Does anyone know if it's really bad news if when a shock is at it's maximum travel the spring is loose.

Reason for asking is that we've got 12" max travel shocks (AVO) and 8" springs on the front. When the ride height is ok, the shock isn't at it's maximum travel. If the wheel then deflects downward (ie into a pothole or after launching over a hump backed bridge ) surely the shock will extend to it's maximum (in extreme cases) but the spring will not keep up.

This then means that the spring will for a moment be free floating and when the wheel then returns to the normal ride height, the spring may not be in the correct position. I'm worried that this may be a) dangerous and b) may knacker the spring seats top and bottom.

Any opinions or am I worrying too much?

The spring is pushing the shock as far apart as possible. Therefore the spring needs to be compresed to be fitted onto the shock. This is irrespective of being fitted to the car.
So if you hit a pot hole, you would need something actually trying to pull the shock apart before the spring would move.

Hi ,

I believe for SVA you must have a shock with spring load at all extremes of travel.

But as far as the operation of the shock is concerned you should have no worries about it being loose in full droop. Most race cars are like this.

All that is pulling the shock is the weight of the wheel and when you hit a pot hole things happen so fast it is unlikely the wheel weight will pull the shock apart against the rebound damping enough to unseat the spring anyway.

Kind regards,

Darren

Feel free to correct me but the maximum extent of the shock doesn't suddenly become longer just because the shock is fitted to the car . . . . . .

Darren,
As I need to pass the SVA then I do have to have the spring load throughout the travel if that's what's required.

John,
Forgive me for being dim but... what?
I don't understand your last post. Are you questioning Darren's statement about the rebound damping?

For what it's worth I'd feel happier if the spring was rigid and if SVA requires it anyway then I have no choice.

Since my original post I've adjusted my rear spring seats so that the spring is under pressure when the wheel is off the ground and when lowered the spring/shock compress under the weight nicely to give me the correct ride height (trailing arms parallel to the ground). However the fronts are still too high. I think the only cure for this is to buy lesser poundage springs. The ones Luego supplied are 300lb which seem too much for the Fireblade engine. The only other options I can think of would be to buy shorter shocks so the spring is more compressed to start with or the lighter springs maybe 250lb so that the weight of the front end pushes them down the the right ride height.

Any thoughts on a solve for this are as usual gratefully received.

Hi Andy,

It woul dbe worth checking the SVA regs, as i am not building mine for the road i am only recalling that from other peoples comments over the years.

If you need longer and softer springs i have 275 and 175 springs in stock that are longer. Also if you need the correct length shock i sell a kit for £220 for 4 with springs, and i often split them into pairs for people in your position.

You might also consider using helper springs, which are very soft spring made from flat coils that are only there to prevent your type of problem. I can get hold of these for you if you need them, but, i will have to check on spring diameters first. I guess yours are 1.9" ID?

Darren

quote:

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Originally posted by andyd
Does anyone know if it's really bad news if when a shock is at it's maximum travel the spring is loose.

Reason for asking is that we've got 12" max travel shocks (AVO) and 8" springs on the front. When the ride height is ok, the shock isn't at it's maximum travel. If the wheel then deflects downward (ie into a pothole or after launching over a hump backed bridge ) surely the shock will extend to it's maximum (in extreme cases) but the spring will not keep up.

This then means that the spring will for a moment be free floating and when the wheel then returns to the normal ride height, the spring may not be in the correct position. I'm worried that this may be a) dangerous and b) may knacker the spring seats top and bottom.

Any opinions or am I worrying too much?

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quote:

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Originally posted by JohnFol
Feel free to correct me but the maximum extent of the shock doesn't suddenly become longer just because the shock is fitted to the car . . . . . .

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Imagine a shock with no spring fitted. Now pull the shock as far apart as it will go. It will hit a mechanical limit (bump stop or whatever it's called). Measure the distance between the top and bottom spring mounts. Measure the height of the sping.

For me the spring is the taller of the 2, therefor even when the wheel has hit a pot hole, the spring is still being held in compression.

Might be a different design, but that was my concern. .

quote:

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Originally posted by andyd
Does anyone know if it's really bad news if when a shock is at it's maximum travel the spring is loose.

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John,
Thanks, I understand what you meant now.

FastWestie,
Yes we have adjustable springs seats but this will a) make the spring "harder" which will mean that the weight of the front end will not compress hardly at all and b) it will not lower the ride height which is really what we are after.

You're right about the top spring seat. Obvious really but I didn't think of that

The only way to achieve what you want is a longer spring or shorter shock.

If you wind up the spring platform this will not stiffen the spring! It will add preload and hence raise the ride height, its different to stiffening the spring. It will of course stop it coming of its platform and one cheat will be to run the higher ride height for SVA and then lower it again after.

You really need not worry about unseating the spring in operation. Like i said most race cars will run in this condition. If you run over a pot hole, the spring load cannot possibly push the shock to the limits of travel against the rebound damping force fast enough for it to unseat the spring, before the wheel is back out of the pot hole or the chassis has caught up with the wheel in the pot hole. Believe me it just doesn't happen.

Darren

quote:

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Originally posted by dozracing
If you run over a pot hole, the spring load cannot possibly push the shock to the limits of travel against the rebound damping force fast enough for it to unseat the spring, before the wheel is back out of the pot hole or the chassis has caught up with the wheel in the pot hole. Believe me it just doesn't happen.

Darren

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andyd:

quote:

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Yes we have adjustable springs seats but this will a) make the spring "harder"

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I have 12" front shocks, with 8 or 9 inch springs, adjustable ride height 275lb/in rate

I have 11.5" rear shocks with 7 or 8" 175lb/in springs. I can also get practically any spring rate you desire for a good price (depends on rate).

Shock kit (4 off with springs) is £220

See website www.gtscougar.freeserve.co.uk for full details, or email off list doz@gtscougar.freeserve.co.uk

Kind regards,

Darren

Thanks for all the input.

Rorty, thanks for explaining the spring "hardness" thing. I didn't realise that these springs are linear.

Darren, we are going to wait until we've got all the weight that we'llhave over the front in before making the change. I'll maybe contact you then once we've decided how low we need to go. Thanks.