a343f slipping after transgo install

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Sep 28, 2014
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745
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Atlanta
I recently installed a Transgo shift kit in my turbo truck prior to sending it to the tuner. I hadn't driven the truck after installing it as I needed to get a tune done to operate it safely. Now the tuner is having trouble with it slipping between 3rd and 4th. While I was in there, I turned the line pressure adjustment to high to further increase shift firmness. Transmission fluid level is correct at temperature.
Anyone with transmission knowledge have any suggestions? Transmission worked perfectly before install.

Thanks

Truck build thread here
 
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You have left out one of the balls or a spring, I would pull the valve body again and make sure everything moves correctly, or re-install the old parts and see if it is doing the same thing. I had wanted to try this in my Cummins swap but never got around to it
 
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745
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I have an extra transmission. I may pull the valve body out of it and take it to the tuner to swap in just to get the thing finished and back home. Really should've waited to install the kit until after everything was running with the turbo install. The thing is I checked and rechecked and checked again when installing it. Is it possible that the hydraulics just haven't filled back up or something? He says it feels like low line pressure.
 
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745
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I followed this thread and the directions exactly. I feel fairly confident that I didn't leave anything out, but possibly installed incorrectly?
 
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745
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Was the transmission rebuilt with the transgo or did you put it in and bump the line pressures on an older unit? If the unit was older it's possible seals that were marginal with normal pressure are now leaking with the increase and causing issues.
It was not rebuilt. Which seals are we talking about?
 
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I recently installed a Transgo shift kit in my turbo truck prior to sending it to the tuner. I hadn't driven the truck after installing it as I needed to get a tune done to operate it safely. Now the tuner is having trouble with it slipping between 3rd and 4th. While I was in there, I turned the line pressure adjustment to high to further increase shift firmness. Transmission fluid level is correct at temperature.
Anyone with transmission knowledge have any suggestions? Transmission worked perfectly before install.

Thanks

Truck build thread here
Which drill bit size did you use? I thought I remembered seeing that in one of your threads you left out the diverter tube, did it get put back in and seal up well?
 
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I assume u keep the stock end plugs, if everything was running correctly before u did the Trango set like u stated, my guess is turning up the line pressure is causing bleed by passed the end plugs, this bleed by can become an issue in an OEM unit as it gets higher in mileage. Whenever I put a Transgo in a A340 I also do the end plug upgrade 9774119K A340E/F/H, LATE END PLUG KIT, O-RINGED - https://www.transmissionpartsusa.com/9774119K_A340E_F_H_LATE_END_PLUG_KIT_O_RINGED_p/400-09774119k.htm
 
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745
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Which drill bit size did you use? I thought I remembered seeing that in one of your threads you left out the diverter tube, did it get put back in and seal up well?
Yep, dropped the pan and the filter and reinstalled the tube, no drama there. I drilled to The truck setting, removed the two balls as indicated in the instructions and the thread above, and replaced the springs as directed. It sucks that I can’t drive it and report myself, I have to relay the info my tuner is giving me. (He’s an hour and a half away)
 
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Yep, dropped the pan and the filter and reinstalled the tube, no drama there. I drilled to The truck setting, removed the two balls as indicated in the instructions and the thread above, and replaced the springs as directed. It sucks that I can’t drive it and report myself, I have to relay the info my tuner is giving me. (He’s an hour and a half away)
So this might not be what you want to hear, but with the extra power your turbo setup is capable of making you might needed to have gone to a larger hole size than the truck drilling. Did the tuner tell you at what power level it is slipping? I did my transmission to the "hot rod" size and just a touch bigger. If it is 10+psi I would bet your trans is slipping....
 
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Question: as you drill the hole larger and larger are there any negative effects ie: harsher shifts with normal acceleration?? IDK
 
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Question: as you drill the hole larger and larger are there any negative effects ie: harsher shifts with normal acceleration?? IDK
Yes like everything it is a tradeoff. If you firm your clamping force up you will have more firm shifts. The more power you make the more clamping force you need so under power you don't notice the harder shifts, but if you are in low range I always use 2nd gear start because that 1-2 shift can be pretty harsh. lol.
 
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I wouldn't go to hot rod size, truck size is more then enough... the shifts will be to strong that type of energy being felt through the rest of the trans can lead to other issues. i'd call transgo before u think about doing said to talk it over with them and they will tell u this. Supra turbo A340 don't require anything larger then the OEM sizing u already drilled out to truck.
 
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I wouldn't go to hot rod size, truck size is more then enough... the shifts will be to strong that type of energy being felt through the rest of the trans can lead to other issues. i'd call transgo before u think about doing said to talk it over with them and they will tell u this. Supra turbo A340 don't require anything larger then the OEM sizing u already drilled out to truck.
Did hot rod, back in 2013-2014 it has been just fine.
 
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U already stated u don't start out in 1 gear, and other variables like how much one drives, type of driving, and temps of where u live in a cold area the shifts will be very harsh until trans reaches operating temps.
 
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U already stated u don't start out in 1 gear, and other variables like how much one drives, type of driving, and temps of where u live in a cold area the shifts will be very harsh until trans reaches operating temps.
I have lived in Colorado, Utah and Washington, it gets plenty cold. I don't think you understand what you are talking about.

You make mention of the MKIV supra not needing to drill. I am sure you already know that the GTE automatic transmission has electronically controlled line pressure the 80 series does not. You can adjust the line pressure in the tune on a MKIV supra on an 80 you can not.

I am sure you have an example of your turbo'd 80 series making it work right?
 
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745
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So this might not be what you want to hear, but with the extra power your turbo setup is capable of making you might needed to have gone to a larger hole size than the truck drilling. Did the tuner tell you at what power level it is slipping? I did my transmission to the "hot rod" size and just a touch bigger. If it is 10+psi I would bet your trans is slipping....
Well, he has not had an issue with it slipping on the dyno but he's been keeping it in 2nd while tuning. He took it out on the road to get some driveability data and that's when he said it slips going from 3 to 4. He says it feels like not enough line pressure to hold the frictions. I dont think he was getting on it, but I'll ask.

I did email Transgo who responded really quickly (really nice to get good customer service). He said it sounds like the "B0 (aka OD brake)" is not holding correctly and that I should hook up a pressure gauge. I just bought a spare a343f just the other day that I was planning to build up for power so I might just pull that valve body and drive it up to the tuners and swap it in just to get the thing finished and home.
 
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745
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I assume u keep the stock end plugs, if everything was running correctly before u did the Trango set like u stated, my guess is turning up the line pressure is causing bleed by passed the end plugs, this bleed by can become an issue in an OEM unit as it gets higher in mileage. Whenever I put a Transgo in a A340 I also do the end plug upgrade 9774119K A340E/F/H, LATE END PLUG KIT, O-RINGED - https://www.transmissionpartsusa.com/9774119K_A340E_F_H_LATE_END_PLUG_KIT_O_RINGED_p/400-09774119k.htm
Ok thank you! I did bump up the pressure setting on this thing which I think boosts line pressure? Maybe that was a bad idea. The trans only ahs 160k miles on it but I'll pick up some end plugs.
1653484913045.png
 
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Ok thank you! I did bump up the pressure setting on this thing which I think boosts line pressure? Maybe that was a bad idea. The trans only ahs 160k miles on it but I'll pick up some end plugs.
View attachment 3017793
Not a bad place to look but seems unlikely to me….

Maybe take a look at the lockdown cable and make sure it’s adjusted properly, might be some stretch.
 

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