Just been through this issue but i'm sure a few of you will be aware of this.My coupe failed MOT on rear brake efficiency and front ball joint.Sorted brakes but had an argument with the guy about the ball joint,old one in my opinion was perfect,a bit late,just spent a small fortune buying a good quality whole suspension arm.
I told MOT guy i didn't agree and i took it elsewhere,'they' failed it on the same issue,ball joint!!,'but',they told me previous MOT garage had got wording wrong on the
fail sheet,instead of saying 'ball joint excessive play',or whatever it was,it should be 'excessive play in ball joint fixing point',ie the hub!!
He even told me he's heard of people going away from other garages and buying two whole complete suspension arms when ball joint wear has been mis-diagnosed,then returned for retest and it fails again!!Please be wary of this at MOT time.I'll also tell you how i fixed the wear,MOT guy was good enough to give me a little tip,drop ball joint out of hub,use a thin cutting disc on a hand held angle grinder and 'carefully' just run it through the opening of the ball joint clamp,rest the grinder disc against the gap and carefully just let the disc do the work!
Done this this morning,in conjunction with a new clamp bolt,returned to MOT station and it got through no problem!!

Tell me you didn't just take a grinder to your uprights?

If you've ovaled the hole no grinding of the slot will restore the wear.

No,i just ran the grinding disc slowly into the actual gap that tightens up to secure the ball joint.Took it back and it passed mot no problem,no advisories at MOT either,happy chappy!

Not convinced that what you've done is safe. Movement at the upright/ball joint pin is wear in the upright. You can't restore the interface grinding where you have.

It is safe, its just passed an mot, and it was an mot guy that told me to do it, its an old trick that people have done for years to take up the wear in the hub clamp..I cant really understand why you're so concerned at what I've done? Opening up the gap with the grinding disc that the clamp bolt tightens up, only means it will now draw in more and grip onto the ball joint pin more securely!Which it has done to meet mot regulations.
Just so were on the same page here, im talking about the hole that the ball joint goes up into on the hub.It has worn out to a larger circumference than it should be, hence it no longer grips the ball joint pin/stub properly.

Passing an MOT doesn't mean something is safe.

The MOT is designed to test component's operation within their normal operating parameters - altering something with an angle grinder isn't making it pass the test, its cheating the test.

rant over... as you were.

My concern is that originally the hole looks like a C shape when it's open. With the bolt in it's an o shape. The fact that you had play there indicates the hole is now oval when closed (say like this 0). Taking a bit out of the clamp so you can close it further doesn't resolve the oval.

The significance of the oval is that you now have reduced clamp area on the ball joint. So while you passed the MOT with 1 guy prying on the joint, the full weight of the car over a bump could be enough to pull it out.

No, it's passing the test.To cheat someone is to deviously do something to fool another person by underhanded means so they have no knowledge of your intentions.To carry out a fix suggested by 'someone' working for an organisation then renders the possibility of 'cheating' that 'someone'/organisation an impossible task!As 'you' were.

You'll not win robbo. Nothing other than textbook perfection seems to be tollerated here.
Anyone deviating from original specification will be shot down in flames.

Just because it may be perfectly adequate and safe for the rest of the cars natural life, you'll still be vilified.

As a main dealer technician for Mercedes and VW we'd often get bulletins for "manufacturer modifications" on all manor of subjects like this.

szkom's point is a good one and fair, but I would have another concern. The ball joint is also a form of bearing and the load in that bearing is shared over a large area of the ball and socket.

With the fix you've described, you will no doubt pass an MOT, as you will temporarily reduce the play, but the new shaped surfaces will not clamp evenly and provide a good bearing surface to share the load.

Most likely you will get very fast wear and the joint will become loose again in no time. As for how safe it is, or is not, I wouldn't like to say, but I have the benefit of more than 20 years in the bearing industry, including 5 years with SKF and I know what I'm talking about and based on his comments, so does szkom.

You may be pleased you passed your MOT and with the "fix" you applied, but people on here are giving their opinions for your benefit. There's an awful lot of combined knowledge in this forum and sometimes it's good to listen.

Not having a go; just trying to provide a balanced opinion based on many years of relevant knowledge.

I thinks all will be fine so long as you used a genuine Bosch angle grinder.

So long as it's from the Bosch Professional series.

You guys are fairly new to the forum, we've had some proper spanners on here. Including grinding calipers so.pads fit, using lump hammers to fit pads etc etc.
We've also seen a few cars loose hubs front and rear through bad practice and poor maintenance, 1 resulting in a near fatality and a car rolling at speed. The concern is there for others as well as your own safety, not everyone understands the loads a ball joint suffers or the consequences of failure, you're not pratting about with a moris minor or an old mini this is a 1,600 kg car of decent performance.

On a further note I'd hate to buy a car that had had an angle grinder taken to items that are safety critical.....

I see the time and time again on this forum.
Yes grinding callipers and hammering pads in is obviously the wrong way to do things.
I may be new to the forum but I have all my papers, served my time on an apprenticeship and worked for three main dealers and independent garages for 20 plus years.

I'm withdrawing from this debate and possibly any others in the future.
Too many threads end up in petty arguments.

Surely pin on the ball joint should be clamped firmly when fitted correctly with brand new parts? If this is the case, how does the pin, or the hole wear? If either wear this suggests that there is friction from parts moving?

I was off the understanding the pin was static, and the ball moved in the joint. Could be wrong though.

What the guy from the mot station says was its a relatively common problem.Caused by people bashing in the clamp bolt initally, at not quite the right part of the ball joint pin , then vibration and play causes more wear as the damaged bolt allows up and down movement.Also bad quality metal on the hubs was mentioned.

You're quite right, I dont understand why people start petty arguments.I come on this forum to merely mention what a couple of mechanics said to me then cheating etc is mentioned, I dont get it?

The car was rattled around on jiggle plates on the garages ramps to simulate road use,the joint is totaly secure, only 1mm was removed on each face of the clamp, it was carefully done in a jig and not 'pratted about with'.

Fellas I was mearly giving the other side of the story so you understand where some, not all, of the concern comes from.

Steve my comment about new to the forum meant you didn't know what shite we've put up with in the past, I wouldn't question anyones skills with a spanner especially as everything I know is passed from father to son!

Robbo - you never mentioned jigs or wiggle plates, from your description I assumed pretty much as others and a grider was taken to an up right in the hope of a flat surface and a better grip.

Gentlemen, you all appear to be fiercely agreeing with each other...

Steve, please don't exclude yourself; we need more input from mechanics for precisely this reason.

Robbo, if the MOT is happy with that, then it's happy. As I understand it, you've opened the clamping gap in the hub carrier to increase the clamping force? As your man has said, wear in that clamp is probably down to the cotter bolt being placed incorrectly at some time in the past, allowing movement vertically as it's settled into the groove cut for it. There should never be any wear in that clamp; the only time it moves is when the ball joint pin is removed or inserted.

Personally, I wouldn't have done it; I'm leery of bending cast iron parts which don't have a huge tension strength. The correct approach would be to replace the hub carrier, I think. I think the MOT inspector is talking through his elbows if he's recommending that course of action.

Nonetheless: please understand that if people are disagreeing with your fix, it's not just to disagree with your fix. What we try (and often fail!) to do here is to find the best solutions for problems, and safety is always a concern. Don't take it personally!

Imo it Sounds more like a temporary solution rather than a permanent one either way 12months mot can't be bad

Exactly, I will replace the hub when I get around to it.Just spent far to much lately, I need a breather!;-)

I'm not taking anything personally at all, im perfectly calm, I cant take anything persinally as it wasn't my fix, I never took this off my own back to do, it was suggested by a mechanic.

I feel I must apologise for ny outburst.
We all inrerpret things differently in written word.
Without actually having the thing in your hands and examining it thoroughly it's very difficult to pass judgment on things.

Id had a tough day, apologies to all

Had this problem on my 1st coupe when it was less than 3 years old!

Wishbone pin was still knocking in the hub carrier even after replacing the wishbones and pinch bolts with original Fiat parts, so had to replace both hub carriers. About £500 the pair from Desira Fiat iirc.

A couple of pics showing the clamping joint:





Opening the gap by 2mm to give more clamping force must be just about doubling the gap. Possibly OK as a short term solution but will obviously significantly increase the stress on the casting.

Shiny!

Pics are from March 2002, they won't be quite as shiny today.