Rear Rack Checks Before Install

Rear Rack Checks Before Install
By: DiamondSleeper
(From: http://www.preludepower.com/forums/showthread.php?t=286448)

Understanding the 4WS Gearbox

The service manual does not describe the way the gearbox needs to be set up initially. It basically says don’t mess with it and pin it as soon as you remove it. Well, if it came from salvage you can’t be 100% sure the input shaft has not been moved unless you talk to the guy who removed it from the car.

What I have learned personally is that if someone comes along and plays with the gearbox to see how it works while you have it sitting on the bench and rotates the shaft 360 degrees or more from its original position and you don’t know any better, you are going to run into problems. The gearbox is now out of sync./ rig or whatever you would like to call it. Although a rigging pin can always be installed at every 360 degree rotation of the input shaft, it does not necessarily mean the gearbox is centered or set up correctly. You may not notice this if the protective boots are still installed on the output shafts “tie rod shafts” and no measurements are taken to verify the correct travel of the tie rod shafts before installation. You may just have a system that, after being installed, is impossible to set up and align correctly.

If you want to be sure of where you are at the beginning, then its important to understand a few things about how this thing works. First, the input shaft “splined shaft” on the gearbox rotates continuously in both directions due to Honda’s use of a planetary gear setup inside the gearbox. There are no stops inside the gearbox to keep it from being rotated to the point of being out of sync./ rig. You may think you feel some resistance or something that feels like a stop at certain points while rotating the shaft. This is just a lack of lubrication in the planetary assembly at random points. This can occur until the grease inside gets re-distributed as you run the planetary gear assembly through a complete cycle. “all the possible positions”. Then it will rotate freely though a complete cycle. Caution: Do not force it to move. Work it back and forth until it moves freely.

To put it simply, from actually witnessing what takes place with the cover off of the gearbox, it takes 32 rotations of the input shaft to cycle the gearbox one time. The gearbox will center the output shafts “tie rod shafts” twice every 32 rotations, once every 16 rotations, but only one of these centered positions is the correct centered position. Each of these centered position creates a completely different action when the gearbox is operated. The first thing that needs to be done is to get to one of the two centered positions and then determine if it is the correct one or not. If you have the back cover off, it is simple to see and the photos show what to look for. The correct one shows the planetary gear resting at the bottom with the ring gear teeth visible at the top. The incorrect one shows the planetary gear at the top engaged with the ring gear with the gear teeth not visible. You can further confirm which is correct by watching the action of the output shafts “tie rod shafts”. Visualize what the wheels are supposed to do as the output shafts move. The correct centered position provides full travel LH or RH when you simulate full steering wheel movement while the incorrect one does not. The easiest way to watch the travel, in my opinion, is to have the boots pulled back or the gearbox cover off.

The gear teeth should be visible at the top:

There is a small line machined into the gear, if the gearbox in in the correct position it will be pointing down with a small hole visible above it:

Simulated full steering wheel movement is 1 1/8 turns of the gearbox input shaft from one of the centered positions in either direction. I established this by watching the gearbox input shaft while someone else turned the steering wheel full travel. Again only one of these centered positions can be correct. It is the one that achieves the greater amount of travel before starting back in the opposite direction at 1 1/8 turns on the input shaft. (See the photo with the gearbox cover off above). If you have a Honda service manual and look at this cut away view, its interesting to see that it is showing the assembly in the same position as the photo with the correct centered position. That is the only clue the service manual gives as to the correct centered position. I guess I could have just said look at the service manual cutaway view for the correct centered position but we don’t all have service manuals.