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Discussion Starter · #1 ·
So I started this a while ago, got 90% of the way there and then got distracted by other things. I'm realistically a few days of work from ordering it, but you know, who has a few days of solid time to work on their hobby?


You can read the original thread here Making My Own Control Arms For anyone who doesn't know yet, I can't follow it up there anyway after I was banned on that forum after I complained about SopranoStu. Matt Yates, the owner, used this to leverage Stu for money he was owed then banned me. If you care about that sort of thing I still have all the conversations saved and am happy to share so you can make up your own mind. It isn't really a loss though, I don't have to argue with conaero and Zep showing up and disparaging me as being unsafe and going on about insurance and what not for a part I had no intention to sell. A bit rich from a couple of guys selling counterfeit AP racing rotors which are "insured" by a company they can't disclose because they have a "NDA"... Right... Moving on.

Catching y'all up:

I used some worn arms which I got from the always helpful New Model Wreckers, in Sydney Australia (they'll ship internationally) as dimensional references. I sent these to an engineering firm that had a CMM (Co-ordinate Measuring Machine) so I could copy the geometry exactly.

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I then sent a sample of an arm off to a lab so I could work out exactly which alloy the arms were made from so I could use these properties to complete FEA (Finite Element Analysis). The alloy is 4343, and using this I can economically outperform the OEM arms using 6061.

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I think broke a bone in my foot. It seemed like a good idea at the time.
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I moved onto the bushings where I made accurate models of the OEM parts so that I could explore more cost-effective options.

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I did a bit of research into far more cost effective bushings since I can control the dimensions of the bushings in my own part.

After that I just kind of started filming DIY videos DIY Videos and chilling out a bit and lost interest in this. After the success of the brake kit Why I'm Making My Own Brakes, the exhaust and the clutch I figured it was time to revisit this. A few people have asked me about it (thanks for the support, especially those of you who have been on sportsmaserati for a while) and then this post popped up and I felt motivated to finish the project Bushings & Polyurethane Bushings

It was a bit demoralising getting setup and bullied by Matt Yates, he had the audacity to pressure the mods here to edit my posts and comments (and I suspect he wanted me banned here as well) which was pretty exhausting. Motivation has returned now though, so I figure I'll finish this. I may even make them available to others just to upset him further since pettiness is tremendously motivating.

In case you're wondering why this is necessary - the captured ball joint has a 100% failure rate, and the only solution is to replace the whole arm. How much are the arms you ask?

The lower arms are 1364.90GBP and the upper are 2639.39GBP, each. That's right, it would cost you 8008.58GBP to replace the control arms on your car, if you source the parts yourself and don't pay any labour. Right now, the arms I designed will cost less than half that and have a replaceable ball joint so that this issue never happens again.
 

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Nicely done! So do you plan on using the normal spec bushings? Is there really no way of replacing the balljoint in the original arms? Do you have pictures of the balljoint without the rubber? I assume the problem is, that during manufacturing, the balljoint is closed by "crimping" on something on top of the ball to hold it in place, and you cannot open and close the balljoint again without the neccesary bonding strength?
 

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Yup yup yup. All of this (and much more) is within the thread started by Lambertius over on sportsmaserati. Worth a read if you want to go down a rabbit hole.:

 

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Ah yes, now I found the pictures. How thick was that lip crimped on top? How much material is left between the inside and outside of the aluminum cylinder? Is it maybe enough for some threads? With how much axial load are you designing your control arms?
 

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Discussion Starter · #5 ·
Ah yes, now I found the pictures. How thick was that lip crimped on top? How much material is left between the inside and outside of the aluminum cylinder? Is it maybe enough for some threads? With how much axial load are you designing your control arms?
There isn't enough material on the existing arms to install a new ball joint. I get shown the Lamborghini ball joint refurb thing from time to time, and that will not work on these arms. Another guy was looking at doing that once, and I messaged him and it wasn't cost effective.

The control arms I'm making will be a 1:1 copy of the OEM in terms of load. That is why I went and identified the alloy, so that I could model and OEM part and test its failure modes.
 

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I have also seen the Lamborghini repair but i am not that conviced by that. I thought about a big fine threaded nut to hold the top part in place. But as I do not have a dissasembled part in front of me, I cannot make an educated guess on possibilities. Do you intend to make the ball joint replacable by a screwable top part?
 

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Discussion Starter · #7 ·
I have also seen the Lamborghini repair but i am not that conviced by that. I thought about a big fine threaded nut to hold the top part in place. But as I do not have a dissasembled part in front of me, I cannot make an educated guess on possibilities. Do you intend to make the ball joint replacable by a screwable top part?
It will be a conventional press fit ball joint - once you get play, you buy another $100 joint and off you go. The other possibility is to use a rose joint which is cheaper, more robust but a little higher on the NVH. though considering the NVH of the standard vehicle I think it would be suitable.
 

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The front and rear lowers are all available as pattern parts and so availability is fine and cost is (relatively) low.

The front upper has a replaceable joint part so the entire arm doesn't need replacing.

Its the rear uppers that are the big problem and seem like it may be worthwhile focusing attention there first. There are no pattern parts available and they are also NLA from Maserati now.
 

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Discussion Starter · #9 ·
I'm only focusing on the rears as that is what I'm having trouble with. The top arm is definitely OEM only remaining, and when I asked the lower pattern is also NLA, just not updated on the website. Even if it is available, what I can make would be similarly priced and solve the issues with the joint still.
 

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Taking another look at this, why go through all the effort of casting a new control arm? It looks to me like any race shop familiar with building control arms would be able to fabricate a set.

Looking at the design - the front mount bears the brunt of the load with the rear mount of the A-frame really there to prevent any rotation of the hub assembly. As such, you could likely use cromo tube of sufficient size to support the ball joint in from the front mount, while the rear being bent to clear the coilover and an insert drilled/welded for the mounting point. You may add a pound or two to the assembly weight, but given that it is not rotational in nature I find that to be negligible.

Finding replaceable bushings for the body mounting point should not be hard. The ball joint may be a bit more difficult but certainly not impossible. I am sure if the taper and length were available it can be sourced from a manufacturers parts catalogue.

Not discrediting this effort, as it is really awesome work, but it seems a bit overkill for an application that is not really rocket science. Especially since it appears everything is on a single plain (perhaps I am wrong on this - I don't have the arm in front of me). Please feel free to correct me if I am missing something significant here - which I will admit is a very real possibility.
 

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I don't think changing the design very much is a good way to go, especially in countries, where there are very rigid rules to modifying cars. As I am coming from the land of the TÜVs this is the most concerning for me.
I think having a very similar part out of better material makes it easier for most people to show that this stuff is not dangerous.
And as I do drive the car flat out from time to time, I would find it very annoying if I would loose a wheel. I am not saying that this is likely to happen but much harder to prove to the engineer that is registering the mod/repair.

On a completely different note: Does anyone have the dimensions of the rubber gaitors for the balljoints? So diameter on both ends as well as length would be what I need.
 

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Discussion Starter · #12 ·
In Australia you can replace things with OEM equivalents and then it doesn't count as a modified car - so that is the motivation of keeping it as similar as possible. It would also make getting TUV certification a lot easier if I do that. Realistically though, so long as it looks OEM, being such a rare car most people wouldn't know.

Taking another look at this, why go through all the effort of casting a new control arm?
I'm not casting the arms. The initial plan was to make these just for me, a casting wouldn't be cost effective so they'll be made out of billet because they are in a single plane. The original parts weren't cast, they were die cast. Originally a lot of people thought they were drop forged but there are no differences in the surface hardness to indicate that.

It looks to me like any race shop familiar with building control arms would be able to fabricate a set.
Having someone else do it for me would defeat the purpose of doing my own project! For everyone else though, having a custom solution that everyone needs to source themselves isn't particularly helpful. I have some photos from the suspension of the Trofeo cars, that is pretty standard racing suspension but this means it doesn't have mounting points for the auto leveling for the headlights. They also don't have the same rear brakes, so the hubs are different. There are no dust covers on the joints either, so not really suitable for road use. The adjustability from both forward and rear parts of the frame would mean that a basic wheel alignment wouldn't be an option. I mean, sure you can do anything but is it a cost-effective solution?

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Finding replaceable bushings for the body mounting point should not be hard.
There are very few aftermarket bushings that fit these cars, and even fewer that are flanblocs which is what is actually used. By making my own arms I can pick any appropriately rated bushings I like. You will have a very bad time finding an appropriate flanbloc.

The ball joint may be a bit more difficult but certainly not impossible. I am sure if the taper and length were available it can be sourced from a manufacturers parts catalogue.
The ball joint cannot be replaced. It is machined into the arm itself and you will not be able to machine it out safely, there won't be enough material left. The teflon cups wear and you are left with play.

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The first couple of points make sense. I'm just outlining another possibility for those that want to approach in a different manor.

Re: the ball joints and bushings: I am aware of the problems in replacement with the stock setup. I was referring to the relative ease of sourcing an equivalent part should a custom arm be created.
 

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I knew you were looking into making arms, but I wasn't aware of all the progress you had already made. Keenly following! I injected my rear control arm bushings (all cracked) with red grease and then created my own dust covers for them, hoping nothing would be on its way out any time soon. The idea of having to replace these — and with an OEM part that will prematurely fail once again, at that — puts a lump in my throat. I am confident that, sooner or later, there will be a solution; otherwise, our cars will someday no longer be on the road.

Good luck in your endeavor.
 

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Separately, what is the deal at the front of the car? I've heard that those parts are serviceable without the replacement of an entire control arm, though I've also heard of people replacing the whole arm. (Perhaps there's a difference between serviceability of the upper, and that of the lower, too.)
 

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Discussion Starter · #17 ·
Separately, what is the deal at the front of the car? I've heard that those parts are serviceable without the replacement of an entire control arm, though I've also heard of people replacing the whole arm. (Perhaps there's a difference between serviceability of the upper, and that of the lower, too.)
So far as I'm aware the ball joint is a separate part so the problem is alleviated. I am very close to finishing, but allocating spare time when I have a real job and life is the main issue!
 

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So far as I'm aware the ball joint is a separate part so the problem is alleviated. I am very close to finishing, but allocating spare time when I have a real job and life is the main issue!
Wow. Needless to say, it's a shame they didn't employ a similar design for the rear arms. Anyway, glad it's coming along well! I've seen your YouTube videos on your car, and I think the dedication you have is outstanding — especially if you're having to balance your hobby with work and life. (y)
 

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The front UPPER is the only one with a separate part for the ball joint. All others (both rears and bottom front) are not. This company says they can replace them all though. Curious what process:

 

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Discussion Starter · #20 ·
The front UPPER is the only one with a separate part for the ball joint. All others (both rears and bottom front) are not. This company says they can replace them all though. Curious what process:

Sweet, I've contacted them. I'll report back with how it goes!
 
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