Getrag 242 teardown question

[DaHose]

Hey everyone,

 

I am experimenting with a 4-speed tranny that has a bad second gear.  I want to open it up, and can't find good reference material. 

 

From what I have gathered, it looks like you start by removing the big nut holding on the output flange, and pull the output flange.

Next, you remove all the number bolts around the outer edge (back of tranny), and use a special tool to push the input shaft out of the input bearing.

At that point, the whole gearshaft assembly/middle-cartridge will pop out of the transmission.

 

Is that basic summary the correct process for separating the two pieces of the tranny?

 

Thanks.

 

Jose

[Buckeye]

attached file shows step by step disassembly, how to measure components and reassembly. It will require precision measuring tools for re-assembly. I rebuilt mine two years ago and somewhat difficult part was removing bell housing. Beyond that it was fun. Most frequent precision tool used was depth gauge range 1-8" 

Transmission.pdf

[DaHose]

Heya Buckeye,

 

That document is EXACTLY what I needed.  The only really unusual tool you need is the Rillex puller, but pushing through the shaft as I described is an accepted, alternate method.

 

Thanks a bunch!

 

Jose

Edited December 31, 2017 by DaHose

[D.martijn]

I recently pulled my transmission apart, it depends oif you have a bearing with a regular case or plastic case holding the balls apart.

Mine had a plastic case so you have to push the input shaft through.

 

By using some square tubing and a bearing puller I was able to put some force on the shaft. 

[DaHose]

Right on, DMartinj!  That is exactly what I thought of doing.  I will get that taken apart, no problem.  Did you apply heat to the countershaft bushing area, or just push it out cold?  I figure that if you are using pressure to force the shaft out, there is probably no need to heat that area.

 

Thanks!

 

Jose

Edited December 31, 2017 by DaHose

[Zorac]

i took one apart with good intentions, the moment it gave, parts went everywhere!  found a good used one for $100.

 

watch out for the spines on the output (wouldn't want to rebuild one if that was already an issue).  my old tranny had the course spines and they were showing wear.  someone had loaded it up with red locktite to prevent further degradation (and it appeared to be working) but that really sucked for taking it apart.  found a replacement with the fine splines.

[kbmb02]

A tool can be made to push the input shaft through the bearing (and, likewise, another tool to pull the output flange).  -KB

 

 

[andyleonard]

A "Plan B" repair for the loose coarse spline output flanges (which let the shaft move forward and booger up the synchros) was to buy a new output flange and seal, use a whole can of brake cleaner on the parts and loctite the new flange  on. Bernard at BMW of Marin taught me that in 1974 and I'll bet I saved 50 gearboxes over the years. 

 

Tough to get apart.

Edited December 31, 2017 by andyleonard

[TobyB]

Quote

i took one apart with evil intentions, the moment it gave, parts went everywhere! 

 

yes, and aligning everything to get the shift linkage to go back into the front case is... really... really... frustrating.

 

I suspect we'll have to get better at it as time goes by, and the supply goes from 'limited' to 'nonexistant'.

 

Good point about the rear coarse splines- if the output shaft is damaged, you might not want to invest a lot in the rest of the box.

 

t

 

[D.martijn]

6 hours ago, DaHose said:

Right on, DMartinj!  That is exactly what I thought of doing.  I will get that taken apart, no problem.  Did you apply heat to the countershaft bushing area, or just push it out cold?  I figure that if you are using pressure to force the shaft out, there is probably no need to heat that area.

 

Thanks!

 

Jose

 

I did heat up the lower bearing which is covered by a big plastic plug. Can't hurt to heat it up.

 

[Zorac]

1 hour ago, andyleonard said:

A "Plan B" repair for the loose coarse spline output flanges (which let the shaft move forward and booger up the synchros) was to buy a new output flange and seal, use a whole can of brake cleaner on the parts and loctite the new flange  on. Bernard at BMW of Marin taught me that in 1974 and I'll bet I saved 50 gearboxes over the years. 

 

Tough to get apart.

 

sounds like what happened to mine.  probably when they were doing a rear seal on it.  red locktite everywhere.

 

 

56 minutes ago, TobyB said:

 

yes, and aligning everything to get the shift linkage to go back into the front case is... really... really... frustrating.

 

I suspect we'll have to get better at it as time goes by, and the supply goes from 'limited' to 'nonexistant'.

 

Good point about the rear coarse splines- if the output shaft is damaged, you might not want to invest a lot in the rest of the box.

 

t

 

 

i remember all these little bits going everywhere when it finally popped open, primarily the little ball bearings at the end of the shafts for the shift forks.  recycled the case on the old one, but kept most of the internal bits.  figured if the one in the car now ever needs a rebuild, the parts might be useful and without the case they don't take up much space in the garage.

[Zorac]

for reference, here is what fine splines look like.  might save someone some guessing and reading later on.  took me a bit to figure out what i had and what i needed when i was doing this having never worked on one of these before. this all started as just fixing a few seals on the tranny while the engine was out....  then, its a bit slow into second, why not rebuild it...  scope creep....  worked out though as I now have a low mileage, well shifting, 4 speed with no leaks!  it did take 3 seals to get the back to finally seal up.   another oops moment.  these transmissions have two different rear seals which depends on if the shaft is fine or course splined.  and of course i bough the parts for the old tranny and use them, the second seal, i didn't think about it and bough the same one and did it again, and the third seal i finally clued in.

[mvliotta]

Reviving this thread, as I have a specific question and can not find the answer.

 

I would like to eventually replace my 4 speed that has a crunchy 2nd gear with the spare that I have in the garage. The PO reports that the spare is in great mechanical shape. Only issue is that it leaks somewhere along the gasket where the housings meet. 

 

So would like to open up the case just enough to clean it up and put in some new gasket material (RTV)... maybe a 1 cm or 2.  

 

Do do you still need to push the input shaft through the bearing to open up the case a bit to clean up the gasket?