700R4 that only mildly backs up at 1200 rpm

[Gilmore]

Ok I have a 1984 chevy K10 w/350 HO and a TCI Maximizer 700r4. The issue I have is that this is a new transmission and it goes forward like a freight train but backing up is a problem. When I shift into drive with my foot off the brake the truck moves. When I shift the truck in reverse however nothing until I hit 1200 RPMs and even then it’s anemic at best. Any help or good questions are appreciated!

Link to Trans: https://www.jegs.com/i/TCI/890/3714...=Transactional&utm_content=Order+Confirmation

 

[Tank6x2]

Sounds like a plugged flow port, drop filter and check valve ports - may be assembled with debris.

 

[Matt69olds]

If it’s a new transmission, I wouldn’t do anything until you talk to TCI. Make absolutely sure you have followed their installation instructions to the letter before calling them.

I’d be curious to know what they say.

 

[Gilmore]

TCI just tells me I have too much fluid, the trans only take 6qts. I emptied the trans and put back in exactly 6 qts and the same behavior.

 

[Matt69olds]

Find a gauge that reads to 300 psi, put it in the line pressure tap about the manual linkage. See what the pressure is in reverse.

It isn’t normal to need to rev the engine to back up.

Have you driven it yet? If so, get it up to 30mph, put the shifter in 1st, see if it has engine braking. If not, the low/reverse clutch pack is suspect. If it does, the reverse input clutch is the problem.

 

[Gilmore]

Apparently I need to flush the trans and torque converter because you can’t use full synthetic fluid in a TH350, 400 or 700R4 it needs to be petroleum based Dex3.

 

[82sbshortbed]

Yes I use valvoline max life in red bottle at Walmart for cheaper price.

 

[Gilmore]

Yeah I did too but that is full synthetic and apparently is too thin once the trans is warm to allow the reverse clutch to engage.

 

[Bextreme04]

Yes I use valvoline max life in red bottle at Walmart for cheaper price.

Thats a full synthetic Dex VI equivalent. It meets the Dex III spec also, but is slightly thinner than the standard blue bottle Valvoline ATF

 

[Matt69olds]

There is a bleed hole in the reverse input clutch piston, from the factory the hole is a little too big. TransGo include a tiny freeze plug with a very small orifice that make the bleed hole smaller. You can buy the freeze plugs from TransStar and other venders.

Put a pressure gauge on it. TCI lists line pressure specs for each model transmission. Assuming the pump is good, the transmission was built correctly, and the cable is installed and adjusted properly, synthetic fluid isn’t your problem. If TCI is telling you otherwise, it sounds to me like they are backpedaling.

 

[Matt69olds]

700R4 Reverse Piston modification, Teckpak 77761C - Third Generation F-Body Message Boards

Transmissions and Drivetrain - 700R4 Reverse Piston modification, Teckpak 77761C - the ATSG 700R4 book recommends installing an orifice cup plug into the Reverse Input Piston. p. 85, figure 151. Teckpak 77761C. so i ordered a couple of these (about $8), since i'm already paying for shipping. the...

www.thirdgen.org

 

[Gilmore]

There is a bleed hole in the reverse input clutch piston, from the factory the hole is a little too big. TransGo include a tiny freeze plug with a very small orifice that make the bleed hole smaller. You can buy the freeze plugs from TransStar and other venders.

Put a pressure gauge on it. TCI lists line pressure specs for each model transmission. Assuming the pump is good, the transmission was built correctly, and the cable is installed and adjusted properly, synthetic fluid isn’t your problem. If TCI is telling you otherwise, it sounds to me like they are backpedaling.

Well it’s going to cost me $200 to get the transmission and torque converter flushed so I hope your wrong and this works.

 

[Gilmore]

Well it’s going to cost me $200 to get the transmission and torque converter flushed so I hope your wrong and this works.

Well you weren’t wrong, the flush didn’t work now I’m talking to the warranty manager.

 

[DoubleDingo]

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[DoubleDingo]

Well it’s going to cost me $200 to get the transmission and torque converter flushed so I hope your wrong and this works.

Well you weren’t wrong, the flush didn’t work now I’m talking to the warranty manager.

Are you arguing with yourself?...lol...