Wednesday, April 3, 2013


 The drawing shows the shift linkage for a Sonett III, from the shift tower [on the left] to the transmission [on the right]. Both the shift tower and the linkage support [bolted to the transmission] have two bronze bushings [see arrows]. Saab must have managed a "real deal" on the bushings because they get sloppy after only a few jillion shifts, and that, along with the fact that Saab did not add spring in the linkage to load the shifter to the 3rd-4th gate, can make selecting the correct gear a bit of a crap shoot. 
These are the parts for the linkage at the transmission. But first, one other comment: The actual movement--INSIDE THE TRANSMISSION--from neutral to say, 3rd gear, is only about 1/2 inch [13mm] or so. So it doesn't take much slop in the linkage to confuse gear selection. That's why bushing wear can make things sticky-wicket in the shifting department.

Above--the support fixture with all the bolt holes has a bushing in each end. These are the ones that have to be replaced. Problem is, correct SIZE bushings are not available.
 I get bushings that are just larger than the originals, chuck 'em in the lathe, and carefully machine them until they are just about 0.002" larger outside diameter than the inside diameter of the support housing. Then I press them into the housing. Above is my lathe setup for machining the new bushings.
 Here is a photo of the old bushings and the support housing with the new bushings installed. Note that once I press the new bushings into the housing I still have to ream the INSIDE of each bushing to shaft size plus 0.002".  Note that I also drill and tap the housing for a grease zerk so the bushings can actually be lubricated.  [THAT is a novel idea the Saab engineers never thought of, apparently....]
This is the finished product, ready to go into the car. Might last a few jillion more shifts, especially if it gets a squirt of grease now and again...

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