Suspension Parts Requirement - Wishbones, TCAs, Top Links

[Brit-Car-Nut]

the rubber bushes are getting hard to find since Lotus has decided not to continue them. They lowered the prices to move them out, so don't let the price fool you. FGS will continue to make the bushes but will sell them at their huge profit.

The other portion of my post was that any plastic bushes are horrible and don't belong on a car driven anywhere but on a track and then, if you knew anything, you would never use plastic as it flows (changes shape under pressure) too easily to keep the geometry accurate while racing. Track days and autocrosses migh get buy, but serious suspension design has no use for polymers (affordable at least). I am sure someone will come up with a kevlar bush that behaves like metal, but why not just use metal.

The design of the bushes was factored into the wishbone design and getting identical replacements will require analyzing the stock bushes for metal and rubber characteristics. You can't "find" a similar bush and just turn down the outer and bore out the inner. You should make sure the metal bits are the same size and the rubber compound and pliability are the same.

[theelanman]

Lotus decided not to continue making the bush as current methods and chemicals did not allow for a comparative bush to be made......
the 'replica' which was ditched did not have the longevity of the original due to the composition of the rubber.....

[theelanman]

The design of the bushes was factored into the wishbone design and getting identical replacements will require analyzing the stock bushes for metal and rubber characteristics.

the whole suspension set up was copied.....down to the shore rating......

[theelanman]

plastic bushes are horrible and don't belong on a car driven anywhere but on a track and then, if you knew anything, you would never use plastic as it flows (changes shape under pressure) too easily to keep the geometry accurate while racing.

does rubber not deform?.....I think you may find it has a wide and varied range of elasticity.......starting with just temperature....

[Brit-Car-Nut]

Lotus decided not to continue making the bush as current methods and chemicals did not allow for a comparative bush to be made......
the 'replica' which was ditched did not have the longevity of the original due to the composition of the rubber.....

Not true at all. Lotus doesn't sell enough anymore to justify the minimum purchase quantity. This is because their S2 arms (made by FCS) come with bushes installed already.

[Brit-Car-Nut]

plastic bushes are horrible and don't belong on a car driven anywhere but on a track and then, if you knew anything, you would never use plastic as it flows (changes shape under pressure) too easily to keep the geometry accurate while racing.

does rubber not deform?.....I think you may find it has a wide and varied range of elasticity.......starting with just temperature....

Of course rubber deforms. BUT it does so more uniformly than plastic/poly so you can design a system that follows the same geometry continuously. AND it doesn't require continuous greasing to keep it from squeaking like a bad hinge. I have seen plenty of cars with alternative bushings from just about every design concept from rubber to plastic to poly to brass and even some hardened aluminum but for street use, rubber is the only way to go for the smoothest and quietest ride. This is MY OPINION after running a successful auto shop for close to 40 years and 25 years maintaining race cars for my friends and customers.

Jamie: Keep at it. I have a lead on a supplier that provides proper (to factory spec) bushings for Elise and Esprit and is willing to do Elan bushes if anyone asks for them.

[theelanman]

Lotus decided not to continue making the bush as current methods and chemicals did not allow for a comparative bush to be made......
the 'replica' which was ditched did not have the longevity of the original due to the composition of the rubber.....

Not true at all. Lotus doesn't sell enough anymore to justify the minimum purchase quantity. This is because their S2 arms (made by FCS) come with bushes installed already.

they stopped making the S2 arms before the bushes.....

[Elanlover]

Of course rubber deforms. BUT it does so more uniformly than plastic/poly so you can design a system that follows the same geometry continuously. AND it doesn't require continuous greasing to keep it from squeaking like a bad hinge. I have seen plenty of cars with alternative bushings from just about every design concept from rubber to plastic to poly to brass and even some hardened aluminum but for street use, rubber is the only way to go for the smoothest and quietest ride. This is MY OPINION after running a successful auto shop for close to 40 years and 25 years maintaining race cars for my friends and customers.

I have to say that I've heard something similar in the past. They may be more "durable" in terms of lifespan but don't perform nearly as well. You can find poly engine mount bushing on eBay that aren't cheap but I've ben told to avoid them if possible for these reasons.

[dapinky]

Just to thow my 2p (or 2c) worth into the mix......

Both arguments are correct in some part, but in my experience I have established the following:-

Rubber bushes are the best for the job IF THEY ARE WITHIN ORIGINAL SPECIFICATION.....

...by that, I mean that rubber degrades over time with exposure to the elements - it is generally a slow and continual process so as a driver you don't tend to notice until you replace old bushes with new ones, whereupon you notice the difference.

As some 'new' bushes are really what is left of the original manufacturing process, they could well be 25 years old when first used. (would you like to use 25 year old tyres on your car? I wouldn't!)

However, if they have been recently re-made to original spec, then that would be my first choice (generally).

That said, I use Poly bushes in my competition cars as they don't degrade over time - they just give up at some stage in their life. Often due to the material 'shattering' (although it doesn't really fall apart as such)....

I also use them in the elan on SOME components - one of those is the rear wishbones - along with the shock absorbers (top and bottom) as I like the consistancy they provide. (but i replace the shock absorber ones every few years anyway).

I also intend to use poly on the top front wishbones, but keep to rubber on the bottom ones.

Fot the raft, I'd stick to rubber, and for the engine mounts/dampers I'd also stick to rubber.

I only use 'good quality' poly bushes which don't require lubrication - some of the cheaper ones out there can (an do) as John says squeek a bit.

For ease of replacement, it is hard to beat poly if they are a 'loose/push' fit, but if they are bonded to an outer steel sleeve, then the tollerances are very important.

The other consideration when deciding on what is a suiatable replacement is the nature of the bush (ie, what is it actually doing) - if it is just to locate a metal unit and reduce vibration it will have a different composition to one which has a rotational element to it (like on a wishbone).

A bonded rubber rotational bush needs to be of a suitable strength to allow it to 'wind up' as the component moves (drive over a bump etc) and return to it's natural resting position afterwards (hence why some bushes should only be tightened up with the car at its normal ride height/load)....

...poly bushes are not usually like that - the inner sleeve isn't bonded to the poly - so they can be tightened up anywhere you like and the car will still sit right when it settles.

In this case, the material of the bush has to be of a suitable composition to give the same effects as a rubber one which winds up - not easy to achieve, and it is more than just replicating the shore value of the original rubber - but the suppliers/manufacturers I use are well skilled in their trade, and I generally get better results with new poly than i did with old rubber!!!

It may well be the case that in order to fully replicate the behaviour of the old design rubber, the bushes need to be either thicker or thinner than original, so the size of the 'hole' may need to be changed anyway - but to be honest, not really a major consideration on a road car, and even on a track car, probably not much more than a compromise anyway.

In the past I have had cars with no rubber bushings (for pure track use) which use a series of rose joints (rod ends) to set the suspension for the conditions on the day - but such a system would be really cr@p on a road car.

It's all a bit 'horses for courses', coupled with what we can actually get, and at what price.

If OE ones can be sourced, then that would be easiest - but if you need to get some made, it will depend on volume of sale to decide if rubber is worth a production run - poly can be made in smaller batches far cheaper....

[Jeemy]

I've contacted 22 different engineering firms with photos and diagrams regarding the rear wishbones. More soon.

Bushes, I still have no idea on but I have one lead meant to be getting back to me.

[Jeemy]

Well, um, great news! That was surprisingly fast. Group Buy started!