P1870...anyone done the fix

[BladeMaker]

97 yukon with a 4L60E suddenly got the p1870. I'm aware of the service bulletin and am Thinking of trying the fix from sonnax. Has anyone here actually done this repair on their truck? How did the reaming go for you? Pita? what concerns me is the shavings from the reaming and the alignment I'm thinking I need to make some sort of jig but I haven't actually dropped the pan yet and don't intend to until I'm ready to fix and I'm fairly remote so would like to make sure I have all what I will need before I begin. Any experience or photos greatly appreciated. I searched here and found a couple pics but no detailed accounts of the job.

 

[willxfs]

Haven't tried the fix. Wished I would have attempted it 5 years ago when I had the transmission rebuilt because of this code and a terrible 1-2 shift when hot. At that time the original transmission had about 220k miles on it. Back to your problem, I think I've seen a video on the reaming process using the tool supplied by Sonnax. I'll see if I can dig it up and post a link if I find it. If I remember correctly, using the Sonnax reaming tool made the job look pretty straight forward. Good luck.

 

[BladeMaker]

Haven't tried the fix. Wished I would have attempted it 5 years ago when I had the transmission rebuilt because of this code and a terrible 1-2 shift when hot. At that time the original transmission had about 220k miles on it. Back to your problem, I think I've seen a video on the reaming process using the tool supplied by Sonnax. I'll see if I can dig it up and post a link if I find it. If I remember correctly, using the Sonnax reaming tool made the job look pretty straight forward. Good luck.

This tranny is original too. 280 on it never a problem until now. And she did some serious towing in her day. Not much towing anymore. I have the hard 1-2 hot shift. It happend about 4 days apart both times began after hitting a nasty hole in the road. I've heard this has to happen on two consecutive ignition cycles to throw the code but I only noticed it once when I checked and had code. It's possible it happens at the end of a highway trip and I didn't notice it the first time. I have to check If theres a plug or set of wires that could be loose or damaged. It just strikes me as an awfully strange coincidence that it only starts happening after hitting a bad hole in the road. Ran truck for 4 hours. Was fine until 3.5 hours in when I hit the bump. Then it started with the hard shifts. If I end up doing the fix, and I suspect I will, I'll try to post a small write up for the next guy.

 

[99Vortec]

I did an outright valve body replacement on mine. It was pretty dirty work. (Lots of tranny fluid continually leaking with every fastener removed.) 1-5/16" socket worked well to disengage the main wiring harness assembly.

It was about $300 or so if I remember for the upgraded valve body.

Forgot to add. M6-1.0 x 45mm Hex head cap screws make perfect guide pins. (Just Dremel off the heads.)



In retrospect, I think a 4l80E is much superior to the '60.

I believe there is even a wiring harness adapter for the conversion.

 

[BladeMaker]

Think I'm gonna pull it and totally rebuild it while I've got it out. I've got a really good rebuild procedures manual after much much searching online ( can probably find the link in my history if anyone else needs it ). Anyone done a total rebuild and have advice on which rebuild kits are good/bad?

 

[rabbiporkchop]

Think I'm gonna pull it and totally rebuild it while I've got it out. I've got a really good rebuild procedures manual after much much searching online ( can probably find the link in my history if anyone else needs it ). Anyone done a total rebuild and have advice on which rebuild kits are good/bad?

You can buy your parts here.
https://www.wittrans.com