Classic Saab gearbox rebuild

As I said above, I need to get my vice installed or take the pinion to my parents to release the nut, but here's how the official tool holds the shaft

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And the large nut

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Which requires a large spanner

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This part of the dismantling TBC...
 
So I moved onto dismantling and inspecting gears 1-5. The assemblies are dismantled by removing a circlip

1st gear

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Side on view

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Synchro ring outer edge

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And close up of the business bit. Small amount of wear showing, but looks like plenty of life yet.

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Second gear dismantled. Similar condition

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3rd

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4th - the damaged guide ring is held on with a spring clip. Not worked out how to remove this yet! I may have to get a replacement clip as well as the guide ring.

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5th gear

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1st/2nd muff/hub. Same as 3rd/4th

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And reverse

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You lost me @ post #7, enjoying the pics and explanations, keep em coming.

Big achievement if this is not your day job, in your own garage and it all works as it should in the end.
 
That's rather fascinating.. I admit to not knowing sod all about gearboxes either! I didn't even think that an inline FWD design would use this sort of layout! What other cars use it? At what point did Saab switch to a transverse layout?
 
I really hope it all works in the end :D Not attempted anything so complex before. I've rebuilt engines in the past but they're simple in comparison...

And definitely not my day job. Unfortunately.
 
Howard said:
That's rather fascinating.. I admit to not knowing sod all about gearboxes either! I didn't even think that an inline FWD design would use this sort of layout! What other cars use it? At what point did Saab switch to a transverse layout?
Click to expand...

The engines in these cars are actually backwards - the flywheel is towards the front of the car, hence the dead easy clutch change.

The 9000 (1985-) and GM900 (1994-) has transverse. GM influence I guess.
 
So a bit more dismantling and inspection. Starting with the primary drive upper sprocket bearing, first the retaining circlip is released

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Then the bering is pressed out, avoiding the loose circlip inside the sprocket which normally holds in on the primary drive housing. You need to space the sprocket off the press. Unfortunately the spacer I used happened to be the same bore as the sprocket so I then had to press the bearing out the spacer :oops:

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You end up with a collection of parts. All looks good. A new bearing will of course be used but everything else will be retained.

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I then had a look at the cluster gear and its bearings. The small needle bearing (pinion end) is apparently a Saab only part. Hoping to persuade INA to release it to general sale as I doubt Saab will be selling any more.

The thrust washer is heavily worn, it can be turned over, but I'll use a new one and save the old one for desperate measures when new ones can't be found. The inner race has some damage, so that needs replacing too. It's an INA part so hopefully I can source it outside Saab.

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A typical view of the cluster gear teeth - all good

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The primary housing hold the needle bearing for the other end. This bearing is readily available and is pressed out of the housing. The other bearing is pressed in and also has a retainer held in with 4 screws that have threadlock on - very tough to remove and I shall be using new screws as all of them have some damage to the head.

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Done a little bit more inbetween DIY jobs on the house. First up was having a look at removing the ring that holds the guide plate onto 4th gear. No method in the book on how to remove it effectively so I had to improvise. It came apart after about 15 minutes of gentle trying

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Do you think Saab will allocate this a place on the special tools board? I hooked it behind the ring half way round from the end, and pulled firmly but gently. It slipped off a few times, but the ring came off in the end. Not looking forward to putting it back together with a new guide plate!

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And in other news, took the pinion shaft round to my parents and swung on the big spanner. Next step there is to press off the bearings.

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Dismantling wise, only the pinion bearings, inner driver bearings, input shaft assembly and diff bearings to do. All of these need my big press which is still boxed up somewhere.

I have the official puller for doing the diff bearings but the thread is gone so will have to improvise.
 
Nutcase's box is from a classic 900, probably off a light pressure turbo rather than a T16s. (v. late 80's v. early 90's)

I've got a spare box for my NG900 which is very different to this, looks far more normal. (a GM based F25 box) However, I am not as mechanically proficient as nutcase and i'm leaving the thing alone. (I'm capable of most work, but gearboxes i consider to be akin to pandora's box)
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To illustrate the difference. (biggest difference is the longitudinal vs transverse layout)
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Its the same housing as the old 93, but the innards are different. (93 is FM 55507, 900 is FM 55501, my spare is FC 55501) The NG900 (new gen 900) had a unique 3.82 final drive, iirc 3rd gear is a different ratio and this particular box is from a sensonic (ACS) model so has a couple of extra sensors tagged on to it.

I'll stop derailing the thread with nasty GM saab bits now. :p
 
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