[Want] 420R Sport Suspension

[empti]

Looking for the 420R Sport Suspension (coilovers) . I currently have "Track Suspension" but I think the spring is a bit too stiff for road use. 

[pethier]

Shot in the dark:  Have you tried Eibach's selection of sprint-car springs?  I don't even know if they still do this, as it was a long time ago I bought springs for my Europa.

Edited October 11 by pethier
hamfisted typing

[MV8]

It's possible someone changed the springs on your current coilovers from the track spec rate. Aftermarket springs usually have rates and part numbers stenciled on the spring itself. A dial caliper to check wire thickness, counting coils with space between them (active coils), the measured outside diameter, and some math can indicate close to the advertised rate. The rate can also be checked off the car assembled or with the spring removed.

[empti]

@pethierthanks for the advice, this is an option too. Since sport and track suspension uses different collar size, I'd have to source that part too. I am thinking about just getting the whole coilover setup and just swap it in without taking them apart. 

 

@MV8 I think I began to get used to the track suspension after 1000 miles so far. I'll take a look at Eibach's website to see if they offers same spring from factory catalog.  

[JimmyG]

FYI: I spoke with a Caterham suspension dealer/race shop in England. The street/track shocks they sell come with 170lb springs.
I attempted to measure and calculate the OEM spring rate on my 2013 Caterham 360R with the base black Bilsteins, and it appeared to be approximately 120lbs. With the stock springs, I am bottoming out hard on the rear end of the car on rough roads.

[MV8]

Full of fuel and with driver, the rear GC should be 165-205mm with the front 15mm lower than the rear. The adjustable lower seats may fit the standard bilsteins. The bump stop donuts wear too. Are the 120# springs progressive?

[11Budlite]

1 hour ago, MV8 said:

 the rear GC should be 165-205mm with the front 15mm lower than the rear.

 

Where are you measuring to, that seems like a lot? That'd be 6.5"-8" if my math is right.

[MV8]

I agree, but that is the spec from CAT for a 2014 (chosen out of convenience). Here is an excerpt from the 2014 assembly manual and it applies to all 2014 seven model with adjustable spring seats:

"5.9) Cars fitted with adjustable damper platform

Cars fitted with adjustable damper platforms need to be adjusted to achieve the optimum ride height. This is done by lowering or raising the height of the platforms on the threaded sleeve. It is essential that this task is carried out on level ground.

NOTE

Lowering the platforms will decrease ride height, and raising the platforms will increase ride height. For the best results the ride height should be set with the driver in the car and fuel in the tank.

1. Start by adjusting the front dampers to achieve a minimum distance of 150 mm (this can be increased for road use to a maximum of 190 mm) between the ground and the bottom of the lower chassis rail, where the rear leg of the front lower wishbone exits the side of the car. This measurement should be the same on both sides with the car loaded.

2. Now adjust the rear dampers in the same manner to achieve a height 15 mm higher than the front, measured to the underside of the lower chassis rail immediately in front of the 'A' frame mounting point.

NOTE

Adjusting the rear may have an effect on the front therefore it is good practice to check between front and rear several times during adjustment

3. Once the desired ride heights have been set ensure that the platforms are locked together to avoid movement."

 

GC spec from Lotus has been 6" to the rails but the sump is lower than the rails and road testers likely considered sump clearance to be GC and without a driver onboard. Tests I've read between '57 and '71 indicate 4, 5, 6.2, 3, and 6.5".

Edited yesterday at 10:43 AM by MV8