A common problem found on the Z31 is a Clunk from the rear end of the car when shifting gears or accelerating/decelerating. This is usually caused by worn sub frame bushings and/or differential mount.

Parts Needed

You can choose to replace the Parts with stock Rubber or upgrade to the Polyurethane replacements. Note: The polyurethane replacements are less expensive and will last longer.

Stock rubber Parts

• 1984-1986 Nissan Part # 55476-01P10 Insulator- Differential Mounting
• 1987-1989 Nissan Part # 55476-01P20 Insulator- Differential Mounting
• 2 of Nissan Part# 55466-01P10 - Insulator Member Mounting

Polyurethane Parts

• Prothane Polyurethane Rear Cross member Bushings - $45 from Acadiana Sports Car Orphanage
• Z31 Performance Polyurethane Differential Mount V2 - $160 from Acadiana Sports Car Orphanage

Tools Needed

• Floor Jack
• Jack Stands
• Breaker Bar
• Various Metric Sockets
• Ratchet
• Hacksaw
• Press
• Paint Pen

Procedure

1. Jack the car up and secure on jack stands.
2. Pull the wheels off the rear.
3. Place a floor jack under the differential housing to support it.
4. Remove the two nuts securing the differential Mount to the rear housing.
5. Now Remove the two bolts and two nuts holding the differential mount to the body. The mount should now be free.
6. Replace the old mount with the new one and tighten the mount to body bolts to 22-29 Ft lb of torque. the mount to body nuts are tightened to 43 - 58 Ft lbs of torque. The mount to differential carrier nuts are also tightened to 43 - 58 ft lbs of torque.
7. With everything tight there we can move on. The Rear cross member is only held in by two nuts but removing the rear control arms to pull the cross member is going to be the hard part.
8. First thing to come off is the rear sway bar. There are four bolts holding it in place. Remove them and then drop the sway bar down out of the way. If the sway bar bushings are worn, Now is a good time to replace them as well.
9. Once it is removed you can disconnect the Emergency Brake cables from the calipers and main cable.
10. Now you can start removing the rear control arms from the cross member. There is a regular bolt and nut and a eccentric bolt and nut that hold them each to the cross member.
11. Before loosing anything, Mark the eccentric bolt to cross member with a paint pen so you can align it back up on installation.
12. Once you have the eccentric bolt marked you can remove both nuts from the bolts and punch them from the control arm. This is easier said than done. These bolts have not moved in many years and will be rusted solid. Use PB Blaster on these and let soak to loosen the rust. These bolts are also torqued to between 72 to 87 ft lbs.
13. With the control arms disconnected you can now again place a jack under the differential and remove the four bolts and nuts holding the differential to the cross member.
14. When the differential is loose from the cross member you can now attack the two nuts holding the cross member to the body. These will be tight 58 to 80 Ft lbs.
15. Now with it loose you can remove the remaining four nuts holding the cross member stays on each side. The cross member should be free now to come out of the car.
    
    
    
    
16. With the cross member out you can press out the old bushings or what is left of them, and press in the new ones.
    
    
    This is what they usually look like when they are out.
    
    
17. You can use a cold chisel to punch out the metal sleeve that was the outside of the bushing.
    
    
    
18. Now is also a good time to clean everything up as well
    
    What A Mess.
    
    
19. Assembly is reverse of disassembly.

Sources used on this page:

• 1984-1989 Nissan 300zx FSM
• Bad Bushing picture by: RED300Z
• All other pictures by: Neil86T