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C4 Frame and suspension CAD files
Frame and suspension CAD files
Doesn't anyone have, or know where I can get CAD files for the C4 Corvette's frame and suspension? I found lot of the C4's frame dimensions in the FSM I really want to input the whole suspension into a computer. I'm going to coil overs and this would really help pick out the rate. Also I'm thinking of making some modifications. C4's are camber challenged, but just laying the upper a-arms against the frame doesn't do it. I've tried that, and it compromises braking too much. If anyone has there car apart in the garage, can he measure the easy stuff? A-arms dogbones etc. I can then start work on the CAD file. I'll provide the CAD file to anyone who helps me out. BTW I really hope the upper a-arms in the front aren't pointing DOWN while at rest. That would explain a lot! |
Hi Brian,
Yes, a stock c4 when at rest the upper arms are pointed slightly down (negative camber loss under initial compression :ack: ) also if you look at the cross shaft on the upper "A" arm it is on an upward angle higer in the front then the rear. Anti dive When the suspension is initially compressed you loose camber until you compress it enough to get past the center line, parallel to the ground,(which may never happen in stock trim) only then can you get negative camber gain. Interesting geometry!!! Just rambling Have fun |
OMFG!
That's gotta go! I'll let you know what I come up with. |
11/05 SuperL98 created a thread about Anti-Squat that generated
some informative comments. Perhaps some pieces to your puzzle might be found within. There were images (and measurements IIRC). These no longer display, but perhaps the OP would resurrect them upon request? Anti Squat on a C4 - Why so much? I have some front lower control arms I could pull out for measurements if this would help and if the data isn't already available elsewhere. Mike Antoniak's book, Cor-Vette Specs (ISBN-10: 0933534515) is very thorough. If you don't have it, I will see what might be available there. . |
Thanks, I PM'ed the people in that thread, since it's closed.
The end goal is to put the geometry into a suspension analyzer. Something like this: http://www.mitchellsoftware.com/prod01.htm http://www.mitchellsoftware.com/Geo_1.gif http://www.mitchellsoftware.com/Geo_4.gif I have SolidWorks, and that may handle what I need to do. What I need measured is geometries that are critical to how it moves. ie) center to center distances, but not thicknesses. If it would help I can make drawings showing what I need. Items like the dogbone bushing center-to-center lengths should be easy to measure. On the a-arms for instance, I need the center of the bushing hole to the center of where the ball joint pivot moves, which will be hard to measure. I need to know where the rollbar is connected, where the spring hits, where the shock is connected. These will tell me what spring rates to get. This is no small task, but when it's done, I'm hoping to come up with some simple solutions to some of the handling issues we have. |
Sample info from Cor-Vette Specs for a 1987 model.
This gives an idea of which portions of the quest can be satisfied by obtaining a copy of Mr. Antoniak's book. WIDTH & LENGTH .Tread (front): 59.6" Tread (rear): 60.4" Wheelbase: 96.2" FRONT: Travel full jounce: 3.6" Travel full rebound: 3.7" Spring size: 45.7" x 3.9" x 0.52" (base); 45.7" x 3.9" x 0.56" (Z51) Spring rate: 296 lb/in (base); 380 lb/in (Z51) Spring rate at wheel: 92.6 lb/in (base); 110.9 lb/in (Z51) REAR: Travel full jounce: 3.6" Travel full rebound: 2.8" Spring size: 48.7" x 2.24" x 0.87" (base); 48.7" x 2.24" x 0.98" (Z51) Spring rate: 233 lb/in (base); 330 lb/in (Z51) Spring rate at wheel: 130.2 lb/in (base); 173.6 lb/in (Z51) ECT: Wheel offset: 1.26" Axis inclination at camber: 8.744° Front wheel at curb mass, service caster: 6.0°, +/- 0.5° Front wheel at curb mass, service camber: 0.8°, +/- 0.8° Front wheel at curb mass, service toe-in: 0.0°, +/- 0.1° Rear wheel at curb mass, service camber: 0.0°, +/- 0.5° Rear wheel at curb mass, service toe-in: 0.0°, +/- 0.1° |
Man that was a long time ago :D
The images still seam to be on my CF homepage, but they don't link anymore? Haven't logged in for awhile... logged in and now they seam to have come back up :rolleyes: I did lay the rear out in solidworks and had started on a design with an adjustable control arm bracket, but lets just say I lost the files during an "unplanned" carear change :lol: Haven't had time to do much with that since. P.S. I did my measuring with machinist rulers crawling around on the gagrage floor, just to get the general layout. I wouldn't be machining parts based on them ... without verification ... |
This picture is a BIG help.
http://www.corvetteforum.net/c4/iris/squat1.jpg http://www.corvetteforum.net/c4/iris/antisquat.jpg Combine it with this one http://i242.photobucket.com/albums/f...am/rearend.jpg And a lot of the rear suspension behavior can be done. Do you have these as well? All I have for plans are these pictures. http://temp.corvetteforum.net/c4/iris//sideview.jpg http://temp.corvetteforum.net/c4/iris//dimen.jpg http://temp.corvetteforum.net/c4/iris//1e.jpg http://temp.corvetteforum.net/c4/iris//1d.jpg http://temp.corvetteforum.net/c4/iris//1c.jpg http://temp.corvetteforum.net/c4/iris//1b.jpg http://temp.corvetteforum.net/c4/iris//1a.jpg http://temp.corvetteforum.net/c4/iris//1.jpg Thanks |
Brian,
I was looking for similar info about a year ago while building the C4 suspension mounts on my '69 frame. I ended up doing what looks good to me, measurement-wise, and making most of the pickup points adjustable or replaceable (I put the front A-arm mounts inside the A-arms, allowing me to put about 10* of negative camber in if I wanted to do something that silly.) I can also change the anti-dive and roll center numbers without a lot of the secondary effects that happen when the mounts are fixed in only one spot or plane. I didn't know precisely what a big block car with a C4 suspension would want for geometry specs, so I made them adjustable or replaceable. Keep us updated on your info search. :thumbs: |
I figured you would have these, but if not....
The original "marketing" CAD drawings of the 1984. These show in corvette picturebooks, as overhead slides the marketing guy's would show. How accurate to scale from? Don't know........ http://temp.corvetteforum.net/c4/iri...ette_side1.gif http://temp.corvetteforum.net/c4/iri...tte_frame2.gif http://temp.corvetteforum.net/c4/iri...tte_frame1.gif http://temp.corvetteforum.net/c4/iri...ette_frame.gif BTW ... I am almost sure I ran across a 3D C4 model someone had done for SusProg3D ... back then. Long time ago, but I'll see if I still have a line on it. |
C5 and C6 data you could get thru SEMA's tech transfer program, but I'm not sure what, if anything they have on the C4.
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Interesting thread! What changes do you think can be made?
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I want to get the compete stock geometry down before modifying it.
That way I can measure the stock ones and see how good my model is. 69427, WOW, I thought you bought one of the conversion frames that are available. Aardwolf, The 1st thing I want to do is fix that front geometry. The top a-arm should point up, not down at rest. So either the balljoint needs to go up or the frame side needs to go down, or both. The second thing I want to fix is that rear geometry. The dogbones are way too short! I don't know how many here realize it, but GM actually ripped off Dick Guldstrand's rear suspension design for the C3 when they built the C4. The trouble is the bean counters got a hold of it and messed it up in the process! Take a look at the dogbones, they run all the way to the back of the upright, thus making them at least twice as long. Also instead of a toelink, he has two beafy locating members spaced equally apart and on the same plane. http://www.guldstrand.com/ProdImages...Suspension.jpg I might acually just buy his upright and adapt them to the C4. Not only would I get the better geometry, but I'd get the beefier drivetrain, and cheaper bearings. BTW does anyone have the front pic to go with this one? I used to have it but now I can't find it :( http://i242.photobucket.com/albums/f...am/rearend.jpg |
Originally Posted by BrianCunningham
(Post 1563504064)
I want to get the compete stock geometry down before modifying it.
That way I can measure the stock ones and see how good my model is. 69427, WOW, I thought you bought one of the conversion frames that are available. Aardwolf, The 1st thing I want to do is fix that front geometry. The top a-arm should point up, not down at rest. So either the balljoint needs to go up or the frame side needs to go down, or both. The second thing I want to fix is that rear geometry. The dogbones are way too short! I don't know how many here realize it, but GM actually ripped off Dick Guldstrand's rear suspension design for the C3 when they built the C4. The trouble is the bean counters got a hold of it and messed it up in the process! Take a look at the dogbones, they run all the way to the back of the upright, thus making them at least twice as long. Also instead of a toelink, he has two beafy locating members spaced equally apart and on the same plane. http://www.guldstrand.com/ProdImages...Suspension.jpg I might acually just buy his upright and adapt them to the C4. Not only would I get the better geometry, but I'd get the beefier drivetrain, and cheaper bearings. BTW does anyone have the front pic to go with this one? I used to have it but now I can't find it :( http://i242.photobucket.com/albums/f...am/rearend.jpg Thanks Frank |
Done right I can keep the rear caster the same.
What I'm really after is less fore & aft movement of the tire as it moves up and down. Right now as the inside tire compress it move back quite a bit, and the outside tire moves forward. Here's a rough idea, of course when I'm done with the front I'll need to change the roll axis. http://i242.photobucket.com/albums/f...r_dogbones.jpg |
Brian,
I have C3 (rear) and C5 (front and rear) modeled in Catia V5 but no C4. Download and install the functional demo of Performance Trends Suspsension Analyzer. I know for sure that it comes with all of the C5 points and it may also have C4. |
Originally Posted by BrianCunningham
(Post 1563504064)
.....................
69427, WOW, I thought you bought one of the conversion frames that are available. ......... |
For anyone interested in the C5 suspension points, here's an Excel sheet that I put together a while back.
Right Click -> Save As -Matt |
1st crack at the C4's frame.
This doen't need to be the that accurate, so long as the suspension pick-up points are. It's more for reference. GM's http://i242.photobucket.com/albums/f...bs/chassis.jpg Mine http://i242.photobucket.com/albums/f...s/C4_frame.jpg
Originally Posted by Scooter70
(Post 1563531779)
Brian,
I have C3 (rear) and C5 (front and rear) modeled in Catia V5 but no C4. Download and install the functional demo of Performance Trends Suspsension Analyzer. I know for sure that it comes with all of the C5 points and it may also have C4. Thanks, I'll drop them an email. |
Originally Posted by fmrfast
(Post 1563487926)
Hi Brian,
Yes, a stock c4 when at rest the upper arms are pointed slightly down (negative camber loss under initial compression :ack: ) also if you look at the cross shaft on the upper "A" arm it is on an upward angle higer in the front then the rear. Anti dive When the suspension is initially compressed you loose camber until you compress it enough to get past the center line, parallel to the ground,(which may never happen in stock trim) only then can you get negative camber gain. Interesting geometry!!! Just rambling Have fun |
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