80 replies to this topic

[Carlos W]

But if they fail on a golf buggy what's the worst that's going to happen? The course gets a bit dug up.

 

If they fail at 80mph on a motorway it'll potentially be game over possibly for more than one vehicle and its contents

[The Matt]

It doesn't make the slightest bit of difference whether they're for a golf buggy or a spaceship.

 

It does, though.  That's the thing.

 

The "load rating" will be the resultant of what standard it's designed for.

 

Aerospace design uses large safety factors, golf buggy design uses small safety factors.

 

Soooo, a golf buggy wheel with a load rating of 226kg might fail at 500kg load, a spaceship wheel with a load rating of 226kg might fail at 2250kg load...and may have a vastly improved fatigue life too.

 

I'm not trying to poopoo them, I think they're really cool.  I'm just saying that I think they'll be designed to conform to a totally different standard than other road wheels are.

[Cooperman]

Does the load rating say in what mode the load is considered. If it is a static load, or a straight line dynamic load it will take no account of the side loads on the web of the wheel when cornering with high-grip modern road tyres.

I am old enough to remember the original Mini wheels which were specifically designed for the car, but which failed in hard use even with 145 x 10 Michelin or Dunlop early radial tyres.

I was driving a 1960 Mini Traveller with the original wheels in 1964 and on a long left hand bend a wheel failed. In fact it fractured around the wheel nuts and the wheel & tyre went off on its own. It wasn't my car, but one I had been lent by a motor dealer friend whilst my Cooper was having some preparation done. He had taken it in part-ex and it turned out the wheels had not been changed, which BMC did free for all owners. Luckily no further damage except a worn down swivel pin. Fitted the spare and continued my journey.

The question with the golf buggy wheels is whether the fatigue stress with road tyres fitted has been calculated. That will take in maximum cornering forces over a long period. All alloys fatigue and wheels must be designed with the application in mind.

[MiniNoobJhb]

So now to throw a bit of a spanner in the works.

Would the same thought pattern be followed if the wheels were for quad bikes?
Let's awesome the same load rating (200 odd kgs per wheel) but obviously they built for much harder terrain and much higher speeds.

[The Matt]

Well. Again, they may well be designed and tested to a different level of safety. But I'd assume that the design would take similar factors into account as other road wheel design does.

It's not like I'm trying to write them off, I'm just trying to add into the debate from a design perspective.

[MiniNoobJhb]

I agree 100% with you Matt.

The most boring debates I've ever had are those where there was consensus.

I think the quad bike wheels would be able to withstand a few pothole hits much better than a car wheel would. Lol

[MattMiniS96]

http://www.quadbikes...tml?rimsize=635

[The Matt]

http://www.quadbikes...tml?rimsize=635

None of those will even fit, regardless of whether they're designed/made/tested to a correct standard.

[MattMiniS96]

Yeah I know, but it could start something new

[sonikk4]

Another way of looking at this is does the manufacturer of the Golf Buggy wheels stipulate these can be used on anything else but a Golf Buggy???? And of course suitable for road use??

Now I like the look of them and they suit the car well but if in the event of a failure which causes an accident then you will not have a leg to stand on and could face criminal charges as well as financial penalties.

Doom and gloom, yes you would be right but having had to deal with insurance companies four times so far and having to fight my corner hide each time they look for the smallest issue with which they can use to not pay out. It's not fun.

All I will say here is be very very wary.

[Cooperman]

The ultimate load case which must be considered is a maximum cornering force on the outside wheel on a dry surface at, say, 70 mph. The car will hold a certain radius turn with some understeer and a certain weight will be applied as a side load to the wheel. If, say, the car weighs 750 kg, which a loaded Mini can weigh and let's say 75% of that load goes onto the front wheels of which 80% is taken by the outside wheel. It is possible for a car on really good tyres on a  dry smooth road to generate over 0.8 G sideways load, so that's 0.56 G on the front. That's 0.44 x 750 kg taken through the front wheels = 330 kg. With 75% of that load going through the outside wheel that is 250 kg.

So the basic side loading on the wheel rim is 250 kg, to which a reserve factor must be applied to allow for shock/bump loads and for fatigue. I reckon that figure at which failure can be expected when new should be a factor of 4, so the wheel should take 1000 kg shear load. In fact, as the load is applied between the centre of the heel and the tyre contact point, there is a degree of bending as well, which will tend to increase the required strength. In fact, the bending stresses are what caused the early 850 Mini rims to fail as the higher loads which the Mini suspension was capable of inducing were higher than expected by the design engineers (or so I was once told - and it makes sense).

Would a golf buggy take those sustained loads. That is the big question, but unless I had that in writing from the wheel manufacturers I know I would be reluctant to fit them, however 'nice' they look. If they are cheap, it is for a reason.

[MattMiniS96]

Well I suppose if anyone wants to give it a go the webpage that is linked to the company who sells them on the OP, now does international delivery. If I had the money I'd give it a go..

[evansisgreat]

Would the steel wheels be easier to rate for strength? If the thickness was up to scatch and the welds were of a good standard?
The 7x10 and 6x10 might be an option for someone who was going to band some steels.

[The Matt]

Interestingly, and totally related to this thread:

 

http://www.theminifo...l/#entry3177715

 

There needs to be science and engineering behind modifying vehicles, yet people ignore it.  Safety and reserve factors are there for a reason.  Materials have limits, above which you may be inducing fatigue but not actually be "breaking" something.  Hence having a safety factor, to make sure that you are operating at loads below that limit.

[Ethel]

I like Cooperman's viewpoint. A simpler alternative could be to look for a weaker link. What would it take to shear a ball joint pin using the other  as a fulcrum and the wheel/tyre as your lever?