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BOBIDESIGNOffline
Post subject:   PostPosted: Feb 04, 2016 - 05:51 PM
KitCentral Fellow


Joined: Aug 22, 2004
Posts: 376

Status: Offline
UPDATE:

The current progress of the EU and both US chassis plans is as follows:
A - Floor level [fully completed]
B - Bumpers [fully completed]
C - Engine cradle [fully completed]
*D - Door frames and hinges [not yet started]
E - Engine bay [fully completed]
F - Front end [fully completed]
R - Roof roll-cage [fully completed]
S - Sides of the cockpit [fully completed]
T - Central Tunnel [fully completed]
W - Firewall [fully completed]
*M - Metal sheets and plates [half completed]
MP - Machined parts [fully completed]
SP - Suspension tubes [fully completed]


I discontinued selling my chassis plans several months ago and now started to take inquires for selling the built chassis instead. The most recent updates in this topic are made for the nice people who already use my chassis plans for their builds. In fact, it would be a good idea if I start a new topic in another forum section dedicated for the remaining updates only, and leave the current topic opened just in case, but not writing inside as I don't want to move others' ads for sale down. For those wondering about the current options for my Govedo chassis aimed for Aventador replica builds, it could be either ordered from Finland or Bulgaria (both in Europe), as well as directly from USA at $10,000. I include little bit extra details below:

1. "Rolling chassis package". A fully built and coated chassis complete with wheels, brakes and brake lines, suspension parts, rack&pinion, steering column and steering wheel, pedals, and fuel tank pre-installed. Components, such like: engine, transmission, seats, radiators and pipes, A/C, battery and electrical system are not included. Price is $20,000 + shipping from Bulgaria or Finland, or may be negotiated for purchase at USA depending on the parts of your choice. Shipping requires a large crate box or cargo container.

  2. "Bare chassis package". A fully built bare chassis (just like the above, but no paint, wheels, brakes or any additional OEM or donor parts) is $7500 + shipping from Bulgaria or Finland, or $10,000 from USA. Shipping requires a large crate box or cargo container. A temporary WD-40 protective coat is applied to allow convenient welding of any additional brackets to mount the necessary donor parts of your choice.

 3. "Chassis starter package". An economy package consisting all the necessary separate pre-cut with CNC-laser machine: tubes, metal plates and sheets for the chassis, suspension and wheel hubs (uprights), as well as the CNC-bent roof tubes. All metal plates have dedicated mounting holes and pins for perfectly accurate assembly. The metal tubes, plates and sheets must be assembled and welded by the builder himself using the supplied instruction manual. Price is $5,500 + shipping from Bulgaria or Finland. All fit inside a small wooden crate box whose length is 2000 mm (or about 78"), width is 1000 mm (or about 39") and the height is greatly reduced.

 *Mild steel is used as a primary material. If a more expensive metal type is requested for the chassis, such like stainless or chromoly tubes, that will affect the price according to the specified material cost.

 **No matter the package, a 75% down payment is necessary up front, with the remaining 25% + shipping cost (unless the latter is arranged by the buyer) covered upon shipping of the crate box.


 Keep in mind that my Govedo chassis is not super light, it's designed for high-performance (lots of HP and better tyre grip while high-speed cornering) and driver occupant safety. The roof roll-cage is properly built and use stiff CNC-bent round tubes with over 6 mm wall thickness. It's a far cry from the weak tubing that most replica Lambo chassis use. The same goes for the side protection and the whole structure as well. This adds up to the cost and weight, but I believe that a smart person would rather have safety over slightly cheaper and lighter car. The front suspension features variable camber angle and caster angle depending on the turn degree and direction. My chassis does use some premium components whose price is higher than what the usual kit car builder spends on his/her build. For example, the 36 rod ends by QA1 will cost about $920-960 alone, and brakes are 14" and 14.25" by Wilwood. The small diameter stock Corvette C5 brakes will not fit my wheel hubs, because the latter are designed for strength and use 19" front and 20" big rear wheels, hence the lower ball joints and upper rod ends of the wheel hubs are moved as close as possible to the rim's inside profile to provide better performance and less stress on all the components involved. 17-18" or smaller rims will not fit my suspension (but they also don't look right on an Aventador replica). Also, I recommend using stiffer spring in the front end (to prevent collision of the tyre with the upper side of the wheel well due to the limited space inside), and some stores sell them for slightly higher price than their softer counterparts.


 Attached here are a few pictures of my final design of the Govedo chassis and suspension. I still do improvements on some of the metal sheets on the floor, sides and rear firewall, this is why they are not yet present in the pictures. The weight* (approximate calculation in a 3d software based on steel weight 7800 kg per cubic meter) of the EU version of my chassis should be as follows:

- Bare chassis with no suspension and metal sheets: 274 kg (604 lbs);
- Chassis with partial metal sheets (as shown in the pictures), suspension arms and wheel hubs: 381 kg (840 lbs);
- Chassis with full metal sheets, suspension arms and wheel hubs: 395 kg (871 lbs). Optionally, if 1 mm metal sheet in certain areas is replaced with 2 mm one, for extra frontal crash protection, the weight goes up to 430 kg (948 lbs).

 For comparison, by using the same formula for calculation, a steel replica Diablo (NAERC) chassis with the roll-cage, suspension, 2/3 of the central tunnel, and 1/2 of the metal sheets missing appears to weight about 327 kg (721 lbs). It's said to be 394 kg (868.43 lbs) with suspension.

http://i.imgur.com/gMgSc6v.png
http://i.imgur.com/YkOLuG7.png
http://i.imgur.com/TRrWWXJ.png
http://i.imgur.com/h5hSX3c.png

 If I can help with more information, please, let me know.

 Bobi
 
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BOBIDESIGNOffline
Post subject:   PostPosted: May 22, 2016 - 12:01 AM
KitCentral Fellow


Joined: Aug 22, 2004
Posts: 376

Status: Offline
I optimized the rear wheel hub (a.k.a. upright) by redesigning all metal plates and changing a few wall thicknesses depending on which areas are most affected by the pull forces and twisting. Now the rear wheel hub is up to 20% stronger in certain areas compared to the previous design, yet the weight is reduced from 8,5 kg to 8,1 kg.

For comparison, the NAERC rear wheel hub (used mainly in the replica Diablo and Murcielago builds) weights 5,62 kg while providing a lot lower overall stiffness and transfers 95% higher negative load to the A-arms during sudden acceleration or heavy braking. Considering that my suspension uses only one coil-over per rear wheel, while NAERC's uses two coil-overs per rear wheel, the weight penalty on my wheel hub is not as big as the basic figures suggest. My Govedo rear wheel hub uses a massive 10 mm thick mounting plate for the C5 hub-bearing assembly, while NAERC's rear hub uses two separate plates with a combined thickness of 8,28 mm whose bending resistance is as low as an equivalent of a single plate with wall thickness of about 7 mm. Another interesting comparison with the NAERC rear wheel hub: My upper A-arm is located 77 mm higher, while the lower A-arm is 41 mm lower, both helping to reduce the push or pull forces transferred to the mounting bolts, rod ends and chassis.

https://youtu.be/e35qusPtzP8
 
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BOBIDESIGNOffline
Post subject:   PostPosted: Aug 21, 2016 - 07:40 PM
KitCentral Fellow


Joined: Aug 22, 2004
Posts: 376

Status: Offline
UPDATES:


18 June 2016:

- I did some tiny improvements on the rear wheel hub, as well as on two of the mounting points of the chassis where the upper rear A-arm is attached. These changes will allow for a greater clearance when using thicker (longer along the axis of rotation) nuts for the QA1 rod ends. The front wheel hub is under a similar redesign now;

- Recently I also started to design the metal plates that will serve the role of mounting points for installation of the door hinge;

- The roof will receive an optional X-bracing to further increase the overall stiffness of the chassis and roll-over protection for the occupants. However, this addition will reduce the headroom with about 40 mm, so it's up to the builder to decide if he/she will use that reinforcement. A good compromise will be to use a single diagonal tube going from the passenger's side C-pillar up to the driver's side A-pillar. This way, the driver will still enjoy a maximum headroom while the passenger side will be 40 mm shorter.

- I also made some new renderings to show the current chassis and suspension design. The first 4 images n the top show an earlier state of the design, while the ones at the bottom are newer: http://imgur.com/a/pekFu



29 June 2016:

- I added two optional small cross-sectional plates to the rear hub that will further reinforce the bolt pattern area where the Corvette C5 hub-bearing is mounted. Both pieces will add about 75 grams combined to the total weight of the rear wheel hub. That reinforcement is usually not necessary for when the engine's power is in the range of sub 500 HP.



16 August 2016:

- A few weeks ago I had the chance to go and check again the first built prototype Govedo chassis and thanks to some testing of the actual suspension I was able to collect very useful data of what's good and what could be improved even further. There are two major improvements now:
1. I slightly redesigned one area of the front upright (wheel hub) to increase the amount of free space around the steering toe link;
2. I also shortened a bit the upper control arm toe links (the pair that replaces the upper A-arm) to allow a greater increase of the negative camber angle (up to -1,2 degrees), while maintaining the default camber angle of 0 degrees. Previously, the default camber angle for the front wheels was still same at 0 degrees, but the longer upper control arms allowed only for up to -0,6 degrees optional negative camber angle, and 0,6 degrees positive camber angle (the latter is not necessary at all). With -1,2 mm degrees of camber angle, each front wheel's upper outside wall will be shifted by about 11 mm inside the wheel well.



21 August 2016:

- The Govedo chassis now features an optional X-brace reinforcement to further increase the chassis strength and protection of the occupants. It comes in two variants depending of what the builder will consider as the better option to suit his or her application:

a) Just a single tube in a "front left to back right" configuration (or opposite for RHD cars) that allows to preserve the original headroom for the driver and lowers the passenger's room by 35 mm;

b) Two tubes in a X-brace configuration that offers maximum possible strength at the cost of 35 mm reduced headroom for both persons inside the car.

There will be several extra laser cut plates that I will design in next days. The new addition to the roof and options for installation could be seen at the bottom of this image album: http://imgur.com/a/pekFu
 
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BOBIDESIGNOffline
Post subject:   PostPosted: Aug 24, 2016 - 11:25 PM
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Joined: Aug 22, 2004
Posts: 376

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I made most of the changes required for the door hinge mounting plate and they could be seen in the video I recorded today:
https://www.youtube.com/watch?v=XM3k26gb73Q
 
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