12 replies to this topic

[lawrence]

Good morning,
I have recently come across some metro hubs (nos with surface rust) along with new roller bearings and new ball joints (from the wrong age to fit mini arms however can buy the correct ones easily)

I have also got perfectly functioning mini hubs on the car currently and have the spares to rebuild them multiple times.

I am planning to fit adjustable lower arms to my subframe to get my camber spot on for best road holding (currently have 2deg fixed arms which we all know don't make the camber 2deg but add to it).

What are people opinions regarding fitting these metro hubs or should I sell them on? The only reason for fitting them would be the one piece ball joints that I can buy for alot less money nos compared to mini ones.

Thankyou for your opinions in advance
Lawrence

[Spider]

On a Mini, especially one for the road, stick with Mini Hubs.

[Ethel]

It can be done, but they'll be more effort to set up. The kingpin angle is different and can't be adjusted away. That will also effect scrub radius and so wheel offset.

[mini13]

To make them work you need to use the metro steering arms, and also shim out the bump steer. So really you need to convert to rose joint track rod ends.

[tiger99]

You can NEVER get correct geometry. As Ethel has said, the scrub radius will always be wrong, and that is a safety related parameter as it has a critical effect on stability in the event of a burst tyre at speed. It will also completely ruin the steering feel, and you can't shim out the bump steer, and rose jointed track rod ends do not help. They have their uses, but not to correct fundamental problems.

 

I do appreciate the point about ball joints, but the Mini ball joints are safe and reliable IF SET UP PROPERLY AND REGULARLY GREASED. You can grease all 8 nipples on a Mini in under 10 minutes, every 2000 miles (actually you can go to at least 6000 if you clean the joints of LM grease and use molybentone instead). The perceived problems, some of which directly impact safety, come from people who are too stupid to actually read the manual, because they know it all, or use a grease gun, because you don't do that nowadays. Wrong on both counts, and I find wilful ignorance in any context rather disturbing, especially where it relates to safety. A properly assembled ball joint is good for at least 40k miles, and I have had very much more. Just how many years of Mini driving is that nowadays?

[Spider]

On a Mini, especially one for the road, stick with Mini Hubs.

 

I'll expand a little more on this.

 

I've just gone through a very lengthy 'reverse engineering' process of the Mini Hub and also the entire front suspension geometry of the Mini.

 

The standard Mini Hub already has too much King Pin Angle and the Metro Hubs have more. It's taking a less than idea situation and making it worse.

 

Yes, they can be fit and various other components added or made adjustable to get them more or less sorta doing the something very roughly in the desired direction, but a better - superior - result can be achieved with the standard Mini Hubs and few component changes. Your Wheel Bearings and Drive Flanges will also last considerably longer too.

 

To make these hubs have a hope of working, wheels with LOADS of Positive offset are needed, but such wheels will foul the shock, Radius Rod and likely other parts on a Mini.

 

<EDIT: Off hand, a standard Mini Wheel has around Minus 30 mm ET (Offset), whereas the standard Metro Wheel has around Positive 45 mm ET. That's a difference of around 75 mm on a wheel that's only 115 mm in width to start with. >

Edited by Moke Spider, 24 March 2017 - 11:43 PM.

[tiger99]

Thanks for those numbers, very useful stuff as always.

So now we know why the Metro needed pressed lower arms of somewhat T shape, like many modern cars, rather than a forged lower arm and a tie rod, forming a triangular wishbone. It is all about providing clearance for the wheel offset. You "could" design Metro arms into a Mini, but surely you want it to handle like a Mini, not a Metro?

A point which the unwary should bear in mind (silly me, bit too much hope there...) is that the negative scrub radius was introduced specifically to handle unbalanced front wheel torques without seriously destabilising the vehicle. (The late LJK Setright, last of the real motoring journalists, wrote a few articles about it in Car many years ago. I wish I had kept all my old magazines!)

So woe betide anyone fitting ABS brakes to a Mini or indeed almost any old car, as positive scrub radius was almost universal in the old days. I can't see how a LSD can be tolerable either, but at least with those, the natural instinct to raise your right foot will save the day. Can't do that if braking goes all wrong...

Someone fitted a full Metro subframe to a Mini a very long time ago, complete with K series engine (nice) and front floor and lower bulkhead welded in to get the rear mount (not so nice). It was in one of the monthly comics and I thought it looked stupid with excessively wide arches. Hardly a Mini at all. You could get much of the same results without all the butchery with a custom subframe, which is now the fashion, and the track narrowed compared to the Metro. But again it will never have the feel of a Mini, and surely that is the reason why we drive them?

(Slammers excepted, of course. They can never experience the real pleasure of driving.)

[Ethel]

Are you thinking of the Rover 100 version of the Metty? The earlier A Series one has forged arms, like the Minis, but there's an antiroll bar in place of the tie rods that's more inboard.

My Mini baaed kitcar did originally have Metro swivel hubs and I'd have to say it cornered pretty well. Wish I'd measured it properly.

[Ethel]

Are you thinking of the Rover 100 version of the Metty? The earlier A Series one has forged arms, like the Minis, but there's an antiroll bar in place of the tie rods that's more inboard.

My Mini baaed kitcar did originally have Metro swivel hubs and I'd have to say it cornered pretty well. Wish I'd measured it properly.

[mini13]

a couple of points here, Tiger says you can never get correct geometry, and that is correct... including with the std mini hub.. or any other hub on any car ever made, all you can do is dial these out so they have a minimal effect.

 

 

Also I would kind of disagree with the KPI issue, yes it adds more sterring weight but, you are also reducing the scrub radius with the metro hubs so counteracting the steering weight. Also Moke, you want to check up on the ofsets of mini rims... the are negative not positive.

[tiger99]

The scrub radius and steering weight do not counteract each other in the way that you assume. They BOTH have to be within acceptable limits, scrub radius especially as it directly affects safety, and you can not get even ONE of them nearly right.

Actually you CAN get CORRECT geometry which is usually AS THE DESIGNER INTENDED or close to it. You really would not want mathematically correct geometry as the feel and handling would be poor. You NEED some geometric compromises to make it acceptable and pleasant to drive. Despite the marketing departments of certain manufacturers, you DO NOT NEED AND SHOULD NEVER HAVE geometry that seriously compromises the roadholding and handling.

I will repeat, YOU CAN NOT GET ACCEPTABLE GEOMETRY WITH METRO HUBS ON A MINI.

A certain manufacturer whose products do not have the highest class of handling, despite their price, meddled with McPherson struts (really, on an up-market car?) and introduced extra linkages to correct some geometric errors. They did that but handling was not improved at all. It might have been had they fixed their abysmal semi-trailing arm rear. The rear wheel drive was and is in itself not a problem. (You buy an expensive car and get a cheap, nasty, inferior suspension layout which everyone except your nearest (geographically) competitor regarded as obsolete when the Triumph 2000 or TR6 ceased production. Hmm....

One form of geometrically correct suspension is in fact beam (or DeDion) axles, properly located with Watts linkages. But if you understand gyroscopic theory you will know why these are a very bad idea, made more palatable with power steering of high boost ratio to remove the feel.

Now there is a truly horrid thought. A beam axle rear (a real one, not the same terminology wrongly used by those who want to do away with their subframe) and DeDion front (Hotchkiss axle too
difficult with transverse engine) on a Mini. Just how vile would that be? Perfect geometry, fixed roll centres, wheels always parallel or with fixed camber relative to each other. But.....

Maybe no worse than Metro hubs?

Edited by tiger99, 27 March 2017 - 04:46 PM.

[mini13]

using capitals is not going to make you correct. neoither will diverting the converstion to other obsolete forms of suspension.

 

"as the designer intended it" does not make it correct, lets all run perfect ackerman eh.  

[Spider]

I'll only say / add that I don't necessarily agree with all that's been suggested here, though there are some good points too.

 

But, I'll further add that I can't ever see that there's a 'perfect' set up - everything is a compromise in one way or another, some more than others, so what appears to be one person's 'Jem' is the next guy's 'black dog'.