The ABSOLUTELY essential tool for this job IMHO is a piece of 1" (or thereabouts) thin wall steel tubing about an inch or so long. OD of the mirror post is just under an inch.
A chunk of 1" PVC pipe could be used but the OD of the PVC pipe interferes with gripping the spring retaining ring, which needs to be turned to release the spring. A big pair of curved jaw channel lock piiers is a good tool to use to turn the retaining ring.
Thin wall tubing is the best in this case though.
I originally used a 15/16" socket to compress the spring but it turns out the teeth of the socket interfere with retaining ring notches and make it difficult to turn. Hence the thin wall tubing.
An electric screwdriver is nice to have too. Some of the torx screws used in the assembly are long.
The instructions Gruven supplies are a bit dated. They call for epoxy. It is not needed.
The shaft of the spur gear is a bit long as it turns out. The shaft needs to shortened up some, at least in my case. Otherwise it will bind. The instructions do mention this.
Also, Gruven mentions a possible need to relieve the bracket where the spur gear mounts onto to allow clearance for the spur gear. I'd go ahead and just do that, even if it feels like it doesn't need it.
I nearly met with success this AM after last night's work. Unfortunately, on the last attempt to re-assemble the spring/retainer, the retainer shot off into space. I still haven't managed to find it. Replacing the retaining ring while it's compressed and turning it just the right amount to engage the locking lugs on the mirror post is kinda a seat of the pants thing. The spring covers up the engagement points when compressed, so it's difficult to get a visual if the ring is turned to proper position.
I had the motor housing mounted on the mirror base this AM. It would turn fine as long as the mirror bracket wasn't put on the motor housing. Once that was installed, I'm guessing it would bind on the spur gear shaft. That's why I had to pull it apart again and subsequently shot the ring into low orbit while re-assembling.
Getting the motor housing out of the mirror assembly is pretty easy. A few T15's and away you go. The Gruven instructions work well here. Be sure to cut/scribe some witness marks on the mirror base and mirror arm before pulling it out. It's a confidence booster when re-assembling and is easy to do.
Pulling the motor housing apart takes some time and patience but it can be done.
The collet as they call it, will drop in 3 different locations in a 360 degree movement. Only one is correct. The lowest position heightwise is the correct position of the three.
The big ring gear can be installed in any orientation as long as the teeth are down to engage the shallow notches on the collet.
The "spring cup" must be flush when reassembling the spring/retainer. If not, check your work. Rotating the motor housing will usually do it if you have the collet in the correct position.
Proper tension on the spring (using a vise or arbor press) is another seat of the pants thing. Too much and you can't rotate the retaining ring. Not enough and the retaining ring won't clear the 3 locking lugs on the mirror post. Again, the notches in the retaining ring must clear the 3 lugs on the mirror post so that it will move past them and then rotated into the locked position.
Before replacing the top half of the motor housing on the lower half, I would put it on the mirror arm and test the motor to see it turns freely on the assembly. You'll need an assistant here as the power connector will not stay in place on the motor if the upper motor housing isn't installed.
This brings up another point, the motor has two contacts on one side that mate with the power connector. BE SURE these contacts are facing the mirror post (they will be visible through the connector port on the upper half of the motor housing if the motor is oriented correctly) The instructions don't mention this.
You don't want to wrestle with the motor housing any more than you have to. That goes double for the spring/retainer as well. Lining it all up and getting the ring past the lugs while SLOWLY and CAREFULLY cranking on the vise/arbor press is a pain. Turning the ring the proper amount to engage the lugs is guesswork. Gruven says 1/6 of a turn. I guess it's something like that.
As for me, I've got a complete mirror assembly on order. I don't think the ring will be found any time soon in the cluttered confines of my reloading/basement work area. Approximately 1.2 billion hiding places.
Would I attempt this again knowing what I know now? Probably not. Too many things that can go wrong upon re-assembly. That spring is strong, hence the need for a vise/arbor press.
Good luck to all that attempt this!!!
Edited to add (with a much better attitude):
I found the retaining ring. The spring was on one side of the room while the ring turned up sitting neatly on a shelf like I had put it there on the other side of the room.
Anyway, I pieced it all back together with no incident. (I am getting good at installing the spring retaining ring and I should be, I've had enough practice)
The mirror IS noticeably noisier in operation now. But it works 100% at present. No binding anywhere.
Another tool I'd heartily recommend is a Dremel or equivalent. The collet piece has some tabs that need to be ground off according to Gruven's instructions as they are no longer needed with the beefier brass spur gear. The Dremel also comes in handy to grind down the spur gear shaft to shorten it so it won't bind on the motor/gear housing. (and it probably will). Also the Dremel can be used to hog out the spur gear area on the plastic piece where it mounts to give additional clearance for the gear. Better to just do it to avoid having to tear it all down again. I didn't remove much material. A 1/4" sanding drum worked well for this operation.
Obviously it can be done. Just don't expect it to be easy. Take your time.
Hope this helps.
