REVERSE GEAR MODIFICATION IN 900 5 SPEED TRANSMISSION

Remove the side cover where the dipstick goes in the tranny. Watch out and don't lose the spring and détente ball behind this cover, they shouldn't fly out but know they are there. You should see reverse idler gear right in front of you. It is attached to a arm with a swiveling flat screwdriver type ear to engage the gear. Note the end of this arm at its end away from the idler. The notch cut in it to engage reverse shift fork is offset, not centered. Note which way it is offset. We're going to flip it so the offset is to the other side.

Remove the 10 mm bolt securing the arm to the shaft, remove the e clip holding the swivel to the arm. There is a washer spot-welded to the arm where the swivel came off. Carefully remove this washer in order to place it on the other side of the arm. I use a hammer and chisel with the arm in the vise. You could use a hacksaw if you want. Switch everything to the opposite side of the arm than it was originally so that the offset notch in the top is offset the opposite way than it was. There is a spacer/pivot point that rides in the center of the arm. With the other pieces off the arm, temporarily tighten it in place on the tranny and check for play by pulling in and out on the arm. If you need to adjust for this play, you need to slowly file away the surface of the spacer where it extends from the arm until you can bolt it up and still have free pivot action, but little play. When this feels right(better too loose than too tight so don't go too far with the filing. Make sure the end for the gear turns smoothly in the washer you removed, don't worry about fastening the washer down, it won't go anywhere, its there to strengthen and space the assembly, just file it smooth from the old weld marks(do the same for the arm marks) and secure it with the clip. Reinstall with LocTite on the bolt torqued to 50 INCH/lbs.(snug with a regular wrench will do with the LocTite). If you notice how far reverse is engaged before the mod you see that 50% gear mesh between 1st and the idler is about all you get from the factory.

Turning the notch on the arm to the new position allows full travel and engagement and has repaired boxes that wouldn't move in reverse because the gears' first half's were chewed off. It got these owners going again for a lot less than a rebuild. We incorporate the mod in rebuilds we do to start out life with full engagement of reverse gears and its a much more positive engagement. As always though you still should be fully stopped before attempting to engage reverse, if it doesn't line up, go to first and come back, right in. While the cover is off, clean as much as you can and if you've got a filter change it. This doesn't guarantee normal life in damaged units but will get more miles before the dreaded end in a lot of cases for a little time and oil. A great all purpose sealer for the car line is LocTite's 518 Anaerobic Gasket Eliminator. Its space age stuff that really seals and is factory recommended for a lot of engine and transmission repairs. Parts stores here carry it. No danger of it clogging an oil pickup or passage like excessive silicone sealers that break off and drop down, it only sets in the absence of oxygen (between parts).

After the repair, you might want to check the motor mounts, especially the front one. And to get the best shifting, check the shifter's white plastic ball and bushing on the shaft in the housing. Lubing here with wheel bearing grease smooths things up. Look at the shifter adjustment and on early gearboxes (-86.5) the external centering mechanism and its spring.