Early Lotus Seven identification - plates, chassis numbers, frame numbers, and engine numbers

[Christopher smith]

Definitely not a series 4. Sure looks like a series 3 to me given the relatively wide rear wings (fenders). But any previous owner could have fitted the wider wings like I did to my series 1.

[SENC]

@chuet - that is an S3 body style, not an S4 body style.  No, the unit number on the chassis plate and frame number would not be the same - they were individually numbered (at least during the Lotus run).  If the chassis/unit number is later than 2649, it would likely be an S3 made by Caterham or a replica that got fitted with Lotus badges (not unusual).  Someone else here may recognize some of the bits in the picture and be able to help - but the rear lights, dashboard, and position of the gas filler all suggest to me it was either not built by Lotus or was changed later. 

 

To your S4 question, there were few than 700 built I think - so the Lotus numbering would end in the 3300s, I think.

Edited March 17, 2022 by SENC

[Kiwi-S2]

On 10/21/2021 at 2:29 PM, SENC said:

Several sources indicate the frame number is located in 1 of 2 places in S1-S3 Lotus.  S1s and some S2s will have a metal plate with the number stamped on it welded to the frame just in front of the passenger seat.  If someone has a picture of one they can add, that would be helpful.  At some point (anyone know when?), the practice changed and the rest of the S2s and then S3s had the number stamped directly in the frame beside the brake/clutch master cylinder mount.  I've added a couple pictures of these later stampings, and a drawing with the locations circled.

 

Note this is a different number than the chassis number or VIN, and was frequently (always?) recorded with the chassis number in Lotus records, so together they are very helpful for confirming identification.

 

[Kiwi-S2]

10 hours ago, Kiwi-S2 said:

 

Very early S2, 1961 Lotus 7 America, Universal radiator welded frame plate example. Passenger footwell, RHD car. 

Edited February 7 by Kiwi-S2

[Kiwi-S2]

Adding details 

[1972Series4]

I hope to do two things with this post; help myself out and add to the database of cars. I acquired a 1972 (?) Series 4 Twin Cam from the estate of a long time friend

who passed away in December 2022. The car was I VERY dilapidated condition when I started working on it as the previous owner took it ALL apart and proceeded

to modify it and never finished his dream of building the ultimate D-Mod autocross car. The engine and trans were gone and the ID plate was in an envelope which my wife found in a last ditch effort to find SOME documentation. We found no title or registration but I can take care of that with a "bonded" title in Arizona. The plate number

is    S4 3516 TC.    The plate numerology is self explanatory but I have NO IDEA who built it (Lotus or Caterham) or what year it is. Any help as to an alternate from number

or other info would be much appreciated. Bruce

[MV8]

The last Lotus built chassis to be delivered to Caterham for assembly is supposed to be S4 3535, with Caterham building 3501-3538. It is a grey area as who built which chassis from 3501 to 3535. If a Lotus chassis, it would be the main factory as the Lotus Racing/Components chassis stopped at 2953. I expect it is a 1972 or 1973 S4.

[wdb]

Maybe it WAS. But look at that chassis. 

[SENC]

The Seven Cars Ltd plate would indicate this was built by Caterham.  Caterham closed the deal with Lotus in May 1973 according to the books I have, taking on all the remaining chassis and parts inventory from Lotus shortly thereafter.  So, likely, this is one of the 60ish S4s they built before they started having difficulty getting parts from suppliers and started building the S3 style.  Assuming that is correct, this would be either a 73 or 74 car.

 

John Watson (lotus7register.co.uk) could likely help you further.

Edited February 27 by SENC

[MV8]

On 2/26/2024 at 8:02 PM, wdb said:

Maybe it WAS. But look at that chassis. 

It may not be entirely original, but the S4 chassis is radically different from any others.

 

I've read the agreement was made by May '73 with the formal (including the "hand shake") in June at the Lotus pub.

Edited March 2 by MV8

[fogrocker60]

Here is the only number I can find on my S4 seven. It is stamped/ etched into the left front rail in front of the Master and Clutch cylinder.  Help?

[1972Series4]

Sorry I didn't get back sooner but I've been busy painting the car, then spent all day Wednesday cleaning up the mess (see picks) and Thursday mowing the yard, 1 acre plus.

I finally got out this afternoon and sanded the paint off frame rails on both sides of the car thinking maybe there was an ID that was covered by paint. Nothing. It was on the upper rail, right?
 

[EdWills]

According to Bruce Robinson of Arch Motors, Arch did not commence building chassis frames for the Lotus Seven until January 1968. Even then, they were panelled by another company (J.W. Eve and company).  Arch only started panelling their chassis when Caterham took over from Lotus circa 1973. If any genuine Lotus Seven chassis is questioned with a build date prior to January 1968, it should have been assembled by fusion welding at Universal Radiator (from Northampton in the U.K., with Unirad placing their chassis build number on the brake bracket as BXXXX or BLXXXX for left hand drive cars).  Arch of course, used the Chapman approved method of gas flux braze or bronze welding technique, and any replacement chassis produced after Lotus sold the rights to the 7, would most likely  be braze welded.  Arch produced many suspension parts for Lotus (including the Seven) long before January 1968, including  chassis for such cars as the Lotus 23 and for other companies (e.g. Lola).  Arch chassis should have the frame number stamped with ‘AM’ followed by numbers.  They later identified their replacement completed, panelled chassis as ‘CBU’ units.  I have one as ‘CBUXXX’ but this was only noted on the plastic cover of the alloy protective sheets when it was delivered.  When Lotus took delivery of chassis from Universal and later Arch, as shown in photographs of the time (and pointed out by another forum member in the U.K.), they would be stored at Lotus, stacked outside in all weather conditions in random order as they came off the lorry (truck).  The fitter charged with identifying the chassis with the Lotus plate to be attached, would normally use a scriber to place the Lotus car identification number on the plate.  My original 1969 registered car built in October 1968 with a Unirad chassis,  had the Lotus ‘vin’ number scribed on the plate. The plate that was  pop riveted by the fitter would have no bearing on the chassis build number.  My vin number and Unirad build number are 19 numbers apart.  I have records of another car where they are 34 numbers apart.  The first delivered, would be the last off the pile of chassis to be identified probably. Dave Bean among many others (ebay) sold duplicate genuine looking Lotus vin plates and Simple Sevens documented 3 ‘genuine’ Lotus Seven Series  2 cars all with the exact same plate letter/numbers, one in Europe, one in the U.S, and another possibly in the U.K.  John Watson of the Lotus Seven Registry compiled as many details of the cars as he could after being presented with the Lotus Factory records by one of the original builders of the cars.  He doesn’t have every one, but still tries to gather all the info he can.  Likewise John Donohoe at Simple Sevens.  Its fascinating trying to determine the true identity of some cars that have been reconstructed using one, two or possibly three cars with bits and pieces from each.  As a club racing car, a number must have been scrapped due to excessive race damage.  Cheers, Will