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Advice on Transmission Cleaning & Rebuild

6

67TXStang

Member
My 3 speed transmission has been leaking from the shift seals since I purchased it. The entire transmission and undercarriage are covered in gear oil. I removed the transmission on Sunday. Since there is nothing wrong with the way it operates, my plan was to clean it up, replace the bearings and seals, and then reinstall it.

I've been cleaning the transmission with degreaser and it is taking forever. I took off the top cover once the case was fairly clean and then took off the tail housing to clean. I then noticed there is a film of dark grease film on the inside of the case and on all the components. Seems a waste to clean the entire oustide and not the inside.

Any suggestions on cleaning the outside easier? I've never rebuilt a transmission before. Would this be something I should take on? If so, should I have someone hot tank the transmission to clean it up?
 
You'll not want to hot-tank an assembled transmission... it'll have to be disassembled for that to happen.

Personally, if it's operating okay, I'd leave the internals alone and focus on hitting the outside with a de-greaser. A good de-greasing and a wire brush will get off 90% of the crud.
 
Another Craig? WTF?
Anyhow, +1 on Sanborn's comments. If it's working OK, just scrub the outside.
 
"cmayna" said:
Another Craig? WTF?
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and he has a 67 coupe!

"cmayna" said:
Anyhow, +1 on Sanborn's comments. If it's working OK, just scrub the outside.
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if you clean it up, can you just put new seals in it? I had an AOD on my T-Bird leaking from the front seal and shifter seal. I yanked it out replaced the seals and no more leaks!

I saw a cool Harley shirt the other day you might need, it said "My bike is not leaking, it's marking it's territory"

Good Luck, (one of the other Craig's)
 
I've been reading a little about replacing the shift seals. They are o-rings which must be installed by pulling out the shift lever from the inside and sliding it over the end. From what I understand, I need to pull the input shaft to create enough room for the job. I then need to pull the shift shafts to get to the shift levers. (Someone please correct me if I am wrong).

Once I learned I would need to take these steps, that is when I started thinking of pulling everything out to clean it up and install new bearings and possibly syncros. As I said before, I've not done this before so I'm not sure my persistence allow would get me through the job.
 
I rebuilt (modified) a T5 I had in my 85 GT after destroying the syncro's. I also "built" a C4 for drag racing in my 1st 67 which was a major challenge but not as bad as I thought it would be. In both cases I didn't know what I was getting into but it turned out okay. If you have any mechanical aptitude and some patience you can do anything!
 
From what I understand, I need to pull the input shaft to create enough room for the job. I then need to pull the shift shafts to get to the shift levers. (Someone please correct me if I am wrong).
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Hmmm...... something in my memory banks is telling me that on a C4 you can change the shift shaft seal by dropping the valve body. I want to say it could be done with the trans. still in the car, which would contradict your above statement. Not 100% on this though.....
 
while that IS true Dave, his is not an auto trans 3 speed, it's a manual. he has a top cover, lever"S" and syncros, not often found in C4's. I may have confused you with my comments, sorry. :scar

C6, but pretty much the same as a C4
picture174pv2.jpg
 
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Craig let me know if you want to go C4.
I'm pulling all my auto stuff and going stick.
It's getting a fresh rebuild and has a few goodies in it.
I see you're in College Station and I'm in Katy.
Joe
 
I'm partial to manual transmissions. I'll be keeping this one.

Are the suggestions to keep it together because it is a difficult job or the 'if it ain't broke don't try to fix it' philosophy?
 
"67TXStang" said:
I'm partial to manual transmissions. I'll be keeping this one.

Are the suggestions to keep it together because it is a difficult job or the 'if it ain't broke don't try to fix it' philosophy?
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I'd say if it's leaking and it bothers you, it's broke. I also say take a stab at it. Worst thing is you have to haul the parts over to a shop to get help putting it back together if you can't. just my 2 cents
 
To remove the shift lever, I had to remove the input shaft and most of the gears from the output shaft. Since I had it so disassembled already, I decided to rebuild the transmission. The complete rebuild kit (bearings, seals, blocker rings, etc) was $120.

The job was not hard. It is suprising how much is just held together with snap rings. The only part I needed hellp with was the installation of a new input bearing. I could not get the old one off. A local machine shop helped me for only $10.

I've put the transmission back together and put it back in the car last night. I'll need to reinstall a few other parts but should be back on the road tomorrow. Thanks for the help and advice.
 

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Awesome job, That really looks great too:
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But dont forget to tighten everything down. Looks like your bell housing is loose.
 
I just bolted the bellhousing to the transmission for the picture. I had to install the bellhousing first due to space constraints.

I've put it back in and have the car back on the ground and ready to go. Unfortunately, it is raining and I really don't want to go in the rain. I'll wait as it is suppose to clear up tomorrow.
 
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