Geometry and setup

Alex Evonosky · #1 (**permalink**) 02-21-2006, 07:24 AM

Geometry and setup

fasterpatrick · #2 (**permalink**) 02-21-2006, 08:47 PM

Gangs all here; Good this one will definetly get the ball rolling. What is the hub to hub width for a car with regular lug wheels front and back my body is72" rear and 71" front.Would like to have a little dish to the wheels and don't need no tirerub. Pat

mickmate · #3 (**permalink**) 02-22-2006, 08:53 PM

Check these ones and let us know what you think track and flange to flange

Johnson · #4 (**permalink**) 02-23-2006, 09:31 PM

I say pick out your tires, wheels, spindles, and hubs, then set them under your car to give the correct fender clearance and measure the hub width. In talking with some of the wheel manufactures, the big mistake people make is to build the car, then try to find a wheel to fit. How much easier is it to pick out your wheels & tires, then build your car to fit them?

fasterpatrick · #5 (**permalink**) 02-23-2006, 09:45 PM

Ya exactly what I was thinking. I have shortend axels from ffr (with lugs) don,t realy want pin drive. but there is plenty of room in the plunge join to move around a bit.

Alex Evonosky · #6 (**permalink**) 02-24-2006, 06:16 AM

I think Johnson is on the right track.
Sometimes, we are so anxious to get started welding, we don't take the time think far enough ahead.
It is like anything else, build from the known measurements:
Body width.
Expected tire size.
Ride height you decided on.
Anti dive angle
Type of suspension, MII, Corvette, BMW,
Also, don,t forget the rear at the sametime you are working on the front.
At this time I purchased the MII Spindles and made temp. brackets to hold them in place while I finished figuring out the actual IC, RC, steering rack placement, upper and lower control PU ponts,
Fab brackets, and tack weld together as you go.
grind off some tack welds re fab different brackets. LOL
Anyway, build from the sides in and bottom up to meet your IC and RC expectations.
Lots to consider and stay on top of.
Of course, all of this is probably easy if you are using a computer program to help you. For me, no program.

Thank you,

fasterpatrick · #7 (**permalink**) 02-24-2006, 07:30 PM

Well, I'm happy that I'm looking at the chassis design from the right angle all four corners in place working toward the middle. Thats where I'm at now, figure tire width, backspace, rotor, hub, and knukle.[IMG]

[/IMG]Will be ordering the front end parts next week, will get them on the jig ASAP. I too prefer to work freehand with computer asist, have and old 2d cad/drafting program to help work out the bugs.

grumpy · #8 (**permalink**) 02-25-2006, 05:57 AM

FP,

Yea, old cad software???, that's probably AutoCAD2000, LOL. I still have my docs and program of ACAD 2.62, now there's a challenge fo the non hun'n'pick gang! Have a stack of BETA (original) pre 1.00 with printed XEROX labeled 360 floppies from the tiny little offices they had in 1980.

If I had just bought the stock, instead of buying the danged $1140 CAD package in the early 80's. Brings back the $6850 IBM PC costs, green screen oldies and memories.

grumpy

Dominik · #9 (**permalink**) 03-26-2006, 02:50 AM

johnson is right,

get your wheel and tire combination first and then look at your control arm lenghts.

however, you want to keep an eye on scrub radius, which is the distance from center of the tire to the line drawn from the upper balljoint through the lower onto the ground.

keep it as small as possible, but you will realise soon that it won't happen if you use a wheel with a decent backspacing to make it look right.

play with the KPI (king pin inclinateion) to get some improvement, but don't go overboard with the angle. 5 degrees is good, 10 possible, but preferably 5 to 7.

the 427's is 2 5/8".

cheers,

dominik

joey_hv · #10 (**permalink**) 12-13-2006, 08:16 AM

reading all these posts from guys that have been where I'm at now..feel like I stole the answer sheet to the exam

awsome info guys, you rock!

scratchbuilders rule!!

fasterpatrick · #11 (**permalink**) 12-13-2006, 09:08 PM

Answer Sheet! Darn And to think I spent way to long studying for this. Here are my Notes.

"When this is finished I'm going to have a notebook burning party. Any group of words that can cause relatively normal heads to spin like this stuff can, should be illegal." This test is harder than an Ivy league college entrance exam, I never took one either. Patrick

treblig · #12 (**permalink**) 07-10-2008, 08:34 PM

F/P
on the road yet!

Larry Spillman · #13 (**permalink**) 01-25-2010, 02:03 PM

If you do make a mistake you can remove rearend have tubes cut or replaced axels shortened and re install its costly but better than searching rearends that wont fit or dont exiist,A lincoln versilles rear end with disc brakes will fit under a 427 bodied car.

Danielg · #14 (**permalink**) 03-29-2011, 09:45 PM

Hey, what do you guy's think? I started this years, 15 or so, ago. It kind of falls into what your discussing, kind of. It's my design, obviously based on a contemporary chassis. factory cobra track front and rear with Halibrand wheels reverse engineered to have the exact measuremnt. Maintained factory 91-92 corvette geometry as to not screw up GM billion in R&D. Rear modifed geometry slightly to eliminate factory "jacking" charactoristics. X-BRACE added in design to increase torsional rigidity. FE engine mounts custom made, factory Contemporary position. Custom sweet Mfg steering rack, for optimum bump steer settings. Carrera coil overs.
All round tube, tig welded 4130N chromemoly. the frame is not finished.

Life has changed, I know have a factory coil over frame. I built this chromemoly one to race. Life changed, I don't need a race car cobra now. I was going to build a second car for my Dad and with him, kind of a hot rod project , which is why its hanging on the wall for storage.
Here's the bummer. I'm thinking of selling it. As of recent I realize I will not be able to do this project with my Father , last week he was diagnosed with cancer. He say's to me sell the damn thing, lets finsih the one so I can drive it. So, here I am. sell it, do what he ssays, build the one as fast as possible?
Daniel

Three Peaks · #15 (**permalink**) 03-29-2011, 09:57 PM

Sorry to hear about your dad, I hope he can get into a successful treatment and you two will have plenty of time to enjoy the Cobra together.

How much are you asking for the chassis and where are you located? Nice looking chassis, did you have any further design drawings or ideas on where it would progress to next? Which body is it designed around?
Bob

Danielg · #16 (**permalink**) 03-29-2011, 10:24 PM

Bob,
thanks, hopefully he'll have many years. reality is that he will be effected.
Regarding the frame, it's based on using a contemprorary cobra body. however it will work on many, such as unique, midstates, era etc.
the engineering is done. the frame needs no more design, less brake line position. it needs to be finish welded. rear end elevation to be determined based on tire choice, ie diameter. right know it is set for 295/50/15.
Price, never thought much about it. The suspension came off a car that had less than 5k on it. I bought the suspension in about 1992
I live in spokane washington.
Daniel