Chassis design finished
So, after countless revisions, I've finally got the chassis layed out on graph paper acurately enough to start cutting metal. What I've come up with so far:
-Chassis width: 46"
-Chassis height: 15"
-Overall length:140"
-Wheelbase: 109"
-Designed ground clearance 5" front to rear
-Engine bay length: 28"
-Passenger compartment length: 64"
-Toe width: 13.5"
-Tunnel width: 10" front, 8" rear
These dimensions reflect the latest round of tape measure action and the intended purpose for this car. I plan on using this chassis as a test mule for various engine and transmission options, to dial them in with easy access prior to installing them into their final destinations. As a result, the engine bay and tranny tunnel need to be big enough to swallow the biggest motors I intend to test, which in this case dictate a minimum length of 28" front to back for a Supra inline-6 and a width at the valve covers of 22" for a small block Chevy or Ford. Also equally important is the toe width, as my big ole' clod hoppers are 5.5" wide, which means 13.5" is absolute minimum, and that only works with a 1" wide gas pedal 1" off the tunnel. The book chassis would never allow for that kind of foot room.
Currently I'm trying to decide if I want to tackle digitization of the chassis drawings. I've got a couple of CAD programs, but I could fire up the T-square and have the tri-view and isometrics done in 1/10th of the time, then just scan in the results. Perhaps I'll get the hang of one of these programs yet. After I get back to the real computer and scanner, I'll post the graph paper sketches for perusal. Real drawings perhaps to follow later on.
I think, based on a rough tally of the weights of the metal tubing and some guestimation as to how much filler I'm going to use that the bare tube chassis will probably be in the 175-200# range. This seems a bit on the high side for a Locost, but there will be some weight savings with the IRS, and I never really believed the 35# claim in the book anyway; I think he meant 35kg. Square 14ga 1" tubing is nearly 1lb/ft, and there is clearly more than 35' in the basic book chasis.
I did stumble into one feature falling out of my chassis changes: The top and bottom rails will be parallel and directly above each other almost the entire length of the vehicle This means no curved wrap-around on the bottom of the front, which I think should make assembly quicker and cleaner. This only really works because the increased track width in the front will require longer control arms. That also means as long as I keep the tire diameter in the front under 23" I can actually improve on the turning radious over the book chassis by being able to turn the wheels quite a bit further before they hit the body. Even with the overall increase in length, assuming similar slip angles and Opel Ackerman angles I should be able to park this thing more easily than a book chassis. I'd call that improvement all-around.
-Chassis width: 46"
-Chassis height: 15"
-Overall length:140"
-Wheelbase: 109"
-Designed ground clearance 5" front to rear
-Engine bay length: 28"
-Passenger compartment length: 64"
-Toe width: 13.5"
-Tunnel width: 10" front, 8" rear
These dimensions reflect the latest round of tape measure action and the intended purpose for this car. I plan on using this chassis as a test mule for various engine and transmission options, to dial them in with easy access prior to installing them into their final destinations. As a result, the engine bay and tranny tunnel need to be big enough to swallow the biggest motors I intend to test, which in this case dictate a minimum length of 28" front to back for a Supra inline-6 and a width at the valve covers of 22" for a small block Chevy or Ford. Also equally important is the toe width, as my big ole' clod hoppers are 5.5" wide, which means 13.5" is absolute minimum, and that only works with a 1" wide gas pedal 1" off the tunnel. The book chassis would never allow for that kind of foot room.
Currently I'm trying to decide if I want to tackle digitization of the chassis drawings. I've got a couple of CAD programs, but I could fire up the T-square and have the tri-view and isometrics done in 1/10th of the time, then just scan in the results. Perhaps I'll get the hang of one of these programs yet. After I get back to the real computer and scanner, I'll post the graph paper sketches for perusal. Real drawings perhaps to follow later on.
I think, based on a rough tally of the weights of the metal tubing and some guestimation as to how much filler I'm going to use that the bare tube chassis will probably be in the 175-200# range. This seems a bit on the high side for a Locost, but there will be some weight savings with the IRS, and I never really believed the 35# claim in the book anyway; I think he meant 35kg. Square 14ga 1" tubing is nearly 1lb/ft, and there is clearly more than 35' in the basic book chasis.
I did stumble into one feature falling out of my chassis changes: The top and bottom rails will be parallel and directly above each other almost the entire length of the vehicle This means no curved wrap-around on the bottom of the front, which I think should make assembly quicker and cleaner. This only really works because the increased track width in the front will require longer control arms. That also means as long as I keep the tire diameter in the front under 23" I can actually improve on the turning radious over the book chassis by being able to turn the wheels quite a bit further before they hit the body. Even with the overall increase in length, assuming similar slip angles and Opel Ackerman angles I should be able to park this thing more easily than a book chassis. I'd call that improvement all-around.
posted by Stephen at 4:15 PM
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