3-speed manual leaking fluid

-
Ken71Twister

Ken71Twister

FABO Gold Member
FABO Gold Member
Joined
Mar 26, 2011
Messages
319
Reaction score
103
Location
Valparaiso, FL
I have a slow but steady drip of fluid from my 71 Duster's 3 speed manual transmission. the drip is coming from the rear of the transmission where the drive shaft/spline enters the transmission. I recently replaced my U-joints and I recall there being a good bit of vibration that probably stressed whaterver seal is in the rear of the transmission. My question is this: If I remove the spline - is there a seal that I can get to and replace without tearing into the transmission - or am I looking at a tougher repair?

Second question: What kind of fluid it recommended for this transmission.

tx,
Ken
 

Attachments

  • 101_0659.jpg
    54.7 KB · Views: 205
The seal is no big deal to change, If the bushing behind it is sloppy its a royal pain in the arse to change without the right tool.
That trans takes 90w GL-4 gear oil.
 
Thanks. I have another question about the 90w GL-4 gear oil. About 25 years ago, I had some work done on the transmission and, when I got it back, it felt like there was molasses in the transmission - I could barely get it to shift on cold mornings. I took it back to the shop (AAMCO) and the owner said that it needed automatic transmission fluid rather than the 90W that he'd put in. He changed it and it has worked fine since. I never double checked this info until now - so your answer makes me wonder why he used automatic transmission fluid, why it gave me trouble when he used the 90W, and why my transmission hasn't had issues with the wrong fluid in it all these years.
 
The factory started to fill manual transmissions with DEXRON ATF back in the 70's and sometimes people would complain about the gears rattling so the fix was to dump out the ATF and fill with 90w. Either type of fluid will provide sufficiant lubrication. I like 90w in my manual transmissions, especially if they've got some miles on them. I live near buffalo and we get some cold temps (-15*f) here sometimes and having 90w in a trans has never given me a problem, yes the first couple of shifts when its that cold feel like stirring a cold pot of molasses but after a few minutes of driving it shifts normal. Also 90w is less likely to leak out of the seals.
Dont put any fancy synthetic fliud in your trans, some of that stuff is too slippery for the syncronizers to work properly.
 
Block the tires, put it in neutral, crawl under the car and push the yoke up and down to see how much play is in the bushing. It shouldn't move much. If it does, replace the bushing when you have the driveshaft out. Check the yoke for wear also. You don't want to reuse one with any grooves worn into it. I use 85-140w with a GL-5 minimum rating in everything I have that needs that type of gear oil. The GL-5 rating will work in a sure grip rear end also. I wouldn't use ATF or engine oil.....they won't handle the loads.
 
Thanks for responses. I went to auto parts store today and now better understand what the seal looks like. Could someone pls advise me on how to remove the seal? It appears that I'll need something approx the same diameter to drive in the new seal - but how do I pull out the old seal without damaging anything else?

Also, will there be a part number on the seal that will help me order the right replacement? (Parts store today told me that there were 3 rear seal options in the book for a 3-speed Duster in 1971.)

tx,
Ken
 
To remove the seal, install a screw in the metal part of the seal and use a slide hammer to remove it.
Or you could use a small hook attachment in the slide hammer.
They usually pop out easily doing it this way and don't wreck anything other than the old seal.
 
The new seal is in place and there are no drips. The slide hammer worked great for pulling the seal.
Tx,
Ken
 
You must log in or register to reply here.
-

Back
Top