hi, going with bilsteins in rear of 914-6 conversion, bought bilstein hd, and adjustable perches, I have to use 2 1/2 springs, anyone know the length and lbs I should use. should I buy a certain make, just street driving not racing, help please

I'm not sure what you mean by 2 1/2 springs. I have Bilsteins with 160 pound progressive springs on my car. If you have adjustable spring perches, you should be able to adjust the rear height of the car using any number of spring lengths and poundages. Is poundages a word??

I think he means springs that have coils wound with a 2.5" inner diameter.

Not sure of the length, but stock springs were in the 60-90 lb/in range. For a Six conversion, you would not want the lower or middle end of that range. In fact, 100 lb/in springs are sold in many places as "stock" replacements. And higher rates may very well be better for you.

But it does depend on the rest of the suspension setup. If you have stock 914 torsion bars up front, and no sway bars at all, then perhaps the 90 or 100s would be a good match. If you have thicker torsion bars (many/most/all 911s used thicker ones than the 914s did) and a good front sway bar, then a higher rate spring would be appropriate.

--DD

Made my own version of adjustable coil overs using 140# springsClick to view attachment

Pic 2Click to view attachment

I bought the rebel racing kit. I figured if Pelican sold it must be good. The springs are 2.25 versus everyone else is selling 2.5" springs. The kit is really light and I went with there 175 lb Eibach springs.

I used Performance Shock Inc. who are located at Infineon Raceway in Sonoma, Ca. They have a ton of experience. You will need to "mock up" your vehicle's expected ride height and then measure from the top of the inside shock tower to the middle of your threaded perch to determine the compressed length.

Your spring rate and spring length will depend several factors and they can guide you in the process. I ended up using 200# in my 6 and it is perfect for my driving needs.

175 lb +/-5, 10" long
If you want to be stiffer and lower, go with 200 lb and 8"
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What everyone else said above is true. Results vary. Buy two sets and have fun testing the difference!
With a little practice, you can swap rear springs in 15 minutes (or less). Spring compressors are not needed.

I'd lean towards the stiffer end of streetability ie 175-200. Of course it is largely subjective and also depends what you have up front and whether you run swaybars on one or both ends. Best to think of the suspension as an integrated system.