Author Topic: Aventador custom chassis drawings for 500 USD / 470 EUR  (Read 52837 times)

plans4sale

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Re: Aventador custom chassis drawings for 500 USD / 470 EUR
« Reply #95 on: August 25, 2015, 12:44:23 PM »
I was just going by nsrdanielsons post where he says your chassis will not fit
NSRdanielson or Inspires kit,  and most likely not aventcars and definitely not eddies or robs. ?


You replied saying you might need to cut the body kit up and stretch /modify it to fit on your chassis . I don't think even an experienced builder will take a body kit they just bought then cut it up to stretch it
This is why the forum quote button was invented two decades ago, in order to avoid accidental misunderstanding or intentionally misleading posts leading to premature suggestions.
 
 As for cutting a body kit to get into more accurate shape, this is exactly what was done by many builders from years. It happens even now with the Aventador body kits. One of the examples is at the Fiero.nl forum, the second one is at MM. Experienced builders know their stuff and can do it properly.
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Tusabes

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Re: Aventador custom chassis drawings for 500 USD / 470 EUR
« Reply #94 on: August 25, 2015, 12:33:12 PM »
I was just going by nsrdanielsons post where he says your chassis will not fit
NSRdanielson or Inspires kit,  and most likely not aventcars and definitely not eddies or robs. ?


You replied saying you might need to cut the body kit up and stretch /modify it to fit on your chassis . I don't think even an experienced builder will take a body kit they just bought then cut it up to stretch it

plans4sale

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Re: Aventador custom chassis drawings for 500 USD / 470 EUR
« Reply #93 on: August 25, 2015, 08:16:43 AM »
O.K., if you want to bring all of this up again over two months later for no apparent reason, I will bite.  You say "The lack of the latter (a swaybar)could allow a softer ride". Needing to use a stiffer spring to compensate for no swaybar gives a softer ride? That is absurd. You also say "Too soft spring...would simply cause unwanted damages to the chassis. This is the main reason for me to choose...higher spring rate". This is what you base a spring rate on? That is also absurd.

 Obviously, for anyone with at least moderate technical understanding, it's not hard to figure out the positives of having stiffer springs in a suspension with limited stroke, such like the case with this kind of sports cars where the front wheels are quite close to the A-pillar base. Not to mention all the other positives a stiffer suspension gains. Anyway, let me explain my point of view again, if my previous post about my decision for the spring rate was not clear enough for you. First off, I have never said what you claim in the underlined text above. I have never said that I will not use a sway bar. I said that even if there is no sway bar on my unusual suspension geometry, the latter will provide some good advantages over a normal type suspension with softer springs. My exact words were: "Based on my suspension geometry that features unusual upper-to-lower arm length ratio and more aggressive angle of the upper, body roll actually can be used to a distinct advantage*. Given the quite high amount of spring rate (I recommended at least 450 lbs, but it's better to use around 550 lbs) and limited coil-over stroke, my suspension can perform quite well even without a sway bar. The lack of the latter could allow a softer ride on uneven surfaces, which is very important for a stiff suspension".

*This is what a distinct advantage looks like (variable camber and caster angle):
http://i.imgur.com/lhVBf6V.png
http://i.imgur.com/eN4sZQv.png
http://i.imgur.com/HsvW3QR.png
 

A higher spring rate and shorter stroke in a hard stopping fast moving sports car will provide:
1. Superior braking performance and mass distribution (springs with lower spring ratio and longer stroke will always perform worse in such case, even if coupled with a gazillion lbs sway bar, because the latter can not compensate for the lack of spring rate, and in most situations will lead to a "kick" in the suddenly tilting front end);
2. Superior high-speed cornering with less body roll and better preserved road contact patch;
3. Lesser negative mass transfer and body tilt towards the front end;
4. Vastly reduced chance for the front wheels to reach the maximum pressure distance they are designed to run.




So wait a second - these chassis plans do not fit a single body out there?  What use is there for these plans if no body fits them ?

This seems like a massive waste of time

 Who claims that those body kits you mentioned can not fit my chassis that was primarily designed to fit any properly built replica Aventador body and uses correct key areas dimensions and scale? Can you provide us with more information of why all body kits ("single body out there") are being considered too inaccurate by you? Is that you? Who already tested all these body kits on top of my chassis to find out they lack the proper scale and proportions to match the genuine Aventador?
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Tusabes

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Re: Aventador custom chassis drawings for 500 USD / 470 EUR
« Reply #92 on: August 25, 2015, 12:11:09 AM »
So wait a second - these chassis plans do not fit a single body out there?  What use is there for these plans if no body fits them ?

This seems like a massive waste of time

76mx

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Re: Aventador custom chassis drawings for 500 USD / 470 EUR
« Reply #91 on: August 24, 2015, 10:07:13 PM »
O.K., if you want to bring all of this up again over two months later for no apparent reason, I will bite.  You say "The lack of the latter (a swaybar)could allow a softer ride". Needing to use a stiffer spring to compensate for no swaybar gives a softer ride? That is absurd. You also say "Too soft spring...would simply cause unwanted damages to the chassis. This is the main reason for me to choose...higher spring rate". This is what you base a spring rate on? That is also absurd.

plans4sale

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Re: Aventador custom chassis drawings for 500 USD / 470 EUR
« Reply #90 on: August 24, 2015, 03:31:50 PM »
Which bodies does this chassis fit? I know it doesnt fit Inspires or mine, and most likely not aventcars and definitely not eddies or robs. ?

My chassis is designed to fit body kits that are fairly accurate to the genuine Aventador's dimensions, shape and proportion. If the body kit is way too inaccurate, it may not fit my chassis, or may require some modifications to be able to fit. I can not tell if the body kits you mentioned will or will not fit my chassis. I know for sure that the first body kit you mentioned could fit my chassis after modifications that require the body to be cut and extended in length and width (pictured below), as well as reworking the door sills:
http://i.imgur.com/P0rZqD5.png
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NSRdanielson (BANNED)

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Re: Aventador custom chassis drawings for 500 USD / 470 EUR
« Reply #89 on: August 24, 2015, 03:01:40 PM »
Which bodies does this chassis fit? I know it doesnt fit Inspires or mine, and most likely not aventcars and definitely not eddies or robs. ?

plans4sale

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Re: Aventador custom chassis drawings for 500 USD / 440 EUR
« Reply #88 on: August 24, 2015, 02:32:53 PM »
UPDATE:

- All the roof tubes and six roof mounting plates are now re-designed for improved visibility through the front windshield and rear quarter windows. Upper tube that connects both A-pillars have been raised with 15 mm to clear as much space as possible for the interior roof pillar covers. This modification also makes the welded joints stronger.

- Along with the heavy duty European "Meyle" lower ball joint, there is an optional alternative "Mevotech" ball joint for the US builders which is slightly smaller but a lot more affordable. This makes it possible to opt for a US-spec chassis plans with either EU suspension plans or US suspension plans:
a) EU chassis with EU suspension ("Meyle" lower ball joints - can be found for 26-30 Euros per unit, available in Europe);
b) US chassis with EU suspension ("Meyle" lower ball joints - can be found for 26-30 Euros per unit, available in Europe);
c) US chassis with US suspension ("Mevotech" lower ball joints - can be found for 14 US Dollars per unit, available in USA).
 Both ball joints are bolt-on type for easier installation and maintenance without the need of special tools and/or use of excessive force with hammer.

- Pre-order discount price has expired as the design is at final stage now. A single license and chassis plans for my Govedo chassis costs 500 US Dollars or 440 Euros* (price in Euros may vary after some time depending on the uncertain currency exchange rate).

P.S.: I would like to thank Glenn (LP700-4 from MM) for his great help with taking exact measurements from the "Mevotech" ball joint. This is what makes our community special. ::beers
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plans4sale

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Re: Aventador custom chassis drawings for 370 USD / 280 EUR
« Reply #87 on: August 16, 2015, 02:45:17 PM »
   I also mention swaybar rating in my answer, something that P4S never mentions. I assume his calculations are without a swaybar, and THAT WILL NOT WORK either.
Based on my suspension geometry that features unusual upper-to-lower arm length ratio and more aggressive angle of the upper, body roll actually can be used to a distinct advantage. Given the quite high amount of spring rate (I recommended at least 450 lbs, but it's better to use around 550 lbs) and limited coil-over stroke, my suspension can perform quite well even without a sway bar. The lack of the latter could allow a softer ride on uneven surfaces, which is very important for a stiff suspension.
 If we assume that the default camber angle of the front wheel is set to exact 0 degrees (though -0,5 degrees is recommended) while the car is moving forward (no turn at all), then the worst camber angle possible for the front wheel* is 0.874 degrees happening at 3.75 degrees of body roll (with -0.5 degrees default camber, that will translate to 0.374 degrees). The virtual point of body roll for this calculation is the middle point on the bottom side of the chassis. However, body roll during moving in forward direction is rarely the case. More important is what is happening with the car while in high-speed cornering. With the front left wheel turning at 15 degrees to the right side, the worst possible camber angle is -1.461 degrees at 3.24 degrees of body roll (or -1.961 degrees if the default camber was -0.5 degrees). This means that the wheel is still in a negative camber angle to prevent excessive tyre deflection and wear in contact with the road patch, as well as reducing the understeer. This is achieved thanks to the use of two toe links instead of a single upper A-arm. The toe links will dynamically alter both, the camber angle and caster angle, resulting in a suspension geometry with superior high-speed cornering performance, compared to a regular double A-arm layout.
 *front wheel on the side of the car that's pushed towards the ground to create body roll.



This subject could fill another thread, but let me give this brief example more to show a concept than to be absolutely accurate. A 100lb spring and a 300lb bar gives a total rating of 400lb on that corner. A 300lb spring and a 100lb bar gives a 400lb rating on that corner. The debate over which is correct has been going on since the wheel was invented, but you must consider them together. When P4S says 400lbs on the front, that is as much as you would want to go for both combined, I do not care what the geometry looks like.
I do not agree with what you refer as to "absolutely accurate" in the above examples. There is no way that a 100 lbs spring and 300 lbs sway bar will give a total rating of 400 lbs on a corner, since the combined spring rate for both wheels would be 200 lbs, which can never be more than that number even if you have a 1,000,000 lbs sway bar. A 1,000,000 lbs sway bar will not help a 100 lbs spring to achieve 1,000,100 lbs on that corner. Also, 100 lbs spring and 300 lbs sway bar does not equal to 300 lbs spring and 100 lbs sway bar. This is not a simple mathematics where 2+2=4. They both can't be compared, as you did above. This is most prominent while hard braking from a fast speed in a straight direction. The 3 times softer springs will undoubtedly perform a lot worse then, not to mention that the sway bar will not contribute with hardening the suspension in this situation. What's more, a too stiff sway bar may hamper the stopping process on an uneven road.
 


   Realistically, to get this rate you need about a 250 lb spring and a 150lb bar. A 7 inch spring coil binds at 4 inches, 4 1/4 to be exact. That leaves 2 3/4 inches of spring stroke, forget the shock. Place the 530lbs guess of P4S over it and it compresses 2 1/8 inches. That leaves 5/8 of an inch for suspension travel. Put a passenger in the car and you do not have even that. If he misses that guess by even 100lbs you do not have that. If the ride height is not absolutely perfect (which it is not going to be in the real world, only on paper) you do not have that. Change the air pressure in a tire and you do not have it. For that matter, what sized tire is this based on, will everyone use the exact same tire? When the spring settles, which it is going to do, you do not have it. All of these will leave it coil bound before the suspension ever has a chance to travel. It may look good on paper, but it is not reality. Go to a 225lb spring and now any slim remote hope is gone. 
 Why change it to the shorter shock in the first place? This is the same question I asked when my problems arose. The shorter shock and smaller spring is less unsprung weight but the bigger spring that is now needed negates this, and it is much harder to make the geometry work with the short one. I do not find an upside to this change.
Considering the limited stroke the front wheels require, a coil-over with too soft spring and too long stroke would simply cause unwanted damages to the chassis, if not accident. This is the main reason for me to choose a shorter coil-over with higher spring rate. Also, the shorter coil-over makes it possible to install it in a more robust area of the chassis.
 


Also on the downside, I understand you have two years of development using the Hardpoint for the longer shock, which is the first starting point of chassis design. You are going to lose every bit of your suspension analysis data. Again just my opinion but any chassis design that is changing Hardpoints after two years of development has more problems that the shock length.   
In my opinion, devoting more time on optimizing a chassis and suspension design could further make it superior to the initial state. Changing means that something is not as before anymore. It could be good, or, it could be bad. In my case, it proved to be better.
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plans4sale

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Re: Aventador custom chassis drawings for 500 USD / 470 EUR
« Reply #86 on: August 14, 2015, 08:18:15 PM »
 UPDATE:

 - The front and rear lower A-arms were fully re-designed. Now they use a larger and 30% more durable heavy duty lower ball joint with 4 mounting bolts. Up until now my suspension design was based on a smaller ball joint with 3 mounting bolts;

- Front upper toe link rods were slightly extended while preserving the mounting holes on both ends where the QA1 rod ends are installed.

 - Main roof tube along the roof line (from A1-pillar through the roof up to the C-pillar) have been slightly modified to add 3 mm wider visibility at each side of the windshield. As a result, this also reduced the head room by 6 mm;

- The A2-pillar is now made from three laser cut metal plates instead of the previously used constant-radius bent tube. The metal plate will allow for tighter fit to the body, hence a better visibility is achieved through the front quarter window;

- Rear bumper support frame is fully designed, complete with removable mounting points in case that the builder needs to take apart the removable engine cradle sitting next to it;

- Most of the sheet metal enclosing the cabin area is already designed.
« Last Edit: August 15, 2015, 04:37:49 AM by plans4sale »
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plans4sale

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Re: Aventador custom chassis drawings for 370 USD / 280 EUR
« Reply #85 on: July 24, 2015, 02:21:53 PM »
UPDATE:
 
 - Fine tuning the rear suspension, sending (SP) plans tomorrow. Front suspension to follow next after figuring out the lower ball joint.
 
 - Roof plans (R) almost ready as well.
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plans4sale

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Re: Aventador custom chassis drawings for 370 USD / 280 EUR
« Reply #84 on: June 06, 2015, 06:17:25 AM »
1. The front wheel must not go more than 40 mm upwards from its neutral position while standing still.
2. The 10" QA1 DS301 coil-over will allow about 33.5 mm stroke from neutral position, which translates to 38.89 mm travel of the wheel upwards.
3. The 7" spring used is proper size and its wire diameter has such a clearance along the coils that it will not bind even if the gas shock is fully compressed.
4. The shift from the previously used 14" coil-over to the new 10" replacement will allow the upper coil-over mounting point to be lowered and attached on a more reinforced area of the chassis.
5. The upper front arms were designed to give enough clearance for a 14" coil-over, so if somebody wants to use any other longer coil-over between 11" and 14" (for example, when an air lift system is installed), he/she is free to do so by simply raising the upper mounting point of the coil-over accordingly.

This is why I consider the DS301 as the perfect coil-over for my front suspension design.
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76mx

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Re: Aventador custom chassis drawings for 370 USD / 280 EUR
« Reply #83 on: June 03, 2015, 05:03:06 PM »
SchulzeA,
   Another good question. Afco told me they were all 4-1/4. I remember thinking at the time that it did not sound right but guessed that whether it was a lot of small wire and a lot of coils or a little big wire and a few coils, they came out the same. At the time I accepted that and was glad to have that waste of time ending, but now as I look back, I am not sure that I accept it as quickly. I do not know the answer to your second question, I told them that the only application I could think of was for the straight axle on the front of a T-Bucket Roadster. If you like I can put you in touch with the engineers for input on your spring winder, but remember Life Rule #39,"One test is worth a thousand engineers".   

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Re: Aventador custom chassis drawings for 370 USD / 280 EUR
« Reply #82 on: June 03, 2015, 10:06:27 AM »
Dang, you guys write a book. Ok, so how do you determine all 7" springs bind at 4.25" without first knowing the wire size and pitch? Picture below shows that not all springs are created equal. I built a spring winder and would like to know what formula you use to find compressed length. Knowing what to expect is much better than finding that I've made a mistake like your custom chassis you built. Doing it right the first time certainly is the best way when possible!

Secondly, what is the application for this DS301 shock/spring setup if it will not function correctly?

Not being rude here, just askin...

plans4sale

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Re: Aventador custom chassis drawings for 370 USD / 280 EUR
« Reply #81 on: June 02, 2015, 01:01:06 PM »
SchulzeA,
   Those are good questions and observations, let me see if I can address all of them. You are absolutely right about the stroke length, that is what I was talking about when I mentioned motion ratio. That wants to be as close to the ball joint as possible for other design considerations. The stroke length of that shock is 2 1/2 inches. As you say, that is shock stroke length, not tire travel.
   Both your response and the first response of P4S concentrate on the shocks, forget about them, they are not the issue, they could be 1 or 100 inch stroke, but there is a problem if a 7 inch spring is the longest that will fit.
   I also mention swaybar rating in my answer, something that P4S never mentions. I assume his calculations are without a swaybar, and THAT WILL NOT WORK either. This subject could fill another thread, but let me give this brief example more to show a concept than to be absolutely accurate. A 100lb spring and a 300lb bar gives a total rating of 400lb on that corner. A 300lb spring and a 100lb bar gives a 400lb rating on that corner. The debate over which is correct has been going on since the wheel was invented, but you must consider them together. When P4S says 400lbs on the front, that is as much as you would want to go for both combined, I do not care what the geometry looks like.
   Realistically, to get this rate you need about a 250 lb spring and a 150lb bar. A 7 inch spring coil binds at 4 inches, 4 1/4 to be exact. That leaves 2 3/4 inches of spring stroke, forget the shock. Place the 530lbs guess of P4S over it and it compresses 2 1/8 inches. That leaves 5/8 of an inch for suspension travel. Put a passenger in the car and you do not have even that. If he misses that guess by even 100lbs you do not have that. If the ride height is not absolutely perfect (which it is not going to be in the real world, only on paper) you do not have that. Change the air pressure in a tire and you do not have it. For that matter, what sized tire is this based on, will everyone use the exact same tire? When the spring settles, which it is going to do, you do not have it. All of these will leave it coil bound before the suspension ever has a chance to travel. It may look good on paper, but it is not reality. Go to a 225lb spring and now any slim remote hope is gone. 
   There is a second way I know this. I have a junk chassis sitting here that was the R&D test bed for the development of that very shock. We got almost the entire chassis done and the prototypes sent to production before either of us realized there was a problem.
   P4S,I am not trying to argue, just save the agony of another junk chassis being built, but if your numbers say it will work, go for it. At the risk of extending what has now become a debate, I have a few observations. Why change it to the shorter shock in the first place? This is the same question I asked when my problems arose. The shorter shock and smaller spring is less unsprung weight but the bigger spring that is now needed negates this, and it is much harder to make the geometry work with the short one. I do not find an upside to this change. Also on the downside, I understand you have two years of development using the Hardpoint for the longer shock, which is the first starting point of chassis design. You are going to lose every bit of your suspension analysis data. Again just my opinion but any chassis design that is changing Hardpoints after two years of development has more problems that the shock length.   
Thank you for your very long post, 76mx! I appreciate the time you spent writing all of this. I will be short: I already have an experience with taking part in designing two sports car suspensions that were tested and used successfully in real cars. Now I design a more advanced, complicated and uncommon suspension layout, and I'm pretty sure it will work properly. Why? Because I do it. Thanks!
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