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Discussion Starter · #1 ·
Hello everyone. Have a 1992 900i which changes gear fine when cold but as soon as it is warmed up it takes a lot of force to get it into and out of 5th gear. It feels like the last part of the gate shrinks when hot and holds onto the gear like a vice, if this makes sense. All other gears are fine though.

I have had "Benny" for 4 years and since this model has no drain for the gearbox, I doubt that the gearbox oil has ever been changed. He is just approaching 230 000 km's (144 000 miles).

Curious if anyone has encountered this before and if an oil change of the gearbox would be the best idea or if this is systematic of another problem. Any ideas greatly appreciated.
 

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Good question Enki - I'll be keeping an eye on this post. My dads 89, 900 just started the same thing. There is a very narrow gate for 5th gear. When cold it goes in - as it warms up, you really have to lean on it to get it in 5th.
 

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Welcome, both of you, to SAABcentral! Post pics of your cars? Please? :cheesy:

This guy had problems with sticking in 5th and difficulty shifting into 5th on a warm gearbox.
http://www.saabcentral.com/forums/showthread.php?t=64702
He found it to be oil-related. YMMV. I've never had a 5th gear problem, but I've still taken his advice and changed my oil to synthetic 5w-40 and it works well. I'm wary of using the Auto Rx snake-oil he suggests to clean it.
It's easy to change the gearbox oil by removing the rear diff cover if you don't have a drain plug. Just seal it up afterwards with Loctite 518. Don't remove the side cover, as this needs an actual gasket.
 

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One thing you'll find about gearbox recommendations is that there is never any agreement on oils. Personally, I absolutely avoid synthetic engine oils because of the additives. It is unclear what their effect on brass syncros is and they were designed for engines specifically. I prefer, and recommend, Redline MTL which was designed with brass syncros in mind. The oil itself is synthetic and has the properties of synthetic which are desireable, high resistance to shearing and breakdown. It was also engineered to have a similar amount of friction to that of 30w oil, which is thought to promote better function of the syncros (where synthetic engine oil may actually be too slippery). This makes some sense if you think about it. The pinion shaft and the gear are moving at different speeds before engaging the gear. Once you start engaging a gear, the synchro uses friction between the sleeve and ring to bring the rotation of the gear on the shaft to a halt, allowing the sleeve to lock the gear to the hub and therefore the pinion shaft with as little damage as possible. Less friction here will only make for delayed synchronization, which would then seem to promote damage to the tips of the ring and gear, particularly if you shift quickly. Also, Redline MTL is a relatively thin oil, similar to 5w-30, which allows the oil to have a thinner layer between gears, promoting good protection.

I've used this oil myself for quite some time now and can say that it works well at cold starts where it is actually cold (like Edmonton, Alberta in January) and performs just as well when warm. I think it just makes sense to use an oil designed with this application specifically in mind because as I've pointed out the needs of a transmission are different than those of an engine. It's not about protecting surfaces alone, but also how those surfaces interact in a transmission, but I'm sure others will disagree. What I do know is that I have nearly 200,000 miles on my transmission and it still works fine.

Edit: Also, yes I believe as well that oil could be part of the problem and could even be enough to cure it. It is also possible that the selector fork is slightly bent, the syncro ring is damaged/burred, or maybe even that the selector shaft itself in somehow worn/damaged internal to the engine which better lubing would help. Just to be sure that we aren't talking about the linkage, does it make it easier to get into 5th by lifting the reverse lockout ring on the shifter? If so, the problem is in the linkage itself and you'll need to adjust it at the joint between transmission and linkage shaft jus above the steering rack (actually easier than it sounds). This usually doesn't change with engine temp, but I suppose it isn't impossible either.
 

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Great information - I will do a complete gear lube change. I want to mention that last week, before my dad when to Myrtle Beach,(600 + miles each way) I checked his gear box oil - nothing on the dip stick!! I put 2.5 Qts of 10W30 to bring it up to the full mark!!

Who knows how long it had been close to bone dry - no visable leaks, then again, being that low, it was probably below any leak points - he never complained of shifting issues.. I am thinking that some crap got stirred up on the trip causing the difficult shifting.

Regardless, a couple of drain and fills within the next couple of weeks is in order.

Thanks,
Brad
 

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..........engine mount maybe?

Could be the engine alignment/position changing slightly when he chassis/engine gets warmer.
RE: oil change, no comment on the oil but the bolts need to be very clean and fresh thread seal applied otherwise? weeping oil everywhere.
 

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..........engine mount maybe?

Could be the engine alignment/position changing slightly when he chassis/engine gets warmer.
RE: oil change, no comment on the oil but the bolts need to be very clean and fresh thread seal applied otherwise? weeping oil everywhere.
I concur that an inspection of the aft motor mounts is in order. Might want to review shifter alignment posts in this forum and keep in mind the back mounts do have an awful lot to do with shifter alignment and performance.
 

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Regardless, a couple of drain and fills within the next couple of weeks is in order.
Running without Oil is almost always fatal. Don't be in a hurry to spend money or time on oil changes or fancy Oil. They can't repair damage. Your theory of "stirred up junk" is unsound.
If, against all odds, it survives a thousand miles or two, throwing money at fancy oil won't be as much of a waste.
 

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I hear ya - It's been driven 1200 miles since I added the 2.5 qts. The shifting issue may be a coincidence with his trip? I am not a subscriber to the fancy oils - I was thinking about regular old 10 or 5W30. I think the motor mount suggestion is worth looking into as well.
 

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I hear ya - It's been driven 1200 miles since I added the 2.5 qts. The shifting issue may be a coincidence with his trip? I am not a subscriber to the fancy oils - I was thinking about regular old 10 or 5W30. I think the motor mount suggestion is worth looking into as well.
Might want to look up posts I have written on the shifter aligning and wear points. Your RH mount is the easiest to inspect-a 1/4 in or so gap between the crossbar and center of the mount means it's OK. Less or signs of fluid on top of the mount means it is gone. It's also the easiest rear mount to change.
 

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Discussion Starter · #12 ·
Thank you all.

Thanks for replies everyone. Am off to the doctor tomorrow with a copy of posts and I will let you know how we get on. All will be well hopefully.
 

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Discussion Starter · #13 ·
Sorry to take so long, but this is what happened. My mechanic, after driving car was sure that gearbox was fine and that the change mechanism was to blame. When he took off gaiter he said everything was dry and flaky and that a holding pin was half off. Adjusted the gate to the best of his ability and lubricated everthing as far as he could.

Is now much improved but still a little sticky when warm but not too much of a problem now. He says he can feel rubbing or resistance further up the change mechanism, but to get to it he says he will need to take out a seat and the carpet to get to it. I will leave that until it gets worse again.

Thanks again everyone and hope this may be of help to others.
 

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I would suggest trhat the rest of your problem is twofold- 1) your teflon bushing inside your rubber bushing on the front of the shifter mechanism is worn, and 2)you have a burr,flake or some other surface defect on the shifter rod on the assembly itself that is binding/cutting/wearing the teflon ring.
 
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