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Re: Eric..kindly another question please. Posted by eric in vermont [Email]  (#2058) [Profile/Gallery]
(more from eric in vermont) on Wed, 12 Mar 2008 17:27:27
In Reply to: Eric..kindly another question please., Larry, Tue, 11 Mar 2008 18:52:55 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Hi Larry,
The first gearbox was not completely taken apart. Meaning I took apart just enough to replace the bearings that were bad. This gearbox did not whine- it crunched! I bought it from a guy in NH, drove it home to VT, and decided I better drain the gearbox oil and see what I would find. Sad to say- a handful of metal. I took the handful to my mechanic friend and said "what do I do now?" "When you get the gearbox out, bring it over and we'll rebuild it." His method was to make me do all the work while he gave me advice. He wanted me to get the feel of it instead of watching him do it. I could hardly even figure out the shift rods at that time! And I don't even recall which bearings we replaced. I asked him if we should replace all of them and he thought, being a good frugal Vermonter, that to be a crazy idea.
Please understand that I am by no means an expert in Saab gearboxes! In my opinion, there are a couple of sources of whining. I think the most prevalent is from the ring and pinion. As mentioned previously, the bearings wear, the nuts loosen, and the ring and pinion no long mesh properly. This causes whining. Another source is the whining (especially in second) which stems from wear (particularly grooves) that develops between a gear and the needle bearings it rides on. The grooves actually develop in the gear itself, as the needle bearings are quite hard. Another source is good old bearing wear. Pitting, spalling, and all sorts of things happen over time.
The gearbox in my 96 Deluxe has a wicked awful whine, particularly on deceleration. It scares the heck out of me! I was running it in freewheel so there was no decel load on the gearbox, but the freewheel is sticky and unreliable so I have to drive in normal mode. Since it occurs in all gears, I point my finger at the R&P. As I drive it, I visualize the shaft nuts getting looser and looser... That's why I'm working on this other gearbox- its for the 96 before it blows up.
So, why would a freshly rebuild gearbox still whine? And why would the rebuilder say "yeah, it will do that for a while." Here's what I think- and again, I'm no expert! Think about the situation- the gearbox is getting sloppy. The nuts are getting loose. The bearings are wearing. The R&P is not set correctly due to all this and its getting worse. The wear and movement are rapidly increasing the more its driven. This causes the R&P to separate more and more, causing funny wear patterns because the engagement is not right. Finally, you take it to your friendly VSaab trans guy and he rebuilds it. He carefully sets the R&P backlash up, but the gear surfaces are no longer smooth. So when you first run it, it makes some noise until those surfaces smooth out a bit. The worse the wear, the longer it may whine after a rebuild. Make sense? It's just my theory. Jack Lawrence shot blasts the R&P to help out this problem and to provide a degree of hardening. There may be other reasons for a whine after a rebuild, like new gearsets.
Also, its not just the nut on the pinion shaft that loosens up. They ALL do. I found several transmissions that had all three shaft nuts less than finger tight. It just seems the pinion shaft is the worst culprit and is mentioned most often.
Again, I feel a little hesitant talking about all this- there are more knowledgable people than me on this topic! Please correct me if there are any errors in what I say. But I'm sure willing to share my experiences and theories if it can help someone out.
Eric in Vermont
posted by 68.142.42...
, Mon, 10 Mar 2008 14:43:35, Wed, 12 Mar 2008 17:27:27 <-- Viewing This Message, Thu, 13 Mar 2008 06:37:26, Tue, 11 Mar 2008 17:04:24, Wed, 12 Mar 2008 05:35:29
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