Help with re-sealing 5spd transmission control shaft

[takayuki]

I have a bad transmission control shaft o-ring. Hoping that this is something i can do without having to remove the transmission.

I had an extra transmission lying around so I thought i should play around with it before I fix the actual transmission that is in the car.

So far, I removed shifter, and a pin with a clip that is on the external part of the transmission, and a plug with a spring and a plunger. I also removed the cap that is staked in at the end of the transmission control shaft. I can pull the control shaft far enough to expose the o-ring,but i am unable to pull the shaft out completely. I highly doubt that i can work the new o-ring into place. There are some obstacles to deal with.   My question is, can this o-ring be replaced without having to disassemble the transmission?

 

https://drive.google.com/file/d/0B6QMNI1hrz_iWVJzVjBWZEpuNXc/view?usp=sharing

Edited June 24, 2016 by takayuki

[Zed Head]

I can't remember if it was Dave WM or KDMatt or someone else that had a thread on it (there was a flurry of transmission work a while back), but somebody just went through this seal replacement.  You don't have to disassemble the gears, but you do need to remove the rear housing (case) so that you can remove the striking lever.  It's hard to get fingers and tools in there but it is doable.  Check the FSM MT chapter.  Here's a picture from 1978, you didn't say if you had an early (77-79) or late 5 speed.  But I think that they're all essentially the same.  You can see the o-ring, #3.

[EuroDat]

Hi takayuki, You will need to remove the transmission.

You won't be able to replace the O-ring until you remove the "striking guide" and to do that, the "striking rod" needs to come out. That is the bad news, because the striking rod won't come out without removing the rear extension to get to the striking lever.

It could be possible to do it in the car by lowering the back of the transmission and removing the rear extension. I have not done it, never had a reason to just remove the rear extension. My jobs generally turn into "while Im at it, may as well do ....."

If you do go forward and remove the striking guide, replace the lip seal for the striking rod. Its probably not much beter. The part number is 32858-U6702 in the attachment.

Tranny_Rebuild_FEB2012.pdf

[EuroDat]

You could order a couple extra o-rings and try to stretch the O-ring over the selector end of the striking guide. Depends on how long the "ears" on the selector are. Put the o-ring in a cup of hot water first and use a Ty-rape or piece of insulated electriacl wire thought the o-ring to help pull it over. Don't use screwdrivers or such to pry it over, they only damage the o-ring. The chances it will work without breaking the O-ring are not great, but they don't cost much, and if it succeeded, if would save a lot of time.

The NBR compound won't give you that much stretch before breaking. EPDM would stretch more, but it is only suitable for brake fluid.

[Dave WM]

yep just went thru this a bit ago. Pull trans, remove rear extension, remove part 1 and 2 per diagram, tap strike rod until it knocks part 7 off (its just a press on fit) then you can replace both the o ring and the seal (3 and 5). You will have already removed 8 and 11 in order to get the rear ext off. None of this was hard.

start here at about 3:10

 

Edited June 25, 2016 by Dave WM

[Dave WM]

here is some more starting at the begining

[takayuki]

thanks for the replies! I'm going to try the hot water method first.... if not.. i'm gonna let this leak until I rebuild the tranny with a different gearset....

[EuroDat]

If you try it, warm the striking guide with a hair dryer. Not to hot to touch, just warm. I would try to get it over the top selector pivot section first and then pull it over the back of the striking rod. It's a big ask, but they might stretch enough and they only cost a couple of dollars. It could stop the oil leak without pulling the tranny out.

Try it on the spare tranny first to practice what works best. You could also try a softer compound. The softer compounds, like shore 60, generally stretch a little further. The nissan o-rings are shore 70. The o-ring size is 24 x 2.5mm (ID x CS) in NBR or FPM (viton). You could try fluorosilicone (fvmq) They stretch more than the nbr or viton compounds, but are not so easy to find, mostly special order. Fvmq can be found in shore 50 are stretches well. The softer compounds will loose their sealing quality over time at a faster rate, but it should last 4 to 5 years.

Don't use silicone, it will react with oil and leak in no time. Its not the same as fluorosilicone.