the confidence to push the limits. So a car that is stable and trustworthy with predictable break away will be faster than a car with higher limits but unpredictable over-the-limit behaviour. Dodgy scrub radius leading to severe single-wheel-bump kickback and tramlining under brakes will take away the confidence a driver needs.

When it comes to cars, just because a little bit is good, it doesn't mean a lot is better.

M
Author:  deleted [ Fri Feb 16, 2007 3:22 pm ]
Post subject: 
im actually fitting spacer drums to my car today, mainly to fill out the flares. I have widish tyres, but the offset was such that they didnt actually scrub against anything with the standard drums.

Do i stand to gain/lose anything aside of looks?
Author:  Lillee [ Fri Feb 16, 2007 3:36 pm ]
Post subject: 
I can't remember what number or page it is but I have seen the ADR book at a tyre/wheel place and it actaully states:

"Wheel spacers of any type are not legal on any cars in Australia."
Author:  Mick [ Fri Feb 16, 2007 3:51 pm ]
Post subject: 
Me I always thought that it simply decreased the body roll through a corner (Same as lowering the center of gravity) with the downside of a increased twisting motion through the wheel bearings as the weight distribution is further outboard of the vertical centerline through the wheel bearings which may also lead to the possibilty of snapped stub axles as well.


All that in one breath. Did i simplify it? Can that be compressed into a shorter sentence?

P.S. I used to lathe out the centers of old drums to make small spacers. Cheap and plentiful.
Author:  1071 [ Fri Feb 16, 2007 4:02 pm ]
Post subject: 
I would suggest (based on my experience) that the substitution of aftermarket Contestas for the Mini S type (inset) Contestas will not noticeably affect the handling. And this meets the point of te hquestion exactly as the only practical difference is to increase track by about an inch.

Further wheel widening does affect handling negatively making the car more squirrely and subject to tramlining. I had some old widened steel wheels and they were terrible - not sure if it was thetrack increase or the sidewall angle due to the wheels being too wide for the rubber.

Group Nc Minis have wider tracks than Nbs but it doesn't seem to give them much of an advantage - not that all Nbs are created equal ;)

Cheers, Ian
Page 1 of 2 All times are UTC + 10 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/