SEiW/SDV shock length and spring wieghts

[combatsapph]

Hey all.

I'm building an SDV (pick kit up on 3rd June) and seeing as I already have some GAZ coilovers so I'm wondering if anyone can tell me the shock length and spring rates for an SEiW/SDV chassis.  Also, I take it the shocks use bush mountings?

Thanks in advance for your time.

[Blatman]

Gaz coilover from what? A Westfield or the Saff? If they're from the Saff, they won't even be close....

[combatsapph]

Actually from ebay - bought on a spur of the moment - only cost £20 for four but I haven't measured them yet.  I need to buy springs for them though.

[combatsapph]

So, just measured the shocks and they are 12" front, 13" rear, both open length.

A bit of research suggests about 220lb front springs with 160lb rears.

Sound sinsible?

[Blatman]

For a 'Blade/'Busa!

For an SEi with a Pinto/Vx/Zetec, 275/300 fronts and 150 rears.

If it's an SDV I'm not sure of the shock angles, but if they are similar to an SEi, then 220 fronts will be too soft IMHO. 160's on the rear would be OK, again subject to shock angle...

[combatsapph]

Shock angles are the same on an SDV as on SEiW I'm told.

Thanks Blatman - that's exactly the information I was looking for  

[Jenko]

Having recently asked a few manufactures for prices and spring rates for road / occasional track use, they suggested 175 rear, and 300 front for the spring rates.....This was for my CVH powered car. However, as Blatman quite rightly suggests, I think this is quite a hard set up, but it really depens on what you intend to to with the car......

[Mark B]

220lb springs on the front will be fine *IF* you have a front anti roll bar (speedsports have 200lb fronts as standard), otherwise they will be too soft as blatters says, especially with a pinto under the bonnet....    

[Blatman]

If you have a front roll bar and it's also supporting the front springs, it has preload, which is bad. On a 220lb spring, the front will be too soft when travelling straight and level and you hit a pot hole, and it'll also dive more during heavy braking, making the back go lighetr than it might. Westfields have a hard enough time with the rear brakes locking first without making it worse by having a too soft front end...

So IMHO 220 is too soft for a Pinto.

[nikpro]

If you have a front roll bar and it's also supporting the front springs, it has preload, which is bad.

I don't understand this comment Blatters - if the front springs are equal and the weights on the front wheels are equal how will the ARB have preload? An Arb will stiffen the front of the car surely as it connects both sides and will therefore effectively increase the spring rates?

I may be completely wrong as well - just after some clarity!

[Blatman]

I'm trying to say that an ARB should not have any preload in it when travelling straight and level, so the 220lb springs will see the car pitching a lot more than it might under braking and acceleration.

Mark B says that if you have 220lb springs *and* an ARB, then it will be fine. I disagree with that because the ARB should NOT be supporting the car and therefore "improving" the effective spring rate, unless it's not working properly and therefore enacting extra force in to the front suspension. If the ARB exerts *any* force in to the suspension other than preventing roll, it's not set up/working right. The ARB and springs should work in effective isolation as they are doing two different jobs, in theory at least. So, ARB or not, IMHO 220lb springs are not stiff enough for a Zetec/Vx/Crossflow/Pinto powered car, ARB's fitted or not...

[pete g]

i always thought that was what westfield supplied 220 front

[Blatman]

Ignoring the cornering functions for a minute, think about braking and accelerating is a straight line. IMHO the 220's will be too soft to prevent a fair amount of pitching. The ARB should be doing nothing during dead ahead driving. If it is doing something, it's not functioning properly as it is inducing extra springing to the car. Not good...

If I had 220's on the front of either of my cars, I'd be worried about bashing something on the ground...

[nikpro]

Ignoring the cornering functions for a minute, think about braking and accelerating is a straight line. IMHO the 220's will be too soft to prevent a fair amount of pitching. The ARB should be doing nothing during dead ahead driving. If it is doing something, it's not functioning properly as it is inducing extra springing to the car. Not good...

If I had 220's on the front of either of my cars, I'd be worried about bashing something on the ground...

All is clear now Yeap i agree that travelling straight ahead the ARB should not do anything and softer front springs will cause the car to pitch more under breaking unless there is anti-dive geometry in the suspension.

However if the springs are highly rated and an ARB is fitted the car could be too stif in roll surely... I've been told that the Westfield ARB is particularly stiff but can not confirm this.

[Blatman]

Of course there is a balance to be struck, but the theory is that the springs are supporting the car, and the ARB's are controlling roll. The two should be considered as separate systems, even though they obviously interact. But that interaction should be as small as possible, otherwise you end up with stiff springs supporting the car 'cos the ARB doesn't control roll, or a soft car with ARB's contributing to the suspension action. Striking that balance is where the real skill is, not in just setting up, but in enabling the driver to provide reliable feedback to the person doing the set up. The *biggest* factor in set up is whether the driver can actually tell what's going on. *Anyone* can say "ooohhh it's really oversteery", but knowing what's causing the oversteer, and where and how it manifests itself is the most important part of getting it right... IMHO of course...