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Discussion Starter · #1 · (Edited)
This was my intended trans for my 86 SPG project.
The gear in the pics is the only one that is chewed.
I have a new reverse gear for it, and everything else is very nice.
Can I run this trans with this one chewed up gear?
Not sure what it does anyway.
Is it just for reverse, or no?

View attachment 16568

View attachment 16569
 

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short answer.. replace it. it will only get even more chewed, which means the bits that break away are being carried in the oil, there is a slight chance that one of the broken particles could end up destroying other gears and bearings.
 

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Discussion Starter · #3 ·
This being the first time I have attempted to put a Saab transmission together, I am not too happy about taking this one apart any more than I have to. Pulling the pinion is one thing I was hoping to NOT have to do, but I suppose I must...

I do not want this trans breaking on me.
 

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This being the first time I have attempted to put a Saab transmission together, I am not too happy about taking this one apart any more than I have to. Pulling the pinion is one thing I was hoping to NOT have to do, but I suppose I must...

I do not want this trans breaking on me.
You don't need to pull the pinion out to replace the reverse gear, but it may not be a bad time to refresh the pinion bearings. If you pull all the gears off the pinion shaft, you can just put them right back on so long as you leave the spacer/washer that sits between the reverse gear and the pinion bearing retaining nut alone. If nothing else, you can turn the case up on end and wash out the pinion bearing as well as possible.

HOWEVER, you will want to be very critical in examining the pinion bearing before reassembly. If it feels even the slightest bit rough (with some weight on it) or sloppy, you'll want to have a new one pressed in. This is where you need the measuring device to check the pinion position in the case, which you should check before removal and then after re-installation.
 

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Discussion Starter · #5 ·
It WAS a fresh tranny, but the previous builder forgot to put the oil catcher in the chain case, so the rear chain snapped and cracked the transfer case. The pinion shaft turns very smooth and tight, and the diff gears look good.

Isn't the reverse gear the long, barrel shaped gear that sits behind the 5th gear? That one is bad, but I have another good one. The gear in question here is the one on the pinion shaft in the picture. The one on the left, to be exact. Can I replace that one gear without pulling the pinion shaft? I have a really nice Saab trans repair manual, but it does not tell me enough about this one issue.
 

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You're probably talking about the reverse idler gear. The gear that you are showing in the photo (on the left) is the reverse gear. The gear on the right is 1st gear and they count up from there toward the front of the transmission with 5th gear in the transfer (edited for mistake in terminology) case by itself. Note that the syncro in the photo is the 1st/2nd gear syncro, so when it is positioned onto the righthand gear in the photo, the transmission is in 1st.

The reverse idler gear would be the gear that is missing in the photo and resides just in front of the reverse gear on it's own shaft, moved by the metal lever in the photo.
 

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Discussion Starter · #7 ·
Got it. Thanks.

So, to replace the reverse gear, the pinion shaft must come out? Kinda' looks that way...
 

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Got it. Thanks.

So, to replace the reverse gear, the pinion shaft must come out? Kinda' looks that way...
No, the pinion shaft is bolted to the case from the differential end, the reverse gear (and all other gears) are removed from the transfer case end. The shaft can remain in the case. Just be sure to leave the spacer/washer on the opposite side of the reverse gear from 1st. It's right against the nut and keeps the length of the pinion shaft in relation to the transfer case end at a critical dimension.

When you take 1st out, the reverse gear will probably come with it since 1st is actually mounted on part of the reverse gear. They often seem stuck together, but you can get them apart with a little force without hurting anything.
 

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Discussion Starter · #10 ·
No, the pinion shaft is bolted to the case from the differential end, the reverse gear (and all other gears) are removed from the transfer case end. The shaft can remain in the case. Just be sure to leave the spacer/washer on the opposite side of the reverse gear from 1st. It's right against the nut and keeps the length of the pinion shaft in relation to the transfer case end at a critical dimension.

When you take 1st out, the reverse gear will probably come with it since 1st is actually mounted on part of the reverse gear. They often seem stuck together, but you can get them apart with a little force without hurting anything.
Just spent some time trying to get the gears off the pinion shaft from the transfer case side.
These gears do not just slide off, and there is no room for a puller behind the gear. The bearing looks pressed on to me. Special tool needed?
 

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Just spent some time trying to get the gears off the pinion shaft from the transfer case side.
These gears do not just slide off, and there is no room for a puller behind the gear. The bearing looks pressed on to me. Special tool needed?
Normally, they do just slide off; quite easily in fact. I had one once where one of the spacers, perhaps around the 4th gear, welded itself to the shaft. For that one, crwchf01 lent me his 20ton press, I loosened the bolts holding the pinion housing (from the differential side) and pressed the shaft until the offending spacer popped free. After that, everything else came out easily. If you find that this is the case, the shaft may possibly be damaged. In my case, the shaft was useless.
 

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Discussion Starter · #12 ·
It must just be damaged.
I took the 4 bolts off on the diff side and whacked it good from the other side with a large copper hammer.
Didn't budge.
I have another blown trans I will examine, and use as a learning tool.
 

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It must just be damaged.
I took the 4 bolts off on the diff side and whacked it good from the other side with a large copper hammer.
Didn't budge.
I have another blown trans I will examine, and use as a learning tool.
That sounds a lot like the one I had trouble with. I smacked it pretty well for some time with a dead blow hammer before going to the press. It took a huge amount of force to pop it free.
 

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Special tool needed?
There is a Special Tool for the purpose of forcing the Pinion Shaft out of the case. It's rarely needed and doesn't work very well. A soft-faced hammer on the end of the Shaft (protected by the Nut you removed) works better. Usually, when such force is needed, there is damage to the Pinion Shaft. Normally, if there were no damage, the gears would slide off easily by hand.

Note: If all you do is replace the Pinion Bearings, you do not need to reset Pinion Depth or Differential Carrier Bearing pre-load or Ring Gear backlash as long as all Shims go back where they were.
 

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Discussion Starter · #15 ·
I just wanted the reverse gear out of it for another trans.
I am trying to make 1 good trans out of 5 spares I have, all with different problems ranging from broken chain cases, to obliterated gears.
I'll try another one and see if it comes apart.
 

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Don't give up.
Once you know that the matched Ring & Pinion Shaft are trashed, you can hammer away with abandon to salvage the Gears, Bushings, Synchro Springs, Muffs, Hubs, Shims, etc.


Edit
Dang, I seem to have slipped over the 5,000 post mark.
Note to self: Get a life.
 

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Discussion Starter · #17 ·
Don't give up.
Once you know that the matched Ring & Pinion Shaft are trashed, you can hammer away with abandon to salvage the Gears, Bushings, Synchro Springs, Muffs, Hubs, Shims, etc.


Edit
Dang, I seem to have slipped over the 5,000 post mark.
Note to self: Get a life.
5000 posts!
Hey moderator, please present this man with the coveted golden keyboard...
 

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Discussion Starter · #18 ·
Finally got the shaft out. The pinion shaft is galled heavily, and the reverse gear I wanted has a chip I did not see before.
It's a boat anchor.

Next I will open up donor trans #3 and continue my search for usable gears.
 

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Finally got the shaft out. The pinion shaft is galled heavily, and the reverse gear I wanted has a chip I did not see before.
It's a boat anchor.

Next I will open up donor trans #3 and continue my search for usable gears.
When I come across transmissions at the self service yards, the first thing I do is pull the side covers so I can rotate and check the reverse gears. I also check the transfer case from the side to see if the 5th gear spring has broken out of the syncro. If those two things look promising (no spring remnants and reasonable reverse gear/idler) it's worthwhile to pull it out. There is an abundance of pretty much everything except the reverse gear and idler.

I looked into dozens of transmissions and I've only found 1 perfect reverse and idler set. Eventually, you just have to settle for less chewed up than normal. ;)
 

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Discussion Starter · #20 ·
I have a perfect idler, and I am probably going to just leave the slightly chewed reverse gear in trans #1. It's just reverse, and the rest of the gears are excellent.

All of the donor transmissions I am going through, are from parts cars that are long gone, so I haven't spent anything.

I did get a new set of chains/sprockets, and a great looking chain case from this latest teardown.

Transmissions are the 1 thing I have never taken apart on a c900, so this is quite a learning experience.
 
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