Tamiya 1/12 Lotus 72C Conversion
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Tamiya 1/12 Lotus 72C Conversion
1/12 Lotus 72C Rear Suspension Conversion
This is bit of a treatise on the rear suspension of the Lotus 72C, part of an overall conversion of a 1/12 Tamiya Lotus 72D to Jochen Rindt’s car that I started about ten years ago. Recently, while reading the book Jochen Rindt, Uncrowned Champion, I pulled the kit out to take a look at how far I had taken the project. The answer was: not very far. I had added the NACA ducts to the nose and done a few other minor things like assemble the engine block, but that was about it.
Part of what had stopped me years ago was the 72C rear suspension. At the time, I had been unable to find much, if any, information on what the exact configuration was. Since then, I had acquired access to more resources and a lot more information has become available on the internet, so I decided to see if I could discover enough information to model the 72C rear suspension.
Rindt raced only one 72, chassis #2 (72/2), so I decided to start with Michael Oliver’s book and carefully go through all the modifications listed for 72/2, from its debut at the Spanish Grand Prix through Rindt’s fatal crash in practice at Monza. At Spain, and at the non-championship International Trophy race, it was in the original 72A configuration, with anti-dive/anti-squat suspension geometry. Prior to Spa, the car was rebuilt as a 72C (there was no 72B) and, among other modifications, the anti-dive/anti-squat was removed from the suspension. Rindt did not trust the 72C enough to drive it at Spa, preferring instead to use his proven 49C, and his first drive in the rebuilt car was the next race at Zandvoort, which he won.
According to Oliver, after the rebuild there were only two changes to 72/2’s rear suspension. Prior to the French Grand Prix the dampers were moved outboard, away from the exhaust pipes, and prior to the German Grand Prix the suspension arms (front and rear) were chrome plated. I had decided, for various reasons, that I would build the Zandvoort version, the car’s first win.
Unfortunately, Oliver’s book does not go into detail about exactly what removing the anti-squat entailed, and there are not many good 72C rear suspension photos around, especially with the inboard dampers. The original 72A suspension is pretty well documented, with photos and several cutaway drawings available, and the later 72D configuration, which the model represents, is also well known. The question was, exactly what was the 72C’s suspension configuration, was it more 72A, or 72D, or something completely different? I started searching on the internet and, in the end, with the information I was able to find (photos and drawings) plus a few assumptions, I was able to assemble a reasonably clear picture.
What I found was somewhat of a surprise to me. I had suspected that I might have to completely scratchbuild something similar to a 72A type rear suspension (not a simple task), but, in many respects, the 72C’s suspension turns out to be very similar to the 72D’s. In fact, the 72D rear suspension was apparently a refinement and simplification of the 72C’s, not a major change, as I had always assumed, and some of the kit’s suspension parts can be used as-is or slightly modified.
The photo below show the components that are the major differences between the 72C and 72D suspension: At the top is the suspension attachment frame. On the 72C the rear suspension was attached to the car using a one-piece frame that completely encircled the transaxle, rather than the separate top and bottom frames used on the 72D. I constructed the 72C frame using modified kit components connected by fabricated plastic sides with drilled lightening holes. Next are the two lower suspension arms, which are quite different from the 72D’s simple parallel links and were built up using kit pieces and plastic rod. The rear attachment points for the lower arms are mounted on a plate sandwiched between the two gearbox casings, while the front attachment points are apparently brackets of some sort attached to the side of the DFV. (I say apparently, because I was unable to find any photos or description of exactly what these attachments might be. More on that below.) At the bottom of the photo is the aforementioned plate, which was stamped from either aluminum or stainless steel with reinforcing at the bottom where the suspension arms attached. This piece was scratchbuilt from sheet plastic and attachment brackets from the kit.
Here are some shots of it all semi-assembled: The upper suspension arms, pushrods, torsion bar arms, drive shafts, dampers and uprights are all used basically unchanged from the kit and maintain the same geometry as the 72D, which greatly simplifies things. Torsion bars, anti-roll bar and leading links are not yet in place. The plate, to which the bottom arms are attached at the rear, is held between the two parts of the gearbox case. The plate is actually very thin, but in the stamping process the edges were bent perpendicular to the plate for stiffness, so the edge appears to be thicker. Still to be added to the uprights are the rather dainty tubular brackets for the rear anti-roll bar links. The brake discs have been thinned down and the edges will be filled to represent solid rotors. The bottoms of the dampers are attached inboard as they were at Zandvoort. For the rest of the 1970 season the bottom attachment point was outboard at the front of the upright, an easily accomplished change and, again, very similar to 72D configuration.
This is a photo of my rather crude effort at one of the lower arm’s front attachment points: This was made by bashing kit pieces. The critical thing here is that it must align both horizontally and vertically with the location of the rear attachment point, which means that it has to protrude fairly far from the side of the engine block. As noted earlier, I have no idea what the actual attachment point looks like, it was buried behind/under the exhaust pipes and I have found no photos or drawings that show it. There is one 72 that is still in C configuration (I found some photos of it in an old “Supercar Classics” magazine, but none show the lower arm front attachment) and I assume that it still has the original attachment brackets. Perhaps at some point in time some information might surface that would make a more accurate representation possible. In the meantime, the good news is that since you can’t see it on the real car you won’t be able to see it on the model either.
Sorry for this lengthy post on what is a fairly esoteric subject, hopefully it will be of interest and use to some. I would add that, aside from converting the Tamiya kit, I think that most of this could also be applied to correcting the 1/20 MFH 72C which, disappointingly, comes with a 72D rear suspension.
Steve Sobieralski
This is bit of a treatise on the rear suspension of the Lotus 72C, part of an overall conversion of a 1/12 Tamiya Lotus 72D to Jochen Rindt’s car that I started about ten years ago. Recently, while reading the book Jochen Rindt, Uncrowned Champion, I pulled the kit out to take a look at how far I had taken the project. The answer was: not very far. I had added the NACA ducts to the nose and done a few other minor things like assemble the engine block, but that was about it.
Part of what had stopped me years ago was the 72C rear suspension. At the time, I had been unable to find much, if any, information on what the exact configuration was. Since then, I had acquired access to more resources and a lot more information has become available on the internet, so I decided to see if I could discover enough information to model the 72C rear suspension.
Rindt raced only one 72, chassis #2 (72/2), so I decided to start with Michael Oliver’s book and carefully go through all the modifications listed for 72/2, from its debut at the Spanish Grand Prix through Rindt’s fatal crash in practice at Monza. At Spain, and at the non-championship International Trophy race, it was in the original 72A configuration, with anti-dive/anti-squat suspension geometry. Prior to Spa, the car was rebuilt as a 72C (there was no 72B) and, among other modifications, the anti-dive/anti-squat was removed from the suspension. Rindt did not trust the 72C enough to drive it at Spa, preferring instead to use his proven 49C, and his first drive in the rebuilt car was the next race at Zandvoort, which he won.
According to Oliver, after the rebuild there were only two changes to 72/2’s rear suspension. Prior to the French Grand Prix the dampers were moved outboard, away from the exhaust pipes, and prior to the German Grand Prix the suspension arms (front and rear) were chrome plated. I had decided, for various reasons, that I would build the Zandvoort version, the car’s first win.
Unfortunately, Oliver’s book does not go into detail about exactly what removing the anti-squat entailed, and there are not many good 72C rear suspension photos around, especially with the inboard dampers. The original 72A suspension is pretty well documented, with photos and several cutaway drawings available, and the later 72D configuration, which the model represents, is also well known. The question was, exactly what was the 72C’s suspension configuration, was it more 72A, or 72D, or something completely different? I started searching on the internet and, in the end, with the information I was able to find (photos and drawings) plus a few assumptions, I was able to assemble a reasonably clear picture.
What I found was somewhat of a surprise to me. I had suspected that I might have to completely scratchbuild something similar to a 72A type rear suspension (not a simple task), but, in many respects, the 72C’s suspension turns out to be very similar to the 72D’s. In fact, the 72D rear suspension was apparently a refinement and simplification of the 72C’s, not a major change, as I had always assumed, and some of the kit’s suspension parts can be used as-is or slightly modified.
The photo below show the components that are the major differences between the 72C and 72D suspension: At the top is the suspension attachment frame. On the 72C the rear suspension was attached to the car using a one-piece frame that completely encircled the transaxle, rather than the separate top and bottom frames used on the 72D. I constructed the 72C frame using modified kit components connected by fabricated plastic sides with drilled lightening holes. Next are the two lower suspension arms, which are quite different from the 72D’s simple parallel links and were built up using kit pieces and plastic rod. The rear attachment points for the lower arms are mounted on a plate sandwiched between the two gearbox casings, while the front attachment points are apparently brackets of some sort attached to the side of the DFV. (I say apparently, because I was unable to find any photos or description of exactly what these attachments might be. More on that below.) At the bottom of the photo is the aforementioned plate, which was stamped from either aluminum or stainless steel with reinforcing at the bottom where the suspension arms attached. This piece was scratchbuilt from sheet plastic and attachment brackets from the kit.
Here are some shots of it all semi-assembled: The upper suspension arms, pushrods, torsion bar arms, drive shafts, dampers and uprights are all used basically unchanged from the kit and maintain the same geometry as the 72D, which greatly simplifies things. Torsion bars, anti-roll bar and leading links are not yet in place. The plate, to which the bottom arms are attached at the rear, is held between the two parts of the gearbox case. The plate is actually very thin, but in the stamping process the edges were bent perpendicular to the plate for stiffness, so the edge appears to be thicker. Still to be added to the uprights are the rather dainty tubular brackets for the rear anti-roll bar links. The brake discs have been thinned down and the edges will be filled to represent solid rotors. The bottoms of the dampers are attached inboard as they were at Zandvoort. For the rest of the 1970 season the bottom attachment point was outboard at the front of the upright, an easily accomplished change and, again, very similar to 72D configuration.
This is a photo of my rather crude effort at one of the lower arm’s front attachment points: This was made by bashing kit pieces. The critical thing here is that it must align both horizontally and vertically with the location of the rear attachment point, which means that it has to protrude fairly far from the side of the engine block. As noted earlier, I have no idea what the actual attachment point looks like, it was buried behind/under the exhaust pipes and I have found no photos or drawings that show it. There is one 72 that is still in C configuration (I found some photos of it in an old “Supercar Classics” magazine, but none show the lower arm front attachment) and I assume that it still has the original attachment brackets. Perhaps at some point in time some information might surface that would make a more accurate representation possible. In the meantime, the good news is that since you can’t see it on the real car you won’t be able to see it on the model either.
Sorry for this lengthy post on what is a fairly esoteric subject, hopefully it will be of interest and use to some. I would add that, aside from converting the Tamiya kit, I think that most of this could also be applied to correcting the 1/20 MFH 72C which, disappointingly, comes with a 72D rear suspension.
Steve Sobieralski
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Re: Tamiya 1/12 Lotus 72C Conversion
I'm sure interested, nice start !
Steve Mohlenkamp
Steve Mohlenkamp
when I was young, all the boys made model cars, ...some of us just never stopped !
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Re: Tamiya 1/12 Lotus 72C Conversion
Very interesting and useful. Thank you very much for posting it. Please keep it up. I'll be following closely.
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Re: Tamiya 1/12 Lotus 72C Conversion
lotus 72C? You might need these
Sheets will be sold seperatly for 1/12 & 1/8. Don't mind the pink color, this is the clear going on top of printed colors.
Wim
Sheets will be sold seperatly for 1/12 & 1/8. Don't mind the pink color, this is the clear going on top of printed colors.
Wim
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Re: Tamiya 1/12 Lotus 72C Conversion
Great conversion, I will follow with interrest.
Can you post also the previous modifications you made to achieve the 72C version?
Thanks.
Can you post also the previous modifications you made to achieve the 72C version?
Thanks.
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Re: Tamiya 1/12 Lotus 72C Conversion
Where is the Rindt details?bestbalsakits wrote:lotus 72C? You might need these
Sheets will be sold seperatly for 1/12 & 1/8. Don't mind the pink color, this is the clear going on top of printed colors.
Wim
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Re: Tamiya 1/12 Lotus 72C Conversion
afaik, rindts name was not on car when racing the nr 10 72C. And space on sheets was all used, so i let it off.
Wim
Wim
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Re: Tamiya 1/12 Lotus 72C Conversion
Wim,
That looks like a nice decal sheet, mainly oriented towards the 1971 season which would be a much easier conversion for both the 1/12 and 1/8 kits (not many wins for GLTL that year, though). You are right that Rindt's name was not on #10 at Zandvoort, however the "10" decals on your sheet would not be exactly correct for that car because the "1" was noticeably taller than the "0" at all three locations. Looks like there is plenty on the sheet that would be usefull though, so I will probably buy a set. Are they available yet?
Steve Sobieralski
That looks like a nice decal sheet, mainly oriented towards the 1971 season which would be a much easier conversion for both the 1/12 and 1/8 kits (not many wins for GLTL that year, though). You are right that Rindt's name was not on #10 at Zandvoort, however the "10" decals on your sheet would not be exactly correct for that car because the "1" was noticeably taller than the "0" at all three locations. Looks like there is plenty on the sheet that would be usefull though, so I will probably buy a set. Are they available yet?
Steve Sobieralski
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Topic author - Formula e
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Jim Clark, Graham Hill Jochen Rindt, Kimi - Location: Tampa, Florida USA
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Re: Tamiya 1/12 Lotus 72C Conversion
Here are some photos of some of the other work I’ve done on the 72C conversion.
The brake ducts and early front wings have been added to the nose: The radiator pods on the 72C were of a slightly different configuration than the 72D. I have added plastic strips top and bottom to widen them and removed small wedges of material at the rear to curve the sides in: Tamiya casts the rear part of the front subframe integrally with the front bulkhead of the monocoque tub. I used a razor saw to carefully separate them, which has two advantages in my opinion. The sub frame was grey painted steel while the bulkhead was unpainted aluminum. When painting the model, separating them makes it much easier to get a clean line between the two colors. It also makes it much easier to fill and smooth the rather pronounced joint between the tub sides and the bulkhead: Steve Sobieralski
The brake ducts and early front wings have been added to the nose: The radiator pods on the 72C were of a slightly different configuration than the 72D. I have added plastic strips top and bottom to widen them and removed small wedges of material at the rear to curve the sides in: Tamiya casts the rear part of the front subframe integrally with the front bulkhead of the monocoque tub. I used a razor saw to carefully separate them, which has two advantages in my opinion. The sub frame was grey painted steel while the bulkhead was unpainted aluminum. When painting the model, separating them makes it much easier to get a clean line between the two colors. It also makes it much easier to fill and smooth the rather pronounced joint between the tub sides and the bulkhead: Steve Sobieralski
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Re: Tamiya 1/12 Lotus 72C Conversion
Any progress?
Steve
Steve
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