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Lowered Minis And Ball Joints


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#1 robminibcy

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Posted 05 July 2019 - 11:22 PM

Hi, been thinking about lowered minis and ball joints. Whenever people tend to ask about lowered car there's a general consensus that it's a Terrible idea and ball joints will snap...

Now I under stand that lowering has its pros and cons but that's not my question! My question is how are the ball joints affected by lowering the ride height? The travel isn't changed provided the bump stops are retained and I can't believe the ball joints would be pushed beyond their travel by the suspension arm hitting the stop?

So therefore why are there so many comments warning people not to lower cars with horror stories of ball joints failing?

Edited by robminibcy, 05 July 2019 - 11:23 PM.


#2 Tupers

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Posted 05 July 2019 - 11:38 PM

The problem is that what most people today would consider a “lowered” Mini is on knackered cones and virtually sitting on its bump stops to start with.

That means that any harsh impact from hitting a speed bump or pot hole is pushing the suspension beyond where it’s designed to stop. At that point the ball joints pin hits the cup and you start seeing things snap.
It’s not uncommon to see the cup of the ball joint on a lowered mini with dents where the pin has repeatedly impacted it and as these are hardened parts they will eventually shear from misuse.
Unfortunately this isn’t always obvious because of the rubber shield and when they do snap people tend to blame the parts not them selfs.

It’s another case of people seeing that it works fine on race cars but not accounting for the fact the roads and a hell of a lot worse and tracks.

#3 nicklouse

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Posted 06 July 2019 - 01:00 AM

If you are not modding the bump stops and the arms are not actually touching them then you will be fine.

It is only when you get low and start adding too much neg camber and don’t control the suspension in droop that you can have big problems.

#4 Moke Spider

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Posted 06 July 2019 - 03:21 AM

Hi, been thinking about lowered minis and ball joints. Whenever people tend to ask about lowered car there's a general consensus that it's a Terrible idea and ball joints will snap...

Now I under stand that lowering has its pros and cons but that's not my question! My question is how are the ball joints affected by lowering the ride height? The travel isn't changed provided the bump stops are retained and I can't believe the ball joints would be pushed beyond their travel by the suspension arm hitting the stop?

So therefore why are there so many comments warning people not to lower cars with horror stories of ball joints failing?

 

I did some measurements on this to establish exactly what the ball joints will do and how far they articulate. This was done with a set of Original Ball Joints, some of the replacements may not do this. It also used Stock Upper, Lower Arms and Caster Bars.

 

For the purpose of these tests, I did a 'worst case, where I removed the Bump and Rebound Stops, as there's a chance these can break off in 'normal' use (yes, they should be replaced, but you just never know when and how these situations may occur).

 

In Terms of Full Compression (or lowered all the way past the Bump Stop) as far as the Ball Joints go, there's no issue with either Top or Bottom binding and that includes all steering angles too. The Joints were just making contact between the Pins and the Cups at this point. Your Drive Shafts will contact the Window in the Subframe before you reach this point.

 

In Rebound was where where there was an issue. While the Wheels were in a straight ahead position, this was OK, but with Steering inputs, the lower joint did bind and got worse with more steering input.

 

If you have any Negative Camber dialed in, on Rebound, the Lower Ball Joint will lock and breakage is a very real possibility. The Factory in fact recommended packing up the Rebound Stop by 1/8" (3 mm) if any Neg Camber is to be used.



#5 unburntfuelinthemorning

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Posted 06 July 2019 - 06:33 AM

So it's not lowered cars as much as badly maintained cars which are the problem.

 

Minis with missing rebound rubbers used to be so common - probably is still the case.  I always replaced them but never realised how important they were. 

 

I've read plenty about negative camber but never anything about packing the rebound rubber.  I'll remember that one.



#6 Moke Spider

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Posted 06 July 2019 - 07:44 AM

Here's the factory's notes on it;-

 

Xgdhxb7.jpg

 

It wasn't until I did these measurements above that the penny dropped for me on why they insisted this obscure modification be done !



#7 carbon

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Posted 06 July 2019 - 08:00 AM

Here's the factory's notes on it;-

 

Xgdhxb7.jpg

 

It wasn't until I did these measurements above that the penny dropped for me on why they insisted this obscure modification be done !

I don't think this advice is still given by any of the current suppliers of negative camber front suspension arms?

 

I do remember fitting these plates when installing a pair of (hen's teeth) ST arms to the Marcos back in the mid 80's.



#8 unburntfuelinthemorning

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Posted 06 July 2019 - 08:08 AM

I don't think this advice is still given by any of the current suppliers of negative camber front suspension arms?

 

Maybe it would reduce sales if they did.



#9 Cooperman

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Posted 06 July 2019 - 12:14 PM

In all my years with Minis I have never seen that advice to fit a 1/8" plate on the rebound side. 

It's never been a problem, but then I have never lowered a Mini and when I have fited 1.5 deg neg camber arms they have been on rally cars where the ride height is usually raised slightly.



#10 nicklouse

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Posted 06 July 2019 - 08:14 PM

In all my years with Minis I have never seen that advice to fit a 1/8" plate on the rebound side. 
It's never been a problem, but then I have never lowered a Mini and when I have fited 1.5 deg neg camber arms they have been on rally cars where the ride height is usually raised slightly.

ST tuning did as does Vizzard in his book.

#11 unburntfuelinthemorning

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Posted 06 July 2019 - 08:24 PM

In all my years with Minis I have never seen that advice to fit a 1/8" plate on the rebound side. 

It's never been a problem, but then I have never lowered a Mini and when I have fited 1.5 deg neg camber arms they have been on rally cars where the ride height is usually raised slightly.

But Moke seems to be saying it's a problem no matter what the ride height is if you're using negative camber arms and this is why the rebound rubber should be modified.



#12 unburntfuelinthemorning

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Posted 06 July 2019 - 08:30 PM

 

In all my years with Minis I have never seen that advice to fit a 1/8" plate on the rebound side. 
 

ST tuning did as does Vizzard in his book.

 

Are you thinking of the How To Modify Your Mini book?  He mentions front bumpstop reinforcement using 16 gauge plate in the Off Road Prep chapter when using hydrolastic type bumpstops.  I don't think there's anything about modifying the rebound rubbers.



#13 Compdoc

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Posted 06 July 2019 - 10:11 PM

How would the roll centre adjusters, from Minisport, affect this situation, if at all,

https://www.minispor...-1959-2001.html



#14 nicklouse

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Posted 06 July 2019 - 10:12 PM

In all my years with Minis I have never seen that advice to fit a 1/8" plate on the rebound side.

ST tuning did as does Vizzard in his book.
Are you thinking of the How To Modify Your Mini book?  He mentions front bumpstop reinforcement using 16 gauge plate in the Off Road Prep chapter when using hydrolastic type bumpstops.  I don't think there's anything about modifying the rebound rubbers.

There is as that is where I first came across it. Could not have been anywhere else. Miles away from my copy so can’t check. But when I did the lengthening of the standard arms as per his book I also did the rebound spacer.

#15 nicklouse

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Posted 06 July 2019 - 10:18 PM

How would the roll centre adjusters, from Minisport, affect this situation, if at all,
https://www.minispor...-1959-2001.html


Bloody expensive ball joints. Wrong grade nut as well. And you need to be very low to need them and I am still not sure that what they say they do is actually worthwhile.

And as to the angle issue I don’t think it would help. But with a 1/8 spacer and/or the shortened shocks it ain’t an issue.




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