Indeed, the input bearing of the salvage unit looks very good - no oil leaks.

But the input shaft itself has built-up some corrosion (while storage) which I´ve grinded off:



Hope the input shaft seal does still seal sufficiently...

Also the input bearing of the other transmission (from my Fiero) doesn´t leak

[This message has been edited by Moar (edited 01-02-2016).]

Removing seals and bearings of ´86 salvage unit

Removing axle shaft seals (using special tool “1.6L Miata front caliper piston”):




I have forgotten to take pictures of the diff bearing race removal.
I have used a suitable drill chuck and a heavy lead hammer for this.

I´ve found some corrosion on input shaft bearing and fork lever of the ´86 unit, therefore I´ll use the bell housing of the ´88 transmission.
Input bearing and fork lever of my ´88 trans don´t show any corrosion (therefore I´ll replace the output shaft bearing race in the ´88 bell housing later)!


CobraTrans rebuild kit has arrived ($56 only):


And axle stabilizer bearings/seals (bushing type):

I have ordered the left one with the OEM seal in it.
What I have gotten are two different ones! :

Then I have checked the rear input and output shaft bearings:

Fortunately in good condition without any play.

Then I have found a strange modification to the oil supply for the output shaft bearing:

Obviously this should improve the oil flow into the output shaft bore.

[This message has been edited by Moar (edited 03-03-2016).]

Splitting the case of my ´88 Getrag trans:

Metal particles found under the shift shaft cover:


Bellhousing:


Trans case:


More metal particles found on magnet:


Worn diff bearing (bellhousing side):



The worn diff bearing caused an axial misalignment of the differential assembly.
Due to this misalignment the tooth ends of the differential gear grinded on the pinion gear.
I guess this was the reason why my car´s wheels rotated even in neutral with running engine!


The root cause of all this sh*t was the stupid leaking flip up dip stick and leaking axle shaft seals.

Oil leaks in conjunction with a stupid previous owner have destroyed the differential bearings.
Basically oil leaks are not dangerous as long as you refill the oil (so you have always fresh oil)

[This message has been edited by Moar (edited 03-03-2016).]

Comparison of transmission internals:

As both transmission were split I took the opportunity to compare the ´86 with the ´88 Getrag transmissions. Following pictures show some minor design changes "improvements" for the ´88 Getrag. You will see why I´ve written "improvements" under double quotes...

Oil splash shied missing in ´88 model:


Slightly different reverse idler gear shaft bushing (stiffer and easier designed bushing for ´88 model):



Simplified gear design and missing oilways in ´88 model:




I think the main aim for these design changes was to save some manufacturing costs for future MG-282 transmissions.
In my point of view also the flip up tip stick was no improvement (prone to leak)!

[This message has been edited by Moar (edited 03-03-2016).]

Replacing important bearings in the ´86 salvage unit and ´88 bell housing*:

*) As already mentioned above I´ll use the ´88 bell housing due to corrosion on the ´86 unit.
Hope that this was not a bad idea...

Removing worn bearing race (output shaft) of the ´88 bell housing:



This might not be the professional way to remove the output shaft race, but this method woks for every DIY-sefer!

Required “special tools“:
- small drill
- screw driver


Due to the mixed bellhousings it is absolutely necessary to select new shims for proper differential bearing preload.
(However, preload should also be checked if you only replace bearings)
This step is the most important one, because diff bearing preload is directly related to bearing lifetime!
Too less preload will kill your bearings whereas too much will overheat them and may cause bearing seizure.


Acc. to the Getrag manual shims are not selected with the toque-set method (torque-set method usually used for bevel gear axles/differentials on RWD cars with engine in front).

For the Getrag the “Set-Right” method is applied.
For this you will need shim selector kit Kent-Moore J26935.


This special tool will help you to find out the shim size for ZERO axial clearance.
Acc. to the manual you should select a shim which is two sizes larger than the ZERO lash shim.
(= 0.10 mm oversize)

Determining zero lash shim:

First press in the new differential bearing race (on trans case side only!) and put the differential
with new bearing cones in place. On the other side of the differential put the diff bearing race above
the cone and then bolt the transmission together with the shim selector between trans case
and bellhousing.


The differential spacer (black pipe) is preloaded with an internal spring which will adjust automatically to fit your transmission.

Now you can check which shim fits in the resulting gap:

Finally, you can choose an appropriate shim form your shim kit (2 sizes larger).

In my case I have chosen a shim which is 3 sizes (0.15 mm) larger than the ZERO lash shim.
The reason for this is that I may have more run-in as usual due to the mixing of bearing cones and races.
(TIMKEN cones with 15000 km mixed with new KOYO races)

Pressing in new bearing races:

Do NOT forget the differential bearing shim before pressing in differentail races!!!
After this make sure that the shim sits tight (play indicates that you have to press in the race further).

I know mixing cones and races is not recommended and I wouldn´t have done it if I would live in USA.
My final intention was to rebuild both transmission but I have only gotten differential bearings
(new KOYO races and cones) for one transmission rebuild.
Due to the low mileage of the LSD differential with quite new TIMKEN cones on it (about 15.000 km) I decided
to let them in place (these stupid cones cannot be removed without damaging them).
However, I wanted to get at least new diff bearing races and therefore I have installed new KOYO races.
The quite new TIMKEN differential race I swapped from the ´86 trans case into the ´88 trans case
whereas I will use the ´86 bellhousing incl. the other TIMKEN race for assembling the ´88 unit.
I will also install new KOYO cones on the ´88 stock differential assembly. (maybe I will sell the ´88 unit or keep it as spare trans).

This was the only possibility to get 2 working transmissions from one rebuild kit.


Previously drilled holes for output/main shaft bearing race removal closed with JB weld:

[This message has been edited by Moar (edited 03-22-2016).]

[This message has been edited by hobbywrench (edited 01-19-2016).]

------------------
Rodney Dickman

Fiero Parts And Acc's Web Page:
All new web page!:www.rodneydickman.com
Rodney Dickman's Fiero accessories
7604 Treeview Drive
Caledonia, WI 53108
Phone/Fax (262) 835-9575

------------------
Rodney Dickman

Fiero Parts And Acc's Web Page:
All new web page!:www.rodneydickman.com
Rodney Dickman's Fiero accessories
7604 Treeview Drive
Caledonia, WI 53108
Phone/Fax (262) 835-9575