Front spring rates

[techbod]

I'd like to check what spring rates I have fitted on my front suspension,as I reckon I need to replace them. They are from a live axle car fitted with Gaz dampers with adjustable platforms. Fitted when I bought the car so I don't know what they are rated at.

 

Spring dimensions are 8" top to bottom, approx 2.5" coil diameter, wire diameter 3/8" and approx 8 turns that look like they actually do something. Picture here

 

With those stats I believe that gives me a spring rate of around 220? Calculated here.

 

Does that sound like a reasonable rate (mainly road use, A021s 70 section if that matters)?

 

Is there a BC 'recommended' supplier of replacement Gaz springs?

 

thanks

[Jason Plato]

Faulkner

 

 

here is my Duratec R .... C7 TOP

Taffia AO

[techbod]

*arrowup*Thanks for that.

 

Would that be this lot here?

 

 

[James_Russell]

220lb sounds about right to me by the way. I just fitted my race car (1600vx classic grad) with springs of a simular poundage.

 

Q41 ACF Classic Grad #98

[Jason Plato]

😶‍🌫️

 

 

 

here is my Duratec R .... C7 TOP

Taffia AO

[techbod]

Thanks both

Thats me sorted out.

[Jaseb]

Eibach are the only other one I can think of, not cheap but I'd expect them to be lighter than Faulkner due to the materials they use, Nitron sell them as their upgrade spring I believe, just a thought 😬

[SLR No.77]

If the car is predominantly for road use, I'd be tempted to try a slightly softer spring - 220 is good for the track but you may find you can improve the handling with a softer setup.

 

Stu.

[Paul Deslandes]

Unless you measure the coil wire diameter very precisely with a micrometer, the calculated rate can be wildly out as it is a 4th power law relationship. Roughly speaking, a 10 thou" error in measuring a 3/8" dia would result in a 10% rate error.

 

The manufacturer's rate is normally stamped onto the flat end of the spring although you'll probably have to dismantle it to read it.

 

Also note that the effective front spring rate is dependant on whether you have standard or wide-track suspension as the steeper wide track spring/shock angle reduces the effective rate even further than standard track does.

 

 

 

Edited by - Paul Deslandes on 16 Jul 2010 15:15:10

[techbod]

Ok understood I'll break out the micrometer and make sure.

 

The manufacturer's rate is normally stamped onto the flat end of the spring although you'll probably have to dismantle it to read it.

 

I've got the springs off the platforms but can't find any markings to indicate rate - which is why I ended up trying to calculate it.

 

Thanks all.

 

 

 

Edited by - techbod on 16 Jul 2010 20:22:11

[Bricol]

Blue Peter way - you may wish to ask a grown up before you borrow the following:

 

Bathroom scales. Steel rule. Pillar drill / drill press. Piece of thick ply to sit on scales, cut to clear scale.

 

Place scales on table of drill, centrally under chuck. Place ply on scales. Place spring on ply on scales. Wind table up so drill chuck sits on top of spring. Zero scales/make a note of static reading. Place rule on ply and note height of spring relative to ply. Wind drill chuck down, thus compressing spring - stop winding when top of spring has dropped one inch relative to ply - read scales. (Dont read spring height relative to the drill table - the scales will be dropping too).

 

Differnce in readings, in pounds, is the actual spring rate in lbs/in.

 

Easy. And probably quite different to your calculated rate.

 

Bri

[Tim V-W]

Marcus

 

YHM

 

Tim

 

 

[elie boone]

Do you calculate with or without the powdercoat ?

i second Faulkner *thumbup* on a second purchase i got 10%off *thumbup*

[Paul Deslandes]

err.....without powder coat!