Making My Own Control Arms

lambertius

Banned
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341
I thought this had already been answered...


At such an early stage I'd like to wish the OP well in his endeavours.

Thanks.

So you won’t be selling them to our forum members on here then.

I'm selling some unused converse shoes on eBay (women's 7) if anyone really wants to buy something from me. I have an MX-5 radiator to! Common man, I PM'd you about this. I'm at least a year away from anything assuming nothing falls down along the way, let alone worrying about selling anything. Even if that were my goal, engineering compliance, TUV certification or a manufacturing and retail partner are the last steps not the first. Right now I'm a merchant of hopes and dreams.
 

philw696

Member
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25,119
Just been watching an old Top Gear from 97 and the problem Vauxhall had with Wishbones/Control Arms being fake and failing.
Amazing how they got into the manufacturer's supply chain but they did.
 

Gp79

Member
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1,393
And they wonder why 15-20 year old Maserati's are worthless and take years to sell.

yes the parts are expensive but in reality you’d never need to replace 8 wishbones in one go.

After 6 years I have replaced 2 wishbones, one rear upper due to ball joint play and the other upper front due to mounting bolt seized in the bush so just needs new bushes.

An alternative option would be great mind.
 

lambertius

Banned
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341
So a bit of an update;

I've decided to delay the material testing and do another experiment at the same time. While hunting for ball joints I came across a place in Queensland that refurbishes old ball joints. I had a reasonably long chat to the guy who does it and am going to give it a whirl. My plan is to send the 4 arms I've got off the car in to be refurbished and fit them to the car, then resume the material testing on the arms that come off the car. I'll still be able to do the CAD work and measure the existing arms for fitment in the meantime. I've found a metrology lab in Perth with a CMM and am getting some quotes on getting accurate dimensioning of the mounting positions and bushing fitment.

Anyway back to the ball joints...

In principle the process makes a lot of sense, you inject the ball joint with a thermosetting plastic (a proper engineering plastic like what would've been used in the joint in the first place, you can look at how serious plastics get over here) to fill any play, regrease and let the part do its thing. This isn't economical to do for a car with replaceable joints, as there is a bit of labour costs in getting the joint ready which makes it cost the same as replacing the joint. The process is basically only used on trucks and classic cars. So long as the play isn't to the point that it is metal on metal, it should be as resilient as the OEM plastic bushing (so for our cars, 50 000km-100 000km). If it does get to the point that the metal is pitted I was told that the injected plastic will wear quickly.

I'd never heard of a process like this before investigating the ball joints for this car, but it turns out its accepted as safe and operable in Australia, and he has approval from the Queensland Department of Transport. Apparently there was a case or complaint brought by a truck parts supplier to try and get it stopped but the process was deemed safe. The business owner has kindly said he'll send me over a copy of the documents.

So there may be a less costly alternative for people who haven't worn out the joints yet. I'll be running my car with the arms repaired while I work on making a new set, so I'll report in with how that goes!
 

lambertius

Banned
Messages
341
Update!

I've spoken with Balljec who do the ball joint injection and have purchased one of their injection kits. https://www.balljecmarketing.com.au/services

The company is owned by an older guy named Ricky, and he has to be one of the best people I've spoken to in ages. So the story is the company was started up years ago and Ricky purchased it. The founder original had dreams of selling the servicing kits and supplying the rod material but as most cars either have serviceable ball joints or replaceable joints it never took off and he sold it. Ricky runs it as a side business repairing arms on old cars and has in fact repaired arms on our Maserati previously. I was going to send my arms to him to be refurbished, but I'm a madlad and decided to buy a kit and do it myself.

I've got a full set of upper and lower bushings, so right now my plan is to fully refurbish the arms and swap them in. After a lot of discussion with Ricky he's convinced me that the process will work. He said the limitation is that if you don't inject the arm before it is running metal on metal then the rough surface will eat out the injected product and you'll only get a few thousand kms out of the joint. Since I have 8 arms to choose from I'll be picking the best ones to refurbish.

As for designing a total replacement, I've got a quote from a metrology lab so I can get accurate dimensioning. I'll hopefully be dropping off the arms on Monday. I've got a rather nice generic model made already so all I need are the correct dimensions and off I go. The current plan is to replace the ball joint with a rose joint as they're easier to implement and a **** of a lot more available. I'll also be able to pick a generic bushing so that it doesn't cost stupid amounts to implement the arms.

66297

For a bit of fun, the below image was generated using topology optimisation. The shape was modified by AI to achieve a predetermined factor of safety. Once I have accurate dimensions and the material results I'll be able to run the same test against the OEM design and ensure that my design meets or exceeds the factor of safety.

66298
 

rossyl

Member
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3,312
My mind can't understand the injecting process, but best of luck with it. I wonder if a similar thing exists in the UK? There's certainly plenty of classic cars
 

lambertius

Banned
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341
So far as I can tell, this old ozzie guy invented it and never really got it to take off. Speaking to Ricky he said there were only about 100 clients ever. Its literally just a kit, so you could call up Balljec and buy it yourself, but to be honest - if you don't want to wait till I've tried it all out, just send him some arms and he'll refurbish them.
 

Wally

Member
Messages
244
Yes patten ES parts made by the original manufacturers OPAC Turin, it’s even listed in their catalogue but not available to order. I know this as my good buddy Dave Rose is high up in Euro Car Parts and tried to get them but had the door slammed in his face. ECP are the UK supplier for OPAC parts. Charming.
Sorry to correct you but the manufacturer is OCAP....
 

lambertius

Banned
Messages
341
So a bit of info on the ball joint injection.

The short version is that it is considered legal and safe in Australia, though isn't the 'recommended' action. The letter below is from 2001, and nothing has changed since then and it has been done since the 80s.

66529

The kit to do the injections has just arrived, but it will probably be more than a month before I can get to it. I should be taking the arms off to the metrology lab tomorrow to get accurate dimensions, so things are moving along!
 

TimR

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2,656
The short version is that it is considered legal and safe in Australia, though isn't the 'recommended' action. The letter below is from 2001, and nothing has changed since then and it has been done since the 80s.

Basically...they wont make any decisions about it's being unsafe, which they suspect it is...until someone has an accident with it...?
Interesting. And not entirely surprising it hasnt proved a massive money maker, I guess....!

I note, just for context, that the way Australia insures against this sort of 'loss' is way different in that the Aus' Govt' pays from a central fund...
 

lambertius

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341
That isn't my understanding of it? Each state has different laws covering 'compulsory' insurance for vehicles, so far as I am aware the only motor laws that are federal are the ADRs. Each state has different laws dictating road worthiness as well, NSW requires a yearly inspection, WA couldn't care if your vehicle was made mostly of rust so long as you've never let the registration lapse. You can also be held criminally negligent if you run a modified vehicle (there are specific rules dictating what counts as modified, one is changing the induction type of the engine) without getting specific engineering approval. I know that differences in compulsory insurance levels have caused issues with liability between states when a car registered in one state is involved in an accident in another.

Because QT or RMS grant approval for ball joint injection doesn't mean they need to specifically endorse it either. I read that as not a decision about safety but approval. There are plenty of dangerous modifications and parts that are allowed (two piece rotors, suspension changes, etc) and plenty that have no effect that are banned (POD filters, body work lights, BOVs etc). That letter in context of it being challenged by a balljoint supplier is that QT is stating that there is no evidence that the modification is unsafe, therefore it has no decision to make but they have to clarify that they aren't endorsing it either as an endorsement exposes liability. That is the typical way of most things though; medical bodies will say there is no evidence of cancer from mobile phones not that using mobile phones is verifiably safe.

I suspect the real reason it never took off is that most ball joints cost $20-$100 and require zero effort. It really only suits obscure parts like what is on our cars.
 

Paulrv2

Junior Member
Messages
87
I'm going to need some luck, I'm really concerned about finding an appropriate ball joint. It'll exist somewhere but I can feel it in my bones that I'm going to spend a long time looking through catalogues for some obscure part only used on a tractor sold in Argentina...

I have a loose idea of costs, but I really won't be able to pin it down for a while. At the moment likely costs (in AUD) are $5k ($3k-$10k is the range) but knowing tooling costs, what grade material, the cost of the ball joint etc will narrow it down eventually. So that works out to hopefully be around $1250 an arm each.
Is the ball joint produced by Hill Engineering in the UK what you need? They provide that and also special tools for pressing old one out and fitting new one.
 

lambertius

Banned
Messages
341
Is the ball joint produced by Hill Engineering in the UK what you need? They provide that and also special tools for pressing old one out and fitting new one.

Before I started down this path I had the exact same question! It is a different ball joint, that is for the tie rods I believe. So far as I can tell, there are no other solutions.
 

Paulrv2

Junior Member
Messages
87
I just bought my 4200 a couple of weeks ago and don’t yet know whether the control arms are at a problematic stage. The car is going for a thorough check tomorrow so I should be better informed after that. In the interim have been buying a few bits that I’ve seen at reasonable prices that may be needed at some point, including Hill’s produced parts. I needed the T-bar yoke and as ball joints weren’t particularly expensive ordered those as well. Guess I’ll find out where they go on the car when they arrive
 

Zep

Moderator
Messages
9,110
I just bought my 4200 a couple of weeks ago and don’t yet know whether the control arms are at a problematic stage. The car is going for a thorough check tomorrow so I should be better informed after that. In the interim have been buying a few bits that I’ve seen at reasonable prices that may be needed at some point, including Hill’s produced parts. I needed the T-bar yoke and as ball joints weren’t particularly expensive ordered those as well. Guess I’ll find out where they go on the car when they arrive

I guess you mean their rear tie rod spherical bearing? The original is a SKF bearing, they are £15 each and are perfectly good for the job!
 

Paulrv2

Junior Member
Messages
87
I guess you mean their rear tie rod spherical bearing? The original is a SKF bearing, they are £15 each and are perfectly good for the job!
You could be right - it’s described as tie rod ball joint. Guess I’ll find out when they arrive.