67 replies to this topic

[HUBBA.HUBBA]

 

 

Regardless of how the top arm is mounted, his point is still valid. The bottom arm is attached with a rubber bush and that will flex under load.

I don't think it's as easy to decide whether the angle of the ball joint is safe or not as you believe it is. Just because it doesn't bind on the cup doesn't mean it's not under an increased amount of stress.

Think of your knees, a pivoting joint just the same as the ball joints. Lined up as designed, you can stand up with your weight on your legs all day. Now bend your knees to say 110 degrees. Miles off the maximum travel of your leg, but you won't hold like that all day.

There is no evidence that I have seen or that anyone on this entire forum has ever said they have seen, to suggest that it will cause extra load on the ball joint, especially no proof that this extra load is enough to cause definite failure. It's all word of mouth, he said she said stuff as is always the case with the mini scene. If nobody tests it how can it be factual?

The ball joint is still doing its job no matter what angle it's rest position is.

 

 

 

Forget all the conjecture, and frankly you're very naive if you can't understand it:-

 

1) The working angle of the balljoint has a huge effect on the possibility of failure. For one thing certain is that the compressive load becomes a shear stress the more the joint is articulated. I think the analogy of a knee is pretty reasonable, going from compression loads to shear as the angle increases.

 

If someone has drawings of the front suspension then we can get Bow's notation and Mr Tangent out of their boxes and calculated the differences for various angles. 

It's hardly necessary really, anyone with basic engineering understanding should be able to see it. Whether it breaks and how long it takes and under what circumstances are a matter for more serious investigation.

 

Would it be compounded more by having neg chamber aswell?

[Gremlin]

Adam-93rio asked how much to cut the bumpstops down by, no-one has actually advised him on this yet, yet you've just said that he's going to die

[Deathrow]

There's a technical drawing on the front page of http://www.wheeldictionary.net which might be of some use.

[Captain Mainwaring]

 

 

 

Regardless of how the top arm is mounted, his point is still valid. The bottom arm is attached with a rubber bush and that will flex under load.

I don't think it's as easy to decide whether the angle of the ball joint is safe or not as you believe it is. Just because it doesn't bind on the cup doesn't mean it's not under an increased amount of stress.

Think of your knees, a pivoting joint just the same as the ball joints. Lined up as designed, you can stand up with your weight on your legs all day. Now bend your knees to say 110 degrees. Miles off the maximum travel of your leg, but you won't hold like that all day.

There is no evidence that I have seen or that anyone on this entire forum has ever said they have seen, to suggest that it will cause extra load on the ball joint, especially no proof that this extra load is enough to cause definite failure. It's all word of mouth, he said she said stuff as is always the case with the mini scene. If nobody tests it how can it be factual?

The ball joint is still doing its job no matter what angle it's rest position is.

 

 

 

Forget all the conjecture, and frankly you're very naive if you can't understand it:-

 

1) The working angle of the balljoint has a huge effect on the possibility of failure. For one thing certain is that the compressive load becomes a shear stress the more the joint is articulated. I think the analogy of a knee is pretty reasonable, going from compression loads to shear as the angle increases.

 

If someone has drawings of the front suspension then we can get Bow's notation and Mr Tangent out of their boxes and calculated the differences for various angles. 

It's hardly necessary really, anyone with basic engineering understanding should be able to see it. Whether it breaks and how long it takes and under what circumstances are a matter for more serious investigation.

 

Would it be compounded more by having neg chamber aswell?

 

 

Do a drawing yourself and answer your own question - draw a set of stand length bottom arms attached to a hub with ball joints, now extend them for negative camber. How does the geometry change?

[HUBBA.HUBBA]

Regardless of how the top arm is mounted, his point is still valid. The bottom arm is attached with a rubber bush and that will flex under load.
I don't think it's as easy to decide whether the angle of the ball joint is safe or not as you believe it is. Just because it doesn't bind on the cup doesn't mean it's not under an increased amount of stress.
Think of your knees, a pivoting joint just the same as the ball joints. Lined up as designed, you can stand up with your weight on your legs all day. Now bend your knees to say 110 degrees. Miles off the maximum travel of your leg, but you won't hold like that all day.

There is no evidence that I have seen or that anyone on this entire forum has ever said they have seen, to suggest that it will cause extra load on the ball joint, especially no proof that this extra load is enough to cause definite failure. It's all word of mouth, he said she said stuff as is always the case with the mini scene. If nobody tests it how can it be factual?
The ball joint is still doing its job no matter what angle it's rest position is.

 
 
Forget all the conjecture, and frankly you're very naive if you can't understand it:-
 
1) The working angle of the balljoint has a huge effect on the possibility of failure. For one thing certain is that the compressive load becomes a shear stress the more the joint is articulated. I think the analogy of a knee is pretty reasonable, going from compression loads to shear as the angle increases.
 
If someone has drawings of the front suspension then we can get Bow's notation and Mr Tangent out of their boxes and calculated the differences for various angles. 
It's hardly necessary really, anyone with basic engineering understanding should be able to see it. Whether it breaks and how long it takes and under what circumstances are a matter for more serious investigation.

Would it be compounded more by having neg chamber aswell?

 
Do a drawing yourself and answer your own question - draw a set of stand length bottom arms attached to a hub with ball joints, now extend them for negative camber. How does the geometry change?

Does that mean you don't know either!

[adam_93rio]

Everything on the mini scene is word of mouth, for years people have put ball joint failures down to lowering of minis.
How many minis out there are lowered? I dare say at least half
How many have ball joint failures? A hell of a lot less than 1% through life of the ball joint/ when they are changed as a service item
How many of this tiny percentage buy the cheap **** off eBay instead of the proper genuinely made ones from mini spares? For you to answer or predict, I would say if there wasn't a demand for them then there wouldn't be so many still for sale on eBay etc.

I got sick of this thread the first time round, Nothing but haters and doubters. Barely anybody who had actually tested it who could PROVE that it causes ball joint failure. I have said that I change my ball joints for new, good quality replacements (never shimming to take up wear) at least teice a year, and I have been running my car as low as I can get it for a good few years and never had a problem.
Ive had no end of self proclaimed engineers telling me there's extra strain and they aren't strong enough, I've done some calculations a while back, even headed back into my old college to speak to the tutor from my mechanical engineering diploma to check my workings etc. the good quality ball joints have been found to be up to the job for lowered minis even further than I have gone, both practically and theoretically so these people trying to estimate my life expectancy through word of mouth can either deal with the fact that someone is proving you wrong, or (queue bluntness) get on their knees and suck it

I'm not answering any more questions on this subject, and I'll be asking for this thread to be deleted as I'm sick of being told what is right or wrong from pure word of mouth. So I apologise to those people that wanted honest advice on lowering their mini

[Captain Mainwaring]

 

 

 

 

 

Regardless of how the top arm is mounted, his point is still valid. The bottom arm is attached with a rubber bush and that will flex under load.
I don't think it's as easy to decide whether the angle of the ball joint is safe or not as you believe it is. Just because it doesn't bind on the cup doesn't mean it's not under an increased amount of stress.
Think of your knees, a pivoting joint just the same as the ball joints. Lined up as designed, you can stand up with your weight on your legs all day. Now bend your knees to say 110 degrees. Miles off the maximum travel of your leg, but you won't hold like that all day.

There is no evidence that I have seen or that anyone on this entire forum has ever said they have seen, to suggest that it will cause extra load on the ball joint, especially no proof that this extra load is enough to cause definite failure. It's all word of mouth, he said she said stuff as is always the case with the mini scene. If nobody tests it how can it be factual?
The ball joint is still doing its job no matter what angle it's rest position is.

 
 
Forget all the conjecture, and frankly you're very naive if you can't understand it:-
 
1) The working angle of the balljoint has a huge effect on the possibility of failure. For one thing certain is that the compressive load becomes a shear stress the more the joint is articulated. I think the analogy of a knee is pretty reasonable, going from compression loads to shear as the angle increases.
 
If someone has drawings of the front suspension then we can get Bow's notation and Mr Tangent out of their boxes and calculated the differences for various angles. 
It's hardly necessary really, anyone with basic engineering understanding should be able to see it. Whether it breaks and how long it takes and under what circumstances are a matter for more serious investigation.

Would it be compounded more by having neg chamber aswell?

 
Do a drawing yourself and answer your own question - draw a set of stand length bottom arms attached to a hub with ball joints, now extend them for negative camber. How does the geometry change?

Does that mean you don't know either!

 

 

A good reply to be fair  

But....Yes I do know, as would you if you got your pencil out....

Neg camber bottom arms would reduce the ball joint angle at the top of suspension travel and increase it at the bottom -

[Captain Mainwaring]

Everything on the mini scene is word of mouth, for years people have put ball joint failures down to lowering of minis.
How many minis out there are lowered? I dare say at least half
How many have ball joint failures? A hell of a lot less than 1% through life of the ball joint/ when they are changed as a service item
How many of this tiny percentage buy the cheap **** off eBay instead of the proper genuinely made ones from mini spares? For you to answer or predict, I would say if there wasn't a demand for them then there wouldn't be so many still for sale on eBay etc.

I got sick of this thread the first time round, Nothing but haters and doubters. Barely anybody who had actually tested it who could PROVE that it causes ball joint failure. I have said that I change my ball joints for new, good quality replacements (never shimming to take up wear) at least teice a year, and I have been running my car as low as I can get it for a good few years and never had a problem.
Ive had no end of self proclaimed engineers telling me there's extra strain and they aren't strong enough, I've done some calculations a while back, even headed back into my old college to speak to the tutor from my mechanical engineering diploma to check my workings etc. the good quality ball joints have been found to be up to the job for lowered minis even further than I have gone, both practically and theoretically so these people trying to estimate my life expectancy through word of mouth can either deal with the fact that someone is proving you wrong, or (queue bluntness) get on their knees and suck it

I'm not answering any more questions on this subject, and I'll be asking for this thread to be deleted as I'm sick of being told what is right or wrong from pure word of mouth. So I apologise to those people that wanted honest advice on lowering their mini

 

And you just seek to perpetuate the myths by failing to look at things from a purely engineering standpoint.

 

 

It's not about "would this 100% cause failure" - it's about "would this increase the probability of failure".

 

You state "A hell of a lot less than 1% through life of the ball joint/ when they are changed as a service item" 

 

Do you have data to back that up?  If you have calculations, I'll be interested to look over them for you.. I'd be amazed if you've tested 50 ball joints to destruction and analyzed the failure points, and that's what you need to do, to see if the failure fits your model and stress analysis. I looked at MATLAB and as far as I can see, there wasn't a formula for "a hell of a lot less".

 

 

Oh, and you're being told what is right and wrong through engineering experience, not word of mouth or conjecture - face up to it, you accuse others of speculation, when you do just the same thing, the difference is their speculation isn't at the expense of safety. 

You state you've done the analysis and maths on it, if you have, then you can prove easily just how wrong the doubters and hater are - until then, neither side is correct, but safety wins over both.

Edited by Captain Mainwaring, 14 June 2013 - 01:55 AM.