Dolomite Posted February 25, 2018 Report Share Posted February 25, 2018 I’ve done a few searches but couldn’t find what I’m looking for. I’d like to know how much to cut off of stock springs to lower the rear of a 510 about 2 inches. Even if you didn’t go exactly 2”, throw out how much cut and the amount of drop you got. Thanks. 1 Quote Link to comment
Ratwagon1600 Posted February 25, 2018 Report Share Posted February 25, 2018 The rule of thumb is basically for every one inch of height of spring you cut, you lose approximately three inches in total height. There are lots of variables here including, but not limited to spring rates (in lbs), sag i.e. how much they have been thrashed, the rubber that sits in the spring locating point (hopefully you know what im talking about here), shock absorber condition/travel, rolling stock (wheel OD), etc. RW's advice having done this for over thirty years is "less is best". It's a pain in the arse having to pull springs in and out of the rear end, however, better to do it incrementally than to hack heaps out of the spring and fuck it up. Dont forget to shake the bejeebus out of the back of the car (I find it best if you can stand in the trunk and jump up and down), to settle the springs when they are back in. 2 Quote Link to comment
datzenmike Posted February 25, 2018 Report Share Posted February 25, 2018 Trimming springs will increase the spring rate, usually always a good thing but to get a 2" drop possibly too much. At any rate the rear will now be stiffer than the front upsetting the handling. 2 Quote Link to comment
Dolomite Posted February 25, 2018 Author Report Share Posted February 25, 2018 Mike, the front is already pretty low and stiff. I’m just looking to match the rear to the front. 1 Quote Link to comment
Ratwagon1600 Posted February 25, 2018 Report Share Posted February 25, 2018 Increased spring rate in the rear may induce oversteer, however, this can be countered by a number of variables i.e. different tyre pressures, toe in/out, caster adjustment, larger diameter front sway bar etc. If you are using standard springs, the difference in the spring rate should be negligible. 1 Quote Link to comment
Icehouse Posted February 25, 2018 Report Share Posted February 25, 2018 Cut half as much off as you think. That's what I've learned haha. 3 Quote Link to comment
Draker Posted February 25, 2018 Report Share Posted February 25, 2018 When I did my D50 springs, I think I ended up with 1.5 coils. I cut a little at a time, reinstalled. Jounce the rear, roll it back and forth, check. Pull it out again, cut about another quarter coil, and repeat. Then account for a little more drop (not much) after it settles. 1 Quote Link to comment
datzenmike Posted February 25, 2018 Report Share Posted February 25, 2018 I don't know what the ride height is using the D50 coils as they are at full length, but the rate works out to 497.6 lb/in. or about 130 at the axle. Again, I don't know what the stock 510 rear spring rate is (to compare) but the fronts are 89 lb/in so the rears somewhere around 380 or 100 lb/in. at the axle. The Dime quarterly article says cutting one coil off brings it to 5.5 coils and 155 lb/in at the axle. Cutting to 5 coils remaining is 170 lb/in at the axle. 5.5 coils will give a ride height of 6.75" from the ground up to the under side of the rocker just forward of the rear wheels. 150 is a nice conservative amount that I run on my 710 fronts. Can't imaging twice this being run on some 510 for racing... w/e 1 Quote Link to comment
Roadster-ka Posted February 26, 2018 Report Share Posted February 26, 2018 Remember to reset toe in when you get the height you want! 1 Quote Link to comment
Dolomite Posted February 26, 2018 Author Report Share Posted February 26, 2018 Cut half as much off as you think. That's what I've learned haha. This is what I did. I cut 1/2 a coil, it’s still a tad high and the rear is softer than the front still. I’m going to take another 1/2 out when I get around to it. It drives much better now. 1 Quote Link to comment
datzenmike Posted February 26, 2018 Report Share Posted February 26, 2018 If you cut too much (too low, but get the rate where you want it) you can simply shim the spring with rubber 'doughnuts'. 1 Quote Link to comment
Dolomite Posted February 26, 2018 Author Report Share Posted February 26, 2018 Thanks for the advice guys. 1 Quote Link to comment
Doctor510 Posted February 26, 2018 Report Share Posted February 26, 2018 Simple solution, buy a set of Roadster competition FRONT springs, cut off one flat on both. 1 Quote Link to comment
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