odd spring rate setup ?!
Discussion
i recently bought a 1990 eunos on avo coilovers. after pulling them apart to see what was stamped on the springs i have:
front: 8" 450lb
rear: 7" 200lb
the rear felt too soft, and the springs had permanently sagged 1/4" so i've swapped them for some new 7" 225lb which feel much better
the front though, i was expecting them to be 300 - 350lb at the most after changing the rears but was quite suprised to see 450lb
from the ratios i've seen and heard people use i'm thinking of softening the front to something like 300 - 325lb
can anyone advise or give me a reason why the front is/was over 2 times as stiff as the rear?!?!
front: 8" 450lb
rear: 7" 200lb
the rear felt too soft, and the springs had permanently sagged 1/4" so i've swapped them for some new 7" 225lb which feel much better
the front though, i was expecting them to be 300 - 350lb at the most after changing the rears but was quite suprised to see 450lb
from the ratios i've seen and heard people use i'm thinking of softening the front to something like 300 - 325lb
can anyone advise or give me a reason why the front is/was over 2 times as stiff as the rear?!?!
You need stiffness in the springs at the front to reduce the roll and improve turn-in. 400lb is a good happy medium but track-only cars use up to 550lb. This is a bit extreme for a car that gets used on the road though.
The rears need to be much softer to make sure they always have traction, especially in the wet.
The Planet Motorsports car currently has F400 R300 as recommended by Derek (Gazman).
The rears need to be much softer to make sure they always have traction, especially in the wet.
The Planet Motorsports car currently has F400 R300 as recommended by Derek (Gazman).
that makes sense - i understand generally you want to stiffen the non driven axle, but over twice the stiffness does seem a bit extreme...
i met Derek from GAZ when i was at Wheels in Motion about a month or so ago, and he mentioned his test mule was currently running F400/R300 and that it felt good on track, my thinking is to stay with that sort of ratio front to rear only softer, hence F325/R225
i get the impression i'd be better off for fast road and occasional track days with softer springs but maybe slightly stiffer arb's ?!
it doesn't feel right at the moment - turn in is crisp but it feels like the front end is on stilts and wants to lift a wheel when going into a corner at higher speeds
i met Derek from GAZ when i was at Wheels in Motion about a month or so ago, and he mentioned his test mule was currently running F400/R300 and that it felt good on track, my thinking is to stay with that sort of ratio front to rear only softer, hence F325/R225
i get the impression i'd be better off for fast road and occasional track days with softer springs but maybe slightly stiffer arb's ?!
it doesn't feel right at the moment - turn in is crisp but it feels like the front end is on stilts and wants to lift a wheel when going into a corner at higher speeds
I'm running the Flyin Miata ARBs on mine and that made a hell of a difference even with standard shocks/springs.
I would say the Gaz setup I have currently seems plenty soft enough to me if I wind the shocks off to really soft it's a smoother ride than the OEM springs/shocks. So I'm not sure how soft you really want but you sound a bit low to me...
I would say the Gaz setup I have currently seems plenty soft enough to me if I wind the shocks off to really soft it's a smoother ride than the OEM springs/shocks. So I'm not sure how soft you really want but you sound a bit low to me...
I was about to say - its all irrelevant unless we know what ARB's your running.
As I understand it - For pure track use you want to use a very stiff spring with a light ARB - IE the Roll AND the Pitch/Dive (fore/aft) weight transfer is handle well by the stiff spring - and the light ARB effect give maximum traction and turn in.
But - for the road - You should use a stiffer ARB to control the roll of the car and give you 'flat' cornering... thus meaning you can use a softer weight spring to enable good bump absorbption on each of the wheels and thus a good ride with light damping.
The fore/aft weight shift is much, much less of an issue on the road - how often do you use full throttle and more importantly full braking force on the road?
As I understand it - For pure track use you want to use a very stiff spring with a light ARB - IE the Roll AND the Pitch/Dive (fore/aft) weight transfer is handle well by the stiff spring - and the light ARB effect give maximum traction and turn in.
But - for the road - You should use a stiffer ARB to control the roll of the car and give you 'flat' cornering... thus meaning you can use a softer weight spring to enable good bump absorbption on each of the wheels and thus a good ride with light damping.
The fore/aft weight shift is much, much less of an issue on the road - how often do you use full throttle and more importantly full braking force on the road?
well, the front is/was setup slightly higher than the rear also, i guess to reduce dive under braking...
but surely with a front rate so high it could've afforded to allow the car to sit level?!
not sure where to go with it now, but i still think a better ratio like 100/75 or 100/60 is the way forward...
does anyone know what the stock spring rates were?
and of the P5 and GAZ kits?!
but surely with a front rate so high it could've afforded to allow the car to sit level?!
not sure where to go with it now, but i still think a better ratio like 100/75 or 100/60 is the way forward...
does anyone know what the stock spring rates were?
and of the P5 and GAZ kits?!
The maths seems about ok, if i were to measure the right aspects (or be able to?!)
not to sound funny, but i just don't have the kind of money to buy 10 odd differing rates of springs front + rear, my own in house damper revalving service, time on a track/dynamometer access etc.
i'm hoping suspension manufacturers have done the hard work, i'm just choosing a halfway house between a track setup + a road setup - £100 ~ 120 to change spring rates on my existing coilovers until i can afford to buy a whole all in one solution - P5, GAZ etc.
i would have just left it alone but it seems a bit wrong i'm managing to bottom out the travel of a car designed to live solely on track!
i don't wanna hear 'if it aint broke...' :-p
not to sound funny, but i just don't have the kind of money to buy 10 odd differing rates of springs front + rear, my own in house damper revalving service, time on a track/dynamometer access etc.
i'm hoping suspension manufacturers have done the hard work, i'm just choosing a halfway house between a track setup + a road setup - £100 ~ 120 to change spring rates on my existing coilovers until i can afford to buy a whole all in one solution - P5, GAZ etc.
i would have just left it alone but it seems a bit wrong i'm managing to bottom out the travel of a car designed to live solely on track!
i don't wanna hear 'if it aint broke...' :-p
to answer your first question, the reason for those spring rates was probably a thorough lack of testing!!
you are bottoming out as the rears are just too soft for that ride height, there is very little suspension travel at the rear. you can go a fair bit stiffer without upsetting things too much. this of course assumes that the dampers are matched to those spring rates. also, don't neglect bumpstops.
you are bottoming out as the rears are just too soft for that ride height, there is very little suspension travel at the rear. you can go a fair bit stiffer without upsetting things too much. this of course assumes that the dampers are matched to those spring rates. also, don't neglect bumpstops.
Ab Shocks said:
The fact that the car is fitted with Avo units and really soft rears points me towards the sort of set-up that Paul Sheard runs (and very sucessfully I should point out)as a track/race set-up
I however would probably run 350fr and 250rear on Avo as a happy compromise.
that would make sense - there's a wad of receipts from paul sheard - roll bar, ported head, back end rebuild after an off into a tyre wall etc.I however would probably run 350fr and 250rear on Avo as a happy compromise.
at the moment i feel they're under damped, mainly because i don't want to crank up the fronts as the springs are so stiff - very hard ride at low speed, but feels slightly unsettled when pushing on
i think knocking 100lb/in off the front is prob the way forward, i'll be less nervous about increasing the damping + meeting potholes!
snotrag said:
I was about to say - its all irrelevant unless we know what ARB's your running.
As I understand it - For pure track use you want to use a very stiff spring with a light ARB - IE the Roll AND the Pitch/Dive (fore/aft) weight transfer is handle well by the stiff spring - and the light ARB effect give maximum traction and turn in.
But - for the road - You should use a stiffer ARB to control the roll of the car and give you 'flat' cornering... thus meaning you can use a softer weight spring to enable good bump absorbption on each of the wheels and thus a good ride with light damping.
The fore/aft weight shift is much, much less of an issue on the road - how often do you use full throttle and more importantly full braking force on the road?
this makes a lot of sense, i've always been under the impression that going with higher ARB rates was more advantageous than simply putting stiffer and stiffer springs on, although thats not taking into consideration a track environment which is a lot smoother surface, and driving involving a lot of pitching.As I understand it - For pure track use you want to use a very stiff spring with a light ARB - IE the Roll AND the Pitch/Dive (fore/aft) weight transfer is handle well by the stiff spring - and the light ARB effect give maximum traction and turn in.
But - for the road - You should use a stiffer ARB to control the roll of the car and give you 'flat' cornering... thus meaning you can use a softer weight spring to enable good bump absorbption on each of the wheels and thus a good ride with light damping.
The fore/aft weight shift is much, much less of an issue on the road - how often do you use full throttle and more importantly full braking force on the road?
the noble M12 seems to be odd one outin this respect though?!
wiki said:
the M12 performs very well on both road and track, with surprisingly good ride quality, but a rigid feel. This is achieved by having no anti-roll bars on the car. This allows suspension to be made hard without making a back breaking ride.
i wasn't aware peugeot gti's of the 80's + 90's with soft springs and stiff ARBs had a back breaking ride?!what keeps the M12's roll in corners in check without ARB's? surely the springs alone?!
Edited by dylan0451 on Friday 30th October 17:34
Running 350/250 negates the need to run stiffer ARBs IMHO and indeed I run 400/300 on a road car which is even better on Gaz but Avo valving is harder so I do tend to advise about 50lb less, I would try that before wasting your hard earned on ARB's you might not need.
If OEM springs and shocks were fitted you would probably benefit from a stiffer ARB set up but this would not stop wheels lifting under track stylie driving.
If OEM springs and shocks were fitted you would probably benefit from a stiffer ARB set up but this would not stop wheels lifting under track stylie driving.
Edited by Ab Shocks on Saturday 31st October 00:46
Gassing Station | Mazda MX5/Roadster/Miata | Top of Page | What's New | My Stuff