rear suspension

[bengalcharlie]

hi,

When I rebuild my plus two I fitted a new pair of rear springs to the car. It sits perfectly but with the boot fully loaded and wife and kid onboard the car hangs on it rear end . on these springs the car sits about 620 mm from ground level till centre wheelarch. (perfect on 13 inch wheels with 165/80-13 tyres)
I also found the car a little soft in the rear and by measuring the coil I discovered it is 10mm instead of 11mm of the original springs I still have. ( I think that the 10 mm springs are for the baby elan) However after dreading to take the suspension apart again ( last time I managed to remove most of my skin on my index finger trying to pull the shock rod throught the upper lotocone!) I finally took the courage to install my old springs. However now I noticed that the car sits higher and that is a shame. although not driven the car yet it appears to sit aboult 650 mm from ground till centre wheel arch. It might settle a little but probably not as much as I would like it to be.
what would you recommend? just buying slightly shorter springs with same diameter and spring rate or make the suspension adjustable?
If I would go for adjustable spring platforms, do I have to go for 2.25 diameter springs and if so what type of spring rate and length would you recommend ?. I have koni red shocks and a full CV drive shaft conversion fitted to my car. also fitted some autobush bushes to the A-frame today now I have the suspension apart anyway.
cheers
Robin

PS are these coilovers aluminium or steel??

[Higs]

Sadly, the laws of physics mean that you cannot have the correct ride height when both loaded and unloaded - certainly not with a a simple spring/damper arrangement that we have on our cars.

So you have a choice - correct ride height when empty or correct when loaded up or somewhere in between.

Putting stiffer springs on will reduce the effect but will not eliminate it.

As to adjustable ride height, I have not seen one that goes on to the standard upright. Spyder does one but it means going to the smaller spring. Alternatively, they do replacement uprights which have adjustable ride heights that can use either standard or small springs.

They might do a special for you to retain the standard springs and uprights.

Hope this helps.

Richard

[gerrym]

Robin, I've seen your posts and you don't look like the sort to muck around. Bite the bullet and convert your rear struts to 2-1/2" with adjustable spring seats. At least that way you could leave the car in it's lowered state for normal driving: crank it up if you know you will be driving gently with a full load.

Note that in theory if you increase the rear spring rate, you should increase the front as well (similar ratio?).

Also, not sure if I understood your steel versus aluminium question: the threaded spring seat collars are steel, the springs are steel.

Regards

Gerry

check out the Demon Tweaks link for a picture of what you will be adding (welding) to the strut tube body
http://www.demon-tweeks.co.uk/products/ ... ode=RIX031

[andyelan]

Hi Robin

With regard to the soft ride, I would suggest that if you've fitted the Konis with them on their minium setting (as is recommend) then you're actually under-damped. That's what I did and that's my problem. I have recently obtained a pair of new original equipment Armstrongs and they're way stiffer than the Konis. I'm going to fit these this Winter and then I'll have a benchmark on how the car should handle as standard. I also intend to put both sets of shocks on a dyno so I'll then be able to tell how the Konis should be set up so they match the OE Armstrongs.

As far as ride height goes, this is somthing that's puzzled my for a long time but here are my thoughts on the subject (comments from anyone with definitive answers would be welcome just in case I talking rubbish).

Firstly Robin, what year and model is your Plus 2 as that's important, also, I assume it's basically standard.

Lotus, with their soft suspension philosophy always had much more of a problem with the Plus 2 than with the two seater with regard to ride height as the difference between minium and full load was so much more marked. This was born out by the fact that early cars which were prone to scraping exhausts etc when loaded up. Over the years various mod were made to the car to address this problem and it is my belief that at some point the overall ride height was increased (although this is not reflected in any of the literature). It's is easy to see how this was achieved at the front as later cars have longer springs than early cars, however, what was done at the rear is more difficult to understand. To me there is no doubt that later cars ride heigher at the back than early cars, also, late cars have a spacer to limit suspension travel at the back and I can't see how Lotus could have fitted this in isolation as, without a increase in ride height, the car would have simply been hitting the bump-stops all the time. The problem is I've no idea how such an increase in ride height at the back could have been achieved, there's no evedence that spring lengths or other components were ever change.

One thought did occure to me however. When I recently had my car (a late '73 130/5) on the scales I found it to be significantly lighter than specification and this this weight appeared to be missing from the rear. Could it be that an increase in ride height was achieved by weight reduction. If that was the case, then that would have been a very clever way to achieve the extra ground clearance and just the sort of thing Lotus might have come up with.

Just my thoughts anyway

Regards
Andy

[bengalcharlie]

thank you all for your replies. they have been very helpfull and I have been thinking what to do next. I might leave the car alone and order some adjustable spring perches. Sorry being not so clear all the time and speak some double dutch but I am afraid that will never change! ( dutch being raised in belgium)
My car is a very late 69/ early 70 car and was originally a US federal car so not sure about the springs. It seems now that I have the same ride height issues as later cars. As mentioned earlier the springs are both the same height but one is slightly thicker (1mm) and obviously that means it sits higher although I did not realise this upon whilst fitting this the the left rear.
Initially I had some brand new Monroe shocks fitted ( my father used the work at Monroe Europe in Belgium) and they were actually rebranded armstrong shocks. I did find these to soft and thought at the time these were the problem, so replaced these with new konis which improved things but not to complete satisfaction. still a bit loose in the back. I think that the original elan springs fitted to the car are perfect from a ride perspective but not form a ride height perspective. maybe I should put it all together first and go for a drive??
I think a slightly shorter spring (11mm coil) will solve the issues but I agree with Gerry that it then makes sense to make it all adjustable.
I am jealous about you guys living in the UK, you have so many options were to get parts from. Gerry, have you the demon tweeks set on your car??? Happy with it??
Secondly What spring rate should I go for??? I will have both my sets tested so I have some idea what I got.
Will keep you updated and thanks again for all the comment, really appreciated!!!!
cheers
Robin

[bengalcharlie]

I had both sets of springs tested and the 10mm coil is a 80 pound spring, the 11 mm coil is a 100 pound spring. I have decide to fit these 100 pound springs regardless of the raised height and see how they handle. then I have two options, one is to have the springs altered by an inch or so.
The other option is to replace the whole setup with adjustable perches and springs.
I would like to know what kind of spring rates and dimensions are used on the plus two in case you go for the adjustable spring option.
I will keep you informed of my findings once I have the car back on the road.
Robin

[andyelan]

Hi again Robin

The specified rates for Plus 2 rear springs is 93 lbs/inch (they should also be 11.02mm wire dia and 16 inch free length) so the 100 lbs/inch ones you intend to fit should be fine.

Without wanting to labour the point I'm sure from the way you describe things that your problem is too little damping at the rear and not soft springs. Elans rely on alot of damping for the suspension to work properly. Are the Koni dampers you have adjustable? They should be, so you should be able to stiffen them up while they're off the car. Unfortunatly I can't tell you what to set them at and it's difficult to describe how stiff they need to be however I've just done a quick check on my shocks and with the damper body in one hand and the rod (with a nut on) in the other, and pulling as hard as I could, it took me a full 15-20 seconds to fully extend the damper rod. Hopefully that might give you an idea of roughly where you need to be

Regards
Andy

[bengalcharlie]

hi Andy,

I agree, it is always a combination of shock damping and spring rate. You might be quite right that the shocks need to be set a bit harder. First though I will just replace the springs without interfering with the shocks. if not satisfactory I will also stiffen up the shocks. that way I have some idea what is going on if you know what I mean.
shocks have only 12000 km on them so are virtually brand new.
cheers
Robin

[andyelan]

Hi Robin

What you suggest doing is very sensible, my problem is that the Konis I have need to be taken off the car in order to make any adjustment which is a real rave. If you're ok doing this however (or perhaps your shocks can be adjusted in situe), then adjusting one thing at once and a little at a time untill you arrive at the optimum setting is by far the best method. Maybe when you do arrive at some good settings you could let me know what they are. I don't think for a minute there's anything wrong with your Konis, I just think these items are very soft on their minimum settings

Regards
Andy

[bengalcharlie]

no problem Andy, I will let you know. Just surprised about your findings with reagards to the armstrong shocks being firmer. I had the opposite experience.
The konis are firmer, I used to bottom out in dipps and that is gone after installing the konis. At present they are at the standard least firm setting.
Cheers
Robin

[gerrym]

Robin, the picture from the Spyder website gives you a good idea of what the completed conversion looks like

http://www.spydercars.co.uk/el_2_25_kit.htm

Regards

Gerry

[gerrym]

Robin, just one other thing: my Konis were top adjustable. This could be done by lowering the top mount from the car but not removing the strut. It's a good idea to get rid of the half/height fasteners for the Lotocone however, before these round off.

Regards

Gerry

[rgh0]

If I was regulalrly running my plus 2 with children and luggage I would certainly increase the rear spring rate, going up 50% front and rear will only have a small impact on ride but will greatly reduce the drop in the rear when fully loaded. The handling on modern tyres will also improve

The other item to consider is the Aeon rubber springs at the rear- as these help control the rear end when heavily loaded - do you still have them and are they in good condition? As you cant buy them new now many people appear to have either disgarded them or replaced them with a small bump rubber that does not perfrorm as an auxillary spring like the orginal design was intended

Lotus added a 1 inch alloy spacer on the top of the strut in the late plus 2s 130 models to make this Aeon rubber spring come into play earlier to improve the resistance to the rear grounding when heavily load.
cheers
Rohan

[bengalcharlie]

thanks Gerry for the pics of the setup sold by spider cars. I have been looking online to see if a can find a setup in the US, easier and cheaper there I travel to the US frequently. Had a look at summitracing and saw that they have several coilover kits on their website. Unfortunately no dimensions so I sent them an email.
Rohan, I have just a rubber bump stop fitted to the end of the shock shaft which has no other job than preventing the shock botttoming out and damaging the shock. my koni are not top adjustable so you have to take it all apart if you would like to firm up the ride. My gut-feeling tells me that my problem is more spring related than shock.
The slight oversteer feeling only appears in fast long bends where the transfer of weight of the car is a little noticable and the spring would do more work in this situation than the shock.
Anyway time will tell. I have been working all day, first to remove old bushes of another A-frame that I will use. Bushes were rusted rock-solid so after pressing the rubber part away I cut 3 grooves across in the old bush to relief the tension.
still no luck so heated it several times and finally with the help of the steel outer casing from one of the old bushes I could tap the bush out.
It took me two hours just to remove these!! After that gave it a quick wash and fitted the autobush bushes so no more pressing out of bushes in the future. Tomorrow I will finish the job and put it all back on the car and go for a test drive.
cheers
Robin

[jono]

It may not answer the question but here is what I have done, based upon advice gleaned from Tony Thompson:

I have red Koni adjustables on the back with 2.25" adjustable perches. Tony's advice was, for fast road use, to set the Konis to full soft and then adjust 1.5 turns firmer. The rear springs should be 120lb - I used 14" as this provides a good range of adjustment with the perch mounts set at the lowest they can go withot fouling the calipers.

On the front I have TTR's fast road coilovers. The above set up assumes the TTR fast road set up at the front.

I also used Poly bump stops - superflex one's from Demon Tweaks, they are the longest ones in the range around 70mm from memory.

....not tested it all yet however as the car is still a rolling chassis

Jono