Ways of reducing the weight of our cars

[Janner_Sy]

PSS10 Clubsport retails at £1978 plus vat.  I get bugger all off TBH.

  Thats ALOT.  Whats the AST equivalent of the Clubsports?  Do you know which AST kit is on the APR Golf?

[the bruce]

Has anyone considered that removing loads of weight means the springs on their suspension will no longer be correct for the new lighter axle weights?

Why?

[RedRobin]

Has anyone considered that removing loads of weight means the springs on their suspension will no longer be correct for the new lighter axle weights?

....I haven't but I think it's a very valid and interesting point (and typical of Sy  ).

At what point does losing weight begin to effect suspension spring loadings?

Is one solution to have the car corner-weighted again?

[Janner_Sy]

Because the spring rates are designed from the front/rear axle weights, so if you drop 100+kg from the car for instance and are in the market for the best suspension setup for £1xxx+ surely having a set of springs bespoke to your individual car makes sense, why pend all that money for something which isnt optimized for your car?

Edit

This is why the Octavia vRS, despite having an IDENTICAL under pinning, uses a different coilover kit to the Golf GTI.  its dwn to the weight of the car.

An analogy for you:
Driving a lorry that is unloaded is ALOT more uncomfortable than when it is fully loaded because the springs havent got the weight applied o them to make them work efficiently.

This is the same as say a Golf GTI with an uprated suspension kit.  Remove 100kg and the springs are then over rated, thus the ride gets worse and handling "potentially" worse, or at least limiting the potential improvement of the weight loss.

[RedRobin]

EBecause the spting rates are dedigned from the front/rear axle weights do if you drop 100+kg from the car for instance and sre in the market for the best suspension setup for £1xxx+ surely having a set of springs bedpoke to your individual car makes sense

....Indeed, when VWR took advantage of their technical partnership with KW Germany, they ordered springs to suit my individual car.

Some folks have poo-poo'd VWR as just re-badging products and adding a fat profit margin but that hasn't been my experience of them.

I presume that spring ratings are defined by a range rather than a fixed weight value or force.

[Janner_Sy]

I presume that spring ratings are defined by a range rather than a fixed weight value or force.

But as ive edited above, the vRS/GTI despite identical underpinnings use different aftermarket suspension kits.  The only differing point will be the extra weight that the Octavia is burdened with.

if it was fine to ignore the 100kg weight difference wouldnt they, the suspension companies, have just sold it under the same kit rather than a revised one which will of course cost extra for the company to develop and package etc

[RedRobin]

I presume that spring ratings are defined by a range rather than a fixed weight value or force.

But as ive edited above, the vRS/GTI despite identical underpinnings use different aftermarket suspension kits.  The only differing point will be the extra weight that the Octavia is burdened with.

if it was fine to ignore the 100kg weight difference wouldnt they, the suspension companies, have just sold it under the same kit rather than a revised one which will of course cost extra for the company to develop and package etc

....I'm not challenging your knowledge on this but am genuinely interested where the weight thresholds are.

So, in context, at what weight-reduction point does us reducing the weight of our car then require changing our springs according to their rating?

[Janner_Sy]

I presume that spring ratings are defined by a range rather than a fixed weight value or force.

But as ive edited above, the vRS/GTI despite identical underpinnings use different aftermarket suspension kits.  The only differing point will be the extra weight that the Octavia is burdened with.

if it was fine to ignore the 100kg weight difference wouldnt they, the suspension companies, have just sold it under the same kit rather than a revised one which will of course cost extra for the company to develop and package etc

....I'm not challenging your knowledge on this but am genuinely interested where the weight thresholds are.

So, in context, at what weight-reduction point does us reducing the weight of our car then require changing our springs according to their rating?

Looking at the  Octavia vRS there are 2 separate kits for the KW V2 stainless steel kits.  One kit has front axle: 1035kg, rear axle: 1150kg, the other kit is front axle: 1036-1105kg, rear axle: 1150kg.That will be the Petrol and diesel variants of the vRS.  Theres also the non vRS Octavia, still utilizing the same 55mm strut diameter that has the ratings of front axle: 1106-1160kg, rear axle 1150kg.  All have different part numbers.

It looks like 60-70kg increments, although that is only what KW have broken it down to.

So if your running lighter brakes, cntrol arms, hubs, bonnet, battery etc over the front axle you are in that region i guess your in that region.  I know on my fabia removing the rear seat benches, spare tyre/tool kit etc equates to 49kg.  Thats nearly in that region as well.

[the bruce]

Because the spring rates are designed from the front/rear axle weights, so if you drop 100+kg from the car for instance and are in the market for the best suspension setup for £1xxx+ surely having a set of springs bespoke to your individual car makes sense, why pend all that money for something which isnt optimized for your car?

Edit

This is why the Octavia vRS, despite having an IDENTICAL under pinning, uses a different coilover kit to the Golf GTI.  its dwn to the weight of the car.

An analogy for you:
Driving a lorry that is unloaded is ALOT more uncomfortable than when it is fully loaded because the springs havent got the weight applied o them to make them work efficiently.

This is the same as say a Golf GTI with an uprated suspension kit.  Remove 100kg and the springs are then over rated, thus the ride gets worse and handling "potentially" worse, or at least limiting the potential improvement of the weight loss.

When the springs are matched PERFECTLY from a view of handling you would be right.
In real world they are not.
At least with a coilover you'll screw it down after removing weight. At the same time you
increase negative wheel travel (rebound). So you'll have the same travel as before.

Yes, the spring rate to weight ratio changes. It'll become stiffer overall. If you search for
better performance (which someone removing weight surely will) you are happy with that
(very slight) stiffening. Remember removing 100 kg from a 1.4 to vehicle is just 7.X % !!

So for our purpose (fast road & occasional track use) this point isn't critical at all. In fact
it helps more than it does any harm.

[Janner_Sy]

I completely agree, but if people are talking of spending £1500+ on the "ultimate" coilover kit, which is pretty expensive, then IMO you might as well try and tailor your spring rates to match the exact car.

I like doing trackdays, but ultimately unless the car was going to be a track only weapon, id be happier in the sub £1k market where i guess matching the spring rates exactly wont matter as much.

[the bruce]

Yes, but even these "ultimate" Clubsport coilovers usually come with spring rates
of say 70 N/mm to 100 N/mm. If you increase this by 7.X % it's still negligible.  

True racing suspensions for a car of the weight of a GTI start at 200 N/mm and above.
I know a guy running 160 N/mm both on street and when autocrossing.

 

[danishmkvgti]

The retail of the normal PSS10 is 1500 quid.  I think the Clubsport is around 500 quid more.

I will find out next week.

Going to be miles better than the KW offerings.  Better company to deal with too.

You have seen the light Alex, and are moving away from the darkside   

[vRSAlex]

Sy,  Bilstein use the same kits for the mk5 and the vRS. KW don't though.

[rex]

As far as I remember (when looking at B16 codes), Bilstein has the same suspension for GTI, vRS and my 1.4 TSI also...

[Janner_Sy]

Sy,  Bilstein use the same kits for the mk5 and the vRS. KW don't though.

So Bilstein have gone for a one size fits all.  Cheaper to develop that way i guess.