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Esprit Turbo project car - part3 - the further continuation


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If it were me, i'd have correctly anodised Compomotives for car shows and have a set of BBS for everyday road use.    

I know its not the mainstrean view, but I prefer the integrity, simplicity and symmetry of a painted BBS over a polished Compomotive!    

 

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1 hour ago, 910Esprit said:

If it were me, i'd have correctly anodised Compomotives for car shows and have a set of BBS for everyday road use.    

I know its not the mainstrean view, but I prefer the integrity, simplicity and symmetry of a painted BBS over a polished Compomotive!    

 

Swapping between 4-stud comps and 5-stud BBS is a lot of work though!

I am hugely biased of course :) but I like my BBS with satin black inlay then full-face machined the best. They are still looking the same as when I had them done a few years ago despite the machined face being bare alloy. They shimmer with a rainbow effect in the light because of the invisible concentric marks.

I really dont like the original grey BBS, they spoil the cars and were a step backwards from the Comps. I dont know why more people havent done what I did, apart from Car SOS Tim Shaw who seems to have done it to his. Although many people have had the rims of the BBS diamond-cut which is a good halfway step.

 

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Well one wheel lip is away for anodising. Its an experiment to see what sort of finish you will get. Because the lips are over 40 years old there are a lot of imperfections. Each of these may show up, we will see. I will post some pictures when it comes back. When I get the wheel back together thats it. Just tuning to get done.

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Fab in the quest for a perfectly smooth ride there is one thing you overlooked. Tire roundness, unfortunately there is always some variation due to manufacturing. I had my tire guy shave mine the least amount to get a perfectly round tire, made a huge difference in reducing the vibration. Along with your tire balancing it may help.

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Hi Roo, thanks yes your right. I think the tyres are off round as well. I have discovered the cx500 casting is very poor. Close inspection on a lathe revealed the centre has been machined off centre by 0.1 mm. I measured the run out on several lips. It varied between 0.3 and 0.8 mm. I suspect this is the same on all split rim wheels. When I reassemble the wheel I intend to assemble it and loosely bolt it up, put it on the hub and adjust the lip position to achieve the best possible placement. There is a little movement in the lip position before the bolts are tightened. Because the mass of the wheel is very low I suspect the tyre effect maybe significant. My engineering friend does wheel repairs all the time he said he has seen far greater run out that run fine after balancing. The Lotus steering seems very sensitive to imbalance. 
There is a lot to assembling these wheels beyond bolting them up and getting a seal, as I have found out through experience. 
It will be very interesting to see how well the Anodising works. If its sucessful I may take all the wheels apart and rebuild them again. This time using a dial gauge and finally a road force balance. They probably have these machines all over the USA. I can only find two within 60 miles of my house. Maybe a business opportunity for someone?  
How did he shave the tyre, I might have to try that as well?

 

 

 

 

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That all makes sense, the very large scrub radius of the Esprit suspension geometry would tend to amplify any imbalance fed through the steering.

The CX500 casting is indeed poor quality. I spent hours examining and measuring the one I borrowed to do a CAD model from and its not even rotationally symmetrical, the "webs" vary in width all round. 

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10 hours ago, Lotusfab said:

Hi Roo, thanks yes your right. I think the tyres are off round as well. I have discovered the cx500 casting is very poor. Close inspection on a lathe revealed the centre has been machined off centre by 0.1 mm. I measured the run out on several lips. It varied between 0.3 and 0.8 mm. I suspect this is the same on all split rim wheels. When I reassemble the wheel I intend to assemble it and loosely bolt it up, put it on the hub and adjust the lip position to achieve the best possible placement. There is a little movement in the lip position before the bolts are tightened. Because the mass of the wheel is very low I suspect the tyre effect maybe significant. My engineering friend does wheel repairs all the time he said he has seen far greater run out that run fine after balancing. The Lotus steering seems very sensitive to imbalance. 
There is a lot to assembling these wheels beyond bolting them up and getting a seal, as I have found out through experience. 
It will be very interesting to see how well the Anodising works. If its sucessful I may take all the wheels apart and rebuild them again. This time using a dial gauge and finally a road force balance. They probably have these machines all over the USA. I can only find two within 60 miles of my house. Maybe a business opportunity for someone?  
How did he shave the tyre, I might have to try that as well?

 

 

 

 

A good race tyre shop will have the machine to shave tyres. Essentially it's a lathe that uses a tool to shave off small amounts of rubber evenly around the circumference.

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  • 2 weeks later...

Wheel is finally back together. It just needs a balance. The Anodising came out quite well on my spare lip, although it doesn’t cover any flaws, being forty years old there are bound to be some. For authenticity I may have all the wheels done. Once the wheel is back on I need a road force balance and then its a rolling road tune up. 
I wouldn’t recommend split rims for anything, but looks and pottering around. The later BBS wheels are far superior, although split rims are used for racing! 😬😬I think I know two much about how they are constructed- 20 bolts isn’t many! Just like the millions of rivets, bolts and components in an aircraft it doesn’t do well to think too much about how its constructed before you fly! 😀😀😀😀

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I think about that all the time Fabian, especially in engines. As you say, best leave those thoughts behind, and hope the engineers have worked out the maths.

I think racing split rims may be made to far higher tolerances, certainly these days. Machining and design has moved on massively in 40+ years. As can be witnessed by oil leak free engines etc.

I'm sure you've noticed how poor the plastics are on the Esprits. It just goes to show how polymer science, or whatever it is called, has moved on since the 1970s. It seems the Esprit was made close to the beginning of their wider automotive use. My 1960's car has interior trim in bakelite! Though some high quality (aero grade) vinyls also.

Found this aspect very interesting during my own S1 restoration. Perhaps having a Dad who worked at ICI on these relatively new synthetic materials throughout the 1960s and into the late 1980s.

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Lotus bought their own vacuum forming machine which they seemed to be quite proud of and would show off on factory visits.

Thats why all of the crappy ABS parts exist on the Esprits.

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I wonder if those 3 piece wheels would have originally been trued up as a matched set after final assembly as the chance of getting 3 large pieces to run true would be pretty tricky.     

 

 

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I doubt it judging by the quality. The centre casting is very very poor, they don’t bear up to scrutiny. The lips all have variances. I have assembled a wheel that is as good as these can be, given all the limitations. It will be interesting to see how well it runs. It looks pretty! 
heres the Anodised wheel lip, not bad really.FB631C05-412F-4FD7-A79E-3D8870C42A2B.thumb.jpeg.e86f6c290b0e1b9c09f7a7a224869928.jpeg

 

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When I spoke to the Compomotive director on the phone doing my dry sump he said the reason they moved to the external fitting centre like you see on many dry sump CX’s is to increase strength/rigidity and to stop deflation issues on the steering wheels. Shortly after they moved to CX501’s with the 30 hole pattern.

The early wheels do look far better though but as Fabian says you pay the price with quality.

I like the anodised outer, when I enquired I was struggling to find someone to undertake on old aluminium. I would have done mine for sure.

75AB0420-146B-4E03-B222-D5D0C832F006.thumb.jpeg.ea762b9cd9472ff273b346290c08c7d6.jpeg

My set after I refurbed them, you can see the later type fronts.

Dave :) 

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Do or do not, there is no try! 

 

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4 minutes ago, LOTUSMAN33 said:

When I spoke to the Compomotive director on the phone doing my dry sump he said the reason they moved to the external fitting centre like you see on many dry sump CX’s is to increase strength/rigidity and to stop deflation issues on the steering wheels. Shortly after they moved to CX501’s with the 30 hole pattern.

The early wheels do look far better though but as Fabian says you pay the price with quality.

I like the anodised outer, when I enquired I was struggling to find someone to undertake on old aluminium. I would have done mine for sure.

75AB0420-146B-4E03-B222-D5D0C832F006.thumb.jpeg.ea762b9cd9472ff273b346290c08c7d6.jpeg

My set after I refurbed them, you can see the later type fronts.

Dave :) 

They look great Dave. Is your red car restored now? 
on another note have you ever come across a measuring kit made by Dellorto to calibrate pump jets?

I found an old school polisher who did the lip.  He says he can do all the others for me. Maybe a winter job, I want to do some miles this year.

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84DB3A41-DFD0-4BAA-B4E3-94846B780601.thumb.jpeg.3595f15a95d561a32a4fe43734f1a1a2.jpeg

This was the last photo he sent me when he put the wheels back on I gave him later, I will have to email to see if he got the respray done.

No I’ve not seen a pump jet calibration kit, I would be interested though as about to set up my new carbs accelerator pumps on my rig before starting the JPS for the first time. I have a rebuilt set ready to go on the S1 but will hold off putting fuel through these for the time.

Dave :) 

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Do or do not, there is no try! 

 

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4 hours ago, Lotusfab said:

I doubt it judging by the quality. The centre casting is very very poor, they don’t bear up to scrutiny. The lips all have variances. I have assembled a wheel that is as good as these can be, given all the limitations. It will be interesting to see how well it runs. It looks pretty! 
heres the Anodised wheel lip, not bad really.FB631C05-412F-4FD7-A79E-3D8870C42A2B.thumb.jpeg.e86f6c290b0e1b9c09f7a7a224869928.jpeg

 

Hi Fabian,

Where did you get that anodised? (sorry if it has been stated already)

cheers

-Chris

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Well looks like I wont be driving this any time soon. Just had the tyre put on. Balance now perfect and wheel running true, only 10 g needed. Trouble is its leaking! The problem is the tyre shop. They used 42 psi to seat it. When it pops it breaks the sikaflex seal. Hours of work undone in a few minutes! Need to find another shop or way of seating the tyre.

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Think the weak link here is the garage method of tyre install. I think I will make the centre again and try installing the tyre myself with tyre levers.

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