Capt Slow Dork
Feb. 2, 2012 5:52 p.m.

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 :

Knurled Dork
Feb. 3, 2012 7:52 a.m.

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.

weedburner New Reader
Feb. 3, 2012 11:11 a.m.

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.

weedburner New Reader
Feb. 3, 2012 11:16 a.m.

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.

Capt Slow Dork
Feb. 3, 2012 12:34 p.m.

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...

Knurled Dork
Feb. 3, 2012 5:15 p.m.

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.

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