for all of you chassis guys. esp Twin_Turbo. what CAD / method do you guys use to design your chassis, were talkin cornering, road race. not drag. any recommendations? im using ProEngineer and im having a difficult time with it.

please help!!

Chris

 

I work with AutoCAD and haven't gotten too far along either. Good luck. There's a small community out there that are "dabbling" with frame and suspension details but not a lot being shared. Probably not a lot of progress. Interest is there though.

Personally, I'd really like to see a bare-bones C3 frame in Computer Assisted Drafting & Design (in a format all of us can view and use) as a resource for all Corvette Forum members. After that I believe the rest of our car's form will follow (engine parts to scale, wiring harness routes, etc.) because there's a lot of talented folks out there that would contribute. Perhaps in time.

 

 

I've been using ProEngineer for 17 years and I wouldn't recommend anything else, although you do need a high end work station to run it properly.

What kind of problems are you having?

 

im a civil guy, so i am big with AutoCAD but its not the right program for this application. im tryin to get my self started with ProE and im having a difficult time getting taking the measurements of the chassis with a tape and caliper to get really good dimensions. once i put the chassis and design the suspension the way i want it, will i be able to test the kinematics of the entire system, and simulate how it will perform at the track?

 

The assembly will need to be put together using the proper constraints to allow component movement. The Mechanica application will then be used to simulate movement.

Ansys, or some other FEA software will then be used to impose forces on the assembly and simulate the reactions from these forces. Identifying and quantifying these forces could be a bit of a challenge.

All in all, it's going to be a fairly complicated project. Pro/e is one of the more complex CADD softwares out there. But if used correctly, amazing things can be accomplished with it.

You mentioned that you were just getting started with Pro/e. I'm the Design/Drafting Department Manager for a large Defense contracter. On average, it takes approximately 6 months of full time use for someone to become familiar enough with the software to be able to produce useable models.

 

.....and then..... how much time to create a correct model of the frame?
(considering the used steel, any hole, any chamfer, any weld.....)

My opinion is.... weld on some good roll-cage and be in the "safe" area!

 

How do you think Ferrari builds their successful racecars? F1, LMS, etc.

 

I don't think Stroker-427 intended any flames (nor do I), but how much effort are you willing to put into re-inventing the wheel, as it were? There's been a huge amount of previous groundwork already laid when it comes to addressing the C3 chassis' shortcomings on which to lean without necessarily going all the way back to square one, unless you're designing a whole new platform. However, by all means don't let us discourage you if that's what you're about.

 

Well said, I have seen Guildstrand's 5 link and am impressed with his work, as well as John Greenwood, I just wanted to take a stab at it and see what becomes out of it. I just wanna make it a winner at the track. And besides the link systems I have seen are custom and I wanna design mine the way I know how.

I am doing this on my own at my company's equipment yard, If you have links to what others have done, i have seen twin turbo's chassis, and another guy's on the forum, I don't remember the guys name but I know his car is red. But if you have any insight you would like to add, please let me know.

Chris

 

Try TurboCad V10.2, V11 or V12; it's innexpensive, easier than ACAD, it's mature, lots of users, lots of training material, runs well on a PC, its a 2D, 3D drawing package, it can render a 3D model. It is nowhere near ProEngineer. It does not have any FEA type functionality.

 

Of course.... I'm not stating that this is not the right way to do it!
Even in my company we utilize CAD and FEM in order to calculate the frames of our systems!

If you have the skill, the time and the patience to do it..... I'm happy for you and for us.... if you will share your work!

I only say that for the average guy this is a too big job!

 

Matter of fact, Stroker-427 himself just completed re-engineering the rear suspension on his red C3. 84rzv500r is another guy here who has done it. Don't know just how much they'll be willing to share (and I don't have a problem with that), but IMHO when you go this far you'll want to do your own math anyway, as every application has different variables.

Tho I've done a bit of road racing and have earnestly tried to become a student of C3 suspension tech, I'm only on the research (read, "bench racing", lol) side for now, so the best insight I can give is to find some suspension simulation software, or learn how to play with the paper dolls described in Carrol Smith's "Tune to Win" so you can put together a poor man's suspension computer (the larger the scale the better). IMHO, that is where you should spend time calculating, as it's relatively easy to build balsa models or just follow other tried and true examples of chassis stiffening.

BTW, I too have come around to the idea of the telescoping 1/2 shafts to get them out of the equation as upper links, and believe dual trailing links (such as the 5-bar and C4 have) are worth adapting so that "anti-squat" can be introduced. Going full-blown double A-arm SLA looks like a real PITA...

 

Regarding antisquat of an IRS..... there is very litle to do.... because the torque is applyed by the differential directely to the frame.
No reaction at the suspensions!

The only way to have some antisquat is to point the reaction rods upwards..... and it's very hard to have more than 30% antisquat.
Taking in consideration that with live axe it is possible to bild more than 100% antisquat..... I should design the rear suspension in order to avoid wheel-hop (it is the opposite than antisquat) during braking.

In road racing the traction isn't the bigger issue.... but braking and apex speed !!!

The main problem for the C3 IRS are:
1) Jacking
2) Torque steer
3) bump steer

The connection of the T/A isn't too bad for antisquat!

Unless you will race in a track with very tight corners, it is better to invest the max traction of your tires in the apex speed.... and to apply the power very smootly approaching the stright lane.

As you may know, any tire in a particular car, have a maximum traction capability.... and if you corner at the limit..... you can't apply any power to the wheel.

The traction of the tire increase with the load..... but not in a linear way..... double load equal less than double traction.

So the trick is less weight, good tires and good suspension design.

Even if you are able to design a lot of antisquat in a road race car..... it will be not a good move.... because for consequence you will loose a lot of braking efficience at the rear end.
The result will be that any other racer will be able to overtake you when braking....... due to the bad insertion.

Races aren't an exact science....... but the way to design a very good race car is based on phisics, wich is an exact science.

The target is the optimal comprimise between any characteristic.

My opinion, of course.

 

FLEXUSMARK included some cad stuff concerning rear suspension geometry in this post:

http://forums.corvetteforum.com/show...ghlight=6+link

I haven't seen any cad drawings of an entire chassis though. Twin Turbo might have some. Anyone else?

 

If that is true, I think you need to look at your training program or your software. I'm running Solid Edge and it didn't take anywhere near that long.

 

Maybe you're definition of useable parts is different than mine, or maybe the models you work with aren't as complicated as the ones we work with.

Have you ever used Pro/e? There really is no comparison between Solid Edge and Pro/e.

 

Well if you are talking Cad, I would recommend Solidworks. Can handle anything, easy to use and you can put any constraint on it that you can imagine. Top down or bottom up assembly. You can add motion to it, exploded views etc...I have used all the high end cad systems out there from Unigraphics, Autocad, Cadkey, Computer vision, HP. Solidworks is the best bang for the buck. Its about 5K to buy. Autocad is not to good for this, its a good 2d program though.

my .02 worth, thanks

 

I used CATIA V5 to design a chassis based on the SRIII tubular design w/ C5/C4 IFS/IRS. It's a very powerful system used by many of the auto companies worldwide. It is a "parametrized" system and I can get the CG and weight of the frame using a particular tube wall thickness. This can be changed with one dimensional update. The specific gravity (density) of the material can be changed for different materials as well.

I'm overseas at the moment so I don't have access to any vehicle to measure the hard points. Can anyone please help me with the dimensions from the wheel centerlines to the body mounts?

Please check out my website at http://bndtechsource.ucoz.com to see the progress.

 

Solidworks is a great program. Cadkey I believe in terms of wireframe drawings, is better with the last version (V20) before they were bought by another company.