So we are prepping our RX-7 for March's 24hrs of lemons at infineon. The rear springs currently on the car have been cut and are a bit scary. One of the items our team would like to "fix" are these rear springs.
Ideally we would like a spring that has an ID of 4" 8-9" in length and at a rate of 200 lbs/in.
Anyone know a way I could source a set of these cheaply? From my research it seems that 4" springs are kind of hard to find.
I would be particularly interested in finding some domestic crap-pile I could raid parts out of at the junk yard. But if need be I could live with some inexpensive aftermarket parts too...
its a first gen RX-7 :
http://grassrootsmotorsports.com/reader-rides/4646/
Find a Pathfinder in a junkyard. Once you cut them to that length they'll be in the 300lb range.
You may want to not drop the car quite so much - the scary is because of the low. The rear suspension doesn't really move when it's down super low, so it's like having a 30mm swaybar in the back.
i wonder, for a Lemons-like race, how long you could get away with seriously drilled-out upper link bushings.
Aftermarket 5" O.D. coils are what i use, just cut 1/2 a coil from one end so that it will fit into the RX-7's lower spring pocket. I think IMCA modifieds still use 5" coils in the back and are in the same ballpark ratewise, local dirt track swap meet might be a good place to look.
9-1/2" free height is the shortest 5" spring with a 200# rate that i see in the Speedway catalog, $55 ea.
Cut 1/2 coil off to fit the RX-7 spring pocket, it would be about the right height.
Awesome info thanks guys. I didn't realize that 5" would work with just a little "haircut". I don't think that going to 10 1/2 or 11 in springs would necessarily be a bad thing. I am going to consult the rest of the team and see what they think...
I had problems fitting 5" springs without wallowing the upper spring perches out. You also will have interference with the upper links, but it'll be more annoying noises than anything.
