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Coilover springs can be fitted to the Datsun 1200, replacing the front coils springs. In the rear they can supplement the leaf springs. One advantage of coilovers is that many spring rates are available for customizing.
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Overview
With stock Datsun 1200 struts or upgraded struts, you have the option to convert them to coilover spring configuration. Advantages include:
- Adjustable spring height, for lowering or for adjusting different length springs
- Many spring rates are available for customizing
- If using small-diameter springs, you gain
- more room to move the strut inward for extra negative Camber
- more room for tires, or wider tires
Ground Control has fully adjustable Coilovers struts, for $199 USD a pair.
Coilover kit from Ground Control
Discussion: stiffer suspension
Or, you can modify Nissan struts to accept standard 2-1/4 inch coils
Front
An advantage of coilovers on the front is that they are small-diameter. This mean you can move the strut top further to gain addition negative camber.
- Stock springs: 110mm (4.33 in)
- Coilovers: 2 in
The Datsun 1200 strut housing is 45 mm diameter (many other Datsun are 50.8 mm).
Stock strut inserts have a 17mm stroke.
The better coilovers actually have the thread for the top cap on the inside of the threaded sleeves. This way you just have to cut the strut to the length you want and then weld the threaded sleeves on and the cap screws into the top of the sleeve. They also have a turned step on the inside of them where the threaded sleeve rests on the top of the strut body. This way no load is supported simply by a weld.
Remember that the stock spring rate is 91 pounds/inch, so 250 pound springs will result in a very stiff ride, suitable for track racing with a lowered car. Not recommended for bumpy surfaces such as public streets or off-pavement racing. For street use, consider 175 pounds the upper limit.
Ground Control has fully adjustable coilover struts, for $199 USD a pair. See stiffer suspension
- Coilover kit from Ground Control
Paradise Racing has front coilovers for Datsun 1200: Part Number DATF $175. Their softest spring rate (250 pounds) is suitable for racing.
Rear
Coilovers can be easily fitted to the rear of sedans, and less easily to coupes). Some modifications to the shock tower are needed.
One idea is to remove all the leaf springs except the main leaf. The main leaf is left to control placement of the axle housing. The coilovers handle most of the weight of the rear suspension.
Paradise Racing has rear coilovers for Datsun 1200: Part Number DATNAR $349 for non-adjustable, and DATR $499 for 12-position (soft to firm) units. Their softest spring rate (250 pounds) is suitable for racing.
KONI sells 42mm Inside Diameter and 50mm I.D. threaded sleeves for coilover use. They use 2-1/4 inch (57mm) I.D. springs. KONI 80-series are 42mm O.D. shocks, while 30-, 82- and 87-series is 50mm O.D.
Spring Seats
You can buy the spring seats separately from the springs. Since most 'kit's are only available in high spring-rate (stiff) springs, not suitable for streets 1200s, this give you the flexibility to mix and match.
Stock 1200 Spring Seat
If using stock 1200 springs, just reuse the stock spring seat. You can carefully grind the welds off the strut housing, and presto! you have a movable spring seat. Move it to a new position and fasten securely.
Threaded Seats
A coilover 'kit' typically comes with a threaded tube and nut-type seat that can be screwed higher or lower. They typically come in 2-1/4 inch size for 2-1/4" springs.
You can buy these separately and use with your own spring choice.
BMW Spring Seats
Instead of buying new, 2" diameter expensive springs, re-use your existing ones by using BMW removable spring seats.
BMW sports option rear coilovers have a glued on lower spring seat that can be tapped off, the ID is the same size as the datsun OD so can be slid over the Datsun 1200 strut and welded on. They come in late 70s-80s 320i, probably in a lot of other BMW models too.
The BWM spring has a flat bottom, for use use the the BMW seat. However, the top of the spring is the same as the Datsun spring so it fits the 1200 top seat perfect. These BMW springs are around 200 lb/in, suitable for racing 1200s.
Do they work with the stock 1200 springs?
reference: removable spring seat
Seat Fitting
Traditionally, spring seats are welded to the strut body.
NOTE: Unit coilovers (not Strut type), as might be used on the rear suspension of a 1200, often have an integral flange and the seat just is tapped on until it bottoms.
Weld
Welding the spring seat to the strut body is the generally accepting fitting method. Options include:
- Seat welded directly to strut body. This is how the factory did it
- A seat stop is welded to the strut body
- Hybrid: a seat stop is welded to the seat, then that assembly welded to the strut body
Notice the secure welds in this photo, at the bottom of the threaded sleeve:
Strut Collars
Some Datsun fans use a Shaft Collar instead of welding the bottom perch. Works a treat, even some racers and a few commercial spring companies use this method.
Shaft Collar on S310 Strut
- Use a two-piece shaft collar
- Do *not* use a set-screw collar
- Get the kind with cap screws, not set screws. They are double the holding power
- cut/grind the stock Datsun spring cup
- fit the clamp to the strut tube and tighten
- When installing a split collar, it is important that a small gap remain between the two halves of the collar.
- You must use a torque wrench for safe installation
- put the spring cup over the tube, it sits on top of the collar
This is adjustable, like the more traditional threaded collars except instead of being welded, it is clamped to the strut tube. Use s single split Shaft Collar. Instead of threading the seat up/down, loosen and move the collar.
45mm Collar (1.77 inch): For Datsun 1200 and 120Y
- 45mm bore
- 73mm O.D
- 19mm thick
- Weight Steel: 12.5 oz
- Price: Aluminum: About $27 USD, Steel: $23
2" Collar (50.8 mm): For most Datsuns (including 280ZX and B310)
- 2" bore
- 3" O.D
- 11/16 inch thick.
- Weight Aluminum: 4.4 oz
- Weight Steel: 11.0 oz
- Price: About $15 USD for steel
Counterpoint
Some people use a standard muffler clamp instead of a Shaft Collar. That sounds less secure than a Shaft Collar. They use two of the half-circle parts with straight bolts. This is basically a sheet-metal shaft collar.
Are either of these methods safe? Some feel they are not. Others have run them in race cars for years with no problems.