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Learning how to build Lotus Seven replicas...together!
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PostPosted: April 24, 2020, 12:32 pm 
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I have been wanting to jump in on this for a couple years and my current project is winding down (cargo sprinter van to dirtbike hauler/rv lite conversion), but I have a few questions/thoughts. This may be stream of concousness rambling with a few direct q's interspersed.

How much do you need to have planned out in advance before building? large component related

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 have a couple T5 transmissions.

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.

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.

To shorten a v8, what is the real risk of cutting the oil pan shallower? is it mainly over heating, running out in the sump at high rpm hot oil when the pump is at max flow, sucking air while cornering?

I am pondering some hybrid wet/dry sump with just two pumps circulating to a remote reservoir.


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PostPosted: April 24, 2020, 1:18 pm 
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Joined: April 23, 2006, 8:26 pm
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Quote:
How much do you need to have planned out in advance before building? large component related

The more the better. You are the biggest component, so start drawing there. The engine/transmission is second, so you need that before the build (and even design) starts, followed by the gas tank.

Quote:
what is the real risk of cutting the oil pan shallower? is it mainly over heating, running out in the sump at high rpm hot oil when the pump is at max flow, sucking air while cornering?

Sucking air in the corners.

Increasing ground clearance by cutting down the pan works, to a point. Other people add an extra quart of oil, that works as well, to a point. Keep in mind though that often, the transmission bellhousing hangs down as low as the oil pan, so cutting the pan shorter doesn't necessarily gain you ground clearance.

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Last edited by KB58 on April 24, 2020, 3:54 pm, edited 1 time in total.

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PostPosted: April 24, 2020, 1:30 pm 
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Joined: January 11, 2017, 11:06 pm
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Location: Alberta
I used SN95 spindles in my build. You can get upper balljoint adapters that bolt in where the strut went. They are often used for Cobra kits and SLA conversions on the mustangs. Your front track should ideally be a little wider than rear, but whether that matters to you depends on what you want to do with it. If you really wanted to, you could size the chassis to match the rear axle. But if it's an 8.8 that's going to be pretty damn heavy on a Locost. On my book build I used a narrowed 7.5 from a Ranger and converted it to use SN95 rear disc brakes.


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PostPosted: April 24, 2020, 1:32 pm 
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Location: central Arkansas
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.


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PostPosted: April 24, 2020, 6:22 pm 
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Joined: April 3, 2020, 7:37 pm
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tremendous help all around! I feel better already knowing that all these problems have been previously solved, just need to piece the puzzle together

I will get the big parts laid out on the bench and see how i fit in


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PostPosted: May 3, 2020, 3:52 pm 
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Joined: August 2, 2009, 3:34 pm
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If you go the 302 option, it's an easy fit in the engine bay once the accessories have been reomved.

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PostPosted: May 3, 2020, 4:20 pm 
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Trochu wrote:
If you go the 302 option, it's an easy fit in the engine bay once the accessories have been reomved.


thanks ive been searching for donors lately

book or + frame?


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PostPosted: May 3, 2020, 9:52 pm 
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cianpdx wrote:
Trochu wrote:
If you go the 302 option, it's an easy fit in the engine bay once the accessories have been reomved.


thanks ive been searching for donors lately

book or + frame?


I went 442E, just for more footroom and it's way easier to find seats that fit. Not required, but I also went 1.25" 16 gauge bar for the frame.

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PostPosted: May 15, 2020, 6:19 pm 
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Joined: April 3, 2020, 7:37 pm
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OK one more item

I've got two donors

2000 explorer
1994 mustang (no engine)

plan is

engine - explorer 5.0 (need mustang oil pan)
trans - mustang (was V6, so I need some combo of bellhousing, flywheel, clutch)
rear end - mustang (prefer the 7.5 so it is centered. I can always drop in an LSD Later)

I'm hung up on the front suspension, seems logical to take it all off the mustang and get the sn95 adaptors. While expensive, it seems cheaper than getting new spindles, brakes, hubs etc etc for a new setup. what do you think? The explorer uprights will be way too big and heavy right?

Anything else I should pull from the donors? I'll measure the steering racks too.


mustang front setup would be something like this

https://www.speedwaymotors.com/Mustang- ... u=91031944

https://www.amazon.com/Mustang-II-Stock ... B01N9VS0FX


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PostPosted: May 15, 2020, 8:24 pm 
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Joined: July 17, 2008, 9:11 am
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Here is a starting list. Many will need to be modified. I probably left off a lot of tings. YMMV depending on your goals.


-Engine
-Alternator
-Water Pump
-Distributor
-Ignition Coil
-All engine sensors (for ecu)
-Starter and Starter Solenoid
-Intake and Intake plenum flex tubing
-Exhaust Manifold & Exhaust Pipe and Silencer
-Transmission
-Drive Shaft
-Rear axel assembly incl. sub-frame
-Front hub assembly including brakes
-Wheels including tires and lug nuts

-Radiator and Hoses
-Oil cooler and hoses

-Battery and Cables
-Wiring Loom
-Fuse Box(es)
-Flasher unit for signals (and emergency)
-Horn and Horn relay
-All electronic control modules
-Ignition keys

-Fuel Tank sender unit
-Fuel pump
-Fuel Filter

-Master cylinder, brake and clutch
-Clutch, Brake, accelerator pedal Assembly including cables & brake light switch

-Handbrake lever, mounting brackets and cables

-Windshield wiper motor and mechanics
-Windshield washer system
-Heater and fan unit and controls

-Steering rack including all mounting clamps, track rod and swivel joints
-Steering column w/ electronics and controls & Steering wheel
-Steering shaft(s)
-Instrument cluster
-Speedometer cable
-Bucket seats & Seat belts

-Door/trunk lock assy
-Hood / trunk latch assy
-Door latch assy


You cannot save too much until you are done with the build. Here was my starting pile from my donor. It does not show everything I got nor does it include all the above listed parts.
Image

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PostPosted: June 8, 2020, 7:57 pm 
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Joined: June 13, 2014, 11:55 am
Posts: 88
I would add ECU.
Cheaper thangoing aftermarket.
HTH
AA


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