Lowering Blocks

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Revision as of 00:56, 14 January 2015

Blocks may be used for lowering leaf-spring cars like the Datsun 1200. This is the traditional easy, time-tested and inexpensive method. See Lowering for different methods.

Overview

Datsun 1200 use a straight axle mounted on top of the leaf springs, so by fitting blocks between it and the spring, the rear of the car is lowered.

Lowering

Block are available in different heights such a 1.5", 2" , 3" for differing amounts of lowering.

Buy a 1200-specific block, or a "universal" 2.0 inch wide block. "Kits" come with block and U-bolts, so make sure the u-bolt fits a 1200 (M10 bolts, ute needs wider u-bolts than sedan/coupe/wagon). Ute needs 66mm internal width u-bolts (approx. 3-1/8").

Width: 2.0"
Height: whatever you want
Pin: 13mm
Hole: 13mm
U-bolts: 
* M10 x ? (1200 sedan/coupe + 1974 B210) 
* M10 x 3" (1200 ute)

Larger Datsuns use 2.5" wide blocks, so they will not fit the 1200. B10/B110/B210 all use 2.0" wide leaf springs, although the block specifications vary.

Sources:

Bprojects
South Yokohama
JC Whitney
any race shop such as Jegs, Summit

Slight lowering by using B210 isoclamp

NOTE: As with any lowering, the suspension travel becomes restricted compared to the factory ride height.

Plain block with screw in pins

custom-made blocks

Modular blocks, stackable 7mm

Dimensions

click

 
Dimensions
width: 50mm
a: 12mm
b: ~15mm
c: 110mm
d: 8mm
e: 13mm

Ute needs wider bolts for larger axle housing

50mm wide

Datsun 1000 dimensions

50mm wide (same as 1200)
locating nubbins: 1"/25mm (1200 uses small 1/2" nubbins)

Regular Datsun blocks can be used on 1000 by creating a larger sleeve to fit the locator on top and boring out underneath.

Suspension Travel

• Trim the bump stop rubber by 1" to gain more travel
• Fit more compressible shocks
• Stiffen the effective spring constant to make bottoming out less likely, e.g. add leafs or add an overtravel leaf from a ute

Pinion Angle

Correct and Incorrect Angles

From top to bottom:
OK
 1 stock
 2 lowered with straight blocks
 3 angled diff. Transmission must be angled to match
 4 lowered with angled blocks
   NOTE: transmission must be angled to match
NOT OK
 5 only diff angled
 6 only gearbox angled

NOTE that lowering the car does not change the alignment angle. Although the driveshaft angle changes, the pinion-to-transmission angle does not change. Hence, no angle blocks are necessary.

stock alignment angle (black lines)

lowered - alignment angle does not change

Even if the lowering is done unevenly, the important angles do not change. lowered unevenly - alignment angle does not change

Notes

• Lowering blocks are legal in most countries, including most Australian states
• New Zealand reportedly allows max of 50mm lowering blocks
• Square blocks will lift the diff squarely and will not change pinion angle
• Angle-ground blocks will change pinion angle so are NOT recommended. These are normally used with extreme lowering and require the diff angle to be modified or the transmission angle modified
• Handbrake cable will need to be re-adjusted after lowering
• On a BW68-equipped sedan, the blocks make for less access to the brake adjuster and brake bleeder. This is because the BW axle has in bottom-mounted brake cylinders

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