After much toiling in regards to springs and shocks, I'm finding the R1 and R6 shocks have ALOT of preload. I want to run essentially zero preload--but just enough to stop the spring from coming loose. Also, the very low motion ratio of 0.6 in the front would necessitate a bell crank and pushrod system--which IMHO is simply a pain in the neck to package. The lack of the threaded shock body would make ride height adjustment difficult.
In looking at the multiple packaging issues with the large diameter ATV shocks, 3.2" OD springs, 2.2" shock bodies, and the external piggyback reservior, it is VERY tough to thread the needle between the A-arms, tie rods, toe links, and axles. The 45 degree angle of the shock body spherical bearing presents an additional challenge.
Furthermore, a coworker of mine had a coil spring break on his car after hitting a bump and the sudden change in steering, pulling the car towards oncoming traffic.
This got me thinking in regards to using 13 year old springs on the Yamaha 660, and the fatigue life of the spring steel. Plus, the degradation of old shock oil over many years isn't likely to help.
The recent rework of the front suspension and steering to accommodate full lock with the 13" wheels and 10" wide Hoosiers decreased the splay between the front LCA members, making it further difficult to package the ATV shock. Also, the lack of a fully threaded shock body such that the spring perch can move closer to the spherical bearing reduces ride height and preload adjustment.
So, after much more research and reading, I pulled the trigger on GAZ Gold adjustable shocks (13" extended, 9" closed) with 1/2" ID spherical bearings. Much slimmer design with 1.75" body, and 1.9" ID spring, but still giving me a 4" stroke.
Attachment:
GAZ Gold 13 inch.JPG
I am finding the GAZ shocks are standard on the Brunton Super Stalkers, and they also make units for Caterham and Westfield. Granted they are not Ohlins, or Penske, Nitrons, or Koni shocks, but I've read good reviews on them for the most part. Yes, I am loosing independent high speed and low speed compression damping adjustment, and independent rebound adjustment, but I simply can't justify $2,000 on shocks for a toy car.
The QA1 PromoStar Double adjustable shocks (which I believe Kurt B. is using on Midlana?), look like precision units but were still much more cost than I could justify to upper management.
After reworking my suspension calcs, I arrive at 200 lb/in front, and 280 lb/in rear springs. I went with new Eibach 8" length 1-7/8" ID springs, (similar but 2" shorter than below) which should give me enough room to run near zero preload.
Attachment:
EIBACH SPRING 10 INCH_001.jpg
With 4 springs and 4 shocks (with spherical bearings and spring perches) this came out to $753.42.
This is probably the most expensive part of the car, second to the engine.
I'm not a big fan of the Eibach hooker red, and may end up painting the springs black or silver. The springs are special order 3 week lead from Eibach through Summit, and GAZ shocks are about 1 month lead from UK.
Getting these small 13" Hoosier slicks is becoming rather challenging to clear, as it could have been easier to go with larger wheels/tires, but I'm certainly going to try my best to keep everything small and light.
Question: I have not confirmed this yet, but has anyone had issues fitting 1-7/8" ID (1.875") springs on UK made shocks which call for 1.9" springs? Can I assume the 0.025" difference is not an issue with European shocks which call for 1.9" ID springs? (If I need to make a small relief on the spring face to clear the spring perch, it shouldn't be a problem--but I'd rather not.)