Replacing 727 Low/Reverse Band Pin O-Ring in Car

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billytuffnuts

billytuffnuts

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Hey guys,

Have a 727 with a leaky low/reverse band pin o-ring and have some questions on replacing it in car.

I think I have the process understood from searching the site (Remove trans mount/tailshaft. remove pan, remove valve body, loosen low/reverse band, and push pin out far enough to replace o-ring).

My question is more on how are you supporting the transmission during all of this?

I'd normally put a piece of wood & jack under the transmission pan to remove the tail shaft, but what about when removing the valve body? If I remove the tail shaft first, it wouldn't be be supported by the mount any longer.

Am I missing something or is it OK to have the transmission unsupported for a short time?

Will be doing this in my garage with the car on 4 jack stands.
 
I don,t see any reason not to support it. If you dont, remove your Dist. cap it my hit the firewall on a SB. JMO
 
Bottle jack and 2x4 under the bell area up front. Or, brake clean the piss out of it and squirt a bunch of Right Stuff up in there.
 
I've been lazy and just cleaned the area really well and covered it in RTV. It never leaked again!

I've also just cut the nub off of the tail housing and knocked the pin out far enough to swap the o-rings. Knocked the pin back in and ran it. My current 727 has been "modified" that way. No issues but I completely understand why someone would want to do the job properly. I just hate messing with the snap ring in the tail housing! It always kicks my butt.
 
Short of pulling the trans. Make sure to remove speedometer gear. Have new tailshaft gasket and output seal. Depending on how old seal is on selector shaft to the valve body might want to consider it as well, just thinking pulling valve body might cause it to leak. Could pull valve body, loosen rear band adjuster, put pan back on temporarily, support with floor jack and wood, that’d enable you to pull crossmember and mount so you could slide tailshaft housing off. I’ve used a large course thread screw to pull the pin for the band. Issue is if the piece between the actuating arm and the band falls out you will be making up new words reinstalling it. Make absolutely sure fan is well clear of radiator.
 
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Thanks for the advice. I certainly considered cleaning the area around the pin and sealing with RTV but the previous owner had tried that and it either didn't work or stopped working at some point.

@Dubob - Good idea on reinstalling the pan temporarily after loosening the rear servo band, I didn't think of that.

When you say you've use a large course thread screw to the pull the pin, can you expand on that? I'm not sure I follow.
 
Remove the neutral safety switch with the front jacked up. When it quits draining, jack up the back. Douse it good with carb cleaner then air pressure dry. If you can pull it in and out with a magnet to clean if better then do so. Then push it all the way in and silicone. Personally, I would chop off the tang and pull the pin enough to replace the o-ring and silicone it in.
 
Sorry late to the game. The one I pulled on the last one I got in to I found just a lag bolt that would catch in the recess on the pin. Just made it easier to slide the pin out.
 
Thanks - I ended up pulling the VB and pushing the pin out with my finger. It was pretty loose, it almost shot all of the way out but I stopped it before it went past the lever mechanism. Took this as as a sign it was time to adjust the bands.

It really wasn't that bad of a job. Messy, but relatively simple.
 
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