Serious Tranny Trouble - bent stuff?

[Roger 911]

This is basically a follow up to myearlier thread on difficulty getting my 915 into 5th/Rev.

I dropped the engine/tranny out of the car so that I could remove the nosecone and look for issues with the 5/R fork and selector. I guess I got good news and bad news. The good news was that I did not find any metal chunks when I drained the tranny, removed the cover, and removed the nose. The bad news is that I think something is bent.

For those that may not recall my earlier post, the only way I couldget the tranny to go over to the 5/R plane was to apply force to the coupler with a large pair of channel locks. After looking inside my tranny, I think I can see the problem. The dongle, or the little arm with the ball end, gets hung up on the guide for the 3/4 rod. You have to apply force to the shift rod to get the ball end to pop above the 3/4 fulcrum, or notch (bear with me on the terminology), which then allows the finger on the shift rod in the front of the tranny to engage the detent on the 5/R selector shaft. Once you do this, the ball end on the dongle (or little pivot arm) will not slide back into the 3/4 selector fulcrum/slot, again, it must be forced in.

All the gears sets seem to engage and disengage fine after you foce it into that plane. It seems like either this little dongle/pivot arm is bent, or maybe the main shift rod is bent, preventing the dongle from moving freely when all gear sets are in neutral.

Does this make sense? I can't see any obvious issue,like broken teeth, or loose forks, etc. It looks like I'm going to have to take my tranny to a shop, unless anyone out there has another suggestion.

Thanks.

[john walker's workshop]

usually it takes an accident to bend the shift rod/dongle. they do bend though. once the rod is moved toward the 5th/rev shaft so the dongle can engage the notch, the inner shift finger that shifts 1 through 4 is beyond the two internal shift rods.

[Roger 911]

It did get jammed in two gearsat once last fall. I also had some difficulties getting gears at the track last weekend, so I may have forced it more than I should have.

When I rotate the shift rod towards 5/R, the finger for 1-4 gets hung up on the 3-4 selector and can't get beyond itunless I force it.

[Roger 911]

John,

I copied the parts diagram from the Pelican website. This should help me explain a little better.


The problem is when all gear sets are in neutral, #2 - Shift Lever, is hitting #15 - Shift Fork. When I apply pressure, the lever will pop above the fork, which then permits the finger on the gear shift rod to engage the slot on the 5/R shaft.

As I mentioned before, the tranny got jammed between two gears at the track, and I had a mechanic perform "emergency" repair trackside. He removed the cover and unjamed the rods, retuning it to neutral. He cautioned me at that time that something may have gotten bent or out of alignment, but at least I could finish the weekend.

After looking at the diagram, I'm wondering if the #15 Fork may have slid a bit on the 3/4 shaft, #14. Maybe this happened when I jammed it between gears, or when the mechanic un-jammed it. Is it possible to loosen the bolt on the #15 fork through the opening on the bottom of the tranny and adjust this slightly, making sure the forks on both the 1/2 and 3/4 are perfectly aligned?

[john walker's workshop]

the usual reason they get stuck in two gears is that someone had it apart and messed up on the placement of one or both of the two detents that live in plugged bores in the diff and center cases. remove the tap in plugs and see if there's a detent visible down in the bore. there shouldn't be. in neutral, the lever #2 will still be in the slots of the shift rods. only when the shifter is pushed against the 5th/rev does it move out of the slot. if the tab on the shift rod has engaged the 5th/rev shaft's notch and the finger is still not clear of the #15 slot, then i would assume the rod or most likely the 5th/rev tab on it is bent.

[Roger 911]

Originally posted by john walker's workshop
in neutral, the lever #2 will still be in the slots of the shift rods. only when the shifter is pushed against the 5th/rev does it move out of the slot.

The lever is inside the slots on both shift rods in neutral. The problem is that when you rotate the shift rod to get to 5/R, the top of the lever gets caught on the fork #15, preventing it from moving up and out of the slot. Once it is forced beyond the #15 fork, the finger on the main shift rod engages 5/R just fine. To get it back out of the 5/R plane, once again force must be applied to pop the lever back inside the slots for neutral.

[rusnak]

I'm so not going say a "yes trannies are really bent" joke.....

[Roger 911]

John,

With respect to the detents being in place. If the detents were not in place, would it affect the alignment of the forks/slots for neutral, i.e., would the prongs not line up perfectly?

After looking at a few more pictures of trannys on the web (the kind with gears as well as rods!), I think I answered my own question about being able to adjust the fork #15 from the bottom, you can't. When I get home tonight, I am going to make sure that the forks/slots are perfectly aligned for 1/2 and 3/4 when in neutral. I will also try to do a visual inspection of the lever #2 to see if it appears bent at all. If by chance this lever were bent, it would appear that you could remove the cotter pin and replace this from the bottom.

[john walker's workshop]

misplaced detents would not cause your problem. #2 is pretty beefy and probably wouldn't bend. the 5th/rev tab on the shift rod would though.

[Roger 911]

I gues I'm still puzzled by the fact that the lever #2 appears to be catching on the #15 fork, blocking its movement upward. I see how the finger on the main lever #1 could bend, but it appears to engage the slot on the 5/R shaft just fine once the lever #2 is freed from fork #15.

After reading alot of the rebuild posts, I'm contemplating pulling the case appart. Howver, I'm concerned how I would even find the problem if nothing is visually wrong?

[Roger 911]

OK, I got the tranny out and on to my engine stand. I could seeclearly that the lever inside was getting hung up on the 3/4 fork. I adjusted the 3/4 fork (gently with a crowbar), moving it closer to the 1/2 fork, and now I can easily get 5/R.

Question: With the nose cone off the tranny, I noticed that the shaft for 3/4 does not go as far into the case when 3rd is selected, campared to the 1/2 shaft when 1st is selected. When 1st is selected the 1/2 shaft end is almost flush with the end plate. When 3rd is selected, it stickes out about 3mm. Is this normal, or am I not fully engaging 3rd? I know I am at least partially engaging it since the gears turn the flanges.