Rear Transaxle Se7ens

[DLW]

Thanks, escondidoron... I have been pricing out Porsche and Alfa Romeo transaxles, sketching designs for rear-suspension and transaxle areas in a McSorley 4-4-2-style space frame, and I would probably use birch plywood with memory foam bonded on and vinyl or neoprene upholstery, attached to both the floor and rear bulkhead to save space and weight, as seating.

 

Any thoughts on engines? I personally thought that the Porsche or Alfa Romeo engines would be easiest as far as bolting up, but something like a Ford 2.3 or Ford Motorsport Kent repro, a Toyota 22R or a rotary would be easier to set up since there wouldn't be any computers to deal with.

[Sevnn]

I think it is an interesting idea but wanted to warn of possible issues with the gas tank. If the transaxle is very tall you'll have a lot of engineering to get a decent sized tank to fit around it.

[Ian7]

I think it is an interesting idea but wanted to warn of possible issues with the gas tank. If the transaxle is very tall you'll have a lot of engineering to get a decent sized tank to fit around it.

 

Put an ATL fuel cell in the passenger seat location?

[David C]

For rear wheel drive the target does seem to be 40/60. Good weight on the rear wheels for acceleration and weight transfer evens it out for good braking.

 

As far as polar moment goes, my own pet theory backed up by probably no scientific fact or proven rationale goes like this: The nimble feel of a car strongly depends on its resistance to turn in. At the moment of initial turn in, the car is not rotating around its center, it is rotating around the rear tires. The rear tires don't go "out" when you turn in. Well they would if the fronts were on pavement and the rears on ice.

 

I don't think shifting the tranny to the rear axle would detract from the nimble "feel" of the car; I think it would improve. Absolute handling would be a tad lower as aside from handling the lateral acceleration, the tires would also have to rotate the car and if the polar moment were higher this would leave less grip for those lovely g's.

 

Don't forget to consider the tire/wheel sizes in your starting point. It makes a difference if they will be the same size all the way round or staggered with more footprint in the rear.

 

I knew that degree in Biology would come in handy :jester:

[slngsht]

well, the car rotates around the virtual point connecting the lines perpendicular to the front wheels and the extension of the rear axle. That results in a translation, and a rotation motion on the center of mass. So, I think you still want to minimize the polar moment around the center of mass.

[Z3 Stalker]

I would think moving the tranny to the rear means you will need to take into consideration the additional speed of the drive shaft and make sure it is built for the revs it will be doing!!!

[DLW]

During lunch and coffee breaks at work today, and cleaning up after I got home, I thought of Se7ens regularly. Some ideas I came up with:

 

Any year Alfa Romeo Alfetta/Milano/GTV6 transaxle- aluminum case, relatively inexpensive, well-engineered.

 

Alfa Romeo DOHC 2-liter four-cylinder out of Alfetta or Spyder, converted to carburetors and an Alfetta bellhousing and flywheel if Spyder engine is used- simpler than the Alfa Romeo "6C" V6, as well as more adaptable to a vintage esthetic.

 

VDO Cockpit Black gauges, Momo Prototipo steering wheel, lightweight/space-saving "seats" made of birch plywood and memory foam with neoprene upholstery and grommets for harness-type seatbelts, attached directly to rear bulkhead and floor

 

Front suspension featuring unequal-length control-arm architecture with tubular A-arms, coilover shocks and hubs from transaxle donor.

 

Minilite-replica wheels, wider in back than in front, with performance tires

 

Red paint on fiberglass fenders and nosecone to honor the Alfa Romeo(s) that would give their parts, with polished aluminum bonnet, rear panel and side panels, maybe an Alfa Romeo badge on the nose where one would find Lotus, Caterham, Westfield or Birkin badges on conventional Se7ens.

 

I've pretty much settled on an Alfa Romeo as a donor if/when I build a car, since that is one of my favorite factory-built makes and they are abundant in parts-car/donor condition due to poor build quality and rust. If this car gets built, I'll definitely put a thread with pics on this site, and if I like how it turned out, I may try something more complicated, like a III or Eleven replica or even a recreation of the first Lotus.

[BrunnyS1]

During lunch and coffee breaks at work today, and cleaning up after I got home, I thought of Se7ens regularly. Some ideas I came up with:

 

Any year Alfa Romeo Alfetta/Milano/GTV6 transaxle- aluminum case, relatively inexpensive, well-engineered.

 

Alfa Romeo DOHC 2-liter four-cylinder out of Alfetta or Spyder, converted to carburetors and an Alfetta bellhousing and flywheel if Spyder engine is used- simpler than the Alfa Romeo "6C" V6, as well as more adaptable to a vintage esthetic.

 

VDO Cockpit Black gauges, Momo Prototipo steering wheel, lightweight/space-saving "seats" made of birch plywood and memory foam with neoprene upholstery and grommets for harness-type seatbelts, attached directly to rear bulkhead and floor

 

Front suspension featuring unequal-length control-arm architecture with tubular A-arms, coilover shocks and hubs from transaxle donor.

 

Minilite-replica wheels, wider in back than in front, with performance tires

 

Red paint on fiberglass fenders and nosecone to honor the Alfa Romeo(s) that would give their parts, with polished aluminum bonnet, rear panel and side panels, maybe an Alfa Romeo badge on the nose where one would find Lotus, Caterham, Westfield or Birkin badges on conventional Se7ens.

 

I've pretty much settled on an Alfa Romeo as a donor if/when I build a car, since that is one of my favorite factory-built makes and they are abundant in parts-car/donor condition due to poor build quality and rust. If this car gets built, I'll definitely put a thread with pics on this site, and if I like how it turned out, I may try something more complicated, like a III or Eleven replica or even a recreation of the first Lotus.

 

Sorry, I just dont see it.

oh why...lol,

[Mondo]

To each their own... it would definately have a lot of people thinking "why?".

 

I'm no mechanic and haven't gotten past the reason you'd want birch plywood seats? With all this talk of weight, balance, etc... wouldn't it be better to just foam/upholster the bulkhead & floor to make the seats while your at it? Really, it would be hard to make something lighter/better than some of the seats you can buy already out there.

 

This seems more like questions of art over performance, so don't let any of us distract you from your vision.

 

Good luck.

[DLW]

The birch plywood idea was more about adding durable support to the seats without springs or frames than actually showing off the wood, but foam-padding and upholstering the rear bulkhead and doing the same with the floor, albeit with slightly thicker foam.

 

I could possibly buy some foam, neoprene or marine vinyl, a couple cans of spray-on adhesive for the cost of one large sheet of birch plywood and the saw blades needed to cut it, and if I decided that proper lower seat cushions were needed, I could get jumpseat cushions out of something like a Ford Ranger for around $5 at work. Given my size, though, I probably wouldn't need to put any kind of seat cushions in. Thinking back on colors and logos, a common Super 7 circular badge with the whole car painted BRG sounds better.

 

As for foul-weather gear, I plan to do something along the lines of that described in "Build Your Own Sports Car" by Chris Gibbs since it rains much of the year in my neck of the woods, and when I say it rains, it rains a lot. If built, this Se7en would likely replace the full-size Chevy van I drive now except for carrying more than will fit in the Se7en's passenger's seat and on long trips. Any ideas on a lightweight fabric? I intend to use copper or aluminum tube stock to construct the frames of the top and side curtains, but don't know what to use for the side-curtain windows.

 

BrunnyS1, there are many Alfa Romeos in junkyards or for sale inexpensively with good mechanical parts but awful bodies/interiors, and I would use little more than the transaxle, rear De Dion suspension, brakes, driveline and front hubs, an Alfetta bellhousing and flywheel, and the engine out of a Spyder, unless I ran across an Alfetta, in which case I'd use the engine too and not a Spyder engine with an Alfetta bellhousing and flywheel.

Edited July 28, 2010 by DLW
clarification

[BusaNostra]

Are we talking "traditional" length-width-height chassis of a 7 in this project?

[DLW]

Are we talking "traditional" length-width-height chassis of a 7 in this project?

 

No, more along the lines of a McSorley 442-style chassis.

[BusaNostra]

the reason i asked, i have a hood and nose came from the westfield.

i can let you borrow.

since its not a traditional 7 dimension, i doubt the fittings

[DLW]

the reason i asked, i have a hood and nose came from the westfield.

i can let you borrow.

since its not a traditional 7 dimension, i doubt the fittings

 

Thanks... but I don't even have the frame yet, and I may take you up on your offer if/when I build a frame or modify an existing one.