Project GT2 - Lotus Esprit chassis introduction #03 (Jan-22)

AT LAST I have finished this episode, and the main introductions.
The solidworks animation for the chassis took well over 40x man hours to make due to constant software crashes and journeys back and forth between two computers to adjust the timing and voice over to match.
There will be FEA / simulation tests run on the CAD model in future so stay tuned.
Due to this delay the sound recording was disjointed when I played it all back it sounded awful - so the whole lot had to be re-recorded ! (told ya I was a tech boomer!).
I know I said no more slide shows but the chassis is really hard to make an interesting subject to film.
#Lotus #Esprit #projectGT2 #Solidworks

[@JonHimself]

Note on the CAD model : Many people have asked, but at this point there are NO PLANS to release the CAD model into the public in any format. If you think the CAD model can help you with your Esprit project / repairs, drop me a message or reply here, as those that know me personally will attest, I'll be happy to help.

[@guitarhero781]

This is stunning work mate. I can not believe what I am able to learn on KZbin. I'm looking for a car to restore as a hobby. Thank you for uploading this. Bless you mate

[@lateralus1972]

Jon as a 22 year aerospace structural analyst, I've got a crazy idea for you. 😛It looks like you could get some internal U-channel stiffeners inside of the box section on both sides of the shifter. Look at the back side of the frame at 3:08. You could cut a slit across the lower hole to the center hole to feed your stiffeners in. With it being a diagonal cut, you could get a channel width about 2/3 of the beam width. That plate with the holes isn't doing anything structurally anyway in the middle since torsion and bending flow around that area. The stiffeners could be welded or bolted once they are inside the box frame. Captive fasteners on the U-channel might be easiest. If you wanted to repair the access slit later, it would be easy to weld or add a repair plate. You could increase torsional stiffness as well as relieve stress in the gear box cutout by flowing the stress around it with an alternate load path. I did something similar on a large test fixture with a similar beam cutout. I had room on the outside for doublers rather than having to go up the middle. 😉 Just some crazy food for thought! 🤣 I would be happy to model a mockup in solidworks and analyze it in Ansys for fun! Cheers! Jason

[@JonHimself]

Thanks for the input - have you seen the structural analysis video I did? So the plate in the middle is the gear lever translator mount so has to remain unless I switch at some point to a sequential box. it actually does a fair amount to stop the main back bone collapsing due to that huge cut out in the top. What's also not shown here is how busy it gets inside the backbone when all the cooling pipes, oil lines and junk go back in. Its also dip galvanised, I've tried to TIG weld repair before on other zinc'd parts and really struggle with the porosity, the major issue is you cant always get to the other side of the metal so if you have full penetration you start getting weld contamination, so not too keen on tackling this - but it's a worthy mention though because it's similar to the avenue I want to go down, which is to bond and rivet a C shaped cap over the gear lever aperture. The surface area of the bond is considerable, there is no risk of welding causing issues and burning off the zinc. I plan on riveting it in the corners to prevent peel. The chassis will also be supported by the fully roll cage I want to introduce - I think I can increase the torsion to a level where the lightness of the car wont really impact it. I'll probably get around to doing it this winter as I get more time. I have to select a glue and try and run some physical and virtual tests to ensure it will work. Appreciate the thought.

[@tbmike23]

There we have it. I had a random question in my head about the esprit chassis, and the first thing I stumbled on is the most complete breakdown imaginable of that very thing. Cheers!

[@headit317]

This brings back memories as over the years I have rebuilt/repaired/restored several Lotus cars including a Giugiaro Turbo Esprit . In regard to the "GA" initials on the Chassis, I wondered if it could have been connected in any way with Graham Arnold. As you are probably already aware Graham Arnold was the former Sales Director of Lotus and the President of Club Lotus. I look forward to your videos as the project progresses.

[@JonHimself]

Awesome, I hope the GT2 project will not be my last. Before I bought the Esprit I had a busted Elise, early Elan and Banks Europa in negotiations. The Elan would have been a great investment but my heart is always going to be with the Esprit - but who knows another Lotus might be on the cards one day, I'd love to do something different. Possibly Graham Arnold, I've seen them with different initials on them, they're all over the trim panels as well.

[@eriklombard322]

Wow!! I know it took a huge chunk of time but I think it was worth it. I think this video will be a fixture in Esprit history for decades. The production quality is amazing! I imagine some of your coming videos may be similarly important. Cant wait to see how you build on this.

[@JonHimself]

Thanks as always Erik, you're too kind ;) It could have been a lot better - the camera shake, no textures on the animation etc really bugged me, but I have to get on.... luckily I had a good end to the month so I am going to invest in some new equipment for the next episode. Might even buy that impact driver I always wanted 😋

[@LeeePowers]

WOW,is all I can say,Mate! How does this video only have 2.5k views? One of the most in depth videos about the esprit chassis itself. Good stuff.

[@JonHimself]

I know, right? 😂 Joking aside, as soon as I have more time I will finish the other design studies I have done. Glad you liked it.

[@SlippingTime]

Well done Jonathan! We appreciate all the effort to capture the detail and then share it with the world. For me personally I am captivated in comparing it to mine as well as seeing how yours turned out with all the “elbow grease” to clean it up. Now I need to take a closer look where the hot side may have damaged the galvanized bar on mine. I definitely see similarities in the aging of both our chassis. I look forward to watching the future additions to your video series!

[@JonHimself]

Thanks Dean. I was looking back over the history of the car a few days back and it's obvious the main owner doted on the thing and the chassis is in such good condition. It came up almost as good as new (in some cases it is as new). I didn't go too crazy on the nylon wheel as I want something to key onto when I try painting it. Def check out the chassis beam, it's common on all the turbo cars to a greater or lesser degree but if like this its only surface rust it's easily treated and a heat shield applied over the top.

[@SlippingTime]

I have to clean mine to see that exhaust heated area. I am curious what color you plan to paint it.

[@JonHimself]

@@SlippingTime haha so am I, with the cost of the paint I bought it' going to be what ever they sent me - I've had it 3 months, it's supposed to be aluminium which from what I have seen is a dull metallic grey. It was actually a hard choice, they do some great monotones. Light colours show up rust breaking thru and damage a lot easier in my opinion so I went with that.

[@EvolutionNot]

Mega props to you on such a well done video. Solidworks model, animation, and commentary of the chassis was amazing.

[@JonHimself]

Thanks for the kind comments - it is very much appreciated.

[@keithgarland3404]

Just found your channel, love your lotus build project, explanations etc. The scanning and 3d modelling is interesting, and different to other restoration type videos.

[@JonHimself]

Cheers, hope to add more at some point.

[@markriddle2704]

Beautiful thing to see in such detail. Hats off! Excellent job!

[@JonHimself]

Thanks for the kind comment - more to come on this subject and the suspension soon.

[@kwanyeazy]

Amazing work. I'm in the early stages of planning an EV conversion on my 89'. Solidworks skills are on point!

[@JonHimself]

Thanks a lot of effort went into the model and animation. Be interested to see the EV project.

[@benburris4735]

Fascinating how the rear almost looks like it could be replaced with a stressed engine/trans combo, front 2/3rds does look alot like early carbon fiber monocoque designs. Miata and S2000 share this ethos aswell.

[@charleswahlert3353]

What a tremendous job! Beauty is more than skin deep, and this video is a powerful homage to the design. I am looking forward to you progress :) I have modeled a TCS Europa chassis in the past, but not nearly this accurately.

[@JonHimself]

Thanks for the kind comments - I hope I did it justice with what I had to hand at the time. As someone who works heavily in mechanical engineering it's been a real privilege to have been able to study this (in the comfort of my own home).

[@Andrew-jh5uv]

Jon fantastic series any updates mate...seriously one of the best Lotus resto series 👏👏👏

[@dinkydarlings6812]

Insane detail and knowledge. Love it and keep it coming

[@JonHimself]

Thanks, I hope I did it justice, because I doubt I'll have another chance to do it :)

[@xfsr20box]

Cant wait to see some FEA from this model! Hopefully you will delve into the aggressive load conditions for this chassis!

[@JonHimself]

Sadly time is the killer at the moment - I will mainly be looking at the flexing and stressed areas of the chassis to determine any mods I need to make, anything other than that will be back burner stuff as the priority is building the car. The video should be out sometime next week if I can resolve one of the issues I have right now with the simulation failing. As with most things I am trying to split them down into bite size videos, one of the future steps is to look at the roll cage design for example. The other consideration is to ensure the info I put out is accurate and true, so i am getting the results professionally validated - any feedback and suggestions are welcome.

[@deangiacopassi1951]

I've wondered if adding cross plates to the central tube would stiffen up an Esprit. Looking forward to a bit of FEA on the chasis and modifications. The roll cage should be available for the X180R. Good luck.

[@JonHimself]

Yeah - what is really interesting is the torsion for the std chassis. I wasn't expecting that small vertical part of the gear lever tray to play such a large part in stiffening the beam. Most of the solutions are not cost effective though. one of the ones I thought of was to put a similar capping plate to the under side on top of the beam as the return would really strengthen it up - but would it put more stress into the interface area? End of the day for me the roll cage is what is going to happen so the central beam is not going to be so critical, and I still want it to be a Lotus chassis.

[@kostiantynabramov]

Amazing SolidWorks skills. Animation is great!

[@JonHimself]

Thanks - really like your work as well. Animation took a long while, had to run it on 2017 in the end and it crashed every 10mins or so, I was so glad when it was finished !

[@AdrianMelia-0]

Beautiful. Hats off sir!

[@JonHimself]

Thanks, glad you liked it :)

[@AdrianMelia-0]

@@JonHimself seriously. I found your channel because I’m an automotive design engineer interested in the POP2 scanner, and in other videos you have reviewed it in a way that told be everything I wanted to be sure of, so I subscribed, and now this! Although you didn’t say so much about the scanning this time, I can imagine where you did and didn’t use it, and the whole context of its use reinforces my belief that POP2 is right for me. …And your animated assemblies in CAD take a lot of time and skill to prepare, and they’re really clear… and the chassis itself! What a job you have done so far. I’ll stop now but could go on much longer about how impressed I am. Did I mention the coolness of the background music? … 10/10.

[@edwarddemas5685]

Great job ob the CAD model!!!

[@JonHimself]

Thanks, I'll do an update on it sometime - it's got a lot more done to it.

[@edwarddemas5685]

@@JonHimself Do you have a Europa Twin Cam Special or Elan +2 in your stable to do similar CAD work? I work in Aerospace & Defence and CAD tools as you well know are used extensively from early concept proposals all the way thru final design. And by the way I have an original Europa TCS w its factory chassis. My +2 still has it's original chassis however a Spyder tube frame will go into it.

[@JonHimself]

@@edwarddemas5685 I wish I had, barely enough room for the Esprit I'm afraid.

[@windward2818]

The "hack" for chassis design is to project (estimate, simulate) the torsional rigidity of the backbone or chassis. You can do this by loading the chassis with a long lever arm while fixing the other contact points (which mean bolted to the concrete floor or a metal test plate (which is very handy, but also expensive). Just pick a lever arm length for the loading expected (rigidity) using your body weight and add about 15% more length. Then once it is attached to the chassis you can put your weight on it at different points along its length and see how the chassis flexes using a simple scale. It is interesting because you can actually see how it moves in response to the load.

[@JonHimself]

Yep I really wanted to do this but I have zero space to carry it out and I am rushed to get this car finished - those compromises are hard to bear as I'd love to delve a lot further into this, given having a stripped down chassis is a fairly unique situation to be in.

[@ryanstrefling118]

Phenomenal work Jon! I am currently working on a EV version of this Esprit that will use a Tesla Model S motor. The rear chassis had to be redesigned and I'm having some troubles locating suspension, body mounting points and a few other small miscellaneous things. I was curious if you could give me a hand. I sent you a more detailed email a few days ago but haven't heard from you. I was worried that maybe my email was sent to your spam. Look forward to hearing from you!

[@alwAudio]

Wow, a huge amount of work you've put into this and it's really fascinating. Such an elegant chassis design, nothing is wasted, every part has a clear function (or multiple functions). You can see the 'added lightness' everywhere :). The analysis of those cracks and stresses around the gearchange mounting will be interesting. Do you think you'll be welding, or looking at structural adhesives and patches as per later Lotus cars?

[@JonHimself]

I agree, the more I studied it the more you realise just how good it is. If you look at "Soup Classic Motoring's" series 2 chassis from the 70's its very similar, yet Lotus were able to massively increase the spring rate and over double the engine horsepower with the V8 using an almost identical design. Bonded reinforcement has advantages structurally and practically over welding, which threw me initially, but I will cover that fully in a later episode when I have finished my research. Thanks for kind comments :)

[@ckveder99]

Hey Jon - I just sent you an email about the rear control arm mounting holes - hopefully it didn't get caught in your spam filter. Thanks!

[@bernardwarr4187]

Great information and clearly articulated. Do you think the chassis could benefit from bracing the front and rear sections using relatively small tubing, front to back, perhaps along the area of the sill section? Probably using de mountable elements

[@brayworkshop427]

Amazing to learn about how the chassis is engineered. I’m only a spectator, but I’m really interested in these cars. Question: do you think in theory this design would stand up well to being manufactured out of aluminium and would aluminium stand up to the heat of the turbo. Great video! Thanks.

[@JonHimself]

Yes as someone who works in engineering and is into design, it was a great opportunity to really study it. When you use different materials you should change the design to benefit from them. Making this out of aluminium (depending on the grade) would be cost ineffective and over weight. When you look at the Elise for example it is similar in weight but a lot stronger in torsion due to the way it is constructed and bonded (tub construction) to take advantage of the design material. Aluminium significantly weakens around 600c, the turbo has damaged the zinc which melts at $20c so I dont think an aluminium stressed member here would be a good idea.

[@brayworkshop427]

@@JonHimself Thanks for the explanation. So the esprit uses the best material for its specific design. I’d love to see a bare chassis CAD model of the Elise and the Alpine a110.

[@JonHimself]

@@brayworkshop427 maybe one day - if I finish the Esprit, a lunatic Elise is certainly on the cards.

[@cbdzcbdz]

I would love to see a video of your work flow when creating the CAD model. Was this scanned, then each component modeled based on the data from the scan?

[@JonHimself]

Firstly I just looked over it to see how it would have been constructed and identifying the piece parts. Due to the primitive shapes most of the parts didn't need to be scanned - I used manual measuring such as dividers, rules, an inclinometer and wire triangulation to determine each part which was then individually modelled as shown in the assembly animation. I also have access to Lotus' jig dimensions from the workshop manual so I could check the critical dimensions. Scanner was only used to grab some of the complex shapes such as the engine mounts and the gearbox mounts to speed up the process as the chassis obviously cant fit on a desk so the next best thing is to digitise and work off a virtual model instead of walking back and forth to take dimensions and risk getting things wrong - 100x faster too. Oddly if you scanned this part it would probably be less accurate due to compounding / stacking tolerance errors of the scanner which is why I use wires, same way as you would jig an aircraft. Also this is a 'live' part which has slight fatigue and actually flexes when loaded up so this model is actually simulating the chassis when it is full loaded. I took great effort to get it right, about 1 month of 1-2 hours every evening to ensure it was as accurate as possible, as I don't intend to do this job more than once :)

[@seanhiggins704]

@jonHimself this is amazing. Great job. I've just torn down my 89' to the chassis as well and bought a 3d scanner just for this occasion myself. I'm sure you've been asked a lot, but do you have this model available anywhere?

[@west-cam]

Great video Jon. LIke Kwanyeazy, I'm getting started on converting an 88 to EV with a Tesla small drive unit. however, this will require modifications to the rear "hoop" chassis member. I began making the revisions in Fusion 360 using a Lotus chassis I pulled from GrabCAD, but the geometry was not correct. Any chance you'd be willing to share your Chassis CAD file?

[@JonHimself]

Hi Matt, send me an e-mail so i can reply better that way (link in the about page) - I can convert the rear tube section to an STL which should help.

[@west-cam]

@@JonHimself Hey Jon, sent you an email earlier today. thanks.

[@HenryStaals]

Is it possible to stiffen the chassis to stop the flexing .

[@detrmichi]

I would like too make a scale model of the chassis, what are the dimensions of chassis?

[@williamtimmons6149]

Excellent, wish something similsr

[@williamtimmons6149]

Cont'd similar for fiberglass monocoque Lotus Elite which is commonly thought of as another Lotus backbone chassis csr

[@JonHimself]

yep, there was the birth of the composite monocoque right there in the 1950s

[@atillasevic6422]

Hello,l will repair my Lotus.your job is verywell.Can you help for my project.l realy need this scan data.If you can help me ,l will be hapy.