Author Topic: 700r4 TCC/lockup question  (Read 1767 times)

Offline Combat Veteran

  • Newbie
  • Posts: 35
  • Square
700r4 TCC/lockup question
« on: January 04, 2018, 08:10:57 PM »
My first issue since joining, hopefully there are some experienced people here to help.
I recently bought an 87 Custom Deluxe, 135K miles. All original 350, 700r4 and NP208, 3.42 gears. Since getting it, I have had to replace the rear main seal and intake manifold gasket, purchased it leaking. In the process I found the TCC/lockup wiring disconnected. Looking at the loose connector, looks like it has been disconnected a long time. I have been told when larger tires (33's) are installed, some guys disconnect the lockup. I did have it on the highway for about two hours and I could not keep the tranny from going from 3rd to 4th gear. As soon as I got to an uphill, it down shifted. When I got off the gas it upshifted, the whole way. Would reconnecting it prevent this from happening? What about driving around town? No issues with up and down shifting in town. Better gas mileage either way? It shifts smooth otherwise. Thanks, Ron   
1987  slightly modified Custom Deluxe V10, 350TBI, 700R4,  NP208, 4X4,  4.42 gears,  33" Firestone Destination M/T

Offline VileZambonie

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 18979
Re: 700r4 TCC/lockup question
« Reply #1 on: January 05, 2018, 04:33:48 AM »
Some people don't like the lag experienced with the converter having to unlock in highway situations while trying to accelerate. Typically with larger tires and a 3.42:1 ratio you will be in and out of lockup trying to keep up with the pace of today's maniacs on the highway. I would suggest cleaning the connections and plugging it in to see how it performs for you. For the best performance, a better gear ratio would allow it to function optimally. There are other "workarounds" to compensate, one is to adjust the tv cable a little tighter which will delay the upshift. See how it performs with it connected before anything else
,                           ___ 
                         /  _ _ _\_
              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline Combat Veteran

  • Newbie
  • Posts: 35
  • Square
Re: 700r4 TCC/lockup question
« Reply #2 on: January 05, 2018, 09:42:30 AM »
Thank you Sir, I just found the connector on Ebay for less than $10. The original is disintegrated, so I needed a new connector. Once it comes in, hopefully all the wires connected to it are where they need to be and I can try it. I will also check the TV cable for adjustment, if I don't like the way it performs with the TCC/Lockup connected. Thank you again.
1987  slightly modified Custom Deluxe V10, 350TBI, 700R4,  NP208, 4X4,  4.42 gears,  33" Firestone Destination M/T

Offline Combat Veteran

  • Newbie
  • Posts: 35
  • Square
Re: 700r4 TCC/lockup question
« Reply #3 on: January 09, 2018, 08:07:30 PM »
Just installed a new TCC/Lockup fitting for less than $10 from Ebay. The truck runs great, I can't believe they drove it without it. Shifts smooth and no problems with acceleration. Still get to watch the gas gauge go down.   
1987  slightly modified Custom Deluxe V10, 350TBI, 700R4,  NP208, 4X4,  4.42 gears,  33" Firestone Destination M/T