Ever have on of those moments where things go so wrong that you skip the profanity and just feel nausea?

Replacing my rear coupler yesterday. Was feeling good about it. The old boot was intact and no signs of corrosion.
I had heard some horror stories about the old grub screw, so I had my eye on him. Even ordered a new one ahead of time.
I pre soaked with PB blaster, even had some heat on hand.
I immediately stripped it, however. Now I'm lathered up.
After messing around for an hour, I ended up drilling it out carefully (so I thought) with a carbide burr on a dremmel.
Once I got he old coupler off: I see the tip of the screw still imbedded in the guide rod to the tranny, and this big *** gouge next to it.




So now I'm trying to re-heat and pick out the tip of the grub screw, still in there and won't budge. I'm suspicious of a PO's "fix" before me. I can't say I didn't hit the shift rod with the dremmel, but it doesn't really match where I was using it.

I guess it doesn't matter, I'm stuck with what I got in front of me.
I'm thinking I could come up with some wild *** fix that may or may not hold -- or just drop the tranny and replace this inner shift rod.

So that's a question for the forum. I've read about some horror, but never come across this particular disaster.
I have a G28.11, and I'm calling the inner shift rod 928.303.107.30 in PET.
Roger is looking for a replacement. What is the chance I can drop the tranny, pop the top, replace the rod, and not get sucked into a rabbit hole?
Any input, observations, or counseling appreciated.

 

Ok, I'm thinking off the top of my head here, but this is not necessarily a precision part....I think, before I went berserk replacing that shaft, I would grind the damage down to a flat, and then put the coupling back on, mark the screw hole, remove the coupling, then drill me a indentation in the shaft, then put it all back together, with a little loctite, ensuring that my grub screw went into the newly drilled hole, and call it cured....

We do this repair a lot, on damaged shafts, with motor pulleys, rotating at 1800-3450 rpm, and it holds fine....seems like it would work out here......2 cents, with little thought behind it, but I would sure try it before I drop the tranny....or at least polish the existing damage down some, and drill the grub hole out a little...can't hurt....

 

Dave, do you have any small extractors and is there enough room to use?

 

How about a taper pin through the side of the flange, with a concavity in the shaft? Like was used on old Schwinn bike pedal cranks. Put the hub flange back on, and drill through the hub offset so it catches a segment of the shaft. Take the hub out and find a tapered bore and pin. Line it up, drive the taper pin in and drift it, then bend the end of the taper pin, or use a nut on the end.

Close up pic of this will explain the method. It'll hold a bunch and is pretty easy to do.

http://www.ebay.com/itm/like/191430722001

 

Hey Gents, thanks for the feedback!
I very much appreciate the help.

I tried as much heat as I was comfortable using and no joy what so ever.
At this point I was having the same thoughts as Ron: Nothin to loose, worse case I have to go forward with dropping the tranny anyway.

Matt, I couldn't find a set up for the extractors on a 90 degree drill or flex head with enough room to work.

Doc, I will research that idea, thanks man.

So far I ground down everything flat. Old coupler goes on freely but the old grub hole is obliterated. New coupler does not go on freely...will keep everyone informed.

 

Pin the coupler at another location around the 360 perimeter. I think the coupler itself already has another pilot hole already drilled, doesn't it? I'd be temped to make another indentation in the shift rod through a new hole in the coupler, then thread the coupler for the new pointed grub screw.

 

Here's a pic of the coupler, and it does have an additional beefed up section which could be tapped to take a grub screw.

I think your best option, as the existing coupler has a trashed grub screw tapping, is to fit a new coupler but orient it so that the grub screw is on the other undamaged side of the shaft (180 degrees rotated). Tapping the other section on the coupler won't be any help, as the grub screw would be on the bottom or top (standard coupler orientation on the shaft), and would be difficult to access.

If you wanted to use the existing coupler you could tap the other hole, and then orient it so that the hole is on the clean side of the shaft, but the whole coupler would be 90 degrees rotated from its current orientation.

 

I have the shifter rod for you if you decide to go this route. I feel like you are opening a whole other can of worms though. It would seem that once the current shaft is smooth you could install the coupler at 180 degrees, meaning orienting the grub screw to the passenger side. I may be remembering that part wrong but I can think of 27 different things that I would try before replacing the shift rod.

 

David,

With your Dremel and the very small diameter very thin cutting wheel that come in the Dremel kit.. machine in a slot

in what is left of the grub screw It will also slot the shift rod a little but that will not matter, just file any burred edges..use heat (heat surrounding rod) to aid removal of said grub screw. I know you know where to heat Doc but for the others tuning in..

Then make a very stubby custom slotted driver to back it out slowly using a 1/4" stubby ratchet.

File a slight radius on the driver tip that matches up with the radius of the small

cutting wheel for maximum purchase.

 

It's too late for this project ( and I feel your pain!), but my initial "go-to" for this grub screw and other stubborn bolts in tight locations is a , like this:

 

Hey Brian, thanks for the offer man, that is very kind.
I had talked to Roger before you posted this and I have one on order, to use as a plan "B" if needed.
I'm definately on board with trying to salvage the situation without pulling everything apart. I appreciate all the great ideas from everybody.

I'm thinking in terms of the 180 flip.
I have the profile back to normal where the original screw was.
I will try and fit the new coupler tonight and see what happens.

 

I pulled the transaxle for space. Once I had it, the grub screw came out of a pair of vice grips.

I used a chisel and a BFH to remove the coupler. Yes, I lost patience. A new one was cheap enough.

 

I took a few pics tonight.
The first is the "repaired" side.
Second is the good side, i.e. the other side that will get the new indentation for the grub screw.
Third is new coupler showing grub screw profile.
I'm feeling optimistic, again thanks for the input you guys.

 

Looks good and should work

 

I wonder how many of us have pulled a tranny out because of this design flaw.