Cutting down police springs

[pollock]

I just finished my big brake install. I used parts off a 2000 PI on my 89.

As part of the swap, I installed the springs from the 2000 PI. The front end now sits about 1.2" higher than it did.

I am going to trim the springs. I guess I'd like it to sit about 2" lower than it currently does (so it would be about .8" lower than it was before the swap).

How much should I cut off? Full coil?

[1987cp]

eek. I'd probably start by cutting a quarter-coil at a time and driving for a few days to see how you like it. IMO, 700 lb/in coils are already pretty skateboard-like ..., so there's the increase in spring rate to take into account as well.

[pollock]

Thanks for the reply.

I've been driving it as-is and, for my tastes, it could be quite a bit stiffer and I'd be happy. That part doesn't worry me.

Obviously I'm looking to avoid multiple tear-downs, so i'm hoping someone has been down this exact road before.

[1987cp]

To be comparatively certain based on previous work, you'll probably be looking at getting some of the new 925 lb/in springs from Speedway Motors. You obviously already know that just because JoePanther's ride was lowered exactly 3/4 inch based on fender lip to ground measurements, yours might not respond identically, and of course that the spring is roughly halfway out on the lower control arms ... all of which is an excellent argument, in my mind, in favor of the extra hassle of making multiple conservative cuts rather than cutting too much and discovering you need new springs.

I'm thinking lopping a whole coil off a 700 lb/in spring would result in pretty dramatic lowering. Here's a page where I was yapping a bit at random about spring rates .... IIRC, the 700# spring only had 11 or 12 coils, which means a proportionally larger difference in both spring rate and ride height for each coil cut versus a 390# spring with 14 coils.

[1980c10]

I think I cut one coil on one of the old panthers and it was around 3''. Look up the user
have24wheels he cut coils and lowered his.

[87gtVIC]

I think I cut one coil on one of the old panthers and it was around 3''. Look up the user
have24wheels he cut coils and lowered his.

I think he deleted all of his pictures.

[1987cp]

I thought he was the one who lowered his civi car by heating the springs with a torch.

[pollock]

Well, I decided to dust off one of my old engineering textbooks and try to calculate this.

I never measured the free length of the springs before I installed them, so I had to estimate it at 15.0" for calculation purposes. Per the numbers, I need to cut off .55 coil to get a 2" drop.

Once I get it apart, I will measure the free length of the spring and adjust the calculation.

Once I put it back together, I will report back and either be pounding my chest because I got it right, or cussing myself because it's dragging the ground.

Thanks for the replies.

[1980c10]

It can't drag the ground the a arms hit the fram before that lol.

[1987cp]

Sounds like a good step. At least calculating spring rates isn't rocket science. (though folks like Bell and Eibach would probably have you think it is)