Superlight springs and grounding.

[New Barbie]

Does anyone know the rating for standard SL springs. Had my car on the scales and whilst all is now levelled and ride heights are fine the springs were described as soft, especially on the front.

 

The day after this I was checking the car underneath as I had grounded the car at the rear on a recent run it seemed. There were (now fixed) scuff marks on the A-frame forward mounting points which are the lowest part on my car at the rear.

 

My current thinking is to put stiffer springs on the car as I know the ride height is OK from the flat-floor exercise.

 

Anyone help with what rates to recommend, knowing the standard rate would help. Caterham help desk are in not-phone-back-mode and a search of the archives has not come up with anything.

 

Thanks in advance

 

 

[Nick Green]

Standard SL springs are the same as all the standard Caterham-supplied springs:

 

150lb fronts, 90/180 rears (or thereabouts). Seems to be some dispute about the precise values on the rears, or whether they are really triple-rate...

[Peter Carmichael]

Count,

 

Are you running the rear lower than me? Are you running Watts linkage? Perhaps we should get the two orange cars next to each other to compare - I have never had a problem with rear ground clearance on standard springs. If you have a problem it is either ride height or dampers, not the springs. AFAIK, the dampers should be the same spec as mine as well.

[New Barbie]

Peter, I do have the Watts linkage. I'm not sure how it is on your car, but on mine the A-frame mounting points are beneath the chassis rail. On Arnie's car (older, heavier, VX powered dinosaur), this is not the case I think.

 

As regards ride height, I'm not running a different setup to standard. Certainly, I've not deliberately lowered the overall height of the car.

 

The front of the car is a lot softer than the aforementioned VX and I have had a reasonable number of sump scrapes - I have decided simply to tolerate this as I don't want the height of the car any higher. I was going along a bumpy road when the back end grounded but not really so much as to cause this level of concern and I've grounded the back a second time on a different stretch of road so I definitely need to alter something in the setup.

 

Maybe we should stand the two orange cars next to each other and see the difference - at least in ride height. Although, once my new engine is installed, I'd hope the only difference is mine is faster and the nosecone poses a more even aerodynamic profile wink.gif

 

I'll measure it again, but istr, the clearance with no-one in the car is 150mm from the bottom edge of the panel as it meets the rear wing.

 

 

 

 

 

 

[CHRIS CLARK]

Count.

 

I had a look under Al Wains SL at the weekend and was surprised to see that, as you say, the 'A' frame fwd mountings are indeed the lowest point at the rear of the car! Ummmmn.

Mine is of the earlier (inferior?) design that has them tucked away. The lowest point of my car aft of the sump is the seat mounting bolts!

 

I have 'uprated' my springs anyway to 180lbs at rear and 250lbs front with adjustable platforms & damping.

This to cope with the heavyweight additions (me & the sidelights!!!)

[EFA]

Count, I would suggest that your bodily mass which on Saturday before you eat your chips was 1kg more than me if I remember the flat floor readings.....

 

Anyway, you are heavier than Peter, and you seem to carry an unfeasible amount of luggage with you so its logical that you might need slightly stiffer springs.

 

Might I suggest you try some 170's???

 

Peter, how on earth does the Watts Link effect spring rates to any degree of significance?

 

 

 

Fat Arn

Visit the K2 RUM siteid=red>

See the Lotus Seven Club 4 Counties Area Website hereid=green>

 

 

Edited by - fat arnie on 24 Apr 2002 23:34:17

[Peter Carmichael]

Arnie,

 

I specifically said "it is a ride height or damper issue".

 

 

The Watts linkage lets you run lower ride heights without getting silly rear steer characteristics.

 

The Watts linkage also (according to Juno) adds more "pro-squat" to the geometry, which gives excellent traction out of bends, but will also eat into the ride height if Count was on the power at the time of the grounding.

[EFA]

Peter,

 

Make a mental note you said:

 

"The Watts linkage lets you run lower ride heights without getting silly rear steer characteristics." teeth.gifteeth.gifteeth.gif

 

Fat Arn

Visit the K2 RUM siteid=red>

See the Lotus Seven Club 4 Counties Area Website hereid=green>

 

[New Barbie]

It is fair to say I was indeed, "on the power" when the car grounded, but we're not talking high speeds really. The damage is minimal and I simply applied a coating of hammerite to prevent any rusting happening.

 

Sounds like stiffer springs all round are a route to try. Arnie, I carry a toolbag and that's it in the boot. I recall about three of us forming a human chain to unload and then reload your boot so we could get K2RUM under the magic 700kg figure (without driver) you VX boys all crave so much wink.gif