Nitron to Billies.. spring size.. and shocker length...

[TVR Beaver]

That’s a strange one

The original Billies are a different eye to eye length than the Nitrons I’m re-working… has anyone else noticed this?... Also, the spring lengths are reversed on the Nitrons to the Billies:-

Rear
Billes 375mm eye to eye
Nitrons 375mm eye to eye.. so about the same

Fronts
Billes 363mm eye to eye
Nitrons 354mm eye to eye.. so about 10mm shorter?

And as I say,
the longer springs on the Billies are on the front.. where as
the longer springs on the Nitrons are on the back

The shorter springs on the Billies are on the back (and progressive)
The shorter springs on the Nitrons are on the front (and non-progressive)

Is this right?.. or have they been mixed up at some point (don't think so?)

So I could use the Eibach front springs off my fitted Billes (nearly new) and put them on the rear Nitrons….
And then get some new Eibach for the Front when the Nitrons go on

Will have to look up the Std Griff front ratings to see if that fits with my plan of 375 / 325.. to get the 325 on the rears…

Edited by TVR Beaver on Friday 18th November 21:02

[spend]

My data is 216mm F & 267mm R free length of spring, allowing @1/2" preload to suit the Nitrons & TVR chassis geometry ensuring that the spring still has some preload at full droop (but requires spring compression to assemble)

Remember all the common springs fitted are like shoes, they come in std lengths & folks pick the nearest size that fits or seems to fit.

[TVR Beaver]

Measuring the black springs.. (so assume they are Nitron supplied)..

I get 201mm Front and 221 Rear.. so quite a bit shorter than your info?....

Mind you.. the adjustable platform is about half way up the shock on back and front so could easy take longer ones....

You've got to be carefull here.. as the shorter the spring, the more rate you'll get for less movement?.. if you know what I mean...
How do they measure the spring rate .. any idea??.. is it done at say 1/3rd compression???.I'd have to look??....

Any thoughts on the Eye to Eye length for the fronts?.. 10mm less... I guess you just screw it up another 10mm to get the same ride height, but in turn this will reduce your off load fall movement...

[spend]

AFIK all the springs fitted to Nitrons (their own brand or Eibach) have been linear. Joo was very suspect about progressive springs on the TVR IIRC ~ which may largely have been due to experience with those Bills?. I have only designed springs to overcome the problems with lack of pre-load at full droop (springs clattering on seats as they lose contact) and to cushion the initial acceleration returning from full droop (wheel drops down pothole!). I've essentially made a single spring with the equivalent of a tender / helper spring tagged on the end, and they are basically 600/450 springs which is fine with those extreme conditions satisfied and operation over the full extension of the damper IMHO. Any loss of compliance is paid back in full with reduction of bump recoil without the neccessity of over damping when its not needed as far as I am concerned.

[TVR Beaver]

Interesting your at 600 / 450... you'd think on the springs alone it would skip all over the place on our roads.. but I get what you mean on the damper.. you can have them quite soft as the work is being done by the spring...
If you get a bumpy bend... does it not skip round a bit?... Must be a very firm ride??

[JR]

TVR Beaver said:

Interesting your at 600 / 450... you'd think on the springs alone it would skip all over the place on our roads.. but I get what you mean on the damper.. you can have them quite soft as the work is being done by the spring...
If you get a bumpy bend... does it not skip round a bit?... Must be a very firm ride??

You've only got half of the story there:

spend said:

I had some funky springs made with initial rates of 440/380 rising to 600/450 at full compression, and tailored to suit the suspension travel whilst still maintaining preload on the damper seats Telling you the progessive loading would be giving the game away. F1 quality & still only £100 a set custom made if you can spec them!!!!

IMHO still towards the firmer end of the spectrum but does sound like a pretty neat solution.

[spend]

Winding up the dampers is like having seized bearings.... I know which I'd rather have IYSWIM. Stronger springs seem to allow the high speed valving to work distinctly from the slow speed bleed in the damper as well as subjecting less extremes of deflection for the damper to deal with IMHO.

As an aside weight of car & poundage of springs can be very misleading, try going through some of the calcs in Staniforth as an exercise.

[TVR Beaver]

'Staniforth'.. pray tell???

and where do I get the good but cheap springs from.. Its too much.. I need to know the secrets!!...

[spend]

Google 'staniforth suspension'

Google 'spring makers'?

[TVR Beaver]

will have a look....

on another note... how does the spring leave the plate and make a noise??.. unless you are not nipping the spring in the first place?.. but if you do.. and jack up from there its always compressed even at max stroke?.. so how can it come off its seat??


..........................................

Ok.. back from looking... guess you mean:-
Competition car suspension: design ... - Allan Staniforth - ... 4th edition (bought and on it's way )

On the companies there are a few
Coil Springs
Spring Coil Ltd
Don Springs
Turton Springs Ltd...

[spend]

Fully extended rear Nitron is about 250mm seat-seat IIRC, so with 8" spring it's almost certain to lose preload at some stage (& I certainly found it with 9" springs from Joo + my rear ride height is definitely not one of the low ones!)

[TVR Beaver]

spend said:

Fully extended rear Nitron is about 250mm seat-seat IIRC, so with 8" spring it's almost certain to lose preload at some stage (& I certainly found it with 9" springs from Joo + my rear ride height is definitely not one of the low ones!)

Agree.. fully open its 250mm... and with your 267mm spring (or what ever length they were) it would keep in contact if left in its lowest position...
But if your spring is shorter, 221mm for example as mine are, don't you at least nip them / pre-load them slightly as a starting point?? or would this lift the car too high.. are you saying on shorter springs, there is a gap (no nip on the spring when fully extended) to get the car ride hight low enough??

[TVR Beaver]

Thinking of your springs... I'll just write this down as I think it...

So your spring length is 267mm and going on mine I guess thats about 10 1/2 coils
again using my wire size / gap ratio... you could compress yours to 120mm before it became fully coil bound... so a max movement of 147mm... so say the 450 is at max compression 140mm say... but the shocker piston will only move about 95mm... so your only 2/3's the way towards full compression and full rate....
So your spring is 450 on the back... but it's actualy only working to 300?

Okay, I know its rising rate and I've not accounted for that.. and also a bit of pre-load... But it's not like you are running a full on 450 spring as you not getting close to it's limits....

I agree a longer spring is better as it gives a more constant rate....


Mmmmmm.. interesting when you start to think about these things... and the considerations needed...
Right, pub time..

[spend]

Wow! you seem to have derived some wild assumptions there John? Final rates in my design are reached when the springs are compressed little more than an inch, and are then linear for the rest of damper span. You can design all these things in the winding program as you wish (yes you just stuff wire in & the computer on the machine does the hard bit ). I repeat basically what I said above, the soft tender part of the spring gets coil bound in normal stance & is only there to retain preload in full droop (+ fight ridiculous accelerations & momentum when the 'detached from spring' unsprung weight starts coming back up - think sledgehammers..). I quite clearly stated that from many years ago Joo steered me away from the concept of rising rate springs, and I can't say I've gleaned anything from any of the experts I've read/spoken to that would alter that premis.

[TVR Beaver]

Okay... so way off the mark I must try harder ... so you are seeing rate as soon as.... Interesting....

I need to understand more about springs etc... will be an expert by weekend after the book arrives!!

[DarkMatter]

TVR Beaver said:

...and where do I get the good but cheap springs from..

http://www.dfaulknersprings.com/index.htm

[TVR Beaver]

Thanks Andrew.. they look good..... have you tried them yourself?..

What length to go for?... same as what came off.. or longer the better??.. still not sure why they would use a 8" spring when a 9" one would fit no problems??

[DarkMatter]

TVR Beaver said:

Thanks Andrew.. they look good..... have you tried them yourself?..

What length to go for?... same as what came off.. or longer the better??.. still not sure why they would use a 8" spring when a 9" one would fit no problems??

My Griff has Protech dampers which came fitted with 350lb front and 275lb rear. If my recollection is correct the lengths were 9" front and 10" rear, this enabled the spring seats to sit towards the lower end of their adjustment which would probably have enabled a longer spring to be fitted but then that may have made it difficult to lower the ride height if I'd wanted to do so..

I bought from Faulkners a pair of 450lb springs length 9" to put on the front. I moved the existing 9" 350lb springs to the rear meaning I've had to wind up the spring seats a long way to attain the correct ride height. I'm not convinced that things are quite right with such short springs at the rear and have been considering buying some 10" 350lb ones.

I changed the springs because on the hillclimb course I use there is one particular hump which made the car feel unstable, I had been running maximum damping to overcome this but have now found that the stiffer springs have made the car feel more stable and allowed me to soften the damping a bit. I have not noticed any lack of comfort during normal road use either.

(edited to correct typo spotted by TVR Beaver, thx)

Edited by DarkMatter on Monday 21st November 14:07

[TVR Beaver]

'I have noticed any lack of comfort during normal road use either.'... assume it should say ... I have not...?.
.
Intersting.. and going the same way as Dave then... Stiffer springs with softer damping....
.
Will have a word with Nitron today.. and the spring Co. also.. .Cheers....

[TVR Beaver]

spend said:

Wow! you seem to have derived some wild assumptions there John? Final rates in my design are reached when the springs are compressed little more than an inch, and are then linear for the rest of damper span. You can design all these things in the winding program as you wish (yes you just stuff wire in & the computer on the machine does the hard bit ). I repeat basically what I said above, the soft tender part of the spring gets coil bound in normal stance & is only there to retain preload in full droop (+ fight ridiculous accelerations & momentum when the 'detached from spring' unsprung weight starts coming back up - think sledgehammers..). I quite clearly stated that from many years ago Joo steered me away from the concept of rising rate springs, and I can't say I've gleaned anything from any of the experts I've read/spoken to that would alter that premis.

Okay... have been doing a bit of reading now... and measuring.. so to go back to your 450 Lbs / Inch spring...
I'm not sure why you didn't just fit a 10" 450 unit (giving a few mm compression at fully open)... it would have the same result (no loss of contact).. and still increase by 450 Lbs per inch over the 95mm stroke?
Other than you have no option to lower your ride hight if required... Mmmm.. so I guess this is the reason?...
Okay.. so this is failey straight forward??

Edited by TVR Beaver on Monday 21st November 15:31