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Tips, etc, on rear shift coupler bushing replacement?

 
Old 08-22-2010, 12:51 AM
  #16  
SQLGuy
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No luck. I drilled where I was pretty sure the remainder of the screw was, but the extra piece did not come out, nor was I able to get enough penetration to use an extractor or to make a good seat for the new grub screw.

As I see it now, choices are:

1. Grind a flat and drill a bit of a well to use with a normal set screw
2. Pull the transmission and replace the selector shaft
3. Pull the transmission, pull the selector shaft, take it to a machine shop and have them drill a new grub screw hole

Any other suggestions? BTW, once I had the coupler off, I did try heating the shaft up with a torch to see if that would loosen the remaining piece enough to get it out with a screwdriver... obviously, that didn't work either.
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Old 08-22-2010, 01:07 AM
  #17  
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Dang Paul sounds like a heck of a task.
Let me know if I can buy you a beer.
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Old 08-22-2010, 02:04 AM
  #18  
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Hi Paul,

I changed those bushings too on my '78. I don't recall taking the coupler from the shaft was a problem. Perhaps easy for me to say because the TT was and still is out of the car. I could make a picture of the coupler and shaft for you to envision how it's put together so you don't damage the shaft when you proceed with the angle grinder.

Ad
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Old 08-22-2010, 02:16 AM
  #19  
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Hi Ad,

Thanks, but I think you're a few posts out of synch. I've cut/ground down the screw to the point that I have the coupler off the shaft, but the tip of the screw is still in the shaft and doesn't seem to have any intention of coming out.

I wish I knew what adhesive Porsche used for this, because such a high-heat, extremely strong, metal-to-metal glue would have been very helpful in other projects... but it's royal pain in this case.

Cheers,
Paul
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Old 08-22-2010, 02:34 AM
  #20  
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I have to apologize for laughing when I read post 14. Wish i could help, but I know essentially nothing about the coupler or the selector shaft.
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Old 08-24-2010, 04:55 AM
  #21  
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Mission accomplished!

With a variety of bits, starting with a 1/8" cobalt bit, and some Mobil 1 for cutting oil, and a right angle drill, and a right-angle Dremel adapter, and a 1/8" diamond bit/burr, I managed to drill a new socket for the grub screw. After that, things went relatively easily.

So, now she's back together, with a proper grub screw, Loctited in place, and a new boot. Unlike a number of people here, the boot didn't give me any trouble. I didn't have to slice it or grease it... other than a bit of elbow grease. The one point I can recommend on the boot is that, for the narrow end (at the transmission) you can fold over the lip of the boot to the outside before you slide it over the selector shaft, then flip that fold back over and it will go right onto the lip at the tranny.

So, was it worth it? I think so. The bronze bushings didn't do much for the front/back play of the shifter (I guess I'll have to see if the shifter cup helps for that), but they do provide a crisper feel and definitely eliminated any side-to-side play. Having this all torn apart also gave me the opportunity to recenter the shifter a bit, so it no-longer pulls the shift boot off of the shifter frame when pulling hard into 1st.

For reassembling the shifter, I used some thin steel wire to hold the springs compressed after compressing them in a vise, however, I still needed to use some needle nose Vise Grips to compress the assembly fully so I'd have enough room to get the shims and clips in place. I would recommend one or two larger pairs of needle nose Vise Grips as being extremely helpful in this task.

As a recap, though, if you are planning to install bronze shift coupler bushings, don't remove the shift coupler. Just take a medium-large flat head screwdriver and use it to break the inner lips off of the stock plastic bushings. You should then be able to pop the old bushings out with the shift coupler on the car. You might need to screw some wood or sheet metal screws into the old bushings to provide a grip to better pull them out, but, even if you spend an hour (or two) getting the plastic bushings out, it is well worth it, IMO, compared to trying to get that grub screw out. Once the plastic bushings are out, the bronze ones can be pressed in from the outside using a 4" C-clamp.

Josh, I'd like to take you up on that beer. Let's plan something.

Cheers,
Paul
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Old 08-24-2010, 10:32 AM
  #22  
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Most stupid part ever designed in the 928.

Sorry, I feel your pain. I was there some weeks ago and I was very lucky.
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Old 08-24-2010, 10:45 AM
  #23  
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Originally Posted by SQLGuy View Post
Mission accomplished!
...
As a recap, though, if you are planning to install bronze shift coupler bushings, don't remove the shift coupler. Just take a medium-large flat head screwdriver and use it to break the inner lips off of the stock plastic bushings. You should then be able to pop the old bushings out with the shift coupler on the car. You might need to screw some wood or sheet metal screws into the old bushings to provide a grip to better pull them out, but, even if you spend an hour (or two) getting the plastic bushings out, it is well worth it, IMO, compared to trying to get that grub screw out. Once the plastic bushings are out, the bronze ones can be pressed in from the outside using a 4" C-clamp....
I don't agree with the recommendation to replace the coupler bushings in situ.
9 times out of 10 it comes out relatively easy.

Take it out, do it on a bench.

Congrats on beating the beast!
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Old 08-24-2010, 10:56 AM
  #24  
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Paul,

I went through the EXACT steps you did with the same end result. What a major PITA.

I have the butchered old one sitting in my shop as a trophy.

Way to hang in there, it is worth it in the end isn't it?
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Old 08-24-2010, 12:03 PM
  #25  
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Originally Posted by Jadz928 View Post
I don't agree with the recommendation to replace the coupler bushings in situ.
9 times out of 10 it comes out relatively easy.

Take it out, do it on a bench.

Congrats on beating the beast!
But what's the advantage or removing and reinstalling it? Besides the risk of this kind of a grub screw mess, that pin is pretty tight and you're putting quite a bit of strain on the (aluminum? pot metal?) coupler body in pressing it out and in. You also have to realign the linkage afterwards if you remove it, and probably replace the boot after your torch, to loosen the Loctite, has cooked it a bit.

Sorry, but I stick with my conclusions here. I wouldn't remove it unless I'm swapping in OE-type bushings.
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Old 08-24-2010, 12:12 PM
  #26  
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Originally Posted by Bill Ball View Post
I have to apologize for laughing when I read post 14. Wish i could help, but I know essentially nothing about the coupler or the selector shaft.
Yea, talk about crying out need for pictures. Dwayne, one of these in your future work? Please.
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Old 08-22-2011, 11:25 PM
  #27  
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Originally Posted by Jadz928 View Post
I don't agree with the recommendation to replace the coupler bushings in situ.
9 times out of 10 it comes out relatively easy.

Take it out, do it on a bench.
Older thread, but working on this job right now. I agree with Jim on this. My removing the rear coupler on my car has proven to be one of the easiest things I have ever removed on my car.
After getting the car up on lift bars, it literally took me one minute to remove the coupler and another 10 to replace the bushings.
Of course, I still have to put it back in...
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Old 08-23-2011, 12:05 AM
  #28  
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Originally Posted by robot808 View Post
Older thread, but working on this job right now. I agree with Jim on this. My removing the rear coupler on my car has proven to be one of the easiest things I have ever removed on my car.
After getting the car up on lift bars, it literally took me one minute to remove the coupler and another 10 to replace the bushings.
Of course, I still have to put it back in...
Well, we have some sample points of one one way, and some sample points of one the other way.

When I spoke with one of the guys at Motorsport in SLC, I asked him what his typical experience was, as he'd done a lot of them. He said that he always takes his MIG welder and welds a bolt onto the grub screw because he's had too many of them stick. The welded-on bolt makes it a lot easier to apply major torque to the thing, and the heat of welding helps free it up.

I'm probably going to try that when I do the bushings for the GTS... because replacing them in situ is not an option with the new Delrin bushings, which have wings like the stock ones. Hopefully the pin will be easier to remove from the GTS coupler, though, as I was never able to get the original S4 one to budge at all in my 6" bench vise. Otherwise, it might be excuse to get a shop press from HF....

Edit: By the way, I just realized, I never did post this picture of the antagonist in the previous chapter.
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Old 08-23-2011, 12:19 AM
  #29  
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Ha! That looks like my old one but it's in 1 piece. I ended up getting pissed and used a chisel to remove it, then pulled the transmission to finish it off. Amazing how easy that grub screw comes out when it's the only thing left.

While I had everything out I rebuilt the abs harnesses, replaced a bunch of silly gaskets on the transaxle and cleaned everything. Turned out nice!
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Old 08-23-2011, 12:24 AM
  #30  
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Originally Posted by Jadz928 View Post
I don't agree with the recommendation to replace the coupler bushings in situ.
9 times out of 10 it comes out relatively easy.

Take it out, do it on a bench.

Congrats on beating the beast!
You are one lucky **** if you get a 90% removal rate. I freaking hate that job. I get about a 50% removal rate and had one that required the entire trans/TT taken out.
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