cyclopticgaze

bmw 2002

Overhaul of the Shift Lever Support Bracket

Aug 10, 2008

     Ever since I got the car, the shifter has been messed up.  I never knew for sure what the problem was, but something was seriously wrong under the car.  The shift lever flopped all over the place, ever when in gear.  It made simply finding a gear difficult, and wasn't at all drivable.  This was more than just a worn out linkage, something was straight up broken because the entire shift support wobbled all around.  In fact, I suspected that the shift linkage had nothing to do with the problem.  The car has a short-shift kit installed by a previous owner, and it doesn't look terribly old.  I crawled under the car to investigate.


I've supported the transmission with a bottle jack and I've removed the support bracket from spans the tunnel and normally holds up the tranny.  You can see the new yellow transmission mount hanging there, useless now that its bracket is gone.  Straight above the yellow transmission mount is the driveshaft that needs to be dropped down so I can get to the shift lever's mounting bracket (above the drive shaft, shiny black).

transmission support bracket removed


     I had to detach the driveshaft from the transmission to get to the shift mount above.  The transmission attaches to the driveshaft by a rubber guibo with 8 bolts.  They were a pain to slacken, but came off with little fanfare.  But in order to drop the driveshaft, the exhaust center resonator has to be detached and lowered, otherwise the driveshaft will hit it and won't have enough room to pull away (I figured that out the hard way).  The driveshaft's center bearing has to be loosened as well.


The exhaust center piece is detached and dropped (bottom right).  With the guibo unbolted and the center bearing loosened, I was able to pull the driveshaft off the transmission.  Now the shift support is totally exposed so I can easily work on it.

driveshaft dropped


I unbolted the bar that supports the shift mount from below.  It attaches to the transmission just below the tranny's output flange (cross-shaped piece with four holes).  So now there are just two blocks that bolt the shift mount plate to the tranny.  I unbolted the shift mount from these blocks, which are common wear parts.

shift mount unbolted


Here's a close-up of the two blocks than need replaced.  I unbolted the black shift support plate from them and propped it above them.  And here we've found the problem.  You can see the one on the left is completely broken.  Normally these parts 1) are not broken, and 2) have rubber gaskets through the hole to keep the bolts firm but cushioned.  With the part broken and the rubber gone, the entire shift support bracket has no actual support.

broken shift mount attachment


I've replaced the two shift plate mounting blocks, attaching them to the tranny with the hex-head bolts.  I've also pulled the black shift plate mount back down and attached it to the two new mounting pieces.  The shift selector is now firmly mounted to the transmission and doesn't flop around anymore.  Cutting straight down through the picture is a support bar that diagonally attaches to the shift plate and the transmission (seen here).

fixed shift mount attachment


This is the entire shift apparatus, pieced back together.  Up top you can see the foam donut that gets squished between the shift plate and the car's body.  It decreases road noise, prevents air getting into the car from below, and cushions the shift plate as it's pushed tight against the car body.  The whole assembly gets squashed up against the body by adjusting the small bolt on the lower support rod, the bolt next to the reverse light wire on the left (out of focus).

fixed shift mount


With the shift support all done, it's time to reassemble the driveline.  The old rubber guibo didn't look too bad, but they're cheap so I replaced it.  There are eight bolts that attach the guibo to the tranny's output on one side and the driveshaft on the other.  The new guibo has a metal band around it.  It stays on during installation, but once in place, I cut it off.

new guibo


     I've actually been a bad restorer here.  All of those eight bolts running through the guibo are facing the same way.  That is, the nuts are all on the same side.  In fact, half the bolts are supposed to face the front of the car and the other half face the rear.  Look at the first picture on this page for the proper installation.  Some people prefer bolting it up this way because if a nut slackens off, the bolt won't slide back and ravage the transmission.  I just did it this way because it made the rebuild a lot easier, and I haven't heard any convincing arguments against doing it this way.

     From here, I re-mounted the transmission to the car (just like I did recently).  Then I tightened the driveshaft's center bearing, "preloading" it by pushing it forward a few millimeters before bolting it tight.  Lastly, I reconnected the exhaust and promptly got the hell out from under the car, where I've been languishing for too long.