SS1 Suspension - considerations

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SS1 Suspension - considerations

Post by philhoward » Sun Dec 21, 2008 10:31 pm

Copied (and made more generic) from a post made by CNHSS1 - worthy of a sticky..

Firstly, the suspension and more importantly the handling, shouldnt be thought of as changing one item or another, it must be as a cohesive plan of attack or you will loose the lovely balance that the SS1 naturally has, and that Lotus give to all their cars, but the majority of cars dont have. its a hugely complex subject and fascinating for geeks like me, but essentially every change has repercussions on each other area of the suspension and handling.

If the front end is standard ie std OEM Monroe shocks and std rubber bushes, unless these are in tip top condition, the front suspension will be a bit 'wooly' compared to how it left the factory. not a criticism, just facts of life. The Monroe shocks are notoriously poor on the front, and are a tad underdamped even for the std arrangement in my opinion (actually fully agree with Jim, that they should be used as door stops or paperweights, but was being diplomatic...). the front springs will have sagged a fair bit too, affecting their rate and the cars ride height (and centre of gravity). Reliant specs say 6'' ride height F&R measured at jacking points.

If it were me, i would try 225lb if a car is generally used with only the driver (no passenger) and you need a reasonably good, but 'uprated' ride and no more than 250lb if you regularly have a passenger and luggage etc. Try to keep the ride height the same F&R when loaded with driver/and or passenger (ignore what it looks like stationery as thats irrelavant).

Couple of pointers..
If the car was fitted with polybushes, these sharpen up the handling no end returning it to as new or better feel, and basically will outlast the rest of the car! they do however, drop the effective spring rate due to the fact that they are free to pivot rather than the std rubber-lastic jobbies where the inner and outer are joined together. the effect is small granted, but there nonetheless.
Secondly, the original springs, as with most Reliant components, were built to a price and as such aint the greatest material. its not uncommon to see 15-20yr old SS1s with the front lower wishbones almost on the bumpstop rubbers through the springs going soft and sagging. This has the effect of the car running on the bumpstops as springs, over anything other than straight ahead driving, giving odd, rapidly increasing effective spring rate which buggers the handling no end!
Thirdly, and allied to above, is ride height. The car should be level and no less than 5'' at the jacking points F&R in my opinion for a road car, even with stiffer springing F&R. The amount of std SS1 you see with 'arse high' stance where the front springs are shot, or rear scraping the ground with too short ' aftermarket' springs and dampers at Curboro each year never ceases to amaze me!
4th, tyres. the sidewall stiffness of tyres vary massively, and this has a huge effect on the cars springing/damping and handling. the more performance orientated tyres (sporty rather than 'ditchfinder' brands) tend to be stiffer allowing the suspension to do its job properly. trouble with SS1s, is that the commonly used 185/60-14 size isnt the domain of hot hatches, so budget family car type tyres are what you usually get offered. Not saying they are bad tyres, but that they probably are quiter, longer lasting etc rather than the sporting qualities an Scimitar 2 seater deserves. the Sabres 195/50-15 suffers less as this is still a hot hatch size so sporty tyres are still easily available.

Tyre pressures. I preffered 24 F&R winter, and 26 F&R for the rest of the year (using various Yokohama road tyres on my road cars). i always run the same pressure F&R so that the tyre behaves the same at both ends. on road tyres the pressure helps to keep the sidewalls stiff, but the same pressures means that if the cars displaying an odd handling trait, you know its suspension/damping not the tyres playing silly buggers!
one last thing, and it may help to reduce the issues youre having now, look at the front anti-roll bar droplinks. As Std, the book says something like 1.5 turns of thread should stick out from above the nut of the long pin holding the whole assembly together. dependant on how worn/soggy the bushes are, i would increase that thread showing appreciably (could be 10-15mm). this takes the 'sog' out of the assembly, so that when cornering loads are imposed on the chassis, the loads are fed into the A/R bar straight away rather than wasting the first 10degrees of chassis (body) roll in just taking up the slack in the soggy bushes! NOTE: if you are using polys here, this doesnt need to be done.


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Springs - again from CNHSS1

Post by philhoward » Tue Feb 09, 2010 9:28 pm

re front springs, mentioning dropping it an 1", but from what point? SS1 front springs are different to the Chevette they are based on and are renowned as being poor material, so sag badly with age. the correct original ride height for an SS1 is 150mm/6" under each of the 4 jacking points on the sill. I'll wager that your cars is already lower than that.
as for getting new springs made, consider exactly what you want the car to do. Daily driver with rubber bushes and 250lb will feel like a tight-ish, taut road car feel but still handle pot holes and give nice feel if you dont drop below 5" ride height. if to be used as a 'fast road', trackday/sprint car, then id go for 300-350lbs personally as below that the handling beneifts wont be maximised. what tyres are you going to use? decent road tyres or List 1b rubber such as R888s etc? again more grip will need stiffer springs and/or front anti-roll bar really and definitely poly bushes or you will be wasting your cash on springs. Again dont go too low on any spring or else the lower wishbones hit the bumpstops very quickly so your effective spring rate goes up from the spring rate (say 250lb) to double/triple that almost instantly as the bumpstop spring assister comes into play. if you intend on going low, then you need to minimise roll (more to do with roll bars than springs in this case) or again you will induce understeer when the bumpstops increase the spring rate massively.

rears are easier as others have said, its a generic coilover setup. AVO used to list both 14" and 13" 'open' lengths suitable for the SS1s and Spax made 13.5" specifically for the SS1. Personally id go for adjustable spring seat on whatever make you choose, allows for new springs to sag (which they do...) and also allows a bit of adjustment for ride height if fully laden/track work.
Dont go any shorter than 13" open though, 13s fine but 12s are too short really, i have them on my racer and theres F-all travel!

Rear spring rates are even more contentious than fronts (read the various stickies and search for posts on suspension in the SS1 and Competition sections...) but dont go mad on rear spring rates. In my opinion they are the easiest change to bugger up the SS1s nice chassis balance. 225lb are my fave, with 250lb for light track work. A full on racer can handle more, but the rest of the car suspension has to be optimised and has to run much stickier tyres, but your call of course mate.
also remember that due to the nature of the semi-trailing arm design at the rear, camber change (gain) during compression of the suspension also changes the camber but in a fixed manner, it cant be varied. Using 13" or 13.5" open rear shocks will help to stop the rear wheels going into positive camber in droop (also known as 'jacking') but careful adjustment of the damping allied with spring rates and static ride height selection, will stop the car gaining excessive camber and compromising the tyre contact patch under bump or hard acceleration. Often excessive wheelspin off the line is just too much squat, causing the rear contact patch to be reduced appreciably. The pi55-poor method to overcome this is just to ramp up the rear spring rates

Nick & Raz will advise on contcat details for getting custom springs made for the front as they have both done it. Worth listening to the compie guys though, as they have been there, done that and generally learned the hard way what doesnt work (all compies have a box of spare springs )

cheers
CNH
Taken from this post


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Re: SS1 Suspension - considerations

Post by stevesims » Sat Mar 28, 2015 10:42 am

Trial car front suspension.
I have fitted standard chevette front springs on my car in the past and although they are taller than Reliants standard fit the gained ground clearance was soon lost as the springs sagged .Am I right in saying that the spring rate is less than Reliants?
I then tried and have since run with 1'1/2 spacers with standard springs.
This has given me a good gain in ground clearance but the top of the spring does not sit correctly around the chassis "cone" .
Also I need more bounce as the car hits ramps/steps on the trial sections (usually hard stone ).
A fellow trial SS1 competitor uses coil over inboard pushing the top wishbone down.
He has gained more ground clearance and bounce.However he goes through top wishbones alarmingly quick as they crack around the top upright .
Now, I want to order some bespoke springs from a manufacturer to go taller on the front without spacers and have some bounce.
I am thinking of a spring rate of 210 lbs and another 3 inches in spring length.The dampers will need to be repositioned which is no problem.
What do you think ?



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Re: SS1 Suspension - considerations

Post by CNHSS1 » Sat Mar 28, 2015 11:33 am

Hi Steve
Im 99%sure the ss1 and chevette are the same rate as std, 180lbs. The issue is the length. For the same given wire diameter a shorter spring will be stiffer, and vice versa.

Your idea for custom springs is bang on though. They will ask you to measure the fitted length of the std springs on the car ie when the cars on the ground ( pig to measure unless you have a ramp) and then the free length ie the full length of the spring when on the bench. Yhis gives them your original info.
You then tell them how much extra ride height you need and how much extra rate, and they will choose the wire diamter, number of coils and overall length required.

On my sabre i use uprates between the wishbone springs and then much lighter additional springs on the coilovers. The beauty is when its slippery i can wind the coilov3r helper springs back off or remove them and wind them back into play when the grips up. As they are lighter helper springs ratger than taking the full cars weight it doesnt stress the wishbones anywhere near as much.

Good luck :-)


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Re: SS1 Suspension - considerations

Post by stevesims » Sat Mar 28, 2015 4:50 pm

Thanks Craig.
I have a spare car in the garage with no wings fitted so I can do the measurements as required.
Any recommendations for a spring manufacturing company?



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Re: SS1 Suspension - considerations

Post by CNHSS1 » Sat Mar 28, 2015 5:55 pm

If you have a Blue Book to hand th3res a place in the back of there, something like Coilsprings UK. If not, Nick Hall had some made so he will have a contact. In fact i think its been posted on here before maybe be Nick Hall or Reliant Reviver iirc


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Re: SS1 Suspension - considerations

Post by stevesims » Sat Mar 28, 2015 7:29 pm

I'm not Sure I'm yet at top level Motorsport but I will give these lads a call on Monday
http://www.coilsprings.co.uk
Thanks for your help Craig.



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Re: SS1 Suspension - considerations

Post by Jhdelta » Tue Jul 18, 2017 6:19 pm

Are the 1800 turbo front springs any longer or higher rated overmthe 1600 type, notice some new ones for sale recently



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Re: SS1 Suspension - considerations

Post by scimjim » Tue Jul 18, 2017 6:29 pm

Nope, all the same as standard.


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Re: SS1 Suspension - considerations

Post by Jhdelta » Tue Jul 25, 2017 10:19 pm

So what should i have on the shopping list for springs and shocks, I would like an extra 2-3 inches of ride height over standard with adustable shocks



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SS1 Suspension - considerations

Post by AndyM » Tue Apr 24, 2018 6:48 pm

https://rover.ebay.com/rover/0/0/0?mpre ... 2057208963

Would these be a good fit for my standard SS1? I’m not very technical but these are chevette and offer a couple of options on height?



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SS1 Suspension - considerations

Post by Oaksey » Tue Apr 24, 2018 6:59 pm

No, both shocks and springs are different to Chevette. Shocks are readily available from Protech, Gaz, Spax, AVO etc but I think springs are getting tricky now?


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SS1 Suspension - considerations

Post by AndyM » Tue Apr 24, 2018 7:06 pm

Thanks Josh, I will do some more research. I was hoping for an easy kit for my mechanic to fit before Prescott, it was a bit soft at Gurston at the weekend.



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SS1 Suspension - considerations

Post by Corky » Tue Apr 24, 2018 7:42 pm

The traders would be your best bet for speed. QRG sell AVO and GW sell Spax. It’ll be IRO £600 with the springs though !

You could save a few quid by going direct to GAZ, but it’s a six week lead time.


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SS1 Suspension - considerations

Post by efi_sprintgte » Tue Apr 24, 2018 7:52 pm

AndyM wrote:
Tue Apr 24, 2018 7:06 pm
Thanks Josh, I will do some more research. I was hoping for an easy kit for my mechanic to fit before Prescott, it was a bit soft at Gurston at the weekend.

I would do a few events first myself, all about the seat time.


JC

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