Transmission overhaul

[montmil]

... That's how I broke by bearing puller - the snap-ring certainly does it's job well!

Quoting my old school mechanic grandfather, "If it won't go, force it."  

Monte

[Justin B.]

I have pulled all of the old pressed on bearings...








I made a little two-piece seal installer for the clutch throwout rod seal and installed it into the rear end of the input shaft...






... and installed the new bearings by heating them up with the heat-gun and driving them into place with hammer and proper size socket.  It's important that driving force be applied to the bearing inner race only to prevent bearing damage...


  


I finally installed the shafts into the transmission case, bolted on shim-plate, and measured my bearing height...




I then subtracted the measurement from the shim-plate thickness to get the bearing height.  I then measured the depth of the corresponding hole in the "real" cover and subtracted the bearing height to get the no clearance shim-stack value.  I then subtracted .002" to get my working shim-stack thickness.  I rearranged all of the existing shims and would up only needing to order one .2 mm shim.

I have ordered the shim and next week I should be able to bolt this thing up!!!!  Right now the only thing I can say is that everything sure rotates a lot smoother than it did before!  

[Justin B.]

Rob, the oil can you spotted on the milling table is like this one:

http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=2568853&PMT4NO=57923195

[Rob Valdez 79 R65]

Rob, the oil can you spotted on the milling table is like this one:

http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=2568853&PMT4NO=57923195

Thanks Justin.  It's good to know they are still out there.  I suppose they are a common item in machine shops, though...


And thanks for the nice write up on the transmission!  One for the Library?

[Justin B.]

We'll see if it works when I get done with it!  

[Rob Valdez 79 R65]

We'll see if it works when I get done with it!  

BIG [size=20]LOL![/size]

Thanks Justin!  

[Justin B.]

Well, I got my shims and springs from Moto-Bins today so I put my shim-stacks on top of the bearings, replaced the pawl spring, heated the rear cover and torqued everything back together.  I am able to shift up and down through all gears and roration is smooth with no binding so I guess it's ready to put back in.

The shims I used should give me .0015 - .002 endfloat on the shafts as long as I did all my measurin' and cipherin' correctly!

[Rob Valdez 79 R65]

Are you interested in moving this to the FAQ/Procedures?

[Justin B.]

Here's where some more of the bits go...  The pawl spring in the shift mechanism is reported to be prone to breaking and it's commonly recommended to replace it.  Snowbum indicates his theory is that the boss diameter that the spring slips over is responsible for causing the spring to bind and break and if it is properly relieved there should be no spring issue.  Since I had it apart I figured I'd replace the spring anyway even though there was sufficient clearance between the boss and the spring internal diameter.  The spring is only a couple of bux so I didn't see a reason to cheap out.

The first thing you have to do is get to the spring.  Start by removing the circlip on the R/H segment





Then remove the R/H segment for access to the L/H segment.  Once it is out of the way remove the circlip retaining the L/H segment and lift it out.  You will need to manipulate the shift pawl to get it to slide out but it's not hard.



Here is the actual shift pawl and where the spring is located.  I should have took more pix but I got lazy.  Flipping the shift mechanism over will reveal a clip on the end pf the shaft connected to the the pawl.  Remove the clip and pull the pawl out with shaft and spring.



When you get the spring off you'll see the 'boss" it fits over on the pawl shaft.  Snowbum's article indicates that if the spring fits onto this boss with little to no clearance then it could cause the spring to break due to it binding during operation.  The solution would be to chuck it up in a lathe and turn the boss down to reduce it.

[Justin B.]

Here's a shot out of the ETK that clearly shows the "boss" I referred to earlier...

[Justin B.]

Every body has read the old line from every manual, "Assembly is the reverse of disassembly", yeah, right...  They make it sound so easy.

You first need to replace whatever oil baffles were in the bearing wells in the front of the case back where they came from and heat the front of the transmission case around where the bearings seat.  Then while holding all three shaft assemblies together, along with the shifter forks, you slide the whole mess in!  Once I was sure everything was where it belonged I started tapping the shafts downward with a brass hammer.  One tap on the end of each shaft and repeat until they feel bottomed out.  You don't want to whack 'em very hard or the bearings might be damaged.  After you get all of the shafts and stuff back into the case then reinstall the shift mechanism taking care to reengage the shift forks back into the cam slots in the shifter assembly.  Once you get everything in place use some grease as glue and stick all of your shims on the tops of the bearings and set the rear cover gasket in place:



Then heat up the rear cover around the bearing bores and tap it home as well.  Now torque the rear cover bolts (in a logical torque pattern) and then make sure you can rotate the input shaft and shift through the gears.  If things are too tight then maybe re-warm the cover and front of the case and apply careful rubber mallet action to the rear cover to ensure all of the bearings have seated fully in their bores.  If things are still too tight to rotate then you made a boo-boo somewhere, most likely measured something wrong or miscalculated some shim stack or another.

[Justin B.]

I finally got around to firing up the Junkyard LS after putting the transmission back in.  With it running on the center-strand I was able to shift up and down through all of the gears and I didn't hear anything that wasn't somewhat normal for a boxer transmission spinning around with no load on the output...

As soon as I get re-motivated I'l try to stuff some foam into the seat and take it for a couple of laps around the back yard...

If it works out OK and doesn't blow up in the first couple hundred miles then I feel this was $100 well spent and I won't be afraid to tear into the next one!

[Landlubber]

Justin,

When you machined the holes on the rear cover plate, how did you find the centres for the job please, did you use a coaxial indicator?

[Justin B.]

I have outlined how to make the "shimming plate" in the Wiki but, yes, I did use a coaxial indicator to center the bore under the spindle.  You could also use a regular test indicator with just as good results but I use a coaxial whenever I can due to convenience and I'm basically lazy.