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Learning how to build Lotus Seven replicas...together!
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 Post subject: Re:
PostPosted: June 28, 2022, 12:30 am 
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Miatav8,MstrASE,A&P,F wrote:
I don't think I answered your question though.

Consider the extra weight to be like towing a trailer.

I will assume the bike weighs 380 lbs, requires 92 octane, and is tuned to carry two 180 lb people without detonation under most conditions.

The design weight (gross) would be 740 lbs.

The locost will be 1180 lbs which is 1.59 times the design weight, a 59% increase. If you decide to have a passenger later, with two people onboard, it would be 1360 lbs and 1.84 times the design weight, a 84% increase.

A single occupant in a 1000 lb locost is equivalent to two R1 riders towing a 440 lbs trailer.

Two occupants in a 1000 lb locost is equiv to two R1 riders towing a 620 lb trailer.

If the bike will not detonate at gross on less than 92 octane, then there is a buffer and the load can increase somewhat without detonation if 92 is used.

For a single occupant, a 1.59:1 gear reduction would keep the load on the engine the same as it was designed for at gross, 740 lbs.

For two occupants, the ratio would be 1.84:1.
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Now to figure out the other changes.

The tire change is decreasing the gear reduction and increasing the load, going from 24.48" to 25.04". Think of this like a wrench attached to the axle, where the wrench handle has been lengthened .28" (half the tire diameter increase). When the lever is increased, the leverage the ground has to resist the rotation of the axle increases.

The 2.41:1 chain system is replaced with a 3.70:1 diff, increasing the gear reduction and decreasing the load. This is a gear reduction increase of 1.29:1. What you really want is 1.59-1.84:1 IF the top speed is adequate, 92 octane is required stock, 92 octane is the highest octane you plan to use and there is little or no detonation buffer stock.

A 4.00:1 diff will give you 126 mph and keep loading close to stock. Durability of the bike drivetrain should be close to stock.


So this fella seems to know what he's talking about. I got the old 900RR out this spring, started hard, choke not working. But long story short, it started overheating, I wasn't going fast at all, in fact probably too slow and too high a gear and I'm thinking crappy gas started making it detonate (I should have noticed) and overheat. Problem went away after I got some new gas and added some octane boost to it. Now I'm worried a bit about my BEC!

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 Post subject: Re: R1 rear end ratio??
PostPosted: June 29, 2022, 4:40 pm 
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I wouldn't worry about it at this point in your build. You can revisit gearing or band aid with less timing and octane or ethanol. No project is every really finished. I'm just now putting a shift kit and vette servo in the v6 tracker. I bought a 4.30 diff to go in it but the 5.125:1 diff and 235-65-16 vitara rims were perfect for the 700r4.

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Miata UBJ: ES-2074R ('70s mazda pickup)
http://www.vsusp.com
ford IFS cheap viewtopic.php?f=5&t=13225&p=134742
Frame L x cockpit W x eng bay HT (w/o hood/bonnet/cowl)
Lotus Super Seven: 115 (no spare) x39x7.25
Tiger Avon: 114x40x13.3-12.6
Champion (Book): 114x42x11
Gibbs Haynes: 122x42x14
Voo Doo: 113x44x14
McSorley “442”122x46x14
Collins “241” 127x46x12


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 Post subject: Re: R1 rear end ratio??
PostPosted: August 2, 2022, 8:43 pm 
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I will be swapping my 3.90 for a 3.60 or 3.54. Highway ride sees revs that never drop out of the powerband. It's buzzy and gobbles fuel.


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 Post subject: Re: R1 rear end ratio??
PostPosted: August 23, 2022, 3:03 am 
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Location: Glendale AZ
Think I will go lower. and se if I need to go back up..

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 Post subject: Re: R1 rear end ratio??
PostPosted: August 23, 2022, 8:55 am 
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This topic has me confused, it a track only car and people are talking about highway cruising rpm! Bike trans are great for track use, a tall first gear and very close ratios for the rest. Your not going to have a lot of power, but better aerodynamics. I would try and get about 120 mph at the top of 6th gear. It should rip.

Graham


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 Post subject: Re: R1 rear end ratio??
PostPosted: August 28, 2022, 11:01 pm 
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My car hasn't seen a track yet and I've been using it locally a lot. My car is being built to suit my needs which includes highway use.

FastG wrote:
This topic has me confused, it a track only car and people are talking about highway cruising rpm! Bike trans are great for track use, a tall first gear and very close ratios for the rest. Your not going to have a lot of power, but better aerodynamics. I would try and get about 120 mph at the top of 6th gear. It should rip.

Graham


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 Post subject: Re: R1 rear end ratio??
PostPosted: August 29, 2022, 7:49 am 
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You can see my confusion when asked

"It is track only? Does it need to crawl in traffic at 3 mph? Highway cruising speed?"

The reply was

"track only"

Hmmmmm


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 Post subject: Re: R1 rear end ratio??
PostPosted: September 4, 2022, 11:25 pm 
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So I was playing around with numbers, and if you didn’t have the primary reduction and a lower redline by let’s say, half, then something closer to 4.5 rear end would work nice. In case any one was wondering, I’ve been brainstorming a Busa gearbox bolted to a Honda B16. The output shaft would spin the correct way when directly driven, it would have a flywheel and clutch. Cheap sequential, might could be cool. Or it could be the worst of both worlds, I dunno.


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 Post subject: Re: R1 rear end ratio??
PostPosted: September 5, 2022, 9:33 am 
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Sounds like a lot of work but doable.

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Miata UBJ: ES-2074R ('70s mazda pickup)
http://www.vsusp.com
ford IFS cheap viewtopic.php?f=5&t=13225&p=134742
Frame L x cockpit W x eng bay HT (w/o hood/bonnet/cowl)
Lotus Super Seven: 115 (no spare) x39x7.25
Tiger Avon: 114x40x13.3-12.6
Champion (Book): 114x42x11
Gibbs Haynes: 122x42x14
Voo Doo: 113x44x14
McSorley “442”122x46x14
Collins “241” 127x46x12


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