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ideola
Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI
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 Posted: Sat Jun 06, 2009 6:43 am Post subject: |
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Well, here's the disappointing response from Pelican:
| Glenn @ Pelican wrote: | | Hello, we don't make any of our own parts and those bronze bushings have not been available for quite some time. Long enough that I can't even find out who the vendor was for them anymore. Sorry I couldn't help you with this... |
I'll do some inquiries in a couple of the 914 forums. Incidentally, there are some other (different style) brass bushings made for the 914 side mount, and they are in fact designed with a larger OD and smaller ID, requiring machining-to-fit. Likely that these did too.
In any event, the sealed u-joint is probably a better all-around approach, will continue down that path as well. Time to go look at some torque tubes and shifter assemblies. BRB.
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patand
Joined: 12 Jan 2007
Posts: 91
Location: Sweden
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| Posted: Sun Jun 07, 2009 11:11 pm Post subject: |
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I think I have showed these pictures before on 924board. But since this thread is about improving the linkage I think it is time to show them again. They show how the balljoint was replaced on my linkage:
Of course I used thread lock for the threads. It has now been like this for a little more than 2 years and I almost only use my car driving hard on the tracks and this joint is still working fine. 
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v8carreragts
Joined: 05 Sep 2003
Posts: 665
Location: Tucson, AZ
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ideola
Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI
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| Posted: Mon Jun 08, 2009 10:19 pm Post subject: |
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| v8carreragts wrote: | | Why not just replace the parts? |
Well, because that wouldn't be an improvement over the flawed factory design? Especially when the stock bushings for the rear coupler have slop designed into them (at least according to my gearbox expert)...not ideal for a hard-driven track project.
I had a spare audi-based shift rod lying around from a 4-speed. I cut it off at about the right length to match to the G31 shift rod. It is hollow, and has an inner diameter of just about 16mm. I think getting rid of the guide rod altogether would be ideal. Here's what I'm considering:- Drill and tap four holes on the torque tube for the audi-style saddle mount that holds the ball & socket assembly for the shifter.
- Install a weldable thread bung into the hollow end of a shortened Audi-based shift rod
- Insert an appropriate length of threaded rod
- Attach a steering u-joint to the threaded rod and gear selector input shaft
This will greatly simplify the shift linkage, improve the shifting feel by eliminating virtually all slop, and is composable from existing parts and easily-obtained off-the-shelf components. It also opens up the world of 944 short shift kits since the shifter itself will now be a "standard" item...
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Rasta Monsta
Joined: 12 Jul 2006
Posts: 11724
Location: PacNW
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| Posted: Mon Jun 08, 2009 11:24 pm Post subject: |
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I don't know a lot about gearboxes, but doesn't this assume that the G31 selector shaft requires the same inputs as the Audi (degrees of rotation, longitudinal travel)? Might require some measuring.
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- WeiBe (1987 924S 2.5t) - 931 S3
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Paul
Joined: 02 Nov 2002
Posts: 9491
Location: Southeast Wisconsin
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| Posted: Tue Jun 09, 2009 1:37 am Post subject: |
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Most 944 short shift kits replace the linkage on the Audi tranny, so they will not work on a snail shell.
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White 87 924S "Ghost"
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Owned and repaired 924s since 1977
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Rasta Monsta
Joined: 12 Jul 2006
Posts: 11724
Location: PacNW
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| Posted: Tue Jun 09, 2009 2:40 am Post subject: |
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. . .and speaking of Paul, I think he once put forth a theory that solid bushes in the toofah linkage could lead to vibration damage.
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Toofah King Bad
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ideola
Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI
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| Posted: Tue Jun 09, 2009 4:56 am Post subject: |
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| Rasta Monsta wrote: | | . . .and speaking of Paul, I think he once put forth a theory that solid bushes in the toofah linkage could lead to vibration damage. |
Yeah, and in the same thread, endwrench indicated it was not an issue...
It appears to be a moot point as the brass bits appear to be NLA (no leads on Rennlist), and if I were to make up new bushings from scratch, I'd do them in poly.
Right now, I am still favoring a u-joint for the connection from the shift rod to the gear selector input, regardless of whether I attempt to eliminate the guide tube. I need to do some research on figuring out the degrees of rotation differences between the audi and snailshell shift levers...
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ideola
Joined: 01 Oct 2004
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Location: Spring Lake MI
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Paul
Joined: 02 Nov 2002
Posts: 9491
Location: Southeast Wisconsin
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| Posted: Tue Jun 09, 2009 6:31 am Post subject: |
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In the referenced thread, MonkPuppy reported that his solid bushings rattled enough that he wanted to replace them.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy. |
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Rocco R16V
Joined: 03 May 2009
Posts: 497
Location: PNW
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| Posted: Tue Jun 09, 2009 6:46 am Post subject: |
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Wow, this is exactly the type of discussion I wanted to start, lots of good info here.
| ideola wrote: | | v8carreragts wrote: | | Why not just replace the parts? |
Well, because that wouldn't be an improvement over the flawed factory design? Especially when the stock bushings for the rear coupler have slop designed into them (at least according to my gearbox expert)...not ideal for a hard-driven track project.
I had a spare audi-based shift rod lying around from a 4-speed. I cut it off at about the right length to match to the G31 shift rod. It is hollow, and has an inner diameter of just about 16mm. I think getting rid of the guide rod altogether would be ideal. Here's what I'm considering:- Drill and tap four holes on the torque tube for the audi-style saddle mount that holds the ball & socket assembly for the shifter.
- Install a weldable thread bung into the hollow end of a shortened Audi-based shift rod
- Insert an appropriate length of threaded rod
- Attach a steering u-joint to the threaded rod and gear selector input shaft
This will greatly simplify the shift linkage, improve the shifting feel by eliminating virtually all slop, and is composable from existing parts and easily-obtained off-the-shelf components. It also opens up the world of 944 short shift kits since the shifter itself will now be a "standard" item... |
This is the way i think i will go, thanks for doing the legwork for me Ideola!
| Rasta Monsta wrote: | | I don't know a lot about gearboxes, but doesn't this assume that the G31 selector shaft requires the same inputs as the Audi (degrees of rotation, longitudinal travel)? Might require some measuring. |
I thought about this too and decided it the travel/rotation is different it would only affect how much you would have to move the shift lever while shifting. If after installing I decided the throw is too much, I could change the lever to reduce throw and rotation by lengthening the distance between the TT and the selector rod. This would, however, mean modifying the selector rod also, to lengthen the bent part.
The real problem would be if there was not enough travel to actuate the linkage inside the trans, but i really dont think this will be a problem.
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ideola
Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI
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| Posted: Tue Jun 09, 2009 7:53 am Post subject: |
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| Rocco R16V wrote: | | The real problem would be if there was not enough travel to actuate the linkage inside the trans, but i really dont think this will be a problem. |
Agreed, from looking at the pivot points side by side, it appears to me that the audi setup is designed to throw further than the G31 setup, but I need to investigate further.
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ideola
Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI
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| Posted: Tue Jun 09, 2009 7:55 am Post subject: |
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| Paul wrote: | | In the referenced thread, MonkPuppy reported that his solid bushings rattled enough that he wanted to replace them. |
Yeah, we have one anecdote that says "rattle" and one that says "no rattle". Considering MANY of the 914 guys are running solid brass bushings in their cars (including my local gearbox rebuilder / expert), I tend to believe it would be a good thing to have a more solid setup. As with most of these issues, there are lots of variables that go into the two anecdotes and lacking a hardcore scientific approach to "debugging" the setup or documenting the variables, I think the anecdotes are inconclusive at best.
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v8carreragts
Joined: 05 Sep 2003
Posts: 665
Location: Tucson, AZ
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| Posted: Tue Jun 09, 2009 9:19 am Post subject: |
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The through between gears is definately shorter on a G31 VS the 016. I don't see that this would be a problem with the 016 rod though.
Basically, if you look at the two you will see that the distance between the two pivots on the G31 shift handle are much closer than the distance between the ball pivot and the pin on the 016. This is where the difference is. The bottom pivot on the G31 takes the place of the ball pivot on the 016. The shifting functions the same for both, I.E. same direction for gear changes.
Maybe for the track the stock shift mech. is not very good but when I was driving my 79 (which had all of the parts new) the shifting was very pricise and definite. I guess I will find out in my present car. (if I ever finish it ha, ha) |
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Rasta Monsta
Joined: 12 Jul 2006
Posts: 11724
Location: PacNW
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| Posted: Tue Jun 09, 2009 10:07 am Post subject: |
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| v8carreragts wrote: | | The shifting functions the same for both, I.E. same direction for gear changes. |
Now that would be a laugher if is wasn't (upside down shift pattern? backwards? BOTH?).
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- WeiBe (1987 924S 2.5t) - 931 S3
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