Lotus Elan

Adjustable rear Konis

PostPost by: jono » Tue Aug 14, 2012 9:41 pm

This has been done before but I thought I would re post as my question is quite specific.

I fitted Koni Classic adjustables (the red ones) to the rear of my Plus 2. With this type you have to set them off the car.

I obviously got the initial settings wrong as the car was very, very soft at the rear with the body back in place.

I have just whipped one off this evening and I seem to have them set on minimum + 1/2 a turn. I seem to recall this is what Tony Thompson recommended (even through I did not buy them from him) but he may not have realised they are Koni Classics. Anyway, by any measure they are simply too soft.

The question is can anyone give me a guide on where I should be with the setting. I am almost inclined to set them to max as that feels about 'right'. I have 110lb springs by the way and TTR fast road shocks up front.

I seem to recall Andyelan was active on the old thread and was looking into this very issue however I am not sure he posts here now. If you do, Andy, I would appreciate any new light you can throw onto the matter.

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Jon
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PostPost by: cal44 » Wed Aug 15, 2012 2:13 am

Jon,

I believe they are full oil and not part oil and part gas, right?. Keep in mind the oil shocks always are softer than gas shocks. I prefer oil over gas in the older cars as that is what most (not all) were designed to use.

Also remember when you increase (make harder) the adjustment the shock has less rebound movement than a softer setting. I use soft settings for the street because of bumps, pot holes etc.

I have used oil Koni's for thirty years and still use them. And yes, having to take them off to adjust them is a pain in the arse and frankly in todays world antiquated at best.

You want a harder ride.........go to higher spring rates, shocks are all about the rebound. I don't change much on the Lotus as think Mr. Chapman had it figure out.
I ain't no expert so if someone has a better thought I am always up for a good learning.
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PostPost by: jono » Wed Aug 15, 2012 7:22 am

Mike,

Thanks for these comments. Yes, the shocks are full oil - old school type.

There is a very wide range of stiffness in the adjustment from lightest where you can pump the shock rod in and out by hand very easily to full hard where it takes considerable effort to pull out the rod - probably 15 seconds with constant effort.

The question is where to set it (given that as you rightly say it's a pita having to take them off). I guess I would be happy to get them right enough to 'shake the car down' even if it meant some further fine tuning down the line.

I do have marginally uprated springs at 110 lbs (stock are 95 lbs I think).

The problem is that when set as I had them the rear of the car appeared to have no damping at all - it pushed down very easily and rebounded straight back up. A recipe for chronic understeer I suspect. The front units are TTR fast road set minimum and the front is quite stiff in comparison but not ridiculously so.

Cheers

Jon
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PostPost by: jimj » Wed Aug 15, 2012 8:10 am

I always understood that the key to the excellent Elan handling/ride compromise was soft springs and firm dampers. The front should always be much stiffer than the rear. Having said that my TTR rears set at factory road use were way too harsh, 2 clicks softer made all the difference.
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PostPost by: mikealdren » Wed Aug 15, 2012 11:34 am

In the 1960s most cars had poor suspension geometry and therefore had big changes at the extremes of wheel travel which (as well as other factors) led to lousy handling. The key to brilliant handling (and ride) on Chapman's cars is good geometry and long suspension travel. This allows the dampers to operate over a longer travel giving more control.

Stiffer, shorter suspension travel does make it easier to control the geometry accurately at the expense of ride quality. Yes you can make Elans stiffer and that may have benefits on the track but I think CABC got is about right in the first place for the road.

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PostPost by: jono » Wed Aug 15, 2012 1:31 pm

Good point Mike,

However my rear end is way, way softer than a standard +2 at the moment and that can't be good either

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PostPost by: elj221c » Wed Aug 15, 2012 1:41 pm

The implication from the installation instructions that I used when I installed my Konis in '84 was that the adjustment is for wear compensation.

As I have shortened struts (a la 26R) I had the length and stroke of the strut reduced but more importantly, the strut was re-valved by the supplier for the 120 lb/" springs I fitted .

Unfortunately I have no notes on the setting I used but I believe because of that, I left them on the standard setting. They were stiff enough at that. Maybe the current day spec is different.
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PostPost by: jono » Mon Aug 20, 2012 2:10 pm

I have now adjusted the rear Konis and backed them off 1/2 a turn from full hard.

Having re fitted them and with the car sitting back on its wheels, the car now feels so much better when I do a simple 'bounce' test.

The dampers take 3 or 4 compressions to 'pump up' but after that they feel pretty much right - very similar to my other +2 on std dampers.

But, what a complete PITA through having to remove the struts and springs - probably a full days work :shock: . Externally adjustable valving has to be the way forward.

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PostPost by: cal44 » Tue Aug 21, 2012 11:51 am

Jon,

I'm with you. The external adjustment is the best. I'm not sure why Koni has done this with the vintage oil shocks.
Sure makes the Spax more inviting. I'm not sure if the AVO's are external.

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PostPost by: elj221c » Tue Aug 21, 2012 12:35 pm

cal44 wrote: I'm not sure why Koni has done this with the vintage oil shocks.


As I pointed out earlier in this thread. Adjustable for wear if they have copied their earlier originals.

Unless you are racing why do you need to constantly adjust?

Setting up a car is necessarily a fairly long job unless you have a known previous bench line.
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PostPost by: jono » Tue Aug 21, 2012 1:29 pm

Roy,

The adjustable for wear premise has me confused (not difficult BTW :D )

When the Konis are set to max hard my estimation is they are only slightly stiffer than standard (when I compare to my other 1973 +2 in std trim).

If they are adjustable for wear I would have thought the miniumum setting would equate to standard and you would adjust for progressive wear thereafter by notching them up from time to time. :?

I am assuming that shocks go soft as they wear as opposed to hard but perhaps this assumption is wrong?

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PostPost by: elj221c » Tue Aug 21, 2012 2:58 pm

jono wrote:
If they are adjustable for wear I would have thought the miniumum setting would equate to standard and you would adjust for progressive wear thereafter by notching them up from time to time. :?

I am assuming that shocks go soft as they wear
Jon


That is my understanding. It is on '84 bought Konis though, not the latest 'vintage' spec although they could be the same. I ran them for 30k until the car was pinched without the need for any adjustment.

Does anyone know if the place that modified the valving and shortened the casing and stroke, (not by the same amount, BTW) J W E Banks of Peterborough, are still dealing in shock absorbers? If not, when I finally start the rebuild, I will have to find someone else to refurbish them.
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PostPost by: stugilmour » Thu Aug 23, 2012 12:24 am

Dr Google came up with this. Might be worth a call...

http://www.manta.com/ic/mtz44gg/gb/j-w-e-banks-ltd

J W E Banks Ltd Business Information
St Guthlacs Lodge
Peterborough, CAMBS PE6 0JP, United Kingdom
J W E Banks Ltd is a private company categorized under Pea and Bean Farms (Legumes) and located in Peterborough, CAMBS, United Kingdom.
J W E Banks Ltd also does business as Koni Shock Absorbers .


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PostPost by: fatboyoz » Thu Aug 23, 2012 1:11 am

Roy,
Not sure how much it will cost you to have your Konis overhauled/modified. You may be better off purchasing the top adjustable, limited stroke Koni Sport items from Tony Thompson Racing: TTRSS008.
http://www.tonythompsonracing.co.uk/pricelist.pdf
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Colin.

elj221c wrote:
jono wrote:
If they are adjustable for wear I would have thought the miniumum setting would equate to standard and you would adjust for progressive wear thereafter by notching them up from time to time. :?

I am assuming that shocks go soft as they wear
Jon


That is my understanding. It is on '84 bought Konis though, not the latest 'vintage' spec although they could be the same. I ran them for 30k until the car was pinched without the need for any adjustment.

Does anyone know if the place that modified the valving and shortened the casing and stroke, (not by the same amount, BTW) J W E Banks of Peterborough, are still dealing in shock absorbers? If not, when I finally start the rebuild, I will have to find someone else to refurbish them.
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PostPost by: elj221c » Thu Aug 23, 2012 11:03 am

fatboyoz wrote:You may be better off purchasing the top adjustable, limited stroke Koni Sport
stugilmour wrote:Dr Google came up with this.
J W E Banks Ltd is a private company categorized under Pea and Bean Farms (Legumes) and located in Peterborough, CAMBS, United Kingdom.
J W E Banks Ltd also does business as Koni Shock Absorbers .


Thanks Chaps, already aware. :-) Peas and beans, eh? Thing is, AFAIK they were the main Koni importers in those days. Now others claim that role which is why I wondered........

I will see if they are US when I eventually start the rebuild. The original fitment was a 26R length (I think) Armstrong strut (AS1512) which is why the Konis were shortened at Banks by 5/8". The stroke was reduced by 2". I didn't know they were short until I tried to use a standard strut replacement from Chris Neal!
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