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Discussion Starter · #1 ·
Hi all,

My c900 (auto) has a strong vibration when idling and at a stop in 'drive'. This will go away when placed in neutral or reverse. I initially thought it might be a bad engine mount, but when I took the car in for its roadworthy inspection, the mechanic (SAAB specialist) said it was a worn RH inner driver.

Most of what I've read online talks about inner drivers causing vibration at highway speeds, but I can't find much on vibration at idle. Can vibration at idle also be caused by a worn inner driver? I suppose that it's probably an issue more likely to affect automatics, seeing as when idling in 'drive' there is still a load applied to the driveshaft, as opposed to a manual where there is no load being applied when not in gear.

Anyhow, my RH outer CV was starting to click so I've got the driveshaft out at the moment so I can replace it. To actually replace the inner driver, is it just a matter of pulling the old one out and pushing the new one in? Do I need to mess about with bushings and shims?

Also, since I've got it all apart, should I bother replacing the inner tripod?

Any advice would be much appreciated.

Thanks.
 

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Inner Driver can't make any noise unless its rotating.
Thinking the transmission?

Replacing it is a bit more involved.
You have to unbolt the casting and pull a circlip and push it out of the bearing.
You also have to replace the shims as they set the pinion pre-load.
 

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I'm no expert on this but I've read it a few times on this forum (Jim M please). It's wear on the inner drivers and this symptom only occurs on autos, not manuals. Something to do with the tripod vibrating inside the cup when stationary at idle. I'm sure someone will be along soon to expand on this.
 

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Discussion Starter · #4 ·
I'm no expert on this but I've read it a few times on this forum (Jim M please). It's wear on the inner drivers and this symptom only occurs on autos, not manuals. Something to do with the tripod vibrating inside the cup when stationary at idle. I'm sure someone will be along soon to expand on this.
Yeah I was thinking it had to be an auto specific issue. Anyhow, I've just checked the inner driver and it has some pretty nasty divets in it where the tripod sits, so I'll change it regardless. Hopefully I see an improvement.
 

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Yeah I was thinking it had to be an auto specific issue. Anyhow, I've just checked the inner driver and it has some pretty nasty divets in it where the tripod sits, so I'll change it regardless. Hopefully I see an improvement.
Anything other than a perfect bearing surface inside the driver cup will give problems, whether it auto or manual.
 

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My c900 (auto) has a strong vibration when idling and at a stop in 'drive'. This will go away when placed in neutral or reverse. I initially thought it might be a bad engine mount, but when I took the car in for its roadworthy inspection, the mechanic (SAAB specialist) said it was a worn RH inner driver.
Keep that Saab specialist, that's a tricky one to diagnose.
Yes, automatics only, and that's the classic symptom.
 

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I've replaced a few inner drivers now. Here's one of my old threads querying others about the process. There are a few additional threads embedded that I found helpful.

When I replaced my inners back in September in my black '90 SPG, I renewed the entire assembly (drivers, tripods, CVs plus the all the seals). Could have elected not to replace (for instance) a tripod, but then I'd end up having to take everything apart again if it failed. Recommend you take care of everything while you're in there, if you can.

Best of luck!

http://www.saabcentral.com/forums/showthread.php?t=295617
 
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