Christopher smith

Everyone should consider a good read of Carroll Smith's book Nuts,Bolts,Fasteners and Plumbing. It covers how Indy Cars were designed/assembled in 1990. Part that I felt was particularly important is the proper choice of bolt "grip" length ( that is the non-threaded section) in shear applications. So if anyone is buying replacement bolts that can be critical in highly stressed applications (as in 7s) be careful.

Thanks- great info. 115 hp and 6700 seems fairly tame but great fun to drive! I recall hearing the most competitive 1500 cc Cosworth 7 pre-crossflow engines were running 13 to 1 compression cranking out close to 180 hp at 8000+ rpm. Do the Honda motors need ZDDP?

What engines are the FF cars using now? My experience with Formula Ford is ancient history now but recall they were relatively stock Cortina crossflows with limited mods as far as intake & compression ratio so were not as highly stressed as some of the competitve 7s that were ( much higher compression, dual 40DCOE etc. operating at very high RPM) . I would guess that some ZDDP would be a great idea for any motor driven hard that does not need to protect the platinum.

in my pre-crossflow I used a break-in oil that claimed "high ZZDP". Not sure what high means of course. I would assume the Lucas additive is a concentrate in a synthetic or maybe petroleum base, but not sure what % they may use. I continue to use a mix of 10W30 and 20W50 that has ZDDP, again, no idea on concentration but assume any reputable oil chemist would have a reasonable % suited to flat tappet, high performance cams when no catalytic converter is required. Most oils now probably are formulated with no ZDDP to suite modern engines but I guess there is nothing in there that conflicts with a dose of ZDDP.

Just a chemist's perspective. I got involved just a bit in the 1990s powder coating formulations. For sure there are many varieties with widely different properties such as metal adhesion and elongation (flexibility). Not sure what frame manufacturers are using. When I had the bare frame of my 1959 series 1, I coated it with a 2 part room temperature cured epoxy paint. It has held up well albeit in pretty mild conditions ( never in rain or snow). Any chipping is easily touched up with abrasive paper then oil based primer and oil based top coat.

Anyone interested in initiating a database that indicates cockpit width ( probably at some fixed height from floor) and pedal area width? Both easy to measure and a great guide for prospective buyers of the huge varieties of 7s. I know my size 9 racing shoes are a tight fit in my 1959 series 1 and my 5' 10" 150 lb size is close to the limit (but I have an internal roll cage with dual side bars that almost all other 7s do not, but only cushions for seating). Also, roll bar height from the seat might be of use for those who do not want their head (helmet) too high.

You may want to look at specific grades of clear sheet since some are more scratch and UV light resistant. Plexiglass and Polycarbonate are very different. If you check for polycarbonate at McMaster Carr you will see a nice rundown on different options you can buy

Great idea. I used primer but silicone sounfs

Just a thought on redrilling. When we reskinned my 1959 series 1 it was necessary since the old aluminium was corroded from all those years. But in drilling the new holes for Cleco allignment and then high strength rivets. I always had a great feeling having the drill bit meet substantial resistance indicating that the tube metal was still thick and in good shape. Of course this exposed a tiny bit of uncoated steel. But I never let the car get wet or out in the salt covered roads here in Pennsylvania winters. So I do not worry about exposed metal. Hope it goes well for you.

I got a set of 6 x13 Panasport wheels that have that Minilite look and were colored gold. They drilled the front for Spitfire pattern ( I have GT6 brakes) and the rears were drilled for my A40 (Nash Metropolitan or Sprite type) but I calculated the backspace wrong. They hit the suspension so I gave them away to a Sprite racer. So be sure to watch your calculations.

Looks like the photo of damage was taken from below, so maybe the car ran over a large rock or similar? Hope it can be fixed easily. I modified my frame per the old SCCA D production racing specification but recently added a bit more in the way of a small bolted on "skid plate" more to protect the oil pan than the frame. I think that was typical practice on rally cars, but on the streets around here we have neighborhood citizen highway engineered speed bumps way too often ( have not scraped yet). Also it was a place to put an eye bolt if it ever needs towing and serves as a great front central jacking point.

Would be nice to use as many of your Sprite parts as appropriate. Watching out for suspension attachment points might be important as it possibly changes the roll center for front and rear. That could make for a very ill handling car and after all, superb handling is why all of us are attracted to Lotus designs in the first place. That said, the Sprite rear and series 1 suspension design works ( no suspension attachment point at bottom center of the rear housing like series 2). Works for sure as far as handling goes and I suspect would handle the torque you are liable to apply with a 1275 given how light the car should be. Or are you planning to go all out with the motor and use slicks for some competition? Not so sure about the front as that Sprite suspension is way different from Lotus practice. Staying with the lever shocks means using your wire wheels is easy. If you use a more Lotus 7 approach on the front then the wire wheels might require some sort of adapter? Others may have experience on how to fit AH wire wheel hubs to Triumph Herald/Spitfire uprights/hubs. Maybe simple but I never tried it. I understand that Mike Brotherwood in the UK makes complete frames and might be good to contact. Just another thought-- watch your clearance, rear wheels to frame and trailing arms, as the Sprite rear is fairly narrow.

Not sure, but you may want to be cautious about using a Sprite rear with series 2 type suspension. As I mentioned, the series 2 had that "A frame" under the Triumph TR-10 rear for lateral location and that puts a huge load (twisting I think) on the center of the housing and may crack it. Not sure if you do this, just how to best reinforce the axle housing. I think some builders have adapted the Ford Cortina axle which may be a bit wide or some early Toyota Corolla maybe. You could alternatively use a series 1 type setup like I have. That has upper and lower trailing arms with the lower right having a tube for lateral axle control welded to it that runs at an angle from the rear of the arm to connect to the frame with a bushing pivoting on a stud coming out from the 1 inch square frame that surrounds the rear of the driveshaft tunnel. If you want to try that I can take some measurements and send them. Alternative I guess is fabricating some sort of Panhard rod to locate the rear housing. I am not qualified to design that approach however.

The rear axle on most of the series 1 models were derived from Nash Metropolitan or the A40 model but with 15 inch wire wheels. I understand this is essentially the same as the early bugeye Sprite 948 axle but of course has some plates welded on just inboard of the brakes to attach the trailing arm suspension bits. The Sprite engined 7 America model apparently started as a series 1 but had series 2 looking fiberglass "clamshell" front fenders to comply with USA requirements since cycle fenders were not allowed. I think the early ones (1960?) did not have that "A frame" attachment to the bottom of the center like series 2 ( I understand that move caused a lot of problems as the attachment to the rear housing caused the TR-10 housing to crack unless you welded on a reinforcing plate to carry the suspension load). Instead they had upper and lower trailing arms just inboard of the brakes. But the early 7s had a small Ford side valve motor usually and skinny 15 inch tires so not all that much loading on the various axle parts. Not sure about the ones that were fitted with the Coventry Climax motors for racing as they were probably also treated to various trick parts derived from the Lotus 11 racing experiences. My series 1 , number 475 (so the 75th built) was originally built with an A40 rear axle and a 1300 twin cam Alfa engine so was an oddball but survived quite a few owners, per the official UK paperwork I have, before I shipped it to the USA in 1978 and finally installed a 1500 early Cortina type motor ( dual 40 DCOE etc). All those years with the 1300 seemed to be fine for the axle as it looked perfect inside and out. i understand the somewhat newer Sprite/Midget axle shafts were made with a better heat treatment or alloy and are even less prone to failure than the older bugeye types. Racers usually install a dual bearing set-up for Sprites so you could consider that while you have it all apart. It should be a great drive with a 1275 so good luck.

Not sure on 7s but I think it is caster that has a huge effect on tracking in a straight line. For steering effort it may be worth looking into a removable steering wheel hub and larger wheel. That allows a little more comfortable entry and seems essential with a roll cage anyway. Hope you have some luck with it.

sorry if i went astray on this. It was for Solo but my thoughts were on SCCA ragional and National races rather than solo.

Historical perspective? does anyone have data that indicates why super 7s run in F production now and run with some Sprites and MG Midgets? Did they add loads of ballast? I have not kept up, but certainly remember when the 7 America (Sprite power) was in F since I ran against them with my Sunbeam Alpine. No way we could come close to any super 7 with Cosworth 1500 that ran in D at that time. I think they moved from D to B at one point and back but challenging slower Corvettes, at least on courses like Marlboro with no long straights.

VP also is a good line and maybe a dealer nearby

Just a bit of caution on boosting octane from a chemist. Toluene has been used for a very long time to boost octane. Pure toluene may be a bit toxic on its own, so best to avoid skin contact and breathing fumes of additives or race fuel, or higher octane pump fuel for that matter. But as refined from crude oil ( a process called distillation) the manufacturers try to separate out the benzene, but some toluene sources have contained significant amounts of benzene. Benzene is a known carcinogen that definitely causes big trouble like leukemia if you are exposed too much, so try to avoid sloshing fuel around and never use it as a parts cleaner as was common practice a long time ago. Living around an oil refinery is not a great idea either. i also know about burning pistons and am probably way too cautious with 108 octane racing fuel in that regard.

CarlB- Thanks for asking. Unfortunately I never photographed that area of the car during construction and now it would take quite a bit to take the panels off that cover it up. It is a standard 8 gallon ATL sports cell and Summit Racing has a picture and now a price about 50% higher than back then. Not sure how hard a retrofit would be with body panels in place making welding very tricky. Possibly a couple of supports could be fabricated to hold one up without welding. I think someone must make a custom cell that replaces the standard Lotus ones that fit behind the axle.

sf4018- For sure fire safety is important. I have an 8 gallon ATL fuel cell and have it mounted over the axle a fair bit forward of where Lotus originally had the fuel tank, the idea being that it allows more crush space. I have a hand held Halon extinguisher with quick release on the passenger floor, within reach. I can also reach the kill switch with my 5 point harness tight. The fire sticks you mention are interesting. As a chemist I was curious how they work. Sounds like it will deposit potassium oxide around the area. With humidity, this will then turn to potassium hydroxide which is pretty corrosive, or maybe potassium carbonate if some CO2 is around. But if they put out the fire, that is great and maybe the residue is not that big a deal. Just need to have them tucked away so they do not go flying out at the time you need them most. i think I will get one. Thanks Does anyone know if Caterhams come with those inertia switches that cut off electric fuel pumps in a bad crash? I think most race cars use them now. Sorry to dwell on the safety subject but when I get tailgated by a big SUV it gets me thinking.

I like that idea of an extra cross member. In fact I added one about an inch forward of the lower rear 1 inch square crossmember and the rear of my cage is on top of the 2 with a steel triangle welded in. My floor pan is 304 stainless with really strong rivets making it all very stiff.Adds a bit of weight, but down low is not so bad and 7s are really quick in any case.

CarlB- Great looking cage! Thanks for sharing. I am only familiar with the early Lotus varieties and they did not even have seat belt attachment points. Nice to see that Caterham had provisions for cage attachment. Do all the models have the rear and forward mounting points attached to the lower frame rail? I would guess without factory built in tabs you would need to remove side and bottom panels to weld on attachment provisions.

11Budlite---sorry about the photos-- I have a new phone and have just switched to an Apple computer as well and can not figure out how to get a photo to attach here. But happy to e-mail you some. I am at cgsseries123@gmail.com