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Discussion Starter · #1 · (Edited)
Hello guys,

We have the know-how, experience and tools to make car parts, but as usual, I would appreciate your input as a customers.

We are prototyping GMS performance front control arms (A-arms). There are three main factors we have set as a goal.

1.) Better material, lower weight and built quality
2.) Easier adjustability (4C is a PITA to adjust camber and caster. We did a fair amount of alignments on 4C's, yet we rarely adjust 4C in less than 3-4 hours of work, so we want an improvement here)
3.) Wider adjustability range (more camber and caster)

The idea is:

1.) Inbuilt, increased caster (by installing GMS performance front arms, the caster would be increased to +4° to +5°. I believe there is no reason not to increase it, as it improves every aspect of the handling except a bit of increased steering effort. Precise adjustment would still be done with adjustment shims, but no more excessive stacking of adjustment shims underneath. Usually caster, once set, it's pretty much set, and doesn't need "tweaking" from track to track or tire compound change, like the camber is meant to be.)
2.) "On the fly" adjustable camber. This means that no more shimming would be required. We have a solution in a mind that would allow for the camber to be adjusted, without lifting the front end. With this we would significantly simplify the adjustability, remove the unwanted trade off effect between camber/caster (with shimming you need to sacrifice caster, to get camber or other way around) and we would isolate the caster adjustment from camber adjustment which would significantly simplify the alignment procedure and therefore the costs.
3.) At last but not least, all of the ball joints would be spherical, no rubber bushings. We still have 0% failure of GSM uniballs and are the only fabricators machining the uniball parts from CrMo material instead of mild steel. Machining is demanding, but durability is superior to any other product currently on the market.

What do you think guys?
 

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Again a wonderful approach, Rudi. Thank you so much for thinking all these things through!!
Only problem I see for myself is that you develop your parts faster than I can set aside the budget to do this in a for a family man acceptible pace ;-).

As for the arms, however great the idea of making the arms adjustable, I ask myself how many will effectively change their alignment on the fly. Not to speak of who has the knowledge to do so...
Don't you risk making things too complicated and therefore too expensive, addressing less buyers? It's not clear how big the difference would be, and how much the return would be given the ease of adjustment the first time.
Maybe - in line with the rear arms - you could make two variants: one with better material and uniballs, and a 'race' version with all the toys and goodies.
 

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So, as with the rear arms, I would completely agree with #1 (better build quality), #2 (easier adjustment), and #3 (increased adjustment range - Caster!) for the key goals. The OEM arms have crap welds (same as rear), and have a tendency to rust due to poor paint quality.

One of the things that I had a very hard time with when changing the shims with AlfaWorks versions, was just how much binding there is. What I mean is that I feel the studs are very fragile and high risk of damage, and if they are damaged, I'm not actually sure we can replace them (imbedded into the tub??). When you increase caster, it really causes the bushings in the arms to bind against the studs. The Rubber bushings allow for some flex to prevent damage, but I would be concerned with more solid bushings.

As for the optional aspects.....
1) I have no issue with an increase to +5° in caster and using small shims for fine tuning (call it a "Race" version). As you noted, it is almost set and forget... We have seen some "wander" in the caster (and camber & toe too) between alignments. Basically, it won't stay put..... I think a more robust arm will address most of this...

2) A simpler adjust (and independent) to change camber would be greatly apricated (see comment about fragile studs above). I know my shop would greatly appreciate the simplify!!!

3) I like the more solid bushings, but have a few concerns.... First, variability of manufacture.... We all know that the tub (and most other parts) were not manufactured to very high tolerance, and using the solid parts could cause us not to be able to fit all cars... Second, we have seen one car that replaced the front bushings break an arm pin because of the VERY TIGHT tolerance between the arm and CF body (when aligning for "race" spec). So clearance must be carefully checked...

OR.... outside of the box thinking here....
What I would like to see is a complete replacement of the attachment mechanism, to something like this.... Basically design an attachment piece that no longer requires shims and spacers. It would be the new attachment point just secured to the tub using the existing bolts...
111013


Granted this is for a high downforce race car (Revolution A-One, a Radical type car with CF body), and we need more travel than those cars. However, this type of design (in vertical orientation, if horizontal doesn't get enough travel) would mean that we are putting less stress on the bolts and more likely to brake the pin or arm. It also allows us to deal with some tolerance issues that are bound to pop up with shims like the rear arms. Then simply use an adjustable wishbone to dial in the alignment....

111014


The next issue is how you brace/design the A-Arm. It is less critical vs rear, due to much shorter distances.... BUT.... We have 5 major options for shocks.. OEM (with its big springs), Ohlin (remote reservoir), Nitron (lower mounted reservoir), and Intrax (with a weird side/bottom mount that BARELY clears the OEM arms), and Bilstein/Others without external reservoirs. I think the Intrax could cause issues...

Full video that does show the front A-Arms briefly...
 

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Discussion Starter · #4 ·
Excellent work, keep it comin'.

So, as with the rear arms, I would completely agree with #1 (better build quality), #2 (easier adjustment), and #3 (increased adjustment range - Caster!) for the key goals. The OEM arms have crap welds (same as rear), and have a tendency to rust due to poor paint quality.
Consider it done.

One of the things that I had a very hard time with when changing the shims with AlfaWorks versions, was just how much binding there is. What I mean is that I feel the studs are very fragile and high risk of damage, and if they are damaged, I'm not actually sure we can replace them (imbedded into the tub??). When you increase caster, it really causes the bushings in the arms to bind against the studs. The Rubber bushings allow for some flex to prevent damage, but I would be concerned with more solid bushings.
Agreed, uniballs that will replace rubber bushings will be bind free. Studs can be replaced, it worried me too so i checked some time ago.

As for the optional aspects.....
1) I have no issue with an increase to +5° in caster and using small shims for fine tuning (call it a "Race" version). As you noted, it is almost set and forget... We have seen some "wander" in the caster (and camber & toe too) between alignments. Basically, it won't stay put..... I think a more robust arm will address most of this...

2) A simpler adjust (and independent) to change camber would be greatly apricated (see comment about fragile studs above). I know my shop would greatly appreciate the simplify!!!
There is a problem with aftermarket bushes, or more precisely with OEM arms. As we have learned from the OEM rear arm tolerances are commonly out of specs and so are the fronts. The fronts, in my case, 3 out of 8 aftermarket uniballs felt loose, they were pressed in too easy and when I braked hard for the first time they slid out of the arms housing so I ended up with a bent A-arm. No big deal, it was easily straighten back as OEM material is surprisingly soft, but not the best feeling and I had to secure them so it wouldn't happen again.

3) I like the more solid bushings, but have a few concerns.... First, variability of manufacture.... We all know that the tub (and most other parts) were not manufactured to very high tolerance, and using the solid parts could cause us not to be able to fit all cars... Second, we have seen one car that replaced the front bushings break an arm pin because of the VERY TIGHT tolerance between the arm and CF body (when aligning for "race" spec). So clearance must be carefully checked...
Uniballs or rubber bushings, they all fit into the arm, so as long as the arms are perfect, the precision of the carbon tub doesn't really matter. Any imprecision will only reflect in different number of shims on one or other side to get caster perfect.

I know exactly which car you mean and the reason why the uniball axle (bushing) broke was the following. The aftermarket uniballs had thinner axles so when they fit them to thinner upper spacers (because of more camber) the front A-arm sat on the carbon tub not on the spacer. When tightened the axles was bent and damaged and later failed on the track. The aftermarket thin upper spacers and aftermarket uniballs were not compatible in-between and should have been shimmed not to let the A-arm hit the tub. There are 4 uniballs and 8x M10 bolts for 200-250kg front end weight per side, so it is impossible to break the axles, don't worry.

OR.... outside of the box thinking here....
What I would like to see is a complete replacement of the attachment mechanism, to something like this.... Basically design an attachment piece that no longer requires shims and spacers. It would be the new attachment point just secured to the tub using the existing bolts...
This can be done, but at least for caster it would be still feasible to use shims for precision alignment, due to carbon tub imperfection. Camber as mentioned above, could be adjustable "on the fly", without shims.

The next issue is how you brace/design the A-Arm. It is less critical vs rear, due to much shorter distances.... BUT.... We have 5 major options for shocks.. OEM (with its big springs), Ohlin (remote reservoir), Nitron (lower mounted reservoir), and Intrax (with a weird side/bottom mount that BARELY clears the OEM arms), and Bilstein/Others without external reservoirs. I think the Intrax could cause issues...
I'll try to stay within OEM dimensions, but better material and thinner tubes. I have available OEM and Nitron suspension for test fit.
 

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I’m actually more interested by the front arms (provided camber and caster adjustment is made easier) than the rear arms. Maybe that’s because I have your great uniballs already
 

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I still believe the rear of the car is the major problem. The engine sits way too high, antiroll bars are too long, the weight of the car is bigger on the driver side. With front upgraded arms I don't believe there is anything to win on the racetrack if the race blocks are already installed because the rear is the weak link.
 

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We need to remove some serious weight from the rear and somehow (if possible) to lower the center of gravity. I looked at the engine of our car vs a regular audi a3 and it sits higher in the alfa. - not to mention compared to a porsche
 

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@cipsony - I completely agree about the height of the engine. I wish it could be lower, and I think they could have actually done more work to lower the engine. When I did some initial survey, there seems to be room to lower the the engine at least 1". Perhaps a dry sump could help some, but the bell housing also causes issues...

Anyways, the HUGE advantage of the Flat-6 is that you can really reduce the CG....
 

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Discussion Starter · #9 · (Edited)
If you have the camber and the caster, than you have everything you need to race. But things can be improved noticeably. With upgraded front arms the front rubber bushings will be replaced with uniballs for improved feedback and precision and adjustability range will be wider and easier. With camber and caster plates/shims right now, you must keep the positive caster low to keep the negative camber high, so you need to run lots of static negative camber for the corners but you are loosing braking capabilities with running only on the inner edges of the front tires. With increased positive caster we will be able to afford lower static negative camber, and increase dynamic negative camber, so we will get best of the both worlds - enough of dynamic negative camber in corners and less on straights providing wide tire patch on braking. GT3 race cars run north of +9° of caster, with most of these cars somewhere around +11°. Stock 4C only runs around +2°30'.

Of course, inline-4 is the tallest of the engine layouts, but it's best bang for the buck in terms of performance and maintenance and in our case it's all aluminum, so it's not too heavy. In 4C engine sits no higher than in any other mid engine, inline-4, car, let's say Lotus Exige, Lotus Elise, Toyota MR2. It can't go lower due to oil pan in the bottom because it would hit the subframe brace when engine is tilting on acc. or decc. We could probably lower the stock engine, without major mods (with 3x new engine mounts) for about 5-10 mm. Anything more than that, dry sump and extensive rear wheel hub mods would be required. Perhaps tilting the engine a bit woudl be an option. Also in 4C, the engine is placed well in-front of the rear axle and the turbo is mounted low, so weight distribution is decent. Audi's on the other hand are notorious for being nose heavy due to having engines well over front axles and 4x4 versions being even worse, so even perhaps the engine might be a bit lower in Audi (I haven't measured the Audi), it shouldn't be a major difference compared to 4C, as both are inline-4, both have wet oil sump so they can't go much lower than what they already are. Of course flat-4 or more precisely boxer layout would be great in terms of CG, but there are other disadvantages to this layout, so it's a trade off.

Roll bars are long because the car is wide, not much can be done here.

Weight distirbution of the 4C should be a bit less rear biased (about 45/55 would be perfect), but the cross weight is as good as it gets. Stock 4C's, with driver in, are very, very close to 50/50 cross weight which means the car will take the left and the right corners the same way. Either always understeer, always oversteer, but never understeer in one corner and oversteer in the other. That's what's the most desired in the world of motorsport - cross-weight balance and 4C is near perfect in this aspect.

Even though the marketing articles are saying that the 4C's body panels are sheet moulded SMC (with a weight of 1.5g/cm³ this material is decidedly lighter than steel (~7.8 g/cm³) and aluminium (~2.7 g/cm³)), the thickness of this panels makes the parts far heavier than the alu would be. I guess the production of SMC parts is simpler and cheaper than alu, not to mention carbon fiber, so that's why they went this way - my guess. With carbon fiber parts at least 30-40 kg can be saved at the rear and Scara73 has proven this by getting his car with under 800kg of dry weight.

Of course one of the reasons for going in to fabrication of GMS performance front arms is also the demand for replacement front bushings which are getting worn out quite often lately, so we would like to offer a complete, plug and play solution, not only the bushings or uniball inserts.
 

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1: Regarding caster vs camber limitations, a fellow 4C owner had the studs replaced with longer studs, a relatively simple modification if mechanic had done it before if I understood him correct.
2: Applauded.
3: Applauded.

So, if main goal is 1, then it might be an unnecessarily complicated solution. However, I'd like to see some deep dive in how the angles change during suspension travel. To me, it seems like there was made some "less than perfect" decisions here by AR. Thinking about bump steer for example. I assume its combination of things, but if its possible to improve some of them, it would be great. Deep dive in scrub radius would be excellent, as I have not understood it properly:p

If you change one or two angles, it affects other behavior as well. For example my car steering wheel is close to not self centering at max left /right. Had the same on my RX8 after lowering(but with alignment set to OEM original), spacers magically rectified that problem.

On my 4C, I can also feel the front wheels "fighting" sideways at max, very easy to feel when its wet and driving slow. Maybe the increased camber and caster has done something to scrub radius, I have a gut feel for this.

Disclaimer, I do not know much about suspension, just enough to acknowledge my lack of knowledge:)
 

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If you have the camber and the caster, than you have everything you need to race. But things can be improved noticeably. With upgraded front arms the front rubber bushings will be replaced with uniballs for improved feedback and precision and adjustability range will be wider and easier. With camber and caster plates/shims right now, you must keep the positive caster low to keep the negative camber high, so you need to run lots of static negative camber for the corners but you are loosing braking capabilities with running only on the inner edges of the front tires. With increased positive caster we will be able to afford lower static negative camber, and increase dynamic negative camber, so we will get best of the both worlds - enough of dynamic negative camber in corners and less on straights providing wide tire patch on braking. GT3 race cars run north of +9° of caster, with most of these cars somewhere around +11°. Stock 4C only runs around +2°30'.

Of course, inline-4 is the tallest of the engine layouts, but it's best bang for the buck in terms of performance and maintenance and in our case it's all aluminum, so it's not too heavy. In 4C engine sits no higher than in any other mid engine, inline-4, car, let's say Lotus Exige, Lotus Elise, Toyota MR2. It can't go lower due to oil pan in the bottom because it would hit the subframe brace when engine is tilting on acc. or decc. We could probably lower the stock engine, without major mods (with 3x new engine mounts) for about 5-10 mm. Anything more than that, dry sump and extensive rear wheel hub mods would be required. Perhaps tilting the engine a bit woudl be an option. Also in 4C, the engine is placed well in-front of the rear axle and the turbo is mounted low, so weight distribution is decent. Audi's on the other hand are notorious for being nose heavy due to having engines well over front axles and 4x4 versions being even worse, so even perhaps the engine might be a bit lower in Audi (I haven't measured the Audi), it shouldn't be a major difference compared to 4C, as both are inline-4, both have wet oil sump so they can't go much lower than what they already are. Of course flat-4 or more precisely boxer layout would be great in terms of CG, but there are other disadvantages to this layout, so it's a trade off.

Roll bars are long because the car is wide, not much can be done here.

Weight distirbution of the 4C should be a bit less rear biased (about 45/55 would be perfect), but the cross weight is as good as it gets. Stock 4C's, with driver in, are very, very close to 50/50 cross weight which means the car will take the left and the right corners the same way. Either always understeer, always oversteer, but never understeer in one corner and oversteer in the other. That's what's the most desired in the world of motorsport - cross-weight balance and 4C is near perfect in this aspect.

Even though the marketing articles are saying that the 4C's body panels are sheet moulded SMC (with a weight of 1.5g/cm³ this material is decidedly lighter than steel (~7.8 g/cm³) and aluminium (~2.7 g/cm³)), the thickness of this panels makes the parts far heavier than the alu would be. I guess the production of SMC parts is simpler and cheaper than alu, not to mention carbon fiber, so that's why they went this way - my guess. With carbon fiber parts at least 30-40 kg can be saved at the rear and Scara73 has proven this by getting his car with under 800kg of dry weight.

Of course one of the reasons for going in to fabrication of GMS performance front arms is also the demand for replacement front bushings which are getting worn out quite often lately, so we would like to offer a complete, plug and play solution, not only the bushings or uniball inserts.
The comparation with the Audi A3 was not made to point out the performance of the audi or the technological achievement --> It's a family / grocery car. It was the car parked next to my alfa so easy to measure. It doesn't matter how the A3 performs on the race track but more the fact that a family car with 15 cm ground clearance has the engine lower than a sports car with a ground clearance of 10 cm. How the audi performs is really irrelevant in this discussion. The comparation with lotus is probably better but I don't have one to measure.

The rollbars --> I'm not referring to their overall length but the length of the end arms (not links), especially on the rear --> Because the end arms are quite long their effect is quite reduced --> You also stated this at one point if you remember.

Carbon fiber body panels are a solution --> Expensive but efficient (assuming everyone already upgraded to a lightweight battery + engine cover removal and other things)
 

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Aren’t longer arms better? I thought that’s why they are used on race cars, but e.g. also the DeTomaso Guara:
 

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Discussion Starter · #13 · (Edited)
On my 4C, I can also feel the front wheels "fighting" sideways at max, very easy to feel when its wet and driving slow. Maybe the increased camber and caster has done something to scrub radius, I have a gut feel for this.

Disclaimer, I do not know much about suspension, just enough to acknowledge my lack of knowledge:)
I'm making a suspension kinematics analyze on 4C's front end, until then...

I'll try to provide the most accurate explanation of what could and should be improved, as there is much more to the the front end geometry than the back end and it is not just camber, caster and toe. The "dislikes" we have with 4C's front end feel - the tramlining, the violent feedback to the steering wheel when you hit the bump, etc., braking instability and high speed numbness are hidden right in there and we can solve it. You don't believe me? Well, let me share just a few simplified explanations for the beginning.

The steering on 4C feels light as soon as you move, even though we don't have power assisted steering right and it gets perhaps even too light at higher speeds doesn't it? 4C also doesn't self center the steering wheel very well, does it? It's not a car you would let run without holding the steering wheel down the straight road, would you? Now this could be solved with more kingpin inclination but there are drawbacks. Let's assume you would have 0°00' of camber, then, because of kingpin inclination, the more you would turn the wheel left or right, the more positive camber you would gain and we already know that positive camber is not something we want. The more the kingpin inclination the worse the positive camber gain when turning the wheel. With stock spec. 4C, even though the camber is about -1°00' you would still quickly gain positive camber with wheels turning if any decent amount of kingpin inclination would be built in. You can fight this by adding caster. The more the caster the more the dynamic gain of negative camber and that is exactly what we want to compensate for positive kingpin inclination causing positive camber gain. Ideally we would want lots of positive caster and minimal negative camber so when we would be driving straight, the camber would be zero'd and the full tire patch would be in contact with the ground and when we would turn the wheel and lean in to the corner, the negative camber would increase to compensate for body roll and kingpin inclination and again keep the entire tire patch on the ground. That would be ideal. Now 4C in stock format runs very low kingpin inclination and positive caster at about +2°30' only and when you brake hard and your car's nose dives, your car is nose tilted way over +2°30', meaning that you are actually having a negative front caster, causing significant instability issues under braking. The other specs like low kingpin inclination (poor self centering), low caster (low stability under braking especially, low dynamic negative camber gain), etc are not the most sporty either. Why would they designed it like that? I believe that the one and only reason for that is to keep the steering effort low when you are maneuvering around at low speeds, because we don't have a hydraulic steering. Not much of real racers were probably aimed to buy 4C but more like a well suited middle aged fellas with rather thick wallets instead of a hands of a Pop-Eye. :D That's good, but lots of performance aspects are sacrificed because of this.

Bonus fact, and I don't want to go too deep with it. The 4C has also built in quite a lot of positive scrub radius as this is commonly used to increase the feedback from the wheels to the steering wheel, especially much needed in electric power steering, less so in hydraulic power steering and not at all in non assisted steering like we have. Because of that, every pothole, every rock, every bump you hit with the front wheel sends a kick to the steering wheel. Now the only reason I see the 4C has this is because they probably designed it based on some other MR platform car that actually has a power assisted steering. reducing positive scrub radius will make 4C less nervous and "calm" the steering wheel feel. Now this can be solved with higher ET front wheels, but majority of the wheels on the market for 4C are providing even more of positive scrub radius and so do wheel spacers, so if you want to get it right, don't just buy whatever wheel fits the wheel gap the nicest if you actually care about the handling.

That's a a bit simplified explanation of what is going on a 4C's front end and I'll report back when I get the kinematics done.

With change of uprights we could change the kingpin inclination and Ackerman effect, but this is a bit too much of involvement for now and as it looks from kinematics analyze it looks decent. But with GMS performance front arms we can alter the caster, camber, resulting in the weight of the steering wheel, straight line stability, dynamic negative camber gain, bump steer, etc. And we will do so if necessary to get the front end feel even more right and tight, even though some slow speed maneuvering might require a few gym visits and a can of Pop-Eye's spinach. This car was idea'd to be driver's car but somewhere in between it got a bit soft and we'll sort it out. 🖤
 

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I'm making a suspension kinematics analyze on 4C's front end, until then...

I'll try to provide the most accurate explanation of what could and should be improved, as there is much more to the the front end geometry than the back end and it is not just camber, caster and toe. The "dislikes" we have with 4C's front end feel - the tramlining, the violent feedback to the steering wheel when you hit the bump, etc., braking instability and high speed numbness are hidden right in there and we can solve it. You don't believe me? Well, let me share just a few simplified explanations for the beginning.

The steering on 4C feels light as soon as you move, even though we don't have power assisted steering right and it gets perhaps even too light at higher speeds doesn't it? 4C also doesn't self center the steering wheel very well, does it? It's not a car you would let run without holding the steering wheel down the straight road, would you? Now this could be solved with more kingpin inclination but there are drawbacks. Let's assume you would have 0°00' of camber, then, because of kingpin inclination, the more you would turn the wheel left or right, the more positive camber you would gain and we already know that positive camber is not something we want. The more the kingpin inclination the worse the positive camber gain when turning the wheel. With stock spec. 4C, even though the camber is about -1°00' you would still quickly gain positive camber with wheels turning if any decent amount of kingpin inclination would be built in. You can fight this by adding caster. The more the caster the more the dynamic gain of negative camber and that is exactly what we want to compensate for positive kingpin inclination causing positive camber gain. Ideally we would want lots of positive caster and minimal negative camber so when we would be driving straight, the camber would be zero'd and the full tire patch would be in contact with the ground and when we would turn the wheel and lean in to the corner, the negative camber would increase to compensate for body roll and kingpin inclination and again keep the entire tire patch on the ground. That would be ideal. Now 4C in stock format runs very low kingpin inclination and positive caster at about +2°30' only and when you brake hard and your car's nose dives, your car is nose tilted way over +2°30', meaning that you are actually having a negative front caster, causing significant instability issues under braking. The other specs like low kingpin inclination (poor self centering), low caster (low stability under braking especially, low dynamic negative camber gain), etc are not the most sporty either. Why would they designed it like that? I believe that the one and only reason for that is to keep the steering effort low when you are maneuvering around at low speeds, because we don't have a hydraulic steering. Not much of real racers were probably aimed to buy 4C but more like a well suited middle aged fellas with rather thick wallets instead of a hands of a Pop-Eye. :D That's good, but lots of performance aspects are sacrificed because of this.

Bonus fact, and I don't want to go too deep with it. The 4C has also built in quite a lot of positive scrub radius as this is commonly used to increase the feedback from the wheels to the steering wheel, especially much needed in electric power steering, less so in hydraulic power steering and not at all in non assisted steering like we have. Because of that, every pothole, every rock, every bump you hit with the front wheel sends a kick to the steering wheel. Now the only reason I see the 4C has this is because they probably designed it based on some other MR platform car that actually has a power assisted steering. reducing positive scrub radius will make 4C less nervous and "calm" the steering wheel feel. Now this can be solved with higher ET front wheels, but majority of the wheels on the market for 4C are providing even more of positive scrub radius and so do wheel spacers, so if you want to get it right, don't just buy whatever wheel fits the wheel gap the nicest if you actually care about the handling.

That's a a bit simplified explanation of what is going on a 4C's front end and I'll report back when I get the kinematics done.

With GMS performance front arms we can alter the kingpin inclination, caster, camber and scrub radius. And we will do so if necessary to get the front end feel even more right and tight, even though some slow speed maneuvering might require a few gym visits and a can of Pop-Eye's spinach. This car was idea'd to be driver's car but somewhere in between it got a bit soft and we'll sort it out. 🖤
OK, you talked me into it....Good logic, Rudi. Looking forward to seeing how your front arms solve the problem.
 

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Surely king pin inclination, KPI, is a factor of the upright. The angle between the vertical face of the hub and a vertical line through the pick up points on the upright. Changes to the wishbone will not alter this, only changes to the upright.
That is my understanding but I'll welcome being corrected if wrong.
 

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Discussion Starter · #16 ·
You are right, I corrected my upper post. With all the brainstorming the suspension kinematics yesterday I forgot to write an important sentence about kingpin modification and Ackerman effect.
 

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Not much of real racers were probably aimed to buy 4C but more like a well suited middle aged fellas with rather thick wallets instead of a hands of a Pop-Eye.
OUCH, but how did you know? We haven't ever met! LOL
 
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Discussion Starter · #18 · (Edited)
Racers are always broke so you can't sell them anything and car manufacturers are absolutely aware of that, so that's why we don't get lots of "driver's cars". Ferrari, Porsche, Lamborghini, they all started with selling racing cars and then slowly transformed towards more "regular" cars or VW (Volks-Wagen, which means people's car) that would suite the wider clientele. Even Lotus lately lost its direction a bit.

Now all the mentioned brands make a living from this - later kind of cars, and not the race cars or "driver's cars" if you like and some of the manufacturers are able to sell regular cars at unreasonable high prices usually reserved for "race" cars with all the new technology and expensive craftsmanship. The reason they can sell regular cars at this altered price, is because of the pedigree and history. VW Touareg and Porsche Cayeene is pretty much the same thing except the price tag difference in-between. The next example would be BMW which was well known for being a "drivers car" and the hype that started with BMW E30 M3 is still the hype that is used to sell newer BMW's. The BMW M2 marketing red string was that this is the reincarnation, the successor of the BMW E30 M3, although the BMW E30 M3 was significantly different and more advanced compared to regular E30 series. The engine, the body, the suspension, etc. It truly was a race car built and homologated for the street to make it eligible for touring racing - DTM. BMW M2 is just a regular BMW 2 with minor changes and nothing remarkable on the market. The selling numbers? Outstanding. The profit compared to BMW E30 M30 Incomparable, of course in favor of BMW M2. Now where is the BMW's "drivers car" philosophy? It's gone. It's just the hype that remained and it is used to sell the cars, but the cars are far more regular cars than "driver's" cars.

Now where does that put Alfa Romeo? Well Alfa Romeo was as Ferrari, Porsche and others, selling race cars in the beginning, but sooner than all the mentioned brands, started to move in to regular cars production. By doing this, they neglected the racing program and soon they had to fight for market share in the regular car market where other newly established manufacturers were better choice (reliability, affordability etc.). So what happened is that Alfa Romeo's market share started to shrink as they were recognized neither as a "driver's car" neither as a good regular car but as an expensive and unreliable car. So not so long ago (few years) Alfa Romeo decided to change that and return to the roots, so they needed a true "driver's car" and 4C was the key. But, lots has changed since the early years of motorsport. Back then, wealthy people used to buy race cars with street license, as a status symbol. This cars were hard to tame, hard to drive, a true driver's cars, a cars like Ferrari's used to be, but they meant something. Today it's different. People want to buy car that it's practical, reliable, capable in hands of inexperienced driver and comfortable. A car that looks sporty, but it is docile to drive and easy to handle, able to lap decent times even though you don't know how to drive. This kind of customers have the money and the buying power and they want the car to work for them, they don't want hardcore car they'll never master. We live in an instant society. We want it all and we want it now. We don't want to spend 100k€ on a street legal race car that will make our ears bleed on a long run and require engine revision every few years and when you'll finally get to a duel on a backroad with some hothatch that just accidentally drove by, you'll probably loose because of you driver skills and hard to drive on a limit, car's specs. In a day or so you will perhaps even find onboard video from the other driver's perspective, beating your 100k€ car with a 30k€ hothatch and the video will go viral and that's a complete fail for for today's standards. Your ego will be hurt. So the safe bet is to have a car that we can drive one-handed over the water puddles, stop at the grocery store, can't miss a shift, cant oversteer in to a tree and yet being able to hit the race track once or twice a year and set the fastest lap time possible, even though we don't even remotely know and can find the limits of the car. But hey, don't worry, the car will do that for you. Just sit in and you're ready to win. That is selling the car's today. The Nürburgring lap times are selling cars today.

So, when you hear a guy talking about hardcore cars, true driver's car and stuff like this it's usually a rather young, not too wealthy guy that even if manufacturers would release the very true "driver's" car, probably couldn't buy. So manufacturers have no interest in such cars. It's more viable to make a capable race car to build the brands reputation and then sell regular car under the impression that this is the same car, just more comfortable. The car that makes you a winner with comfort and not much effort needed. A car that makes you an instant winner. That's how today's car industry is like.

Me, I'm not a wealthy guy, neither I come from a wealthy family, so always strived for a "hardcore", "driver's" car, but affordable, as this was my only option. I was always tuning my regular cars and racing pretty much everyone I could and I especially enjoyed racing against wealthier drivers with better cars because it gave me special ego satisfaction to beat them with my rat cars, and I only achieved that because I was willing to sacrifice my car's comfort for the sake of faster lap times and because I drove more on the edge and knew my car better. Well, with years, I believe I got wiser and more self confident, so I don't have to "pump" my ego with racing everyone I meet, but I rather seek perfection within my car and my driving and within my budget limitations. I'm happy I was able to afford 4C, but I'd still prefer a tad more driver's involvement, a tad bit more "driver's" car as I like the feeling of taming the car.

Now back to the red string. The 4C had the idea of a proper "driver's" car, that would place the Alfa Romeo back in the business of sport, "driver's" cars selling, but I believe that the selling department was strongly pulling the lines toward making more "user friendly", regular car and the engineer had the job to make "driver's" car. Well in the end, the 4C was caught somewhere in between, still being a bit too hardcore for daily use and yet not so perfect on the track. 4C will never be very comfortable and useful daily car, but it has all the ingredients for a "driver's" car. That's where my idea of 4C is heading. A bit more spicy version of stock 4C. A car that will reward you a bit more when you drive it right, a car that will run a bit faster lap times than others at the price of slight more driver involvement. A car that will have the modern technology, yet it will provide immersive feeling. A car that you will have a respect for every time you sit in and go for a drive. A fine line between analogue and modern, "driver's" car.
 

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Discussion Starter · #19 · (Edited)
Some insight:

Upper control arms are slightly tilted upwards and lower control arms are slightly tilted downwards. When the front suspension extends, negative camber reduces. When the front suspension compresses, negative camber increases. Good.

-10mm (non sport suspension) is max what the 4C should be lowered to keep the suspension geometry work the best in stock format at front and rear. Lowering for more than 10mm, each time the car's suspension will compress for more than 10mm, the track width will narrow, reducing the grip. Good as long as you don't lower the car too much.

For cars lowered more than 10mm (10mm lower on standard suspension), geometry is out of its optimal range and should be revised to prevent negative effect of over-lowered car.

That's for today. Next time bump steer, scrub radius, kingpin inclination etc.
 
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