Taking a look inside my 930 transmission - looking for advice from the gurus..

[HFR_Racer]

I'm in the process of several projects on my 930 and I've arrived at the synchros. This past summer I completed all of the preliminary/advised adjustments and repalcement of worn parts in the shifting linkage. My 930 still shifts into 1st and 2nd hard and I'm not interested in double-clutching forever.

I've attached the mandatory engine pull photo even though this isn't my first time.

First a shot of my baby though.





Now for the subject material...

1) The reverse gear teeth appear to be acceptable



2) I'm interested in the funciton of this particular detent. Anyone?


3) A little sludge in the bottom of the case but no chunks.


4) This appears to be normal bearing wear for 87k miles. Any opinions? No gouges or pitting. Only a bit of dulling to the roller bearing surface. The bearings rollers are excellent though.


5) The pinion shaft bearing race looks the same.




I'm editing on the fly so more photos to come. I'll remove this comment when I'm done.

[HFR_Racer]

6) The shifter fork..




7) Pinion shaft roller bearing looks good to me. No damage to the roller surfaces. Thats a hair on the one roller face.



8) Same with the input shaft roller bearing at the rear case.




9) 2nd dog teeth look worn. How about the synchro band? Does that look bad as well? If so, how can you tell? What is the determining factor?




1st dog teeth look worn as well:

[HFR_Racer]

11) 3rd gear dog teeth look worn but 4th is ok.







For cost reasons I am only freshening the pinion shaft this season since I plan to pull the engine next winter. I will do the input shaft and differential bearings next year.

Thank you for your comments,
HFR_Racer

[sc_rufctr]

As I posted my reply you added the extra photos... Well done!

Now just the ring and pinion please.

(I deleted my first reply to tidy up your thread)

[HFR_Racer]

The ring and pinion are in excellent shape... I hope to get some comments on the shape of my 1st and 2nd synchro bands. It looks like the PO installed new 1st gear dog teeth years back. Maybe it's common that the second gear dog teeth look worse than 1st? I am also interested in comments on if I need to replace the roller bearings since the races are getting dull (even though this appears to be normal wear).

Thanks to everyone for looking and commenting.

[sc_rufctr]

Up for views...

[mark '87 930]

HFR_Racer, I just rebuilt my 4 spd tranny as well, but I went all out and spent the wad on all synchros and dogs. I also had bearings and sleeves which were shot, likely due to a bad rebuild some time back.

The answer to your first question about that one long detent. That's for your reverse gear tension. It's so you don't accidentally go into reverse instead of first gear. Notice how much 'force' you need to exert on the shifter to move it over to get into reverse, the detent you show is what you are compressing in that motion.

Second gear takes the biggest beating. I replaced the 2'nd gear synchro hub and the slider as well. I also did third and that slider too, along with the synchros themselves.

Fun fun.. It was simple with the right tools. The longest bit was waiting for parts.

[mark '87 930]

I forgot to mention that shinny synchros normally mean they are worn. You can measure them too according to the factory spec. For the price, I just replaced them (and all the brake bands as well as stop/anchor blocks).

[sc_rufctr]

Ok...

Generally your trans looks very typical to good. The bearings look great and the gear wear surfaces look fine.
Also your shift fork looks "normal"...

Now for the bad news.

All four of your synchro rings look like they are done. That is the "friction" coating has worn off. (from what I can see)
These should definitely be replaced. Which also means the 1/2 slider and 3/4 slider.
(This is very typical)

The dog teeth are all worn but obviously first a second are the worst.
So you could just replace those two and you'd have a nice shifting gearbox.
At a pinch you could just replace first only... Depends on your budget.
(This is also very typical)

One thing that you should consider is replacing the differential support bearings.
The reason for this is that they are very stressed in normal use.

[Peter Zimmermann]

Buy:
1st speed synchro
2nd speed synchro
1st speed dog teeth
2nd speed dog teeth
1/2 shift slider
Gasket set (or individual gaskets as needed)
Evaluate gear needle bearings/bushings/blocks/bands at disassembly
Obtain required tools.

FYI: Also, buy new collared shaft nuts, never re-use them (like already has been done).

[mark '87 930]

I would agree with Pete. If money is an issue (as it seems to be), but you want to fix your 1/2 issues, get the parts Pete mentioned (they're not cheap BTW). The 'tool' for removing the 1/2 synchro hubs (dog teeth) really only works for 1st gear.. not 2nd very well... (ask me how I know).

In doing research, I came to the conclusion that when you synchro bands, you should also replace the brake bands.

[HFR_Racer]

It seems that the pinion shaft nut is no longer available. Does anyone stock them or is there an alternate part#. This is for the pinion nut only.

Thanks to all that replied.

[Determined]

Nice write up

[Discseven]

930 gearbox.... new & old dogs for 2nd. New & old syncro rings.







...And nice Turbot HF!



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