Lotus 7 / Locost Pics & Builds

I spent a few years around FSAE cars and I can imagine a BEC Locost would have to tackle very similar issues.

Since cars don't lean like bikes, you will need to figure out how to keep oil from sloshing away from the pick-up and the engine from losing pressure. Its probably due to the tight tolerances and RPMs but bike engines do not seem very tolerant to oil starvation. It doesn't matter how you do it but it needs to be done if the car will be driven hard and what needs done is going to be dependent on the engine model.

The second issue is shifting - dog boxes are a different animal to shift (no pun intended). You need to be firm and intentional but not abusive. We had a couple of bent shift forks and rounded dog teeth from people either forcing it into gear or the shifter relying on the transmission lever's return spring to return it to the neutral position. The fix was learning how the box feels and adding a few springs to the shift lever to help it return to center.

My car currently has around 5k miles and the only big failure was from 10" slicks tearing apart a 25 year old differential bushing. I think a BEC could be just as durable if it is sorted out. If I ever talk myself into building another one, it will probably be a BEC.

Flight Service wrote: I have never understood the "let's cut up a sports car to make an old looking sports car!" A Miata donor for a Locost (other than a specific class build) seems idiotic to me. You have a sports car, but you want a sports car?

I cringe a little when I see a decent looking/running Miata getting turned into a Locost but the two cars provide such significantly different driving experiences that I don't think its fair to say you are turning a sports car into a sports car. Both cars being convertibles is the only similarity between the driving experiences.

11 degrees, I think. Mostly, it's an artifact of the lens near the side of the image.

See that dust? That's a set of RA1s burning off Larry Webster was doing "skidpad testing", he was just lapping around and around like this.

Has anyone ever tried a Goldwing engine & gearbox in a BEC or locost? I know they're not as glamours as 'busa engines, but they are by no means weak, and they have reverse.

HappyAndy wrote: Has anyone ever tried a Goldwing engine & gearbox in a BEC or locost? I know they're not as glamours as 'busa engines, but they are by no means weak, and they have reverse.

good thought! It turns out it has been discussed before:
http://www.locostusa.com/forums/viewtopic.php?f=4&t=15343
http://www.locostusa.com/forums/viewtopic.php?f=5&t=1077
http://www.locostusa.com/forums/viewtopic.php?f=10&t=1077&start=15

atm92484 wrote:

Flight Service wrote: I have never understood the "let's cut up a sports car to make an old looking sports car!" A Miata donor for a Locost (other than a specific class build) seems idiotic to me. You have a sports car, but you want a sports car?

I cringe a little when I see a decent looking/running Miata getting turned into a Locost but the two cars provide such significantly different driving experiences that I don't think its fair to say you are turning a sports car into a sports car. Both cars being convertibles is the only similarity between the driving experiences.

Both are sports cars and both are very different driving experiences. I just don't see why I would waste my time with the Miata. I see the compact pickup conversion or the the original family sedan conversion. I just don't get the sports car one. Now if I had one wrecked and just laying around, it would be something to do....

Flight Service, you left out "rusty old station wagon", that was my donor choice.

I see your logic but I think the issue boils down to performance. If you want to just cruise, 60-80 hp (or less) will be perfectly adequate and it will be a pretty fun car. Suzuki 3 cylinders seem like pretty appealing options for this goal.

If you want more power for autocrossing or track days, the Miata engine is easy since you don't have to fiddle with making an engine mate to a random transmission then find a clutch, flywheel, and starter that will work. Plus the donor has dual a-arms on all four corners so even the suspension pieces are well suited to the Locost.

If I ever do another one it will probably have a solid rear axle or at most a DeDion. I would be interested to see how the car's dynamics change not having an IRS.

Based on the behavior of my 2400 lb MG* with a solid axle, don't waste your time. It's best to think of unsprung weight as a percentage of total weight, and solid axles are heavy. DeDion, that might be interesting. It's either the best of both worlds or the worst of both

(*) before you all start, said MG has no MG suspension parts underneath. The front half is a Miata. I am comparing it to a car of the same front suspension design, overall weight, chassis rigidity and weight distribution.

I like the Idea of De-deons for Lotus 7 type cars. The typical solid axle approaches 15-20% unsprung weight (Axle and Rims/tires) very easily and does not typically have adjustable camber/toe (Without resorting the hot wrench). You can reduce the unsprung weight by about half, gain adjustable camber/toe and still have a suspension that works well with the original chassis layout of the Seven. If I ever build one it's the route I'm going.

nocones wrote: I like the Idea of De-deons for Lotus 7 type cars. The typical solid axle approaches 15-20% unsprung weight (Axle and Rims/tires) very easily and does not typically have adjustable camber/toe (Without resorting the hot wrench). You can reduce the unsprung weight by about half, gain adjustable camber/toe and still have a suspension that works well with the original chassis layout of the Seven. If I ever build one it's the route I'm going.

My brother's Super Stalker has a 150 lb. axle, along with heavy wheels and tires, for probably around 28% unsprung weight at the back. Hitting a bump in it is downright painful, while hitting the same bump in a mid-engine car with IRS, you could hardly feel it.

A straight axle car can be just as fast as an IRS car on a smooth track, but on public streets, IRS or de Dion is far more comfortable.

I have only one data point regarding putting a sportbike engine in a Locost, getting a ride in a Hayabusa-powered Locost:

1. It's hard to smoothly engage the clutch. The owner, who'd had it a couple years, still stalled it several times.

2. 70 mph on the freeway = 6000 rpm, which I grew tired of in a hurry.

3. Due to the lack of a flywheel, the drivetrain got into a strange oscillation, where unless the driver was either accelerating or decelerating, the car would start this slight bucking back and forth, as if his foot had a regular twitch.

4. For all the noise, it wasn't any faster than a car engine. The 200 hp is generated with high rpm, which takes time to achieve, so it doesn't have much bottom end.

5. No reverse.

That said, for the track, I can't think of anything better. Light weight, sequential gearbox, high-reving. But for the street, no thanks, but that's just me.

Even though the Locost based sports car* I'm building is being designed around IRS, the idea of a DeDion is very appealing to me as well. I guess am in the camp that mostly considers it the "best of both worlds" more than the "worst of both worlds"...Although, as with any suspension design, it's certainly not perfect and there are still plenty of compromises that must be made.

Damn...Now I have to talk myself out of a DeDion, all over again. Thanks a lot!

*No sports cars have been, or will be, harmed in the making of this sports car...Not even wrecked ones.

It's worth pointing out that Caterham has been using DeDions for years. They seem to work okay, although I believe there's heavy wear at the pivot bushing where the axle tube (if that's the right term) connects to the frame.

kb58 wrote: I have only one data point regarding putting a sportbike engine in a Locost, getting a ride in a Hayabusa-powered Locost: 1. It's hard to smoothly engage the clutch. The owner, who'd had it a couple years, still stalled it several times. 2. 70 mph on the freeway = 6000 rpm, which I grew tired of in a hurry. 3. Due to the lack of a flywheel, the drivetrain got into a strange oscillation, where unless the driver was either accelerating or decelerating, the car would start this slight bucking back and forth, as if his foot had a regular twitch. 4. For all the noise, it wasn't any faster than a car engine. The 200 hp is generated with high rpm, which takes time to achieve, so it doesn't have much bottom end. 4. No reverse. That said, for the *track*, I can't think of anything better. Light weight, sequential gearbox, high-reving. But for the street, no thanks, but that's just me.

The clutch modulation issue is actually a design flaw of the hayabusa, the clutch is on a centrifugal setup that increases plate pressure as rpms rise to make for light lever but good holding strength. It makes it really easy to stall when blipping as the clutch is released, because the blip effectively drops the clutch without you changing pedal at all. There is a fix. Here it is:

http://www.brocksperformance.com/Ultra-Light-Billet-Clutch-Mod+I270461+C29.aspx