cianpdx wrote:
How much do you need to have planned out in advance before building? large component related
You need to decide on the frame width. That's the minimum width seats you can comfortably sit in, driveshaft tunnel width, and transmission width, which determines the footwell width, which is dependent on how much room you need to operate the pedals.
I built a 7 with a 302/T5. The main case of the T5 is big and blocky; even setting the driveline over to the passenger side an inch, it was still very tight in the footwell.
I bought a couple of sheets of plywood to build a mockup of the cockpit. It was probably the best $30 I ever spent; it certainly saved a bunch of guesswork, and probably prevented me from welding myself into a hole.
Once you've orbited about the above and settled on a frame width, you then take your rear axle, mount the wheels, and measure the inside-to-inside space between the tires. You need, theoretically, about an inch of space between the inside of the tire and the outside of the frame. In practice, the top of the tire moves closer to the chassis on bump, the locating linkage can skew the rear as it moves, and under side load, the entire tire carcass can flex sideways. An inch and a half might not be excessive. It's one of those guesswork things.
If the tire gap and chassis are copactic, you're good to go. If it's too narrow, you can run spacers or different wheels. If it's giving you more than 1-1/2" per side, you could make the chassis wider; that directly affects driving comfort.
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I have a SN95 mustang without an engine that I can take whatever I need. It is left over from a lucky dog race car build 3 years ago. I am guessing the knuckles are no good becuase it uses strut front suspension. Steering column good. Rack too wide?
I used an '86 donor; the rack worked with the inner A-arm pivots adjusted to compensate. You'll have to design your own A-arm geometry around the rack width. You can spend a lot of time chasing your tail with front end geometry, but in practice as long as you avoid bump steer and crazy camber change, the range of "acceptable" is so wide you would have to work hard to go badly wrong. Making the lower arm horizontal is a fair compromise of geometries. There are several companies that sell bolt-on upper control arm brackets for the SN95 spindles (look at Cobra kit vendors); that sets your kingpin inclination, spindle height, and upper ball joint location. So the only things you need to fiddle with are the upper control arm angle and length, and the length is already set by the bump steer geometry. (inner pivots must line up with rack ball joints)
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For the engine I have some attachment to the 302 from my lucky dog car. But also think a 4 cyl would be easy to integrate and more true to the roots. Then again a toyota v8 would be awesome too, but DOHC with variable valves would be really tall.
Options, options... your main constraint there will be transmission availability and size. I ground off some of the projecting fins and knobs and hammer-formed side panels to get about 1/4" of clearance for the T5 I used. Might not be an issue with a different model T5, your chassis width, and your space requirements.
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If I go v8 probably will go with oversized frame, i am also 6' 4" and have big feet. Will the sn95 axle be too wide? Any concerns with the front track being a few inches narrower? I am guessing it could be accomodated by the a-arms, but I don't want it to look out of proportion.
Several guys here have used the SN95 rear; a keyword search will turn them up. You can make the front track anything you want by adjusting tierod length. Generally, a narrow front track will promote understeer. Most people favor same track at both ends, or wider in front.
I built mine in 2001, using Ron Champion's book and some Lotus drawings I found on the web. I adjusted the chassis width to fit me and the rear I was using (modified Nissan IRS), but it never occurred to me that I could have made the chassis and scuttle taller. Using Champion's dimensions, the distributor was above the hood line and stock valve covers barely fit. Not an issue if you don't mind a hole in the hood or plan on running a bulge or scoop, but if you want everything tucked in under the hood you're going to have to do more engine/induction juggling.
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To shorten a v8, what is the real risk of cutting the oil pan shallower?
The "double hump" Ford pans are already shallow enough that the bottom of the bellhousing is your lowest point. For other engines, you can cut an inch or two off the bottom of the pan without hurting much; the Gibbs book recommends that to get the OHC Pinto engine mostly under the hood. (carburetor still sticks out...)
I, personally, have not had great luck cutting oil pans and making them oil-tight afterward. The professionals I took various pans to later didn't do any better. This has been a complete non-issue for most people...
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I am pondering some hybrid wet/dry sump with just two pumps circulating to a remote reservoir.
You'd still probably wind up having to find a smaller clutch and bellhousing, and lots of transmissions are fat-bellied enough to hang pretty low, too. Used dry sump bits are cheap enough on eBay, but I suggest you bolt all the driveline bits together on the floor and look at where your potential problem areas are.
Almost all carbureted RWD engines have the intake manifold cut at an angle so the carb sits level while the tailshaft points down between 2.5 and 5 degrees; this was done to minimize transmission hump and driveshaft tunnel space. Not an issue on injection manifolds or FWD stuff. Offenhauser and others make "carb wedges" to set the carburetor level if the engine is installed level, which is done for some marine installations. You can tune the carb to work properly at a tilt, but the wedges (or re-machining the manifold) simplifies things.
Whatever driveline you use, consider how you're going to get it in and out, how you're going to access the bolts and speedometer cable (if needed), and how you're going to get the driveshaft out. Some builders figure it's rare enough not to be an issue, and they might have to pull the engine and transmission to replace a U-joint. Others are more maintenance-minded, and want to be able to remove any part separately. No "best" way here, other than not being surprised down the road or building yourself into a hole.