Steering Wheel Shimmy When Hot
The NB Fairlane (for those who don't know the NB story for the purpose of this exercise think NA with MPEFI 6 and 4 speed auto and a few NC parts) has developed steering wheel shimmy (vibration in the steering on braking) but only when the car is hot and the there are high ambient temperatures.
For example I just did a long 40 km drive in the relative cool of the evening finished off with several consecutive heavy braking application but there was no shimmy. However, on a hot summer day after the car gets hot (say 10 km) the shimmy appears with all use of the brakes. I have yet to check the front disk runout to see if they are warped but I suspect not as I cannot feels any pulsations through the brake pedal and the discs aren't that old. I have also had warped disks before and it felt different. Nonetheless, when I get a moment I will get out the dial indicator and check.
The suspension seems OK; I can't see any obvious faults, all is tight and it tracks well. I have just replaced the Super Pro poly bushing rack mounts as the rack has kept coming loose and the old bushes had hardened considerably over the new ones. The shimmy was there before I did this and I thought that was the cause. My wife who usually drives the car thinks the shimmy was there all the time until I replaced the mounts (i.e it wasn't temperature dependent).
The steering gear fluid is at the correct level but I think I might try flushing it and adjusting the pad/damper in the rack as well. Anyone come across a similar problem or can suggest the cause?