Getrag 242 four speed reassembly issues

[janneman]

Hello,

 

I'm the owner of a BMW E30 316 with a faulty getrag 242/19 (four speed) gearbox. The input shaft bearing started making (a lot of) noise, so I tore the gearbox down and replaced the bearing. This was my first (car) gearbox repair so it didnt all go as planned of course.

 

Yesterday I reassembled the gearbox again with a fresh gasket, new input shaft bearing and seals on the input shaft side. I did not disassemble anything beyond pulling the gearbox apart as I only wanted to replace the input shaft bearing.

 

The first issue I encountered was that when i closed the gearbox I heard something drop on the floor. I found later that it is one of the four roll pins on the selector shaft, #2 on this diagram: RealOEM.com - Online BMW Parts Catalog

 

 

The second issue is that now neutral is equal to fourth gear, and the gearbox locks up on all other gears. This is probably because the input shaft is jammed into the output shaft, binding them together. I reassembled the gearbox by first inserting the new bearing into the gearbox housing and then installing the housing by slowly tightening the bolts. I don't know in which gear the gearbox was during reassembly, maybe I should have put it in 3rd or 4th. The shim on the inner ring, outer side of the input shaft bearing does also not fit because of the same reason.

 

Now my questions are:

1: How important is the one missing roll pin? I know I should replace it and I probably will, but I would like to know the function of it if only one of four is missing.

2: Is there a way without special bmw tools to pull the input shaft out of the gearbox a bit so it will spin freely?

3: If I have to open the gearbox again, how do I go about reassembling it without jamming the two shafts? Putting it in a certain gear or use some tool for it?

 

Many thanks!

[TobyB]

 

 

the input shaft setup's similar in all these transmissions- this thread has lots of details on how to deal

wit that.

 

1.- very.  Each roll pin attaches a shift fork to the shifter shaft.

2. you'll have to make something, but, yes.

3. hoo boy- that's the trick.  The E21 manual is in the documents section, and it gives details.

Personally, I want 3d printer filament that's gear oil solvent so that I can print a couple of brackets to hold

things in place while it's being assembled...

 

Good luck!

t

 

[Yoda]

I don’t know how to help with any of your other questions, but with neutral being 4th gear, I had a very similar issue. If you take out the reverse switch, you can push the center of the hole in and it should pop down. After I pushed in the center, the transmission was now in neutral and could spin correctly in all gears. I think what happens is that the transmission gets stuck in reverse, and won’t spin correctly. 
I hope this ends up being the issue for you, but maybe not. I’d recommend giving it a shot!

 

[janneman]

13 hours ago, TobyB said:

 

 

the input shaft setup's similar in all these transmissions- this thread has lots of details on how to deal

wit that.

 

1.- very.  Each roll pin attaches a shift fork to the shifter shaft.

2. you'll have to make something, but, yes.

3. hoo boy- that's the trick.  The E21 manual is in the documents section, and it gives details.

Personally, I want 3d printer filament that's gear oil solvent so that I can print a couple of brackets to hold

things in place while it's being assembled...

 

Good luck!

t

 

 

Thanks, this is very helpful. I only searched on getrag 242 and could not find anything on how do reassemble it, and that there would be an issue with pulling the input shaft out of the box. I could not even find a picture of the BMW tool, now i finally know how it works. If I knew in advance I would have copied the bmw tool. Currently my machine shop is in the middle of moving so i can't really make anything.

 

I don't mean the actual roll pins (those that are real roll pins of rolled sheet metal), but the four small disks that seem to serve as some kind of bearing on the selector shaft. It seems to me that they function as a bearing inside the bushing that indexes the selector shaft on rotation. RealOEM calls them roll pins for some reason so I used that name.

 

As for the printed brackets, PVA might be an option but I don't know if I would want to fill my gearbox with water. Probably can't do much damage if it's for a short period, especially if all parts inside are still covered in oil. HIPS and limonene might be an alternative but as limonene is a solvent I don't know how seals and gaskets will react. I like the idea 

[dlacey]

3 hours ago, janneman said:

printed brackets, PVA might be an option but I don't know if I would want to fill my gearbox with water.

Candle wax - should be oil soluble

[TobyB]

Hmm- I wonder if I could get candle wax to print!  

But that's a good point- waxes ought to work as temporary holders...

I wonder what's in museum wax...

 

I'm having a hard time picturing what the discs might be.

There are several interlock pills (look like elongated ball bearings)

between the shift rods...

 

t

[janneman]

4 minutes ago, TobyB said:

Hmm- I wonder if I could get candle wax to print!  

But that's a good point- waxes ought to work as temporary holders...

I wonder what's in museum wax...

 

I'm having a hard time picturing what the discs might be.

There are several interlock pills (look like elongated ball bearings)

between the shift rods...

 

t

 

Their location is shown in the link I posted above on realOEM. Their OEM number is 23317539086, you'll get pictures when you google that.

 

So there aren't any tricks to get te gearbox together like it should without making or buying special tools?

[janneman]

Short update: I am currently copying the BMW tool to pull the inout shaft out of the gearbox. It is my own interpretation of it using materials I had on hand but it should have the same functionality. Cut the threads yesterday with an M40x1.5 cutting plate I found in my workshop, now I have some serious muscle ache. I'll do it on the lathe next time. It should be done by next weekend I think

 

As for the small part I found after assembly, it seems it really just acts as a small bearing in a set of four. They seem to be fixed on the selector shaft by four pins integral to the shaft itself. Why this one dropped free I don't know yet. I might just get the gearbox in working order as it is right now and try to drive it. The getrag 242 gasket is hard to get here

 

Another question, I read somewhere here that you should absolutely not use hypoid oil in the gearbox. Why is that? I currently use Eurol Transyn, which has API GL4 specification and is suitable for both gearboxes as final drives. It does not specificate that it is a hypoid oil, but as it can be used in final drives I assume that it is

[janneman]

Got the gearbox in working order and it is now sitting in the car.

 

In hindsight I think during assembly maybe the 3th/4th gear shaft got engaged while the selector shaft still was in neutral. I have taken it apart and assembled it again twice and both times it was already shifting as it should even before I used the tool. But I did put it in 3th or 4th gear the last two times so maybe that helped.

 

As for the missing roll pin as BMW calls it, I've taken some pictures of its location when i opened the gearbox again. On the bottom of the selector shaft in this picture you can see it missing. I have no idea how it ever got out of there, it is completely locked in place. To put it back I had to loosen the allen screw on top, pull out the 3th/4th gear shaft and wiggle the selector shaft along some obstacles so i could get it out enough. I never loosened this allen screw before and even then it is practically impossible for the selector shaft to move out enough to let the roller fall out. Maybe a factory defect?

 

The tool worked perfectly. I think it can't really be done without it. I turned a flange that will fit into the input bearing bore and that can be locked in place with the three bolts. Cut M40x1.5 threads on a pipe of about 50mm. Pressed it into the flange and welded it. Made M40x1.5 threads in a rectangular piece of steel that I milled so that it would partially fit in a square tube. Then made two holes in the right location for two pins that will pull on the shaft. I added some pictures of it here. If someone wants to reassemble their gearbox and has access to some machinery I can highly recommend it.

 

I just have to shorten the tube to the right length, weld a cover on it and weld the rectangular piece with threads in place to make it also usuable to disassemble the gearbox

 

Edited March 11, 2023 by janneman

[TobyB]

Yeah!

 

Thanks for the pictures.

 

It used to be easier to find good used boxes than to fix these-

I suppose the supply's drying up, and we'll be inside more

of them now...

 

t