Independent Rear

[Beagler]

Glad to see the article in the club mag. I thought the rear end in my Westfield a much better option than the Dediion in the Caterham. Will look forward to the conversion kit.

[Beagler]

Spoke to Simon at Meteor sadly no kits only in house conversion.

[SLR No.77]

So why not get Simon to do it 

[Stewart Collier]

I see there's a £1,000 saving for the first 10 conversions.

[Beagler]

Would  have enjoyed converting my Caterham as a Winter project and the reduced cost.

[ScottR400D]

I wonder what the insurance implications of this are? I'm bound to inform my insurer of changes and modifications, as I'm sure we all are. Is any formal type approval, or manufacturer approval needed for such a significant change?

I quite like the idea but I understand at the moment there's only 1 car been fitted and done a few thousand miles, and there are none at all running with the final iteration?

In addition that car's fitted with adjustable dampers and progressive springs so isn't going to be a direct comparison for many of us.

Food for thought though  

 

[Beagler]

Additional explanation from Simon at Meteor,

 

"The install a quite more detailed and accurate I am afraid.  We have so many jigs for production and to ensure the positioning of the rear cage is accurate.  We also have a full laser and 3D camera alignment system to ensure it is all correct"

[Benton]

Taken from Simon's website .....

Although we remove a very small section of the lower chassis rail that in the standard car attaches to the lower basket this could be reversed in the future if wanted very easily.

We prefabricate a rear “basket”, wishbones and upright which is then welded onto the rear bulkhead.

Basically fitting some sort of revised rear basket, not exactly a home DIY job!
How does this new basket tie up with the existing rear skin, hopefully Simon will be along later to explain. 

 

[ScottR400D]

Hmm. I'd have to think long and hard about a permanent change which that really is though thinking about it welding in the basket is likely the only way. 

[Golf Juliet Tango]

Welded or brazed like Arch?

[moorsd123]

I wish they had compared lap times in the article. I know it's not all about track time and the independent suspension is likely to be a lot more compliant on the road. Would have just been interesting to see what (if any) difference the independent vs De Dion setups had on lap times?

[Shortshift]

Ever considered a Birkin IRS?  Rather nicely executed...

 

I am curious to see the hub carriers in greater detail...

James

 

[John Vine]

Mmmm... that IS neat! 

The only info I've been able to find so far is under "Rear Suspension Assembly" here.  I can't find a Birkin SA website at all.

JV

[Shortshift]

Good find, John.  Looks as though the rear carriers were cast, initially, with later ones being machined from solid billet.  But an important point is that the car is S3 sized and looks to be properly engineered for IRS.  Intriguing!

James

[John Vine]

I see that the Birkin upper wishbone is offset (with the damper mounted centrally on the lower one) in order to accommodate the driveshaft.  The Meteor ones sit centrally one above the other with the damper attached to the rear of the hub carrier (which explains the asymmetrical upper wishbone). 

(ETA: In fact, this is more a trick of the light, I think, as both designs will have two lower mounts on the hub-carrier.)

Both versions look very tidy to me.  I'm a little surprised, though, that CC haven't already implemented iRS on the S3/SV.  Presumably, this is simply down to cost, even though they've done it on the CSR?

JV

[Geoff Brown]

#15 JV - The CC 'development glacier' moves incredibly slowly for projects such as this & of course ££££s are required.

The IRS development is a no brainer going forward with the Seven. Hopefully Meteor hold all the rights & registered. If so they there is money in that especially if Caterham  wish to adopt. But highly unlikely ?

[Shortshift]

"Hopefully Meteor hold all the rights & registered. If so they there is money in that especially if Caterham  wish to adopt"

Oh dear...

James

[SLR No.77]

Meteor's intellectual property can only apply to the detail of their (Simon's) own interpretation of an IRS setup in a Seven and the way it's been achieved. The IRS concept itself is well established and of course Caterham were there long before Meteor!

[Shortshift]

Thank you Stu; I clearly have less energy than you!

James

[ScottR400D]

#16 I would suggest IRS has been a no brainer for many years and CC are obviously well aware of it. 

But if it hasn't been adopted to date and given that the EV might not be in the mode of the traditional 7, which may well die out over the medium term, it's likely all a bit late. 

[aerobod - near CYYC]

Although a double wishbone rear has a number of benefits for road use, the deDion has one benefit for track use that I would choose as my top-of-the-list item for wanting to still use it if I had the option of either. It is the very predictable and controllable handling on the limit without any sudden snap-back of the suspension when the car starts to slide.

With a double wishbone setup, as the tyres lose grip the previously loaded outside wheel camber change due to the inner bottom pivot moving outwards compared with the top pivot as body roll suddenly changes, this can cause a traction snap-back, with a consequent launch sideways across the track if the car has started to spin.

[SamC]

Only if your suspension has been designed by someone without any knowledge of camber gain and how do design a proper suspension geometry.

[aerobod - near CYYC]

Not necessarily the case, as all parameters can't cover all scenarios, it can be minimised, but not really eliminated as the inertia of different components will change the relationship between the movement of the inner pivots and arc of the wishbones (and movement of the outer ball joints) in different ways under different load conditions. It is about the dynamic loading/unloading of the suspension as opposed to the static geometry effects of the suspension movement.

[SamC]

Ok. Don't agree in the slightest (being a designer of suspension for 20 years), but we'll agree to disagree as it is largely irrelevant in the context of this discussion!

Ultimately the % gains that the IRS systems (CSR/Meteor etc) give the Caterham are smaller than on bigger, heavier vehicles so they aren't as game changing. Hence the reason that the weight/cost/complexity trades have never seemed to pay off to the 'mass' (!) market.

All just my opinion of course.

 

[simon_h]

Caterham investigated irs on the s3 many years ago and discounted it then. There was a development chassis on the rack when I was there in 2012. It's too expensive to implement, the gains minimal on an S3, CSR was just an SV with irs and inboard front dampers, and they wouldn't be able to recover the costs of it as a standalone S3 model. I'm not getting into the why's and wherefores of an aftermarket conversion as that is a completely different thing. The aftermarket doesn't have to worry about everything that a OE manufacturer does.