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Yep :-)  thats why the Elite and Eclat shouldn't be lowered with shorter springs:

There is no way of adjusting the rear camber  to compensate as the car is lowered, causing a lowered eclat or elite to squat on the inside of its rims. The rear suspension follows a prescribed arc as the suspension compresses, allowing the car to effectively lean over on its outside tyre as the car rolls into a corner. I believe this body roll/negative camber relationship is what provides the Lotus handling magic and if you drop the ride height it upsets the roll angle.

We had a breif discussion of this on Charlie Crokers air ride car thread. For it to work effectively, its got to be riding at standard ride height - and for me, that kind of defeats the the point of installing air ride. An excel would have been a better choice for installing variable ride height, but Charlie didnt seem fussed as it was designed for the look, and to be a talking point on the scene, rather than cornering performance.

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Hi Dunc.  Don't the shims between the diff and drive shaft adjust the camber?  With the drive shaft acting as the upper suspension arm and the radius arm effectively being able to move in any plane due to the rubber mount the hub/wheel still moves in the same way as if it  was  pivoting on the lower bolt, doesn't it?  The effect of the drive shaft as the suspension goes into bump (or droop) causes the whole radius arm (along with the hub carrier, of course) to twist on it's mount (along an axis in line with the length of the car).  I don't believe it acts like a "swing axle".  The motion is just the same as the Excel, but achieved differently.  You still have unequal length suspension arms.  You could easily adjust the camber with adjustable rear lower links if zero shims in place didn't give the desired setting.  That's the problem with fitting a different diff - unless the drive shafts are the same length as the originals the suspension geometry is upset in bump/droop.

Pete

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Hi Pete,

I think adding shims between the drum and flange will add a smidgen of positive camber, but I suspect only by a tiny bit as the radius rods in play. I'm not sure what it will do to toe - widening the track behind a fixed pivot would ordinarily invoke some toe in, but given the radius rod is behind the shaft, the hub will splay towards toe out at the same time?

My point was more that you can buy adjustable upper wishbone mounts/links for other conventional IRS cars that make adjustment a breeze, but on the elite and eclat it becomes a proper pain in the @rse.... 

 

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Hi dunc - you could easily make up adjustable rear lower links using a turnbuckle - perhaps Mike Taylor's Excel kit could be used, or make some from scratch using rod ends (I don't think it would add too much harshness since the diff and radius arm are rubber mounted).  I've not done an alignment on an Elite yet - before I fit mine on my restoration would it be worth converting them?  I'd be happy to make up more than one set if you're interested, and think it would be worthwhile.  What do you think?  You're right with the toe I think - increasing negative camber by lengthening the rear link would increase toe, but this could be remedied with the shims at the front end.  You would then have easier adjustment of camber and toe.

Pete

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But Pete are you saying you can improve on the rear geometry as designed?

Tom

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Hi Tom - no, just make it easier to adjust so you can alter/experiment with the settings if you want to.  Messing about making up shims to adjust the camber seems like a lot of trouble once the drive shaft are bolted on (although you've still got to mess about with the washers on the forward end of the radius arm).

Pete

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Not sure why you would want to alter the rear suspension design on the Elite. I have driven mine into corners that few cars could do as fast and as comfortable with ease of control that can only be described as awesome. And most people, owning this car, seldom will reach the limit and really can't with the tires available today on the 14 inch rims it came with. That is why I went to a 16 inch wheel to be able to buy Z rated high performance tires.

I realize that these wheel bearings do take a lot of stress and have read where they many times only go around 25,000 miles before needing to be replaced. I have yet to replace mine but think that I may go to a larger bearing, in the future, like used on the older Jags and  Corvettes as they are the same design and don't have any issues like the Elite does. I think replacing larger u-joints as well for the same reason is a good idea especially if you have more power like I have and want to use it.

Others have tried to alter the design with an upper link but it doesn't work all that well from what I have read.

These cars where made and fine tuned to be driven fast and Colin's favorite driver was an Elite. This is the same rear end design that was used on Lotus's F1 cars in the early 60's so it is a tried and proven system even though it may be somewhat flawed.

Like many flawed or weak designed things on the Elite, one can try and fix them or just live with them and fix it when it breaks. Talking about it and making a change for the better are two different things and I would be surprised if anyone could make an improvement with this design without really making a number of major changes in the total package design and make an improvement from a company that dominated F1 grandprix racing during the time this car was produced. Many have tried and I don't know of any that have been successful.

Just my two cents.

Richard

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My original post was just to explain my "so that's how it works" moment!  I'm not trying to alter the basic set-up at all - as you say Richard it may be flawed but it's fundamentally sound.  The talk of making adjustments evolved just as part of the discussion - making those adjustments easier can only be a good thing surely!   

Pete

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¬†I think the poor availability of the original tyre size could be a good reason for adjustable suspension geometryūüĎć

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The talk of making adjustments evolved just as part of the discussion - making those adjustments easier can only be a good thing surely!   

Pete

You are right Pete in that, anything can be made better and it all starts in ones head thinking about it. Lotus did have great suspension and chassis designs as proven in their domination of grandprix cars and these designs ended up, many times, in their road cars thankfully.  But you need to remember, a racing car only needs to stay together for, at best, a couple hundred miles to be successful and Colin only built street cars to subsidize his racing program. These are not 100,000+ mile commuter type autos. They will need much more maintenance that most road cars that are built to get to work and the grocery store and back home.  Not to go out and be Joe racer on the back highways like many who buy these types of cars want to do. 

It would take a bunch to improve the road holding design and put it on an Elite, IMHO, for one simple reason and that would be that the pickup points on the chassis are very difficult to change as it is so light weight in construction being mostly thin sheet metal.

The reason the Elite and many other Lotus street cars can hold the road so well in the corners is that the whole of design keeps the tire flat on the road giving maximum tire contact (adhesion) with the road so as to take advantage of the whole width of the tire during hard cornering.

Hey.... Lotus cars being so finely tuned are the reason many, including me, buy Lotus street cars in the first place.  I have even, in the past, tried to buy a couple of Lotus racing cars but the deals fell through not being my fault whatsoever, sad to say. A Lotus 11 and a 30. Dirt cheap too in the day !!

 

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4 hours ago, Elite 4.9 said:

 

It would take a bunch to improve the road holding design and put it on an Elite, IMHO, for one simple reason and that would be that the pickup points on the chassis are very difficult to change as it is so light weight in construction being mostly thin sheet metal.

 

Although you could put Excel running gear under the Elite, which is just as competent a setup, and much more bulletproof!

Richard

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1 hour ago, rjwooll said:

which is just as competent a setup

Is it really? It is more bulletproof surely, but not quite as good in execution I have heard. Would like to hear from those that have both or have driven both to compare notes.

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5 hours ago, Clive59 said:

Is it really? It is more bulletproof surely, but not quite as good in execution I have heard. Would like to hear from those that have both or have driven both to compare notes.

Yes, it would be interesting to hear people's experiences. I doubt it was a backward step as it was overseen by no less an engineer than Mike Kimberley (who won 'the war of the top link' with Chapman, before his death).

There used to be a general misconception that the Excel had 'Toyota' suspension - which I initially shared. In fact, all that happened was that Lotus started using certain Toyota components as they were well engineered, durable, and more cost-effective. I believe the top link design itself first saw light of day in the Esprit Turbo, the original suspension/driveshaft design of the Esprit being similar to the Elite/Eclat and probably not able to handle the Turbo power output.

I've also heard mixed reports about the Spyder conversion; some say the geometry was flawed, but I read a report somewhere that this may be due to one of the joints being incorrectly installed. I wish I could find it! The Spyder Donnington V8 conversion replaced the whole setup with a Jag irs and diff.

Cheers, Richard

 

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1 hour ago, rjwooll said:

Yes, it would be interesting to hear people's experiences. I doubt it was a backward step as it was overseen by no less an engineer than Mike Kimberley (who won 'the war of the top link' with Chapman, before his death).

There used to be a general misconception that the Excel had 'Toyota' suspension - which I initially shared. In fact, all that happened was that Lotus started using certain Toyota components as they were well engineered, durable, and more cost-effective. I believe the top link design itself first saw light of day in the Esprit Turbo, the original suspension/driveshaft design of the Esprit being similar to the Elite/Eclat and probably not able to handle the Turbo power output.

I've also heard mixed reports about the Spyder conversion; some say the geometry was flawed, but I read a report somewhere that this may be due to one of the joints being incorrectly installed. I wish I could find it! The Spyder Donnington V8 conversion replaced the whole setup with a Jag irs and diff.

Cheers, Richard

 

Yup, Jag LSD diff and inboard discs. Top link rear suspension too. Problem was Spyder mounted the front bush horizontally, causing rear steering because of the bush flexing. Once this is changed the rear handles as it should, and the UJ's (only 1 per side now, the other a CV joint) last 'forever'.

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I read the "critique" from an engineer owner who had fitted the spyder top link conversion to his elite published his thoughts on the web (his was not a spyder donnington - just an elite with a Spyder top link mount kit fitted, so retained the lotus diff and shafts, but with modified hubs and a CV joint driveshaft from a Sierra). He felt the height of the inboard mount for the Spyder top link on the chassis was too low, and wanted to experiment with welding a "tower" onto his chassis to raise the position of the inboard upper link mount. He described "roll oversteer" and after spending a fair bit converting his car, went back to the standard Lotus setup, noing a vast improvement. I recall he wrote that fundamentally he still believed a top link was the way to go, but wanted to develop it to make it work to his satisfaction before refitting it.

I dont think he ever updated the blog again, which was a shame as he was knowledgable and had done a proper engineering analysis/appraisal.

I recall Spyder used to produce a number of chassis "upgrades" for our cars, with tubular rear arms offered (I have a pair) and I seem to recall a "wide track" front end conversion allowing the use of a vented disc from a ford.

A good friend has recently acquired a Donnington, so hopefully we can have a play with it and find out what its like. He reckons it needs setting up as it doesnt seem to drive very well. I have one of those Laser pointer alignment things that I bought myself for christmas, so I'm hoping we can sort it out and get everything pointing in the right direction. Too many projects... lol

On the handling of the eclat v excel - I've owned both and they drive totally differently to each other. Both are undoubtedly fine handling cars, but my prference was for the Eclat. Admittedly my Excel was tired and desperately needed a new set of dampers, so perhaps an unfair comparison, but I preferred the way the eclat drove and handled. Perversely, I also preferred the eclats brakes, being very disappointed in the braking performance of the all round discs of the excel. I suspect the single pot calipers on the excel are the week point in comparison to the triple pots up front on the elite/eclat. My feeling was that some fettling of the standard brakes in the Excel could yield huge improvements - I looked at a Previa ABS twin pot caliper, which gave a bigger clamp area and looked like it would bolt straight up to the carrier, but sold the Excel on to a new owner before investigating further.

Dunc 

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The UJ joints are landrover S3 propshaft joints and they survive in Landrovers without issue. Our issue is the wider angle of deflection and the shocks that the suspension transmits into the joint.

I did some research a while back and a supplier mentioned going for a joint with a thrust washer would help. These joints have been on the left hand driveshaft of my eclat taking punishment for some time without failure. I thought I had finally broken them during our NC500 run last summer, but stripping it down showed the movement to come from a knackered diff rather than movemenmt in the joint.

Dunc

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That's very interesting information Denis247 and Dunc.

Denis, do you have any drawings etc showing the bush in question and its mounting?

Cheers, Richard

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I've taken the opportunity to rebuild my drive shafts with Hardy Spicer 163s - described as "wide-angle heavy duty".¬† It'll probably be another year before they get tested though¬†ūüôĄ.

Pete

 

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On 01/02/2020 at 12:48, rjwooll said:

That's very interesting information Denis247 and Dunc.

Denis, do you have any drawings etc showing the bush in question and its mounting?

Cheers, Richard

For some reason Spyder changed the orientation of this bush to horizontal from vertical The result was that the wishbone was able to move quite a bit, causing rear wheel steering. Mine has this bracket removed and now has a bush like the one used in the front lower wishbone, and problem resolved.

 

DSC00720 ed.jpg

Edited by Denis247
typo

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I like that removable link between the diff pickup points.

Pete

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53 minutes ago, EXCEL V8 said:

I like that removable link between the diff pickup points.

Pete

Makes dropping the diff out easier, and adds strength. You can make out the rear top link mounting point too.

 

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I recall he wrote that fundamentally he still believed a top link was the way to go, but wanted to develop it to make it work to his satisfaction before refitting it.

If you follow Lotus's F1 evolution in chassis design in the  later part of the 1960's, you would see they went from a F1 design that the Elite had a close copy of, to a design that had a top link and didn't use the drive shafts as upper links. It is a sound design and does work better but uses more parts and is more complicated. And most other F1 constructor teams followed suit as did much of the road production design of suspensions in sports cars and now in many other cars as well.

It just works very well but it took Lotus to figure it all out early on. Lotus had another company, other than their road car production company, that did work for many other car manufactures of street type cars and help them figure out their suspension designs as well. Not sure this Lotus company still exists and are still in business but, some companies actually bought Lotus like Toyota, and GM to finely get a similar system working in their street cars.

The Toyota MR2 and the Corvette were just two customers that benefited and used Lotus Engineering to help them in suspension design. Smart move on their part for sure.

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One other factor that no one has as yet mentioned is the roll over center that the whole design dictates of the rear suspension on the Elite which is just above ground level. All the geometry in this design works to put it there which also makes for one VERY fast cornering car. I have taken corners so fast, I though I was afraid, in mid corner, of over doing it and may be in trouble when in fact, I wasn't even that close to the limit. No sliding whatsoever even on very old nearly worn out tires, years ago. It actually blew my friends away that were riding with me. They were simply amazed at the road manners of this car. So was I!!

This is one thing I love about the Elite, in that, one can drive very enthusiastically without getting close to the limit and enjoy this car like it was made for such fast driving. It was touted, by the Lotus factory, as being able to corner 15% faster that the Europa which is saying quite a lot. Some Europa guys think this could never be but I have driven both cars and believe it. The stance of the Elite is very similar to two cars considered to be the top performers of their day, the F40 Ferrari and the M1 McLaren both of similar wheel base, height, width and weight.

Lotus didn't go backward in design and you will never see an F1 car with the Europa dimensions. This is not to say the Europa is a bad design, as I think it is a great one and love driving them. It just is too narrow and small for fast corning like the Elite can do and similar more modern Lotus cars.

The Elite could very well have been a two seater as it has the same wheel base of the older Corvettes and no one would think this car would ever be a 4 seater.

Just imagine what the body could look like with just two seats?                                                                                   I think all Lotus had to do was make a two seat version of this car and sales would have gone through the roof along with a Rover aluminum V8 to match. 

And maybe even a rag top. 

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I know what you mean,¬† but it might get mistaken for some other designsūü§Ē20200217_222538.jpg.b824282b34cbf3703d89916fcfa1ffdc.jpg20200217_222524.jpg.308d17854c2f148b1a19815dc5c0eb6b.jpg20200217_222504.jpg.25d680bc1d66dcf8c7c2f933c7ed844c.jpg

ūüėÜI always think it's the back end that makes the elite stand out ūüėÄ

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