Revision as of 02:48, 8 November 2012

Lowering the car makes it handle transitions better. And it looks cool.

1 Overview
2 Front
3 Rear Suspension
- 3.1 Lowering Blocks
- 3.2 Flipping

Overview

Common ways to lower the 1200:

Fit ready-made lowering front coil springs
Re-arch the rear leaf springs (or fit lowering blocks).

These and more advanced lowering methods are discussed below.

Front

Using shorter springs can lower the car further, but steps must be taken to keep the spring from falling out of the lower seat at full suspension droop. The end coils of the spring must be securely wired to strapped to both the top and bottom seats.

Lowering Springs

The best, but most expensive way to lower the front is to fit custom springs, of the certain length and spring rate. King Springs is popular vendor for 1200. Also Nissan Competition made lowering springs.

See main article: Lowering Springs

Lowering the spring perch

You can carefully cut the lower spring perch and position it lower.

METHOD 1: The perch can be re-welded in the new position.

METHOD 2: The perch can use commercial-grade shaft collars to fix it. See lowering with strut collars

Cut Springs Yourself, or Pay a Professional?

If you need extra stiff springs, or want to carefully match the springs to an intended result, you can't go wrong by working with a professional, reputable spring company. Since their business is springs, they presumably won't make stupid mistakes like cut the springs too far

Coil Spring Swap Candidates

B110 uses 110mm O.D. diameter coils 100mm I.D. B210 & B310 rates are only 1% to 2% higher than rate of B110 -- but they are longer.

280ZX rear coil springs fit in the front of the B110, cut to suitable length (B110 are 13.3" long) and are a good way to get firmer springs, just right for a sporting street 1200.

S130 1983 280ZX
 Front 150mm coils
  127 lb/in
  S130: 12.1" long (white/yellow)
  GS130: 12.4" long (white/white)
  S130J: 12.8" long (red/blue)
 Rear 100mm coils
  126 lb/in
  S130: 14.5" long
  GS130: 14.8" long (also S130J)

Since 280Z rear coils are 100mm, they would be good for extra-firm upgrade. Cut them down more than 2 inches to use in the 1200.

S30 1975 280Z 100mm front & 100mm rear
 front GS30: 8.5 coils @ 115 lb/in (16.7" long)
 front S30 : 9.5 coils @ 103 lb/in (16.0" long)
 rear coils: 8.5 coils @ 198 lb/in (15.4" long)

Roll Center Spacers

When Lowering the front suspension, if going ultra-low, strut spacers (roll center adapters) are used. They are intended to correct the lower arm angle when the vehicle height is dropped, to minimize bump steer.

See main article: Roll Center Adjusters

Rear Suspension

Lowering blocks are the low-buck solution, but using modified springs is a better way. The spring eyes can be "reversed" or the leaf(s) can be flattened
discussion: reverse eye leaf suspension
discussion: Lowering rear end of a 1200

Here's what they do in USA and Japan.

From "best/most expensive" to "more controversial/less expensive"

Fit special-design lowering springs
Re-arch the leaf springs
fit lowering blocks
Flip main leaf

Lowering Blocks

See main article: Lowering Blocks

Flipping

One way to lower the rear is to add another spring to your rear leaf spring pack and reverse one onto the top of the pack, while flipping it. This should lower and stiffen the rear end slightly.

We accept no responsibility for damage to your self, others personally or property. YOU take the risk of working on your car and should follow all safe and accepted work practices.

To flip the rear leaf springs:

up the car, take off the wheels

Make sure you use axle stands on the rear chasis and another pair on the rear axle assembly so it doesnt drop to the ground.
Unbolt the U bolts from the rear axle, spring pack and then un bolt the front 3 mounts for the leaves. Unbolt the rear bolts and remove the spring pack
Now using G clamps, compress the spring pack and unbolt the center locating bolt. Then slowly undo G clamps releasing the spring pack to individual leaves
Flip the 2nd bottom spring onto the top of the pack and added another longer 2nd bottom leaf.
Using a long screw driver through the center locating holes, loosely repacking them then doing them up tight and slowly with the G clamps again till completely compressed. USe the screw driver tho keep the leaves aligned. Once compressed, re insert the center securing bolt and tighten.
Re installation is reverse procedure of removal