Christopher smith

I have wondered for some time about S1 vs. S2 frame design. I think the photos last night clear that up. Thanks. I had read in a couple of places that Lotus decided that the S1 frame was more complex than necessary and started to remove tubes. Looks like the 3/4 inch round diagonals that triangulate the frame next to the S1 driver's ( and passenger's) upper and also lower leg areas were removed. Apparently Lotus thought the stressed inner skins in those areas compensated but I also heard that not everyone agreed--- something about rigidity? Perhaps they were looking at the very complex T61 "birdcage" Maserati being built at that time and decided to go the opposite direction.

I can send the "SCCA approved" Lotus drawing of the front frame area modifications. I assume some of our very racers in the USA found that cornering loads with wide slicks cracked the front frame members when way more than design loads were applied. They consist of 4 tube diagonals nicely placed as 3/4 inch round tubing. Pretty easy with the bare frame. I also added a couple more since my Series 1 was designed with a stressed member full floor pan all the way from the very back up and around the engine bay with appropriate cut outs below the diff and oil pan areas. I opted for a shorter floor pan similar to Series 2 (nothing in the engine bay) with higher strength aluminium for most but a 2024 stainless steel section across under the driver/passenger butt area. Highest strength aircraft "Cherry" rivets used throughout. By the way, Aircraft Spruce is a great place to find strong bolts and many other items and I would guess paint primer suited to aluminium.

Sure sounds like you are going through quite a decision process, much like mine years ago when I imported my 1959 Series 1 that already had fiberglass clamshells and nose but no rear wings, petrol tank, engine or trans. Otherwise pretty stock. Series 1 had Sprite type rears and those tiny drum brakes up front that I replaced with Triumph GT6 discs. My 1500 Cortina GT motor was a tight fit particularly because the previous owner in the UK had trashed the unusual 1300 Alfa twincam and trans but wanted to go Ford power and welded in a mounting structure. I just developed a leak in my concentric slave cylinder so this should be fun fixing. Good luck with your project.

Graham- great insight and advice- thanks from all of us with concentric clutch actuation.

Thanks all---That bleeding advice sounds good. A few sessions of that vs. pulling the engine to change a cylinder? Seems like a good trade.Wondering how crap could migrate up to the master cylinder reservoir but I am only a chemist, not a hydraulic engineer.

Just a thought on that transmission choice for your build. I had a couple of Cortina boxes but beyond repair, so I coupled a Pinto box to my pre-crossflow 1500. I used a concentric slave cylinder and that just failed last week. It is 7 years old but few miles and no real abuse. I noticed clutch fluid in the Tilton master cylinder reservoir got pretty black and the next day all the fluid leaked out of the concentric unit. Perhaps rubber particles from he master caused the slave to fail? Now I am faced with quite an extensive job getting the new cylinder in place as everything is a very tight fit. Perhaps I should have worked out a different clutch actuation at the start but have a new concentric coming and I guess a new Tilton master cylinder will be necessary. Hope you have better luck.

A call to Dave Bean might give you the answer.

My local airport seemed quite happy to sell me 100LL. No alcohol and some lead so works in older planes. Expensive, but not as much as race fuel that has way more octane than I actually need.

Joe7- for sure RHD is fine. I learned to drive with my brother's 1949 MG-TC and now with my series 1 7 it is even narrower, so no problems if you follow the curb line (or edge of road in any case). You do get a few surprised looks but is that because of RHD or just that a 7 looks so unusual here?

I call mine a Lotus 7 series 123. Mostly series 1 but engine like a later series 2 and wings from a series 3 plus all sorts of safety upgrades including flying a Union Jack from the rear of the roll cage in hopes that others will see it and nut turn into me. Driving RHD is not so difficult with such a narrow car. Major insult if someone asks if it is a dune buggy. yes, there are some very stupid people on the loose but most others enjoy a short history of 7s.

Ran around a bit waking up the neighbors. Surprising how much attention a loud 7 gets from an unmuffled 1500 here in the colonies.

The 1959 series 1 I have was redone with new panels in the foot well area but pretty tight for a size 9 shoe. I have my old racing shoes about 1/4 inch narrower and they work.Hope you find something that works for you.

I had a friend with a Triumph GT6 and learned those front brakes would be a bolt on. So I did that with racing pads.Not sure how much better than a Spitfire set-up but sure do the job. Designed for a much heavier car with higher top speed and he is doing well in vintage racing. I really have not pushed that hard however as my car is getting pretty old and so am I.

I was looking into avgas as an alternative to racing fuel and noted that airplane fuel is rated on a different scale than automotive fuel. They apparently have a rating for cruising ( lean setting) and a much higher rating (rich setting ) for take off. Worth checking further perhaps to be sure, but maybe 100LL a low lead version with no alcohol to mess up engine parts, is equivalent to 105 octane on automobile standards rating system. Getting your octane rating up with lead means they may not be using as much aromatic ( molecular structure---chemists term) content. I hope the unleaded stuff they now have has more octane boost from xylene and maybe toluene for winter but absolutely no benzene. Just an fyi--- benzene is a genuinely proven carcinogen (leukemia) and even xylene and toluene are kind of nasty, so be careful in any case not to spill and get skin contact or breath fumes.too much.

If anyone wants to try metal shaping themselves and spend $ on equipment you can check Eastwood. They even offered a course in metal fab methods. I certainly am short on skill but had a friend with a lot of the specialized equipment and engineering skill.

Van- I am about 300 meters just outside the northwest corner of Philadelphia

Yes-Sunoco in Havertown works fine but if you are closer to Northeast Philadelphia there is a hot rod oriented place, Philadelphia Racing Engines 268 Geiger Road 215-9693550. Good to call first to be sure but they stock 5 gallon pails Sunoco 110 and the VP equivalent slightly cheaper and other grades but 110 is no alcohol with lead.. Anyone tried Avgas low lead?

Van---The original rear axle on most of the series 1 was Morris Minor type. Mine was originally sourced from an Austin A40 with 4.22 to 1. So Sprite is perfect and lighter than some newer ones if I understand correctly. You are welcome to measure mine as well as suspension which is very different from series 2 and 3 if you want to. Series 2 and 3 stress the axle housing and many failures ( cracking) of the TR10 housing were reported. I think some of the later ones used Escort Mk1 and Ital axles after the source of TR10 ran out. That Axminster firm looks interesting for complex body parts. We used 3003 H14 for most and annealed where bends were tricky. Floor is higher strength alloys with really strong rivets.

MV8- your recommendation on clamshells and nose is exactly what I did a long time ago. I drove to Caterham and they assured me they would fit-- and yes they did fir my series 1 #475 so should be good on an exact replica frame. So now I call it a series 123. The cowling will probably be the hardest part to bend an exact replica. I was lucky and mine was in decent shape when I imported #475 less engine, trans and rear "wings" from England. I like the look.

Congratulations-Great job! Remarkable how it looks better crafted and so much like mine in almost all color and detail including RHD----classic for sure. Only differences I see is that mine started as a series 1 "basket case" #475 I imported from UK a long time ago and I fitted a full cage and pre-crossflow Cortina GT intending to go SCCA which was D production class back then.

If weight reduction is really important and you want to upgrade on safety from impacts, then polycarbonate is a good bet and outperforms acrylic ( Plexiglass). There are scratch resistant coatings and you can cut it yourself. I just looked again at the McMaster Carr info and it looks fairly expensive. Glass is approximately 2.5X more dense ( heavier) and polycarbonate ( Lexan trade name) is used for bullet proof structures like bank teller screens. But the laminated safety glass works fine since the polyvinylbutyral film between the sheets does a good job but it is not a do it yourself option- at least not for me.

Just a safety point--- if the very old looking aircraft type lap belt is of interest, a prospective buyer should be aware that sunlight degradation of nylon is real. That is why there is a time stamp on new belts and racing organizations want to see relatively new belts used. A new set ( including shoulder harness and anti-submarine belt ) is cheap insurance for the track or in the event a huge SUV comes at you on the street.

Does anyone recall the story details from around 1970-80 era where someone was "caught" raising the rear attachment points for clamshells and SCCA banned that since they were supposed to be a big aero improvement? Seeing so many fast 7s on the track back then, all with clamshells, kind of made me stick with them. My series 1 had already been clamshelled when I picked it up in the UK. It had an Alfa 1300 twin cam before then so the previous owners were not stuck on the originality aspect.

Hope you have luck with that. My 2x40 DCOE set-up on my pre-crossflow fouled the bonnet by maybe 15-20 mm. The bulge I had built cost as much as I paid for the car when I bought it in the UK.

Just a point to remember for builders of 7s and others--- A part that is braze welded can not later be welded with conventional (MIG/TIG)) since the braze material changes the composition of the steel. You must then repair or replace using braze weld.