Shift shaft seal leaking on 700r4?

[PhotonFanatic]

I've determined that my 700R4 transmission is leaking on my 87 R10 truck. Seems to be the shift shaft seal. Is there any special procedure for removing it? I went looking for the usual youtube video, but there doesn't seem to be any showing this particular job. It's clear that the fluid is coming out of that hole, and it even leaves a red droplet hanging on the end of the shaft.

I seem to remember needing to drill a hole in the ones for the TH400 in order to be able to wiggle it outta there. Either that, or use a special tool. Hopefully the 700R4 has a simple removal. I did find this so maybe it's the same as the TH350 and 400:

https://www.amazon.com/dp/B08FTD9RH4/

 

[squaredeal91]

Could possibly drill a small hole in the side of the seal and use a small slide hammer with the right size screw in it and should pop out. I've pulled many seals that way. I made my own slide hammer for doing seals.

 

[squaredeal91]

@NickTransmissions , might be able to shed some light on this.

 

[NickTransmissions]

I've determined that my 700R4 transmission is leaking on my 87 R10 truck. Seems to be the shift shaft seal. Is there any special procedure for removing it? I went looking for the usual youtube video, but there doesn't seem to be any showing this particular job. It's clear that the fluid is coming out of that hole, and it even leaves a red droplet hanging on the end of the shaft.

I seem to remember needing to drill a hole in the ones for the TH400 in order to be able to wiggle it outta there. Either that, or use a special tool. Hopefully the 700R4 has a simple removal. I did find this so maybe it's the same as the TH350 and 400:

https://www.amazon.com/dp/B08FTD9RH4/

There's two methods:

Use the special tool to remove the seal and a 15mm socket to install a new one or

Drop the pan, remove the selector shaft (remove the 15mm retention nut with a wrench, remove the flex spacer with a flat blade screw driver, tap on the rooster comb to get it to unseat from the shaft then remove the shaft) the remove the seal with a small prybar.

Install the new seal with a 15mm socket or bushing driver of the appropriate size.

My 700R4 tear down video shows removal using the 2nd method - skip to 40:00.

 

[PhotonFanatic]

Thank you! Is this still the same size on the newer transmissions as well? Just curious on that one. The removal tool says it works on many different GM transmissions.

 

[NickTransmissions]

Yes, afaik the selector shaft is the same diameter and process is the same when using the removal tool for all applicable transmissions. If dropping the pan, the th400, 4L80E and 6L transmissions use retention pins in addition to everything else (the TH400's resembles a finish nail but it's actually hardened where as a reg nail would break after a while if used in its place).

 

[PhotonFanatic]

Yes, afaik the selector shaft is the same diameter and process is the same when using the removal tool for all applicable transmissions. If dropping the pan, the th400, 4L80E and 6L transmissions use retention pins in addition to everything else (the TH400's resembles a finish nail but it's actually hardened where as a reg nail would break after a while if used in its place).

Would you say it's a bad idea to use a 6L80e in one of these old trucks? Is there any real advantage to having two extra gears? I know it would depend on your setup. I'd be looking to gain MPG out of it, if that's possible. Maybe with 2 extra gears, you could have the best of both worlds. A "fast" truck, that can still turn lower RPM's on at 85 mph.

I live in an area where ya do a lot of highway driving.

 

[NickTransmissions]

Would you say it's a bad idea to use a 6L80e in one of these old trucks? Is there any real advantage to having two extra gears? I know it would depend on your setup. I'd be looking to gain MPG out of it, if that's possible. Maybe with 2 extra gears, you could have the best of both worlds. A "fast" truck, that can still turn lower RPM's on at 85 mph.

I live in an area where ya do a lot of highway driving.

Not worth it IMO. You're paying for the entire harness, pcm etc all of which either must come from the same vehicle or be programmed so the ECM and TEHCM are speaking to each other correctly. You're also playing for integration into your vehicle (x member, drive shaft, u joints, programming and fast adapt relearn costs.

Plus if the trans needs an overhaul, a proper bench build is between $3500-$4500+ vs. $1300-1500 or so for a 700R4. The 6L has two OD gears, the tallest of which is .67 which is only .02 taller than a 700R4/4L60E. All that to save basically no mpg...

 

[PhotonFanatic]

I can't get that shift shaft seal outta there! Those little tools they sell for that job are useless when you have 4 inches to swing the hammer.

 

[squaredeal91]

Not sure if this will help but maybe fill that 4 inches with a block of wood and a bar to pry some pressure?

 

[Ricko1966]

Could possibly drill a small hole in the side of the seal and use a small slide hammer with the right size screw in it and should pop out. I've pulled many seals that way. I made my own slide hammer for doing seals.

Here's a little trick for you on pulling seals. It would do no good on this seal in the car,but it's something to pass along. If you have a seal you can't pull with a puller,don't have a puller,can't pry it with whatever. Look at the seal like a clock face,drive a small punch a small screwdriver,big screw driver depending on seal size,between the seal O D. And the housing I.D. at 12 again at 4 again at 8. Use some common sense don't mangle the housing. Now with the 3 dimples the seal will be to small and pretty much fall out

 

[FireTruck1984]

I can't get that shift shaft seal outta there! Those little tools they sell for that job are useless when you have 4 inches to swing the hammer.

I just recently replaced my seal, the tool works well. Just be persistent. Tap the tool in without the threaded bolt, twist hard with a lot of inward pressure, you’ll feel it bite.. twist again. Insert the bolt and gently crank the wrench. A ratcheting end wrench works best. Good luck !!
and yes… it’s a pain in the @$$ !

At least you only have to replace it once in a Blue Moon… A super Blue Moon !

 

[PhotonFanatic]

I did try the prybar method, but it didn't really help. The pry bar just bent lol

 

[Bextreme04]

Would you say it's a bad idea to use a 6L80e in one of these old trucks? Is there any real advantage to having two extra gears? I know it would depend on your setup. I'd be looking to gain MPG out of it, if that's possible. Maybe with 2 extra gears, you could have the best of both worlds. A "fast" truck, that can still turn lower RPM's on at 85 mph.

I live in an area where ya do a lot of highway driving.

I agree with what Nick said. I have a 6l80 in my 2011 Suburban and when the converter went out at 160k miles, I decided to rebuild it myself. It cost me about $1500 in parts in addition to the cost of the billet converter that you need to get to prevent future failure. They are significantly stronger than a 4l60, but they cost a lot more to rebuild. The biggest issue though is that they are fully electronically controlled. There is no option to run a mechanical control of the transmission and there are very limited and expensive options for transmission controllers that usually require inputs from the engine that are not available on older engines. The only way it would make any kind of sense is if you are LS swapping your square and the engine you are putting in was already paired with a 6L80.

 

[PhotonFanatic]

How about a little jack? Maybe it could be placed between the inner frame of the truck, and the transmission. That way you could just operate the jack and use the pressure to push the removal tool into the seal. Not sure which jack would work though. Maybe one of these?

https://www.amazon.com/dp/B0006J4DH6/

https://www.amazon.com/gp/product/B0BQ2NRCZJ/

Looks like it goes down to 7.75" so that would probably fit between the frame and the transmission. It's also wide enough to contact the seal remove tool and press it in.