Springs - Where?

[tom7]

Following some 'unusual' high speed handling at MIRA on saturday, I've decide that I need to upgrade the suspension springing.

I am currently running standard spring rates on wide track de dion.

Having done a tech search and spoken to other competitors, it seems I need 250lb fronts and 150lb rears.

Where is the best place to go to get these, any idea of price?

 

Mucho thankyou

Tom

[Paul McKenzie]

DT, about £15 ea.

 

Paul

[tom7]

Thanks Paul,

I've phoned Dave K and he quotes £18+VAT, seems OK.

Now all I need to do is measure the free length for each, anybody able to save me the bother of winding down the spring platforms?

 

Tom

[Peter Carmichael]

Tom,

 

You will not be able to run 250 lb springs on the front with a decent ride height. The springs will go slack on the platforms at full droop.

 

You need to run some sort of solution such as helper springs.

[stevefoster]

I've got 260lb fronts that don't have droop problems.

Don't know where they came from though... Not much help that.

Try calling Freestyle and talking to then about whats available to suit.

 

Hants (North) and Berkshire Area club site here

My racing info site

here

 

 

 

[ChrisG]

If you're on the South Coast then Faulkner Springs near Chichester will sort you out and are usually happy to do a deal if you pick em up rather than get em delivered. ive had 2 sets from them in recent months and theyve always provided a good service.

 

Chris

[Petrolhead]

250 LB springs.

 

Is this for a K series or VX?

 

If K, seems very hard ie +100 LB over std springs

 

Now with SL No 148

[Paul McKenzie]

Tom,

Me and my mate John both with VX's are running 7"x1.875" fronts and 10.5"x 2.25" rears on standard Bilsteins and neither of us suffer from droop (at least in the suspension department

You will need to move the circlip for the bottom collars to a different groove

Paul

[tom7]

I read a reply from Dave J recently suggesting 250lb was the right way to go for a K car, although the 7 workshop thought this was a bit stiff.

DT seemed to suggest they offer alternative lengths to try and maintain the standard length springing negating the need for helpers. As soon as I measure them and phone again, I'll see how close they get.

I am open to suggestions as to the best way to go.

 

Tom

[Peter Carmichael]

Tom7 has said he has Bilsteins on a widetrack post '96 K. This has spacers on the dampers to provide extra length and *THERE IS NO PHYSICALLY POSSIBLE WAY* a 250lb/in spring will touch the platforms at full droop with a reasonable ride height unless you apply some sort of corrective measure. Perhaps you Vauxhall owners are forgetting the effect of the boat anchor you keep up front.

 

a) helper springs - more expense but a full solution

b) buy new dampers with a shorter open length - and even more expensive, proper solution

c) take the spacers off - which renders the bumpstops completely ineffective

d) slacken the platforms so you have significant slack at full droop. Consider lockwiring or using tywraps. Avoid humpback bridges and the Mountain at Cadwell.

 

If Dave J is using 250 lb/in springs then that means the two front runners in class 5 in the sprints are using 250 lb/in springs. There is a theory that says they are the wrong rate for a K, but theory isn't everything.

 

Sahf London;

every 1st Wednesday from 19:30 at The Duck just around the corner from Clapham Junction station

 

Edited by - Peter Carmichael on 22 Jun 2004 00:26:49

[Jason Plato]

I'm running 5 " front springs . I cant see the point in carrying the extra length ( ohhhherrr missus ) I have run 250lb front springs , they suit the car well for general use on road and track .

 

I dont have any slack on droop and I am running with the front wishbones level with the ground .

 

I would suggest 250front / 150 rear . But the combination of roll bars is critical and your dampers must be in good condition preferably M1 Billies .

 

Its also wise to have the rear anti roll bar connected to the chassis as I found to my cost at MIRA sprint last weekend ☹️

[tom7]

Dave, Peter,

I have the standard (green 5/8?) arb at the front and the adjustable jobbie at the back, the dampers should be OK as they have only covered 8500 miles, this suspension lark seems a bit of a black art, so I'm grateful to you chaps as the results would suggest you know what's what. Driving talent apart of course 😬

[Jason Plato]

YHM

 

Lotus 7 Club Speed Champion 2003

South Wales Area Organiser

C7 TOP

[Peter Carmichael]

Dave, if you can't see the point of the extra length of spring... then you probably don't appreciate that a longer spring with more coils requires fatter wire and reduces the overall stresses in the spring for any given displacement. A longer spring can be engineered to last the life of the car. A short spring can be running very close to its yield stresses.

 

I had to swap out a set of rear springs because they had given up the fight to stay the same length.

 

Do you have the spacers still on the dampers, or have these been modified?

[Jason Plato]

I do appreciate and understand the stress that springs are under and my decison to run with 5" springs was weighing up the advantages of weight vs life plus the design and manufacture quality of the spring . Please dont assume we are all lesser mortals Peter

 

The quality of the spring is a major factor . I use Faulkner and Eibach springs as other suppliers are cheaper but they can suffer greater sagging over life and the variance between a pair of springs can be high . It is also worth checking the length of the springs on a regular basis .

 

I always suggest the springs are tested before use . I bought a set of springs in 2000 that were tested and found to have 30lb/" difference !! , the test can normally be done by your supplier for a few ££.

 

 

 

 

[Peter Carmichael]

Dave, you are touchy today. Unfortunately I am not a habitual user of smilies.

 

I was replying very literally to your: "I cant see the point in carrying the extra length". It seemed worth mentioning the trade off between weight and life in service. Of course I don't think of you as a lesser mortal.

 

Tom,

 

I ran for several years with 250lb/in front springs as the only modification to a standard Superlight setup. So green bushed front ARB, adjustable rear ARB, rear progressive springs, widetrack front, Bilsteins all round (not M1). This was the setup I had for Clash of The Titans and was 4 and a half years old at the time.

 

It is worth noting that the Bilsteins internal design is very competent - they generally don't deteriorate unless there are signs of fluid leakage on the outside. Bilsteins also show very good consistency unit to unit, so left and right hand side will be a close match. Bilsteins are rebuildable with modified damping. Caterham's standard valving is a bit strange, but is very good for a road-going Seven in that it copes well with great variation in rear axle loading and is very predictable in handling - while outright grip might not be the highest, the controllability and feedback with the standard dampers can be very good. It might be interesting to get a set of Billies rebuilt to match a more race oriented valving.

 

The Bilsteins are also comfotable being mounted at any angle, or indeed inverted, unlike many of the dampers fitted to previous generation Caterhams. It is worth noting that the inclined mounting of the front dampers mean that under cornering accelerations the inside damper "feels" like it is mounted horizontally - many units such as SPAX need to be mounted within a very narrow range of vertical.

[tom7]

Peter,

Thanks for the tip.

Hope to have new springs and approx corner weights sorted in time for Loton park. Although having only spectated there, making it up the hill in one piece may be achievement enough!

 

Cheers