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Technical Information (MGB 4)

Composite Leaf Springs

Last Modified - 01/28/03

Installation Instructions for Composite Springs - MGB4(6)

The aluminum blocks that are supplied with this kit are designed to bring the composite spring back to the original steel spring thickness and are fitted directly below the lower nylatron pad; however, they can be fitted on top of the upper nylatron pad, which would then lower your rear ride height by ½”. Additional items that may be required, which are not supplied with this kit, include: U-bolts (regular or long), lowering blocks, spring locating plates, bump stop pedestals, and lower s/abs attachment plates.

In addition, all nylatron bushings, pads and bolts must be coated liberally with the supplied lubricant prior to installation. Do not remove the front bushing tube; this has already been pre-lubricated. Final tightening of suspension components should be done with the vehicle on the ground.

Be sure to record your spring ID #’s as fitted to the vehicle, i.e. left # and right #.


1. Jack up vehicle and support with axle stands placed under rear axle tubing.

2. Remove road wheels.

3. Disconnect axle check straps and s/abs from their lower attachment point.

4. Disconnect center and rear exhaust mounts. Support exhaust system with bungee cords or mechanics wire.

5. On 1977 models and onwards, disconnect rear sway bar mounting brackets.

6. Jack up vehicle again, this time support body with axle stands placed forward of the road spring front mount bracket. To prevent under vehicle body damage, place 2 blocks of wood between jack stand and vehicle body.

7. Working with one side only, remove axle U-bolts, bump stop pedestal, spring locating plates and lower s/abs attachment plate.

8. Raise rear axle tubing clear of road spring, proceed and remove rear shackle assembly, and lower the spring.

9. Remove front spring mount, bolt and nut. NOTE: Should this bolt be seized, the most effective way for its removal is to hacksaw through the bolt on both sides between the silent bloc bushing and mounting bracket.

10. Install nylatron pads to new composite spring assembly. These may require some pressure to install and can be tapped into position if necessary.

11. Position front spring bushing in mounting bracket and install hardware and tighten. Check for lateral movement; washers are provided to keep this to a minimum. The polyurethane bushing sidewall must not be allowed to make contact with the mounting bracket.

12. Install rear spring shackle assembly with nylatron bushings. Fitment may be tight, in which case you may want to hand fit these bushings to their individual spring shackle.

13. Install upper spring locating plate then lower rear axle tubing onto the spring assembly.

14. Install bump stop pedestal and axle U-bolts.

15. Fit nylon ring onto lower nylatron pad, then install aluminum spacer block followed by lower spring locating plate and s/abs lower attachment plate. Fit new 3/8" SAE locknuts and torque to 10-15 Overtightening will only result in a bent attachment plate. NOTE: If you are converting to the recommended telescopic gas type s/abs set up, it will be necessary to switch the attachment plate with the opposite side, therefore, carryout #16 before proceeding further. Also, be sure to read “Telescopic Shock Absorbers” article, which is enclosed with these instructions. This is extremely important.

16. Repeat operations 7 thru 15 for the opposite side.

17. Jack up vehicle and support with axle stands repositioned under rear axle tubing.

18. Refit center and rear exhaust mounts.

19. Reattach axle check strap and lower s/abs. NOTE: See "Telescopic Shock Absorber" article if converting to telescopic type.

20. On 1977 model and onwards it may be necessary to adjust the sway bar to be able to refit the rear mounting brackets. If this is required, proceed as follows: slacken both L/H and R/H front mounting bush jam nuts, remove locating bolts (it will be necessary to remove the battery for removal of this bolt on the passenger's side). Equally adjust both bushings until both front and rear mountings line up. Install and tighten bolts and nuts, including jam nuts, and reinstall battery.

21. Refit road wheels.

22. Jack up vehicle, remove axle stands, lower vehicle and tighten rear axle and suspension components

For additional information select from one of the following categories:

MGB4...Composite Leaf Spring Overview

MGB4(1)...An Introduction to Composite Springs

MGB4(2)...MGB Vehicle Weights

MGB4(3)...MGB Vehicle Lean Problems

MGB4(4)...MGB Anticipated Ride Heights

MGB4(5)...Marketing Update

MGB4(7)...Rear Ride Height Adjustable Shackle Pin Kit

MGB4(8)...Rear Telescopic Shock Absorber Choices