Datsun411SSS Posted October 18, 2012 Report Share Posted October 18, 2012 Looking to buy a set of rear springs for a 510. They have to be alot stiffer than stock specs. Let me know what you got. Local preferably. Located in Los Angeles : San Fernando Valley 1 Link to comment
datzenmike Posted October 18, 2012 Report Share Posted October 18, 2012 Not a lot to go on. You don't have a 510 listed in your profile so sedan or wagon? I'll assume a sedan with coils. Dodge D-50 front coils have been used and are documented. In this case '78 Dodge ram 50 2.0L . The Ram was around 14 years with several motors 2 and 4 wd so others will vary but only in initial stiffness. They come with 6 1/2 active coils and spring rate calculates* out to 500 pounds per inch and on a 510 this reduces to 132 (ish). Removing one coil (to 5 1/2 coils and about 9.5" tall) = 155. Removing another half (5) =170 pounds per inch * 11,250,000 X wire thickness to the 4th / 8 X number of coils X diameter to the 3rd Wire diameter= 0.620" coil diameter cl to cl = 4" Active coils = we'll use the 5 1/2 coils as an example... 11,250,000 X (0.620 X 0.620 X0.620 X 0.620 = .14776336) = 1662337.8 over.. ------------------------------------------------------------------------------ 8 X 5.5 = 44 X (4 X 4 X 4 X=64) = 2816 equals = 590pounds per inch Since the 510 rear axle is cantilevered with a ratio of 3.8 we.... 590 / 3.8 = 155.34 pounds per inch..... easy. So now you have the formula for working out the spring rate you want before cutting the spring. Link to comment
Stitebunny Posted October 18, 2012 Report Share Posted October 18, 2012 Whoa! I was wondering how you calculated my spring rate in my strut thread based on a picture. I still haven't measured for an exact calculation.... Link to comment
Dirttrack510 Posted October 19, 2012 Report Share Posted October 19, 2012 These are available from JC Whitney's parts catalog. I bought a set last year and they were very nice and worked great. Link to comment
DADZSUN Posted October 19, 2012 Report Share Posted October 19, 2012 Another option is to purchase an offroad coil spring and then cut it in half (w/o a heat torch, I just used a Sawzall). You can get one for about $150 shipped if you shop around. For example, for the rear you can purchase a single Eibach 1800-300-0400S spring which is 18" long, 3"ID, and 400lbs/in spring rate. You can easily order rates 50lbs higher... Once the 400lbs spring is cut in half, the rate effectively doubles to becomes two ~800lbs 9" long springs complete with a pigtail for the lower spring perch. Divide the spring's rate by 3.81 to get the approximate effective spring rate (~209lbs/in) at the wheel so you can match with the front. Be sure your damper can handle a heavier spring rate AND be sure the spring is coiled clockwise so the pigtail seats in the lower control arm perch as intended (don't ask how I figured that out). Fritz Link to comment
Datsun411SSS Posted October 26, 2012 Author Report Share Posted October 26, 2012 Great info datzenmike. I will be heading to the junk yard this weekend and try to locate those springs. Do you know what the spring rate difference is between the stock 510 and d50 springs? DADZSUN, thank you for the information. If i dont find anything at the junk yard, I will be going this route. The springs will be going on my 67' 411. I tried the stock rear 510 springs on the front of my 411 but was even softer than the stock 411 front springs.. Link to comment
erichwaslike Posted October 26, 2012 Report Share Posted October 26, 2012 use the roadster motorsports springs. stiffer and a drop.... Link to comment
datzenmike Posted October 26, 2012 Report Share Posted October 26, 2012 Great info datzenmike. I will be heading to the junk yard this weekend and try to locate those springs. Do you know what the spring rate difference is between the stock 510 and d50 springs? Usually the front rate matches or should be close to the rear rate. The 510 stock front rate is 81 pounds per inch. so the rears should be about 300 (with the 3.8 cantilever ratio) The stock D-50 coils are 500 pounds so about 131 pounds per inch. So this says the your front springs should be stiffened to a similar rate. I have a 710 and the stock fronts are 100 PPI (pounds per inch) I increased to 150 PPI by doing the math and cutting. I really like it at 150 and have no intention of going higher just so I can brag about how stiff I am. :lol: The D-50s should be measured and calculated and then cut if you want similar. Link to comment
datzenmike Posted October 26, 2012 Report Share Posted October 26, 2012 Cutting or replacing with stiffer springs may drop the ride height perhaps to an undesirable amount. You can simply cut and stack 1/4" aluminum spacers as needed above the spring.. Link to comment
Datsun411SSS Posted October 26, 2012 Author Report Share Posted October 26, 2012 use the roadster motorsports springs. stiffer and a drop.... Are they easily available? I havent seen them for sale anywhere.. Link to comment
Datsun411SSS Posted October 26, 2012 Author Report Share Posted October 26, 2012 Cutting or replacing with stiffer springs may drop the ride height perhaps to an undesirable amount. You can simply cut and stack 1/4" aluminum spacers as needed above the spring.. Great Info !!! I will have to try this this weekend if I can find the D50 springs. Thanks again. Link to comment
Datsun411SSS Posted November 7, 2012 Author Report Share Posted November 7, 2012 Well I went to the local junk yards and was not able to find any D50 trucks... I did find a set of Datsun Roadster springs, does anyone know if the spring rates on those are any higher than the D50 springs? Link to comment
Datsun411SSS Posted November 7, 2012 Author Report Share Posted November 7, 2012 here are the specs on the roadster springs: Front coil spring size - 12.7 x 87.5 x 290 mm - 6 turns Coil spring wire diameter - 12.7mm (0.5in.) Coil spring diameter - 87.5mm (3.44in.) Coil spring free length - 290mm (11.42in.) Link to comment
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