Are there many Lotus produced Seven owners on this forum?

[panamericano]

Short article on an original:

 

https://classicmotorsports.us20.list-manage.com/track/click?u=0e32c785aa03c0e6cb578e7c6&id=8150ac158b&e=07ee42a8dd

 

[EdWills]

Thank you @panamericano for the attachment.  That's a great looking Seven and Craig's hints at improving a race car are invaluable.. I enjoy reading Classic Motorsports magazine, and they have featured Lotus Sevens in the past.  Craig Chima has built and raced some very successful Lotus Seven based cars in the past, and is selling or sold a couple of them on (see https://simplesevens.org) for details on these cars along with his racing successes).

 

Thank you to those who submitted their Lotus Seven serial numbers.  I will add them to my list.

 

There is also a Lotus Seven owner in the U.K. who has purchased a few Lotus Sevens from the U.S., and shipped them back to the U.K. for refreshing or rebuilding.  The Historic Lotus Register (U.K.) has featured some of this gent's cars. Cheers, W.

Edited September 25 by EdWills

[Christopher smith]

Very interesting article. Thanks. Does anyone know the history/reasons why SCCA moved the 7 around in so many production classes?

I recall the 7 America  with the Sprite engine was in F production when I raced in that class in my Sunbeam Alpine late 1970s (and got passed in the corners of course).

The Super 7 with the 1500 pre-clossflow Cosworth and 2x 40 DCOE arrangement was in D production back in the 1960s. For a while it was moved to BP and ran against older Corvettes, beating them on tight tracks like Marlboro, Md. The SCCA production classes were supposed to be based on relative performance with quite a few modifications allowed. Later I think it moved back to D and ran against some pretty fast TR4s. I kind of lost touch with SCCA but much more recently I see that 7s are in FP and run against some pretty fast MG Midgets. I think the 7s may still have the 1500, but I guess has some pretty substantial weights added so can run against those Midgets. Can anyone fill in the blanks for around 1990 to 2020 or so?

[IamScotticus]

5 hours ago, panamericano said:

Short article on an original:

 

https://classicmotorsports.us20.list-manage.com/track/click?u=0e32c785aa03c0e6cb578e7c6&id=8150ac158b&e=07ee42a8dd

 

@craig chima 120 front, 225 rear?

Edited September 26 by IamScotticus

[craig chima]

The spring rates are obviously reversed but otherwise accurate.   As for SCCA, my 7 is still "nominally" competitive at some tracks primarily because thanks to SCCA, it is now a 1600 pound pig racing in F Production with a 1500 pre-crossflow on 34mm chokes racing against 1800 cc Acura Integras, Honda del Sols and CRX's, Mazda Miatas and the like.  I've done a full on CFD analysis on my car in order to maximize straight line speed (126 down into T5 at Road America) but that still leaves me 5-7 mph slower than the "modern" (4 valve DOHC) cars.   As for the MG Midgets, like virtually all of the other "classic" roadsters they haven't been even remotely competitive for at least the last 15 years.   The Runoffs are next week and amongst the 3 Production classes there are a total of 9 what you would think of as traditional Production cars entered.  One in EP, one in FP, and 7 in HP and of those 9, there is only 1 that has a reasonable chance of winning and maybe 2 others that have a chance of being competitive.

[IamScotticus]

Craig,  what axle are you on now? Does the class allow anything other than a Standard 10?

[John B]

@craig chima Hi Craig!

Great to see you're still at it. We raced S2000's against each other in SCCA. 

Your car looks great! I'm wondering if cycle fenders in front might be a little cleaner aerodynamically, and provide less lift (more downforce). 

[Christopher smith]

10 minutes ago, John B said:

@craig chima Hi Craig!

Great to see you're still at it. We raced S2000's against each other in SCCA. 

Your car looks great! I'm wondering if cycle fenders in front might be a little cleaner aerodynamically, and provide less lift (more downforce). 

 

[Christopher smith]

I was wondering about that also given the aerodynamic situation with 7s. I seem to recall a point where SCCA had to clamp down a bit with some clamshell adjustments giving less drag. I think it was raising the rear of the clamshells a bit but wonder what it did for top speed at that time. I think back in 1959-1960 when the first 7s started coming across the ocean that USA federal regulations did not allow cycle fenders and that is why the 7A had clamshells. Some of  us liked the looks so much that most (all?) Series 2 and 3 maybe had clamshells worldwide.

[NSXguy]

On 9/22/2025 at 5:14 PM, EdWills said:

In 1992, a very considerate Lotus Seven owner in New York - who had started a Lotus Seven Registry detailing North American Sevens only, decided to relinquish his entire collection, including a couple of magazines that he had produced, and sent them to me free of charge.  Along with his list, my list of Canadian Series 2 and 3 Lotus Sevens (collected in the early 1980s), listings from 'Bring a Trailer', plus magazines, as well as six Lotus Sevens with serial numbers provided on this forum from 2014,  I have a total  of 155 Lotus Seven Series 1,2,3, and 4 Cars recorded in the U.S. and Canada to date.  Some have full specifications and some just partial information (name and Lotus build number only) provided by the owner.  Some may now have been exported back to the U.K., and some to Europe from N. America.  The list also includes 16 early Caterham 7 cars in N. America, with Caterham and Arch numbers provided. Note:  I do not make the list public, it is just for my interest in order to see how many Lotus Sevens may have survived.

 

John Donohoe on his Simple Sevens site, currently lists Lotus Sevens where owners have provided the Lotus serial number along with their name - some with just a photo of their Seven, or full details of their cars in others.  J.D. also provided further details on other Lotus Sevens in a C.D. that he made available for sale, and it contains even more Seven information along with owners' details and car serial numbers.  

 

There is a lotus@se7ens forum in the U.K., but there have been minimal postings since Covid struck, and there is no function to post photos or drawings unfortunately.  The library on this U.K. forum - dedicated to Lotus Sevens only - is extensive, with information provided by Seven racers, technicians or just owners like myself. It is still available to join, and it worked very nicely side-by-side with USA7s, until posters unfortunately lost interest. There is also a forum that can be accessed from this same U.K. site for Caterham 7, Caterham 21, and other 7 lookalike owners. W  

 

I have a (at least to me) very early Cat 7 that looks very much dimensionally and mechanically similar to a period Lotus 7 s3 (and maybe even s2?- less power/drivetrain). I've always wondered how many late 70s/early 80s Caterhams there are in the states. There are relatively lots more of the 90s 7s that i've come across in person or online , of similar configuration (clamshell, xflow, 4spd, Live axle). ]

-Dez

[craig chima]

Clamshells actually have very little detrimental effect and the "high speed front end lift" is mostly a wives tale.  I've run my car with and without them on the same test day as back-to-back test and straight line speed was virtually the same.  Also confirmed by the CFD analysis of the car.   The much bigger problem on a 7  is the drag caused by the flat leading edge of rear fenders.   About 10x the drag of clamshells.

[Timothy Keith-Lucas]

Oh, Poot! It was so much fun being able to include "V liftoff" among the specs for a clamshell 7 at car shows.

[EdWills]

23 hours ago, Christopher smith said:

Very interesting article. Thanks. Does anyone know the history/reasons why SCCA moved the 7 around in so many production classes?

I recall the 7 America  with the Sprite engine was in F production when I raced in that class in my Sunbeam Alpine late 1970s (and got passed in the corners of course).

The Super 7 with the 1500 pre-clossflow Cosworth and 2x 40 DCOE arrangement was in D production back in the 1960s. For a while it was moved to BP and ran against older Corvettes, beating them on tight tracks like Marlboro, Md. The SCCA production classes were supposed to be based on relative performance with quite a few modifications allowed. Later I think it moved back to D and ran against some pretty fast TR4s. I kind of lost touch with SCCA but much more recently I see that 7s are in FP and run against some pretty fast MG Midgets. I think the 7s may still have the 1500, but I guess has some pretty substantial weights added so can run against those Midgets. Can anyone fill in the blanks for around 1990 to 2020 or so?

If you can purchase a copy of the late Dennis Ortenburger's book "Legend of the Lotus Seven" (or perhaps you have one already?) he has a chapter on some racing Sevens and their owners in the U.S., one of them being Tom Robertson who ran a Series 2. His Seven had fairly soft springing, beefed up chassis frame, spherical joints on suspension arms, Spitfire diff. nose piece and TR7 axles.  The engine was the 116E over-bored with dry-sump. He also used adjustable anti-roll bars front and rear as @craig chima recommends.  Robertson was able to make use of Goodyear Formula Ford tires, which heavier cars could not use.  He beat the works Triumph TR7 team to take the Class 'D' Championship (1977) even after an appeal was launched by Triumph over the use of the nose piece.  Ortenburger features other U.S. racing Sevens in his book, and I wonder where they are now?  

 

Reading stories out of the U.K. and the U.S., it reveals that the Lotus Seven has often (always?) been placed at a deliberate disadvantage by being classed in racing categories with cars that were way over the top in terms of power and engine capacity.  Even so, the Lotus Seven gave them a run for their money. It probably gave Colin Chapman a good chuckle too, even though he had really lost interest in the car. Thank you Craig for all the information..

[EdWills]

20 hours ago, IamScotticus said:

@craig chima 120 front, 225 rear?

Hi Scott.  I think the magazine writer also got the spring rate numbers for the basic Seven Series 2 and 3 wrong.  They were originally 105lbs  on the front and 75lbs on the rear (o.k. we'll give them 80!)  @SENC very kindly sent me a list of Armstrong dampers and springs a while back from an old catalogue. Not sure if they are in the library though? W.

 

My wife thinks that I am lotus intolerant.  I think she meant to say lactose, but either way seems to fit!

Edited September 26 by EdWills

[MV8]

FWIW, I have hand written notes about Armstrong showing 95/54 f/r for an S2, with a row titled "Rate lbs in" that looks a lot like "Rate 105 in".

[EdWills]

40 minutes ago, MV8 said:

FWIW, I have hand written notes about Armstrong showing 95/54 f/r for an S2, with a row titled "Rate lbs in" that looks a lot like "Rate 105 in".

@MV8 I have the same page and totally agree with you.

 

It shows 'Seven Ser. 1 as 93 F, 65 R'.  'Seven Ser. 2 as 95F 54 R.'  

I also have a 'blow-up' of the page, and the 'Rate 105 in' is actually "RATE lbs in.'  The lbs has been lazily written and on my copy is a tad blurred and looks a lot like 105.

 

However, a page from the Armstrong catalogue that was sent to me by one of the members of this forum notes:

 "Mark 7 Series 1 up to C/No. 1000 1959 - 60,  spring rate lbs/inch is 93 front , 65 rear".  

"Mark 7 Series II and Super 7 1960 the spring rate lbs/inch is 95 front, 50 rear"

 

Tony Weale advised in the appendix to his book that the Series 1 used the same Spax damper and spring combination as the Series 2 and 3 on the front of the car.

 

In an article from a 'Motor Sport' magazine (U.K.), Caterham raced an early Seven built by them and the rate was 105F/75R, but the springs sagged due to manufacturing errors.  They then tried 90F/70 R. These spring rates were controlled by rules in the British 1980 Prodsports Championship. The same article advised that for a road-going Caterham 7 (1980-81) fitted with an Ital axle, the rates were 100 F/ 55 R. 

 

Later in Series 2 production (and later copied for Series 3), Mick Lincoln, former co-director at Redline, advised me that Lotus changed their specifications to 105 front, 75 rear as standard.  

 

DSK (U.S.) used to offer street springs rated at 85F/60 R.  Their auto cross springs were 125F/90R.  

 

Tom Robertson used 140F, 100R. on his Series 2 race car (1977).  

 

Dave Bean recommended 115F/75 rear for standard road use.  

 

Mick Beveridge, formerly of Xtra Special Sevens (U.K.), liked 125/11" free length F, with 80/14" free length R. on his road cars, but noted that most companies in the U.K. don't make the 80s, so he went to 100 lbs/inch with 14 inch free length.

 

W.

[craig chima]

Robertson's car is in the Barber Museum and is for all practical purposes the suspension is essentially what you see on most vintage race prepared 7's these days.   Stiffened chassis and upgraded springs, shocks and anti-roll bars.   My current SCCA car has front a-arms that are more than 2x longer than stock and meet at the chassis centerline, has a Formula Ford steering rack, triple adjustable Ohlins shocks, blade type adjustable sway bars, and full floating rotors. Rear end is 3 link design with horizontal watts link and is de-cambered for 1 degree negative and uses full floating axles, floating rotors and Wilwood calipers.    An entirely different animal than my vintage car.

[EdWills]

@craig chima.  I like the way you have engineered the top suspension link.  With your racing rules, are suspension, tires and engine modifications all free choice?  W

Edited September 27 by EdWills

[MV8]

Many interesting custom builds for racing without cutting up an original. Here is one with a similar rear config. Pushrod ifs with a bike drivetrain. Owner went by "Modern Beat". Pics are circa 2010 or so.

[craig chima]

Suspension is free except for no pushrod/pullrod.   Required to keep stock wheelbase, track can increase up to 10% and must also keep original diameter rotors.  Must use original block, head and valve sizes and overbore can be up to .047 but internals are free.   Trans is free but must keep original # of gears and cannot be sequential.