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Discussion Starter · #41 ·
Full lock is not interesting for us as you will never use this at a racetrack.
At more than +5°30' of caster, we got constant rubbing of the inner barrel of the wheel to the control arm when maneuvering on the parking lane or pit box. Sounds bad and damages the inner side of the wheel, so the only option we had, was to limit the caster.

Our connection to steering rack is also modified to adjust bump steer so the plates are just a part of our whole solution.
You moved the entire steering rack higher? Because this is the only option to correct bump steer (unless redesigning the knuckle) if you are planning to raise the mounting point of the upper control arm to the carbon tub (chassis).

You can use it for a street car but if you use too much of the possibilities of adjustment without knowing what you are doing you can easily do no good to your car.
Exactly. Most of the alignment shops don't even bother sorting out left / right differences, although perhaps not that vital, it can be done precisely and I strongly aim to do so. With more adjustability (track width, mounting points, more caster,...) even more problems arise and I doubt many of the shops would have the know how on how and what to adjust.
 

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At more than +5°30' of caster, we got constant rubbing of the inner barrel of the wheel to the control arm when maneuvering on the parking lane or pit box. Sounds bad and damages the inner side of the wheel, so the only option we had, was to limit the caster.

You moved the entire steering rack higher? Because this is the only option to correct bump steer (unless redesigning the knuckle) if you are planning to raise the mounting point of the upper control arm to the carbon tub (chassis).
We did our own end-links for our steering rack or more precisely are still working on them now. Everything hasn’t been tested on a rolling car. So I neither can confirm that problem at 5.5 degrees caster nor do the opposite. Right now the system itself allows that range as you can slide the top wishbones 20mm to the rear and the lower ones 20mm to the front. If you get a rubbing will also be pretty much dependable from the wheel dimensions you are running. So at this stage I can only say what the system is designed for. The specific car it is mounted to will tell you the story of what you can use from that. If you see it is rubbing you loosen the six screws of the top plate and slide it back a few millimeters. But as we both said this is not a playground for any carshop or dealer.
When we have experience with the system on a street legal customer car and different wheel sets we will give the customer an adjustment advice or even put marks for it into the plates. At this point it is honestly too early for me to do this. Probably after the first few Trackdays. Maybe in may or June...

best regards
Alex
 

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Discussion Starter · #43 ·
I understand your idea, but even with custom endlinks (tierods) you can't solve the bump steer issue which you run in to, if you raise the mounting point of upper control arm to the carbon tub (chassis). And you will run in to the wheel rubbing issue. An option would be to lower upper control arm mounting point to the knuckle, but it can't be done without fabricating new knuckles either, so you have a very limited options for the upper control arm.
 

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I understand your idea, but even with custom endlinks (tierods) you can't solve the bump steer issue which you run in to, if you raise the mounting point of upper control arm to the carbon tub (chassis). And again, you will run in to the wheel rubbing issue. An option would be to lower upper control arm mounting point to the knuckle, but it can't be done without fabricating new knuckles either, so you have a very limited options for the upper control arm.
It is just about having the opportunity to move upper and lower wishbones upwards on a y-axis and and sideways on a x-axis at the same time. Right now we are not planning to set the upper wishbone higher but it is always good to have the opportunity to do so if required at some point. We are pretty happy with how the car drives now. We will find out if playing with some of the now adjustable parameters will add performance or not. It is a try and error game as always...

additional the knuckle at the upright where you attach the tie rods has a changed inlay on my racecar. This allows to attach it from eather bottom or top side.
 

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Discussion Starter · #45 · (Edited)
Some insight in to the development. The numbers have been covered / blurred due to know-how. This first drawings have been made in late 2020 and we haven't been fiddling around since then. Small revisons and optimizations take precious time, but there is no way around it if we want to prevent any issue later.
 

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Discussion Starter · #47 ·
We were grinding the CNC for the past few days, testing the durability on the test benches and made a front control arms welding jigs so we can start fabricating the batch soon. I want a few more days of on track testing (mostly due to the control arms), while with the amount of bench, onroad and track testing time spent on the front arm uniballs, I'm already confident enough about them.

The pricing is not set yet as I haven't made the exact costs calculations yet, but here are some estimates. Please allow some potential changes until we make an exact calculations.

GMS PERFORMANCE FRONT ARMS (4x TIG welded, lightweight, 25CrMo4 control arms + 2x upper ball joints + 2x lower extened ball joints extend for roll correction center) + 8x uniball) = 2300€ - 2.600€ (estimated RP)
GMS FRONT ARM UNIBALLS KIT (8x uniball + 1x optional pressing adapter) 900€ - 1000€ (estimated RP)

We will release both upgrades at the same time. GMS FRONT ARM UNIBALLS KIT are more affordable, but will require quite some workshop time and skill to assemble (8x uniballs). A decent upgrade, but unfortunately, the lowered cars will still remain plagued by incorrect roll center and increased body roll because of that, requiring lots of static negative camber to compensate for this. We've discussed this more detailed in upper posts, so I'll skip it this time. The optimal solution for lowered cars are GMS PERFORMANCE FRONT ARMS which also include revised, lower ball joints, to provide corrected roll center and new upper ball joints, but to mount these ball joints, also the control arms had to be revised (wheel clearance), so unfortunately going for uniballs only, won't sort out all the imperfections of the front end of 4C. Both upgrades will sharpen up the handling in a similar way as GMS rear uniballs did, but the first drive experience is not as shockingly different as it is with the uniballs conversion at the rear. A very simplified saying would be, that at the rear end about 70% of improvement is provided by the uniballs and 30% by more rigid rear control arms. At the front, about 30% of improvement is provided by the uniballs (feedback, precision) and about 70% the control arms with revised ball joints (corrected roll center, revised dynamic alignment change, less body roll).

I will post more updates in following days, but at this point I would appreciate to get a rough estimate how many of you would be interested in these upgrades. Please drop a post below:

your username - item (GMS PERFORMANCE FRONT ARMS or GMS FRONT ARM UNIBALLS KIT)

This would help me a lot, so can organize the work accordingly. We plan to fabricate about 10 sets of GMS front control arms and 10 sets of GMS front uniballs this round. We will make another batch later this year, but I would like to finish also other ongoing developments that require our attention right now, so thank you for your understanding and patience.

Here are the prototype front arm GMS uniballs:

Liquid Cosmetics Camera accessory Camera lens Material property

OEM control arms with GMS uniballs:

White Automotive tire Light Black Line

GMS performance front control arms:

...loading

:D
 

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We were grinding the CNC for the past few days, testing the durability on the test benches and made a front control arms welding jigs so we can start fabricating the batch soon. I want a few more days of on track testing (mostly due to the control arms), while with the amount of bench, onroad and track testing time spent on the front arm uniballs, I'm already confident enough about them.

The pricing is not set yet as I haven't made the exact costs calculations yet, but here are some estimates. Please allow some potential changes until we make an exact calculations.

GMS PERFORMANCE FRONT ARMS (4x TIG welded, lightweight, 25CrMo4 control arms + 2x upper ball joints + 2x lower extened ball joints extend for roll correction center) + 8x uniball) = 2300€ - 2.600€ (estimated RP)
GMS FRONT ARM UNIBALLS KIT (8x uniball + 1x optional pressing adapter) 900€ - 1000€ (estimated RP)

We will release both upgrades at the same time. GMS FRONT ARM UNIBALLS KIT are more affordable, but will require quite some workshop time and skill to assemble (8x uniballs). A decent upgrade, but unfortunately, the lowered cars will still remain plagued by incorrect roll center and increased body roll because of that, requiring lots of static negative camber to compensate for this. We've discussed this more detailed in upper posts, so I'll skip it this time. The optimal solution for lowered cars are GMS PERFORMANCE FRONT ARMS which also include revised, lower ball joints, to provide corrected roll center and new upper ball joints, but to mount these ball joints, also the control arms had to be revised (wheel clearance), so unfortunately going for uniballs only, won't sort out all the imperfections of the front end of 4C. Both upgrades will sharpen up the handling in a similar way as GMS rear uniballs did, but the first drive experience is not as shockingly different as it is with the uniballs conversion at the rear. A very simplified saying would be, that at the rear end about 70% of improvement is provided by the uniballs and 30% by more rigid rear control arms. At the front, about 30% of improvement is provided by the uniballs (feedback, precision) and about 70% the control arms with revised ball joints (corrected roll center, revised dynamic alignment change, less body roll).

I will post more updates in following days, but at this point I would appreciate to get a rough estimate how many of you would be interested in these upgrades. Please drop a post below:

your username - item (GMS PERFORMANCE FRONT ARMS or GMS FRONT ARM UNIBALLS KIT)

This would help me a lot, so can organize the work accordingly. We plan to fabricate about 10 sets of GMS front control arms and 10 sets of GMS front uniballs this round. We will make another batch later this year, but I would like to finish also other ongoing developments that require our attention right now, so thank you for your understanding and patience.

Here are the prototype front arm GMS uniballs:

View attachment 115585

OEM control arms with GMS uniballs:

View attachment 115587

GMS performance front control arms:

...loading

:D
Circle Logo Font Pattern Symbol
 

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Adds up to a £3600 with shipping, taxes and installation, which for me, sadly, rules it out :(
 

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Adds up to a £3600 with shipping, taxes and installation, which for me, sadly, rules it out :(
You should try shipping stuff to Oz. Too dicey to risk shipping anything to here from Europe at present. Unfortunately I’m out too, at least for a couple of years.
 

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Discussion Starter · #51 · (Edited)
Thank you both for your input.

I am aware since the beginning of this project, that the costs of this upgrade won't be acceptable for many of you, although the pricing is exactly comparable to the costs of the GMS rear control arms, but we have twice the amount of components here (4x control arms - curved, 4x ball joints, 8x uniball) and the uniballs are a bit more tricky for fabrication and assembling, so with the price not even double the price of GMS rear arms, I'm afraid, the final price won't be far off from upper estimations.

GMS front uniballs kit (8x uniball with center axis + optional pressing adapter) are as mentioned, a bit more complicated for fabrication and assembly compared to GMS rear arm uniballs, so with the price increase of about 20% and twice the amount of uniballs, the final price is expected not to be far from the upper estimations as well.

We daily receive offers from Chinese factories offering us a fabrication of unibals and ball joints at pricing of an ice cream / piece. With my curiosity nature, I couldn't pass it not to ask about an actual offer for fabricating us a product. I would have absolutely no issue with Chinese parts if the standard of the item is good, but so far the conversations always ended in the same dead ends. Option one, the quality (materials), know how (drawings) and tooling (old worn out machines) were not up to our requirements which is usually an e-mail reply stating (we are happy to work for you, but we need the drawings. We don't work with this material, we prefer that material. We use MAG weld, to be cost effective and it is almost as good as TIG. It's a custom part we cannot give a warranty, this part is a hardcraft, so the price will be higher. Can we offer you standard ball joint instead? We have a great success with these. What is your MOQ?). Here is that exact e-mail I've just received this morning:

"This is SYZ Machine. We notice that you are selling lots of ball joints for Alpha. Hereby we would like to introduce our company to you. SYZ has been manufacturer of heavy duty parts, including ball joints for more than 18 years. We only concentrate on race industy. The ball joints you are selling are what we have been making and selling to USA, Europe for many years.

Attached some photos of our factory for your reference.

If you are interested, please feel free to contact us, samples are always available."

Automotive tire Motor vehicle Gas Engineering Mass production Motor vehicle Gas Engineering Auto part Cylinder Tire Wheel Car Vehicle Vehicle registration plate


I don't mean to be rude, but the picture of the threading machine in the center alone, tells me that no high end time will come out of this.

Second option is, when more serious manufacturers (bigger budget) who do have proper tooling (CNC machines) know how and materials to fulfill our requirements, make us an offer it's not far from ours in terms of pricing, yet we would have to hand them over all the technical drawings and with the amount of changes we do since prototype to the final products, this wouldn't be viable. When the batch goes in to fabrication in high end CNC centers, the MOQ for custom parts is usually 1000 or more which is probably more than a lifetime supply of 4C steering parts, let alone the issue if we find out that some changes are required during the fabrication. It's not doable.

Generally, pretty much any CNC workshop can make a balljoint or uniball, but you know what is the biggest problem? When it comes to CAD drawings and know how, which materials to use, what tolerances to use, it's game over. And if we add the know how in terms of handling (what to change in control arms, what geometry to achieve), you are on your own. So that's why we design and draw all the parts on our own with the external help of professionals which we provide all the needed input. Regarding the CNC, we work with a local company with lots of our presence and input during the development and fabrication to be able to make quick adjustment and small updates, to achieve what we are aiming for. A reliable, high end product.

Here are our CNC machines. Capable, mid-range CNC rigs, fulfilling all the requirements we currently have. Here is where we fabricate all our parts except for the wheels (last picture), which requires more capable 5-axis CNC machine we don't have, so a not so local, larger company does it for us.

Gadget Audio equipment Gas Machine Electronic device Product Gas Machine Technology Control panel Engineering Machine Technology Automotive exterior Gas Gas Machine Machine tool Technology Control panel

I hope I've shared enough of insight in to our fabrication that you can evaluate and find out on your own, that our pricing is more than competitive given the quality and the know how included in the GMS parts. OEM front control arm is about 450€ each, so we are not far off with our set, with much, much more sophisticated part. Still for those, who cannot afford the front control arms at the moment, the front arms uniball kit is a very good solution which will reward you with more precise and crispier handling. There is however no denying, that revised control arms will also sort out the roll center issue on lowered cars, which unfortunately the uniballs alone, cannot.

I'll do my best to offer as good price as I can, but please also understand that due to small series it is hard to gather the contractors, so we pay a decent price to all our contractors (TIG welders, CADers, CNC machinists) to make the final product hapoen. Therfore, in terms of pricing, we'll never be able to compare with a large mass market tuning parts like BMW, Honda or similar, where series are huge and therefore the prices are much lower as majority of these parts re coming from China. There are also a lot of "upgrades" on a market that should be upgrades but many times it's just a marketing, without any actual impovement. A bit of alu CNC, some anodizing and parts look good. So it is with carbon parts. Lots of looks, but not much of a performance. I can assure you all, that as long as I stand, the GMS parts won't be like that. We will provide highend parts with maximum performance we can offer and next level customer support, but unfortunately, we will never be the most affordable tuners.

Thank you for your understanding.
 

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Absolutely, Rudi. But I can’t justify these until I sort the suspension with some coil overs. My spare money for toys is limited.
 

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Discussion Starter · #53 ·
I didn't mean to persuade anyone or force sale, just wanted to share some additional insights in to the project and financial calculations behind it in general, not at all because of the post of you and FLORO. I absolutely understand priorities and myself personally would first go for coilovers and only then think about GMS front control arms. We are in a pursuit of a new PR this year, so we have to go an extra mile, because the current mods alone are not enough in our case. I am confident that with this product, we will shave some time off our current PR.

I'll post more development updates in the next days...
 

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I hope I've shared enough of insight in to our fabrication
Thank you for sharing Rudi, it is understandable due to the high quality provided. Keep on paying your team for their skills.

One question... what are these things on top of your rig? Your engineering shoes?

115613
 

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@GMS - What is the optimal lowered height for the new front A-Arms?
 
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Adds up to a £3600 with shipping, taxes and installation, which for me, sadly, rules it out :(
Yes, in the UK (as I am), the taxes added now to anything over 135GBP by Revenue and Customs are a bit off putting. Rudi, I assume EU tax is not taken now on exports?
 

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Discussion Starter · #60 · (Edited)
The lower control arm should always be tilted downwards and at the lowest point of suspension travel, should not go past horizontal level. This way you don't narrow the track width during the suspension travel. This can be achieved by not lowering the car too much (about -15mm from standard non sport setup). For track it's also desired that control arms are unparalell to compensate negative camber gain during suspension travel with positive camber gained during body roll. This unfortunately cannot be achieved on OEM control arms.

You can take a look at your car from the front and see how your lower control arms currently stand. If front lower control arms are pointing upward or horizontal, you're too low. I'll provide more detailed height specs later.

4C OEM control arms:
Parallel, unequal length, double wishbones. This setup provides minimal dynamic camber change during suspension travel. The amount of positive camber gain will be basically the same to the amount of chassis roll angle. Track width changes during the travel (widens or narrows...depending of the height of the car and static postion of the control arms). On lowered cars, the RC (roll center) is also quite lower than CG (center of gravity). This is not desired as more the distance from CG to RC, means more / easier chassis roll. That's why so many complaints on body roll of 4C even with stiff suspension and swaybars. Track width change is partially overcome with use of longer a arms, as the radius of curvature increases, however it's not eliminated completely and it is not even necessary to do so as long as the track width doesn't narrow excessively during the suspension travel. This setup provides stable front end and constant tire patch when driven "easily". However during hard driving the body rolls and positive camber gains occur, reducing tire patch and grip. More static negative camber is a solution, but affects stability and grip when driven "easily" as the tires run only on the inner patch now.

4C GMS control arms:
Non parallel, unequal length, double wishbones. To eliminate the problems caused in the above case, we built in more negative camber gain during suspension travel to compensate for the body roll, we raised RC to match CG and noticeably reduce body roll and we made sure that on lowered cars the lower control arms remain tilted downward which means that during suspension travel, track width only increases.

A simplified explanation would be that GMS front control arms are aimed for track focused users, while OEM control arms perfectly good as long as you don't lower the car too much (-15mm from standard non sport suspension). It's interesting but, -20mm drop from standard suspension is already diminishing the effects of lower CG, by increasing the body roll.

I'll post exact recommended height later as I'm currently testing GMS front arm uniballs in combination with OEM control arms.

Motor vehicle Automotive tire Automotive lighting Automotive design Rim Tire Automotive tire Automotive lighting Motor vehicle Hood

Until then, I invite you to take a look at the position of control arms here. Yes, they are unequal length (upper shorter), unparallel (lower more downward), just the way we did it.

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