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Early B 727 downshift seal

W

wedgie

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My cable operated 727 has developed a major transmission leak. Traced it to the throttle pressure (downshift) seal. Actually came out easily. The new NAPA seal installed albost too easily IMO. Just by hand while laying under the car. I did install the seal in the right direction with the smooth side toward the arm. I used a 7/16" thinwall deep socket to try pushing deeper into the case. Just by hand, no hammer. Small, thin 5/16" flat washer same OD as the seal, then I put the old seal on the shaft thinking that it would provide pressure to the new seal. A thin 5/16" nylon washer, then the arm as tightly pushing everything into the case as I couls by hand. While putting the downward pressure on the arm, I tightened it. I did not use the thick original washer as there was no room now.
Still leaks from the kickdown. Here's my question; because of the ease of the installation of the seal, is there an oversize seal available? Just didn't feel tight enough to me.
Thanks.
 
wedgie said:
My cable operated 727 has developed a major transmission leak. Traced it to the throttle pressure (downshift) seal. Actually came out easily. The new NAPA seal installed albost too easily IMO. Just by hand while laying under the car. I did install the seal in the right direction with the smooth side toward the arm. I used a 7/16" thinwall deep socket to try pushing deeper into the case. Just by hand, no hammer. Small, thin 5/16" flat washer same OD as the seal, then I put the old seal on the shaft thinking that it would provide pressure to the new seal. A thin 5/16" nylon washer, then the arm as tightly pushing everything into the case as I couls by hand. While putting the downward pressure on the arm, I tightened it. I did not use the thick original washer as there was no room now.
Still leaks from the kickdown. Here's my question; because of the ease of the installation of the seal, is there an oversize seal available? Just didn't feel tight enough to me.
Thanks.
Click to expand...
Did you use any sealer on the OD?
 
No, I didn't. I was reluctant about using any because of the fact that it was still leaking and that I also feared contamination of the ATF. I could, I guess, drain my fresh fluid, clean out the seal area with brake clean then install a new seal with black adhesive silicone permatex. probably would stop any leak but if anything got into the fluid ??????
 
Mr. Blais contacted mr with the probable issue(s). He's going to make me a TF expert no matter the cost (to me) haha
Thanks,
John
 
I installed a new seal this morning, following the directions by Mr. Blais. So far, so good.
 
wedgie said:
I installed a new seal this morning, following the directions by Mr. Blais. So far, so good.
Click to expand...
Hello,

I just got a pushbutton 727 that hadn't been ran in 60 plus years up and going. went back to the garage two days later and a stream of ATF flowing from beneath. It appears to be the seal you've referenced. Is yours still doing well after applying the sealant to the outside?

Thanks
 
wedgie said:
My cable operated 727 has developed a major transmission leak. Traced it to the throttle pressure (downshift) seal. Actually came out easily. The new NAPA seal installed albost too easily IMO. Just by hand while laying under the car. I did install the seal in the right direction with the smooth side toward the arm. I used a 7/16" thinwall deep socket to try pushing deeper into the case. Just by hand, no hammer. Small, thin 5/16" flat washer same OD as the seal, then I put the old seal on the shaft thinking that it would provide pressure to the new seal. A thin 5/16" nylon washer, then the arm as tightly pushing everything into the case as I couls by hand. While putting the downward pressure on the arm, I tightened it. I did not use the thick original washer as there was no room now.
Still leaks from the kickdown. Here's my question; because of the ease of the installation of the seal, is there an oversize seal available? Just didn't feel tight enough to me.
Thanks.
Click to expand...
Stating the obvious - are you certain the 0-ring is the correct dia and thickness?
 
Plumber452 said:
Hello,

I just got a pushbutton 727 that hadn't been ran in 60 plus years up and going. went back to the garage two days later and a stream of ATF flowing from beneath. It appears to be the seal you've referenced. Is yours still doing well after applying the sealant to the outside?

Thanks
Click to expand...
Did your work involve adjusting the cable? There is an o-ring in the adjuster. If it is the original cable, the cable sheathing can deteriorate causing it to split and leak. Had this on mine before getting a new cable. I repaired it using epoxy that lasted a couple years until having to adjust it breaking the repair. Minimal slack for adjusting creating a crummy chore. Maybe not your hassle, but something I had encountered with leaking.
 
Plumber452 said:
Hello,

I just got a pushbutton 727 that hadn't been ran in 60 plus years up and going. went back to the garage two days later and a stream of ATF flowing from beneath. It appears to be the seal you've referenced. Is yours still doing well after applying the sealant to the outside?

Thanks
Click to expand...

EARLY B said:
Care to share the instructions?
Click to expand...

Read....
Post in thread 'Taking Up New Residence' Taking Up New Residence
 
Ron H said:
Did your work involve adjusting the cable? There is an o-ring in the adjuster. If it is the original cable, the cable sheathing can deteriorate causing it to split and leak. Had this on mine before getting a new cable. I repaired it using epoxy that lasted a couple years until having to adjust it breaking the repair. Minimal slack for adjusting creating a crummy chore. Maybe not your hassle, but something I had encountered with leaking.
Click to expand...
When I got the car the cable sheaths were in bad shape. I read about the adhesive heat shrink tubing and removed/ cleaned the steel cables and installed the heat shrink. That worked great!!!! I ordered a set of replacement 0-rings and replaced the shifter and parking cable 0-rings. The "New" shifter O-ring is leaking but I can clearly see where the bulk of the leak is coming from the Kickdown. I'm steal looking for another shifter O-ring before I drop the pan and install a steel/rubber pan gasket so that I can adjust the shift cable with the pan off.
 
Thanks. Just removed the old seal. Wasn't to bad of a job. The old seal is cracked and the hole for the shaft seems to have gotten way to big!!!!
 
Here's the "Beast" I'm working on

Left Side.jpg


Right Side.jpg
 
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