Cut springs?

[lovemyjdm]

Ok so I may or may not have interest... Let the flaming begin. But! I know there are some guys here that rock it. I need some info on the ride quality, how safe it is, etc. For me right now it comes down to good suspension/cheap wheels or pretty wheels/cut springs

[datzenmike]

Judicious cutting of the coil springs is great for increasing the spring rate.  This gives a firmer ride with less body roll. There is a formula for working out in advance how much to cut to get the rate you want. The Z car is (I believe) about 150 pounds per in. (lb/in.) This means it takes 150 pounds to compress the spring one inch.

 

Cutting the spring to lower a vehicle ride height is unlikely to ever get you the spring rate increase and the height you want at the same time. Basically the lower you go the stiffer the ride you get.

 

I would suggest trimming the lower spring perches off. Grind down the weld so the strut tube is smooth. Put the perch and the spring on and use split collars to support the perch rather than a weld. This makes the ride height totally adjustable without affecting the spring rate.

[lovemyjdm]

Judicious cutting of the coil springs is great for increasing the spring rate.  This gives a firmer ride with less body roll. There is a formula for working out in advance how much to cut to get the rate you want. The Z car is (I believe) about 150 pounds per in. (lb/in.) This means it takes 150 pounds to compress the spring one inch.

 

Cutting the spring to lower a vehicle ride height is unlikely to ever get you the spring rate increase and the height you want at the same time. Basically the lower you go the stiffer the ride you get.

 

I would suggest trimming the lower spring perches off. Grind down the weld so the strut tube is smooth. Put the perch and the spring on and use split collars to support the perch rather than a weld. This makes the ride height totally adjustable without affecting the spring rate.

 

Awesome information to know, thank you

 

Cutting the perches seems almost too simple and cheap not to do. How come everyone seems to go a different route? And how would i determain the correct shocks i would need?  

[datzenmike]

They don't know better so they fall back on the 'monkey see monkey do' and just put coil overs on. They have no idea what rate they started at and just guess at it. When the dust settles they have hundreds tied up in an adjustable ride height that, once set, never gets adjusted again.

 

On my 710 I increased the spring rate 50% from 100 lb/in to 150 for the cost of a cut off wheel for my 6" angle grinder. That same wheel trimmed the perches off and smoothed the weld. Split collars are about $25 a pair so increased spring rate and fully adjustable ride height for about $30. Did it myself.

 

Shocks? Well when you have the strut apart take the gland nut off and see if the original oil filled damper has been replaced in the past with a shock insert. If it has, about all you can do is buy replacements for it at about $80 each? If you still have the original oil filled dampers inside they can be renewed and firmed up by dumping the thin watery oil out and refilling hem with a heavier weight 20W motorcycle fork oil. Thicker oil is harder to push through the internal valving. I have Bellray 20W in my 710 goon and my 710 sedan I tried ATF which is between 7 and 12 W. The springs on it I cut less off of because my wife likes to drive it. The Bellray was $17 a liter.... enough to do almost three struts.

 

Stiffer springs, adjustable height and renewed dampers for less than $50.

[lovemyjdm]

And i was going to be a part of that crowd  :blush:

 

You sir are my hero. My head has been so wrapped up in the coil situation deciding which route i wanted to go and options i had and now they are solved. I will get the split collars, the fork oil, and have at it hopefully within the next week. 

[wayno]

There is a point when you cut off enough spring, there will not be enough spring left to support the weight.

[lovemyjdm]

I understand and thats why i made this post. I knew guys do it and i wanted to make sure i wouldn't cut too much and start to ruin things

[flatcat19]

Your avatar is...um...offensive?

[datzenmike]

The shorter the spring is cut the stiffer it becomes. A side effect is that it does lower the ride height and on a stock strut it would collapse lower and lower until it is close to bottomed out. You could slip spacers between the spring and the lower perch to maintain the ride height where you want it, but with split collars you can push the lower spring perch up to do the same.

 

lovemyjdm, take note that there are limits to lowering a car this way or with coil overs. (probably around 3") As you go lower you get closer to being bottomed out. I don't think you can actually bottom the strut as there are rubber bump stops and that is their job. When lowering it is always advantageous to increase the spring rate to reduce body travel when traveling through a dip in the road specially when at speed. The body is closer to the moving ground and things like manhole lids. 

[damagedduck]

THERE'S ALSO THIS,,

http://community.ratsun.net/topic/28642-custom-coilovers-sunny-specific/

[damagedduck]

Or this...http://community.ratsun.net/topic/32106-completely-lost-on-how-to-lower-my-82-210/

 

For the rear...http://community.ratsun.net/topic/30153-my-home-built-rear-coilovers/

[lovemyjdm]

The shorter the spring is cut the stiffer it becomes. A side effect is that it does lower the ride height and on a stock strut it would collapse lower and lower until it is close to bottomed out. You could slip spacers between the spring and the lower perch to maintain the ride height where you want it, but with split collars you can push the lower spring perch up to do the same.

 

lovemyjdm, take note that there are limits to lowering a car this way or with coil overs. (probably around 3") As you go lower you get closer to being bottomed out. I don't think you can actually bottom the strut as there are rubber bump stops and that is their job. When lowering it is always advantageous to increase the spring rate to reduce body travel when traveling through a dip in the road specially when at speed. The body is closer to the moving ground and things like manhole lids. 

 

No disrespect but I've lived the low life for a while lol And i do understand the 280 is a very different car but i know what its like to drive a lowered car. 

 

 

So what i plan on doing is trim the perches, grind the welds, lower it and put the split collars under it to support it. ill get thicker oil for my dampers (20w motorcycle fork oil). 

Now for the stiffer spring how much do you suggest i cut off? If I'm thinking correct about 1 coil will give me another 100 lb/in??

[datzenmike]

Well first take some measurements on the stock spring to confirm where you are starting from. Be as accurate as you can. Close is not good enough.

 

I need the diameter across the coil... outside to outside is fine. 

The thickness of the wire. This is the most critical measurement. 

The number of active coils. Not the bottom or top loops that rest on the perches just the coils between that actually compress. 

 

From this, the amount needed for a certain increase can be accurately worked out. It's always best to take less off and try it and then remove more if desired. Thing is you can't put back too much removed. The beauty of the split collars is you can lift the wheel and release the collar to loosen the spring and cut more off with it on the car which speeds things up. Myself, on my 710, I increased my spring rate by 50% and it was a big improvement including the increased damper oil thickness. Now my spring rate is much lighter than the Z spring and the car is lighter, but based on this I would try 50% to begin with and see.

 

I can easily work out 175, 200, 225 and 250 lbs/in and how many coils to remove to get this.