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Ahmad Bashir

NOS Getrag 242 Not Shifting

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(Apologies for the long post, I wanted to be thorough) 

Hi guys, 

So I have a peculiar problem with a brand new (NOS) Getrag 242. I have reassembled it and somehow it seems to be stuck in fourth gear. When the selector is set to neutral, the output shaft moves in a 1:1 ratio. When I engage any other gear, the transmission locks up. (Details ahead!)

I'm convinced the fourth gear is only partially engaged when the selector is set to neutral, but I'm not sure. 

Background: 
This is a brand new gearbox that was bought and stored as a spare part from the BMW factory some 40 years ago, however, when it eventually was shipped and reached me, the tranny was stuck in reverse gear. Turned reverse when the selector was neutral, would jam up in any other gear. Should've perhaps removed the end cap of the reverse selector but ended up removing the bell housing to see inside in case something was broken/bent. Once opened, everything was pristine and mint. The reverse gear selector had moved back, engaging the gear — no problem, moved it back in place and it was all good. The transmission shifted fine and operated well, outside the bell housing. 

First Reassembly: I didn't remove the input shaft bearing. Transmission was neutral and was introduced *with the input shaft bearing in place*. Eventually, once the the rear was all bolted down, the input shaft didn't fully get seated (for whatever reason) and therefore I couldn't install the circlip at the input shaft. This led to opening the rear again. 

Second Reassembly: This time, I removed the input shaft bearing and also put box in 4th gear using the selector (to ensure that the front end is even more snug). Result is as seen in the video. The gearbox rotates smoothly when fourth is engaged. All other gears lock the transmission up. When neutral, the gearbox moves in a 1:1 ratio, however there's a clunk and isn't smooth anymore. 

Now it is beyond me as to what is up and why it is behaving in this manner. Any ideas, guys?

 

Video: https://streamable.com/0303oo

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You should get your shift lever assembly connected to transmission and then go through each gear. you jammed trans trying to shift by screwdriver.

Remove screw, spring, bush and pin and then go through each gear. If successful then put trans in neutral and reassemble pin, bush, spring and screw and try again.

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It sounds like the interlock 'pills' between the shafts aren't there-

 

they're oblong 'ball bearings' that keep other shift rods from moving when one is selected.

 

Also, likewise, the detents.

 

Stuck in reverse is a very old problem- Preyupy posted the way you're supposed to drop it to 

get it disengage.

 

t

 

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If you had it apart and reassembled it without the tool for installing the input shaft bearing you probably have jammed the 4th gear synchronizer onto the cone on the gear.  Can you actually select all 5 gears (1-4 +R) even if it "locks up" the transmission?  The shifter goes into all 3 gates?  If so then you don't have a shift rail that has moved out of sequence with the shifter.  

 

You might try putting it in 3rd gear and turn the output flange (it might take a fair amount of force,  NO IMPACT GUNS!!! just a breaker bar and some arm strength)  if the synchro is stuck on the cone this should knock it free.  If not you will need to take it apart again.  The factory tool for installing the front bearing pushes the bearing in place while pulling OUT on the input shaft so you don't jam the synchro onto the cone, it also makes it easy to install the clip on the input shaft)  

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4 hours ago, Preyupy said:

If you had it apart and reassembled it without the tool for installing the input shaft bearing you probably have jammed the 4th gear synchronizer onto the cone on the gear.  Can you actually select all 5 gears (1-4 +R) even if it "locks up" the transmission?  The shifter goes into all 3 gates?  If so then you don't have a shift rail that has moved out of sequence with the shifter.  

 

You might try putting it in 3rd gear and turn the output flange (it might take a fair amount of force,  NO IMPACT GUNS!!! just a breaker bar and some arm strength)  if the synchro is stuck on the cone this should knock it free.  If not you will need to take it apart again.  The factory tool for installing the front bearing pushes the bearing in place while pulling OUT on the input shaft so you don't jam the synchro onto the cone, it also makes it easy to install the clip on the input shaft)  

Brilliant! It worked like a charm. The sychro knocked free with very moderate force. It's running fine now, but the sychro (only 4th) is still showing the tendency to lock up when shifted out. Breaks away with relative ease, but it isn't as...smooth as the rest of them. I have a feeling it's because of the years of storage (perhaps even dry storage. I'm not sure). For now, I've flooded the inside with kerosene, hoping it'll clean up any gunk and residue that might have been in the harder to get areas (I did give it a basic clean up but didn't thoroughly clean it, given it was new and I didn't want to needlessly fiddle with it). I am assuming it'll also have a penetrating effect between the synchros and cones, and hopefully will clean things out for the oil fill. Anything else I should do/you guys would suggest? 

 

Thanks so much!! I had been stressing over this for a while, and was at an absolute loss of ideas!!

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If you have it filled with kerosene hook onto the pilot on the input shaft with a large electric drill and run it in all the gears ( inc Rev) just pouring kerosene in won’t get It to all of the cage bearings between the gears and the main shaft.  When you drain the kerosene fill it with oil and do the same thing then drain it again to get as much of the kerosene out as you can.  

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1 hour ago, Preyupy said:

If you have it filled with kerosene hook onto the pilot on the input shaft with a large electric drill and run it in all the gears ( inc Rev) just pouring kerosene in won’t get It to all of the cage bearings between the gears and the main shaft.  When you drain the kerosene fill it with oil and do the same thing then drain it again to get as much of the kerosene out as you can.  

I was thinking about it, but wasn't sure if it was a good idea for the bearings. Do you think it's safe to do so? I don't want to damage the bearings due to a lack of proper lubricant inside. 

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You wont do any damage with kerosene just spinning it with a drill.  With no load its just spinning.  But I would flush it with oil and then refill it after you are done .

 

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1 hour ago, Preyupy said:

You wont do any damage with kerosene just spinning it with a drill.  With no load its just spinning.  But I would flush it with oil and then refill it after you are done .

 

Perfect! Thanks a bunch. I'll get to it over the weekend :)

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