jbcollier Posted October 17, 2022 Share Posted October 17, 2022 First post!I've just bought a Lotus Seven S3. Serial number is LSB2383 but there is no body number that I can find. To me, the CBU looks like it has been changed but I would appreciate other more expert opinions. I'm not worried either way as both original and properly triangulated later production have their pluses. Here's a link to my photo album on the car. All the car shots are from the seller. Mine are the last three with the VIN plate (posted below, extra large), the place where the chassis number is supposed to be (by the master cylinder), and a photo of reinforcing by the lower a-arm mount.Does the VIN plate look original? Couldn't call it legible that's for sure.Any idea if the CBU is a replacement and, if so, by whom?Other places I should be checking? Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted October 17, 2022 Member Share Posted October 17, 2022 Welcome.I'd start by talking to Martin Phipps, and he'll advise on the best sources for working out what you have.https://www.caterhamlotus7.club/about-us/team https://www.caterhamlotus7.club/forum/chitchat/lotus-7-register-and-historian https://media.lotuscars.com/en/blog/andy-the-archivist.htmlJonathan Link to comment Share on other sites More sharing options...
oilyhands Posted October 17, 2022 Share Posted October 17, 2022 That link isnt going anywhere.. Link to comment Share on other sites More sharing options...
Area Representative paul richards Posted October 17, 2022 Area Representative Share Posted October 17, 2022 What's a CBU? Link to comment Share on other sites More sharing options...
OldAndrewE Posted October 17, 2022 Share Posted October 17, 2022 #3 do you mean this link? Worked for mehttps://jbcollier.smugmug.com/Lotus-Seven-S3/Presumably the chassis should have the Arch Motors chassis no stamped on top of one of the rear damper mount platforms Link to comment Share on other sites More sharing options...
jbcollier Posted October 17, 2022 Author Share Posted October 17, 2022 CBU is Chassis Body Unit.I'll check the rear damper top mounts. Thought that might be a Caterham thing but I'm new to all this. Thanks! Link to comment Share on other sites More sharing options...
OldAndrewE Posted October 17, 2022 Share Posted October 17, 2022 The number will presumably be in the form "AM YY NNN" i.e Arch Motors, year of manufacture, serial no. for that year Link to comment Share on other sites More sharing options...
Area Representative Golf Juliet Tango Posted October 17, 2022 Area Representative Share Posted October 17, 2022 Congratulations on your purchase.There is quite a lot in the archive. Articles should be tagged as "Lotus". Link to comment Share on other sites More sharing options...
John Vine Posted October 17, 2022 Share Posted October 17, 2022 Excellent!Are you sure there's an "L" in the Unit No? AFAIK, the number would be just SB2383.There's some pretty old L7 info here, and something more up-to-date here.I lusted after a Series 3 like this in the late 60's. Unfortunately, it was completely out of reach of my paltry salary at the time.JV Link to comment Share on other sites More sharing options...
simon_h Posted October 17, 2022 Share Posted October 17, 2022 As his car has the steering wheel on the wrong side LSB is correct for a lhd car. The etched by hand detail on the chassis plate is pretty much the same as my Elan, style and handwriting, so it looks like it's pretty original to me Link to comment Share on other sites More sharing options...
jbcollier Posted October 17, 2022 Author Share Posted October 17, 2022 Things are getting curiouser and curiouser. There is no stamping where the S3 usually has one (by the brake master cylinder). I figured, in for a penny, in for a pound, so I cleaned off the top of the upper rear shock mounts, cleaned off the top of the cross tubes in front of the seat bases, and cleaned off a one or two joints in the front compartment. First, there are no numbers at either of those locations. Second, the chassis is welded, not brazed (!!). So it is definitely not an Arch Motors chassis. Any thoughts? Link to comment Share on other sites More sharing options...
simon_h Posted October 17, 2022 Share Posted October 17, 2022 According to the Lotus Seven Register site the S3 started at no.2311, so yours is about 70 on from that. The frames were made by the Universal Radiator Company and Arch so that maybe yours is not from Arch. If the URC gas welded them rather bronze welded them I don't have any idea. Scrape some paint off the welds as the bronze welding does look quite like normal welding when painted, to me anyway, but obviously is a golden colour when not. Just read on a bit further and it appears Arch got Lotus to switch over to bronze welding so its quite likely yours is from the URC as they were slowly phased out during the S3 production in favour of Arch apparently Link to comment Share on other sites More sharing options...
jbcollier Posted October 17, 2022 Author Share Posted October 17, 2022 All settled. It's a Universal Radiator made chassis and they used fusion welding, not brazing. John had it already in his system and is moderately confident it is the real deal. I think moderately is about as confident as you can get with any Seven, so I'm happy. Link to comment Share on other sites More sharing options...
jbcollier Posted October 17, 2022 Author Share Posted October 17, 2022 PS: thanks for your assistance!Now to cut it up so I can fit a small-block Chev in there...:-) Link to comment Share on other sites More sharing options...
simon_h Posted October 17, 2022 Share Posted October 17, 2022 That's good news then. As Caterham are now fusion welding it's gone full circle with the S3 frame Umm and don't do that Link to comment Share on other sites More sharing options...
jbcollier Posted February 2, 2023 Author Share Posted February 2, 2023 Just a final, final update, it is original chassis with updates. They removed the belly pan/floor, drilled out the rivets for the rear tranny mount and welded in the Caterham style one. They then fit the original pan/floor back in, re-riveted everything back in place but leaving the original mount's rivet holes open. Quite the puzzle it's been! Link to comment Share on other sites More sharing options...
TomB Posted February 2, 2023 Share Posted February 2, 2023 Any more pictures apart from the chassis plate? Link to comment Share on other sites More sharing options...
jbcollier Posted August 9, 2023 Author Share Posted August 9, 2023 I removed the pedals as I'm fabricating a cover for the pedal box to help stem the flow of hot air into the passenger area. And, underneath, I found the missing chassis number: Link to comment Share on other sites More sharing options...
OldAndrewE Posted August 9, 2023 Share Posted August 9, 2023 So B is definitely for Universal Radiators. L for LHD? 2071 twentieth chassis in 1971? Is it a 1971 car? Link to comment Share on other sites More sharing options...
jbcollier Posted August 10, 2023 Author Share Posted August 10, 2023 You are right on the letters but I think the 2071 is just a number, not a date. This is a frame builder's number, not a chasis/VIN number. It was a factory build, sold in Canada in 1970 but most probably made in 1969. Link to comment Share on other sites More sharing options...
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