datsun 210 5 speed rear seal won't stay in trans.

[65sprite]

After maybe 50 miles of driving with the 5 speed installed, I noticed a puddle of oil under the trans. I pulled the shift cover and found a small lake in my trans tunnel and the rear seal had spun itself out of the trans and was now on the prop shaft. Naturally I tried the easiest way to repair it by pushing it back in place, no surprise, it didn't work. I assume I can pull the prop shaft and try to re-seat a new seal. Do I just try and drive a new one in? I was thinking about using a dowel with an appropriate diameter an using the old seal in between the dowel and the new seal. I assume it goes in dry with no additional sealing compounds. Any suggestions from anyone with a similar experience appreciated.

 

[Pythias]

I have no idea about the numbers, but make sure you have the right one. There are a couple of them that could be used but only one fits correctly.... ..

 

[nomad]

The big steel flange on the stock seal will interfere with the driveshaft. The flange needs to be removed. Also I cut a access hole under the car and directly below the front U joint. Approx 6x6. Doesn't weaken anything and makes work in that area so much easier.

Kurt.

 

[Billm]

I tried some (blue) urethane seals and they do NOT work for that rear seal. Only the proper (black) rubber seals work. The urethane ones fell out just like you describe.
BillM

 

[65sprite]

The new seal I used was from NAPA. Black, I don't recall that it had a flange on it. I don]t recall that there was a "maybe it is this one, or that. I'm sure I brought the original with me to compare to the new one as is my standard practice when replacing parts. I believe it was fine for the first 49 or so miles, then just walked itself out for no apparent reason.

 

[nomad]

The factory seal's are the one's I've used and sawed the rear flange off. Haven't had a problem.

Kurt.

 

[Guest]

If it were mine I mihgt try aviation permatex (also called 300 IIRC) or 2a or 2b (whichever one doesn't harden)

 

[65sprite]

The factory seal's are the one's I've used and sawed the rear flange off. Haven't had a problem.

Kurt.

I found the original install instructions from Mini Mania. The part # they specify is 11615cr, where they specifically remark that it is the same seal without the flange, "because in the Spridget tunnel it is already protected and un-necessary". I'm sure that is the part I got from NAPA, which does not have a flange. Seems silly to replace it with the flanged one, only to have to cut it off. I did use the recommended synthetic oil initially, then switched to standard 90 weight trans fluid because some folks said the synthetic was too slippery for the old gears and the standard period correct oil would be better. Could the synthetic oil have gotten past the seal and loosened the fit?

 

[Gerard]

Could the synthetic oil have gotten past the seal and loosened the fit?

Absolutely not. I stock and supply factory Nissan seals (w/o flange) with my kits. They fit properly and have never had a complaint, regardless of the oil used. My guess is that whatever you got was not correct tolerance. A lot of aftermarket stuff is like that these days.

 

[nomad]

Was not aware of the flangeless seal's but the original is available cheap from the internet parts sellers.

Kurt.

 

[Billm]

Kurt
The seal that they (Datsun) list for the front (input) is the correct one that we use for the rear seal also.
BillM

 

[nomad]

Thanks Bill. I like having the remains of the flange to bottom against the case so will most likely keep doing things the hard way!

Kurt

 

[BlueMax]

Just curious, have you check your vent pipe or vent hole? Transmission will build up pressure if not vented, enough to push a seal out...

 

[65sprite]

Vent? On the transmission? where?

 

[Gerard]

Vent? On the transmission? where?

Top center.

I have seen these covered with vacuum caps.

 

[nomad]

Good point! It wouldn't be hard to smash the tube shut during installation.

 

[BlueMax]

I remove the vent tube and cut a round piece of open cell foam for the hole to aide in more room for transmission tunnel.

 

[65sprite]

Top center.

I have seen these covered with vacuum caps.

View attachment 26734

Thanks for the pic. Looks like its in the most inaccessible place it could be with the trans installed. It also looks very vulnerable to getting squished during install, so it makes sense that it could be the culprit. If it was squished on the install, is it ok to remove it by cutting it flush, rather than trying to repair while the trans is still mounted?

 

[Gerard]

Thanks for the pic. Looks like its in the most inaccessible place it could be with the trans installed. It also looks very vulnerable to getting squished during install, so it makes sense that it could be the culprit. If it was squished on the install, is it ok to remove it by cutting it flush, rather than trying to repair while the trans is still mounted?

I'm not saying it's not possible, but I have personally never experienced an issue with this getting damaged during install, nor have I heard from anyone else that run into a problem with it. I have them them damaged by careless removal on a couple occasions though. They will snap/pop off, so more likely than it getting squished shut, is for it to just be broken off. The short length and bend make it pretty stiff to bend.

 

[BlueMax]

It’s documented that the castor is preset through the arch of front cross member. The frame rails are manufactured from 18 gauge box tubing. The few cars left today have years of use, as well corrosion from inside of the frame rails. Unless your know what your looking for the engine/transmission angle may have change because the frame rails have started to straighten making the top of transmission closer than normal to the battery box, so damage may be possible. Who ever installed the rear seal would known without question whether the seal fits with the appropriate tension to hold in place. So these are the questions that have to be answered. Pressure inside the case, or the O/D of seal was incorrect and last I/D was too tight forcing the seal to spin in housing working its way out from the motion of the front yoke flange. I believe you will find the correct seal dimensions are 30x45x8