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Tips, etc, on rear shift coupler bushing replacement?

 
Old 07-31-2010, 10:00 PM
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SQLGuy
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Default Tips, etc, on rear shift coupler bushing replacement?

Hi folks,

My car's shifting is not as precise as I think it should be (1st is far enough back and over as to pull the boot off the frame). Since there's a bit of play in the shifter, I thought I should replace the bushings (all original AFAIK).

I have a new ball cup, a pair of 928sRus' bronze coupler bushings, a new "grub" screw, and some small plastic bushings.

I wanted to do the coupler bushings first, since I can feel some side-to-side play in the shift rod at the coupler. Not sure how best to proceed, though...

The coupler on mine is under a boot. How can I get that boot off and out of the way? Is that the one that someone was cursing about recently? I'd appreciate any been-there-done-that suggestions on this and the rest of the job.

Thanks,
Paul

BTW, where do those smaller plastic bushings go?
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Old 07-31-2010, 11:03 PM
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chewy8000
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It's pretty straight forward mark the coupler first so you don't have to realign it on the spline. Use a torch to melt the old ones out. I would go ahead and replace the clutch cup bushing as well if it's a 5 speed.
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Old 07-31-2010, 11:22 PM
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Originally Posted by chewy8000 View Post
as well if it's a 5 speed.
if it wasnt a 5 speed there wouldnt be any bushings.........
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Old 07-31-2010, 11:23 PM
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I used the torch, and heated things up a lot to try to loosen up the set screw. Still broke off the tip of the 4mm allen socket in there, and now can't get the tip out. I don't see any, even highly destructive, way of getting that set screw out now without dropping the transmission.

In the meantime it's occurred to me that there's probably enough room to press out the pin and bushings with the coupler still in place, if I have just the right size C-clamp and spacers.

I don't really want to drop the tranny and cut off the coupler, but I guess that's the alternative if an in-place operation isn't possible. Porsche really did want to make sure that grub screw stayed there, didn't they.
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Old 08-01-2010, 12:34 AM
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Originally Posted by SQLGuy View Post
I used the torch, and heated things up a lot to try to loosen up the set screw. Still broke off the tip of the 4mm allen socket in there, and now can't get the tip out. I don't see any, even highly destructive, way of getting that set screw out now without dropping the transmission.

In the meantime it's occurred to me that there's probably enough room to press out the pin and bushings with the coupler still in place, if I have just the right size C-clamp and spacers.

I don't really want to drop the tranny and cut off the coupler, but I guess that's the alternative if an in-place operation isn't possible. Porsche really did want to make sure that grub screw stayed there, didn't they.
And the rear coupler is way easier to deal with than the front ball cup!!!
Have fun...

p.s. you will need a new rear coupler when you're done, so order one now.
obligatory 928 pic, rsky biz.
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Old 08-01-2010, 12:48 AM
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Right, so what's the total plan now?

Have to drop the tranny, right?

Then I might as well replace shifter shaft seal, input seal, output seals, tranny mounts,.... anything else? None of them are leaking, and the mounts look fine, but...

I don't understand why they didn't just do a pinch bolt on the back like they did on the front. :-{

Yes, by the way, in-place didn't work. I made a custom press from a 4" C-clamp onto which I welded a piece of steel pipe for a spacer. All the torque I could apply in place didn't seem to move the pin at all.

---------Edit----------

Well, I put things back together and back on the ground for now. After further attempts to remove the screw and the bit of allen driver from it, and still no luck, I do think it may be possible to cut the coupler off with an air saw, a Dremel, and some patience. I'll probably try that before dropping the tranny.

Last edited by SQLGuy; 08-01-2010 at 01:59 AM. Reason: More info
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Old 08-01-2010, 08:42 AM
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Is it ok to adjust on the grub screw end or is it best to align on the spline end ?

Rogers bronze bushes rock
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Old 08-01-2010, 10:10 AM
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Sorry for your troubles...

You don't need to drop the tranny.
Start looking for thr right tools.
Right angle drill or dremel... hell, find someone w/a plasma cutter.

I've heard of someone removing rear console, cutting a hole... accessing from the inside/above.

Re pressing in situ... did you try to press out the coupler pin or press in the bushes?
It would be tremendously easier to press in the bushes as they are a light press fit. C-clamp should do that.
Do what Chewy said and burn out the old plastic bushes.
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Old 08-01-2010, 12:57 PM
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Originally Posted by Jadz928 View Post
Sorry for your troubles...

You don't need to drop the tranny.
Start looking for thr right tools.
Right angle drill or dremel... hell, find someone w/a plasma cutter.

I've heard of someone removing rear console, cutting a hole... accessing from the inside/above.

Re pressing in situ... did you try to press out the coupler pin or press in the bushes?
It would be tremendously easier to press in the bushes as they are a light press fit. C-clamp should do that.
Do what Chewy said and burn out the old plastic bushes.
I tried to press out the pin, as I was under the impression (not having seen any point-by-point on this) that the bushings had to fit from the inside of the coupler. If I can swap the bushings from the outside, with the coupler and pin in place, that would be great.

Can you confirm, then, that there isn't a lip on the outside of the coupler to hold the bushings... i.e. that they are just press fit?

Thanks,
Paul
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Old 08-01-2010, 01:31 PM
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Rob Edwards
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The bushings are just a press fit, only lip is on the inside. I managed recently to R&R the rear coupler bearings from brass back to the plastic ones with everything on the car- I'd already split the rubber boot (now held with a ziptie), so I just folded it back. I have a small (it'll fit up in the trans tunnel- I can measure it if anyone cares) 2-ear gear puller that I used to push out the pin in the coupler. Then just lift the rear shift rod/coupler block up out of the coupler body, and then a combination of finger pressure and the gear puller with sockets as drivers will remove the old bushings. Putting the plastic ones with their flanges was a bit fiddly in situ, but can be done.
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Old 08-01-2010, 02:46 PM
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OP wrote he was installing bronze bushes.
They have no lip (flange), nor does the coupler. Installed from the outside, just press in, flush w/the coupler.
The OE plastic ones have a lip (flange) and need to installed inside, which is why the couple pin needs to be pressed out first.
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Old 08-04-2010, 10:46 PM
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So, I had an idea... I called up the local shop I worked with a lot to see if they had any used shift couplers lying around. They had a few. I picked one up which had no bushings in it, cleaned it up, had to clamp it a bit in the diamond-shaped jaws of the vise to make a good press fit for the bushings and pressed in the bronze ones.

Good to go, right? Just need to cut off the old one... Well, no.

As it turns out, while 911 shift couplers are similar they are not identical. Specifically, that "extra" set screw fitting at the top of the 928 coupler is the only one the 911 coupler has. :-(

So, it looks like I'll have to go back to plan A of ordering a used one from 928 International.
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Old 08-21-2010, 11:01 PM
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Well, I'm back working on this. Got the used coupler from 928 International and swapped the bronze bushings into it. It was easy enough to pry the old plastic bushings out without removing the pin (just break off the tabs on the inside, then pull those pieces out afterwards).

Now I'm back to trying to remove the old coupler. The right-angle drill didn't do much. I then went at it with a 4" angle grinder. So far I've cut about 3/8" into where the screw is/was. Tried slotting the remaining stub of the screw to see if it could now be turned out, but it's still pretty solid in there.... Porsche might as well have welded this thing on... Anyway, I'm taking a break before going back in to try to grind the screw the rest of the way out.

I hope other people don't have anywhere near as much of an adventure when they try to replace shift bushings; and, if you're installing the bronze ones, I would definitely recommend you try to just break the old plastic bushings with a screwdriver and pop them out so that you can install the new ones with the coupler in place. I don't think it's neccessary or worth it to try to remove the coupler for this.

Cheers,
Paul
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Old 08-21-2010, 11:45 PM
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This is getting worse.

The writeups I had seen say something like, loosen the clamp and pull the shift lever back to pull the selector shaft off of the coupler. Well, guess what? On my car, with the shift all the way back and the coupler pulled all the way back towards the transmission, there's still about 1/4" of the coupler splined shaft in the selector shaft! In other words, it's looking like I can't get the coupler out without disconnecting the selector shaft from the shifter.

By the way, I ground to the point that the coupler is no-longer attached to the grub screw, but the grub screw is STILL frozen to the transmission selector shaft!

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Old 08-22-2010, 12:22 AM
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Play by play: I disassembled the shift linkage under the shifter, which gave me enough forward play on the selector shaft to separate it from the coupler. This also answered my previously-unanswered question, "Where do the little plastic bushings go?" They go on the shafts at the bottom of shifter, where the springs and e-clips are.

Anyway, the &%&*(*$ coupler is now out of the car, but the tip of the grub screw is still fused into the selector shaft of the transmission. Not sure what to do now... I'm going to try to drill it a bit, but it's a little hard to tell what part is shaft and what is grub screw. I think I may have to just grind a flat on the shaft so that can act a lock point for the set screw....
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