Transmission Installation

 

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IV. Reinstalling the Transmission

I. - Go To Removing the Transmission    II. - Go To Changing Clutch     III. - Go To Changing U-Joint

Gary L. Baker,J.D., M.T., Patent Attorney

traninbell.jpg (59704 bytes)Reassembly is the reverse sequence of disassembly (yuck, yuck - I always wanted to say that.  Too bad it is not true).  The photo at left shows how the parts should look in the bell housing before installation.  The rubber boot is missing on the clutch fork and can be installed later.  A wire clip on the throwout bearing sleeve tends to hold the throwout bearing at the end of the fork.   Behind the fork are spring loaded wires that snap to hold the fork at a pivot point on a knob behind the blister shown on the clutch fork in the photo. 

Before installation of the transmission, grease the transmission main shaft spline, clip the throwout bearing sleeve onto the end of the clutch fork, and slide the sleeve onto the main shaft while inserting the other end of the clutch fork through the hole in the bell housing.  Snap the fork at the back of the blister onto the onto the pivot knob. 

You need to raise the transmission up into the transmission tunnel and align it with the clutch.  I have actually lifted the transmissions into place and mounted them onto the engine by hand several times.  But you can get tired real quick if it does not work the first time.  Alternately, you can use two guys, or slowly raise the transmission by inserting more and more wood blocks under it.   Luckily for me, I borrowed my Dad's transmission jack so many times, he eventually gave it to me.  I believe you can rent a transmission jack for not too much. 

tranup.jpg (485477 bytes)tranoutback.jpg (87741 bytes)I have it set up so I can use compressed air and a pneumatic ratchet to raise and lower the transmission jack without having to crank it by hand.  Raise the transmission until the main shaft is level with the spline hole through the center of the clutch disk.  (In some cases you may have to disconnect the exhaust pipe to make room for the bell housing to pass.)  The transmission has to move forward so the main shaft passes through the clutch disk spline hole, then it fits precisely into the pilot bearing of the fly wheel. 

I have to admit, there have been several occasions where mating the bell housing to the engine block took me hours; usually I do it in a few minutes.  One problem can be having too much grease in the pilot hole.  More often, the problem is not having the clutch plate precisely aligned with the pilot bushing.  If the transmission does not mate up after quite a few tries, it is useless to continue.  You must drop the tranny back out, loosen the pressure plates and recenter the clutch disk with your centering tool, then retorque (11 to 16 ft/lb) the pressure plate bolts.  

tranlongbolt.jpg (411089 bytes)One trick I use to help align the transmission, and help push the transmission onto the engine block, is to run some really long bolts through the bell housing holes to the corresponding threaded holes in the engine block (see the photo, right).  I put at least one of these long bolts in on each side of the bell housing.  They keep the transmission from twisting, orient the alignment stud/holes between the parts and can be used to supplement force to mate the parts.  The perfect long bolt is a 240Z head bolt; it is long and the threads match the engine block threads.  However, the 240Z head bolts only have a couple inches of threads.  I eventually run out of threads while moving the bell housing closer to the block.  Then, I remove the long bolt and add spacers (over sized nuts, etc., I have lying around) to get the long bolt back at the start of its working threaded range to move the bell housing in another inch or so.   Do NOT use this method to force the transmission into the engine if it wouldn't have gone anyway - just use this method to keep things aligned and help move the transmission smoothly forward. 

Because there is no rear engine mount, and the back of the engine has been resting on a block of wood over a jack, you have the option to tilt the engine up or down as an aid to aligning and mounting the transmission. 

trancross.jpg (380559 bytes)When the transmission is within about an inch of the engine, be sure the sheet metal gasket/dust cover is setting properly on the alignment studs provided on the engine block.  Once you have all the main bolts installed, use a jack to raise the back of the transmission into position for installation of the cross member mount at the transmission rear extension.  Push the cross member mount up into place and loosely install the center washers and large nut on to the threaded stud coming from the rear transmission extension.  Line up a cross member side hole with a mounting nut on the underbody using a screw driver so that the first large side bolt can get started threading.  Do the same on the other end of the cross member.  Once all the nuts and bolts are at least started threading in place, then you can tighten them all down.   

Put a little grease on the transmission output shaft and insert the drive shaft front yoke onto the shaft and through the oil seal.  (Note: if the inserted front yoke surface is rough, this may indicate you need a new front yoke and/or rear transmission bushing.)

Mate the rear drive shaft yoke at the differential and loosely insert the bolts, washers and nuts.  Tighten the bolts moderately.  As with removing the bolts, you will have to put the transmission in neutral with the parking brake off so you can rotate the drive line to a new position giving access for wrenches to each nut and bolt pair; then set the parking brake while the bolts are tightened.  Now, do a second round of tightening to 50 ft/lb (good luck!).  I find it very difficult to get these bolts, with poor access to the associated nuts, to reach this high torque.  Of course, I can't even get a torque wrench in there.  So, I do my best.  After everything is together, listen for a rumbling behind you while you drive - it will give you a warning if the bolts get loose.  After about a week of driving, go under again and revisit the tightening of these bolts. 

With the vehicle level, remove the side access oil filler plug and pump in about 90W gear oil until it starts to drip back out of the fill hole.  Return the filler plug. 

Put the slave cylinder back in place so that it   pushes on the clutch fork.  I usually bleed (open and close the bleeder valve as your best friend alternately pushes and releases the clutch pedal) the slave cylinder so it works well and has fresh fluid (usually, what ever you have been using in your brake system). 

Reinstall the back up light wires and speedometer cable.

Lower the car and reinstall the shifter.  Put the bushings in the shifter lever, insert the shift lever into the shifter control arm and slide the pivot pin through the control arm and shifter bushings.  Lock the pin in place with the C-clip.   Replace the inner rubber boot and use the flange to seal the larger rubber boot to the tunnel.  I find the stock spring clips difficult to install around the edge of the final leather boot, so I use those office clips used to bundle thick paper documents.   All these last steps are easier with the center console unscrewed from the tunnel.  While you are at it, check that the screws holding the handle on the ash tray door are tight.  Put down the center console and replace the mounting screws.   Replace the grip handle on the shift lever. 

Test drive to ensure there are no undue vibrations and that the clutch is adjusted to your liking.  The clutch is adjusted by changing the length of the rod going to the master cylinder from the clutch pedal and/or (in some models) changing the length of the rod between the slave cylinder and the clutch fork.    

I. - Go To Removing Transmission    II. - Go To Changing Clutch     III. - Go To Changing U-Joint


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