Lurbie

iTrader: (3)

I had a friend (GM tech with trans experience) help me rebuild my 700r4 and I've had to remove it 2x afterward. I blame my own bad luck with transmissions. Automatic transmissions are my Achille's heal when it comes to auto repair. I bought and installed Dana's ProBuilt Street/Strip kit, but my friend accidentally installed the input sprag backwards, so I had no Overdrive. I didn't drive the car that way, it was on jack stands at idle when we confirmed that's what happened. So I dropped the trans out, we flipped the sprag around and put it back together. I drove it Saturday and it was great except that fluid was leaking out of the front seal during wide open throttle (WOT). I looked online and went back to watch the DVD Dana includes with his kit and discovered we didn't drill the bleed hole larger in the pump. So trans comes out again, I pull the pump, drill the hole to 5/16" (the DVD said 9/32", but I could only buy a long drill bit in 5/16" size). Replaced the pump seals/gaskets and put it in the car again. Drive the car tonight and it's shifting from 1-3 immediately, as if the TV cable isn't even connected. In overdive it would not downshift at WOT either. Manual shifts were firm and solid. I have a pressure gauge installed on the dash. The pressure gauge is a VDO brand and it's only marked every 50 PSI, but I'd say it's approximately 85-90 PSI at idle in P, N, OD, D, and raises to almost 200 PSI in 2 and 1 at idle. Pressures at ~1500 RPM are ~100 PSI and raise to ~240 PSI in 2 and 1. The TV cable is connected, however, in the garage and at idle, I had my son pull the TV cable out in each gear and I had NO line pressure increase when we pull the cable out. So this is clearly why it's immediately upshifting, but how and why is it possible that the TV cable is connected, springs back when pulled out and released (indicating it's connected at the transmission), but gives no line pressure increase when it is pulled? My son says it seems harder to pull out than before, but I don't remember. The only other things I did while the pump was removed for drilling was to install a Normally Open 4th gear apply switch for TCC lockup (which is currently disabled) in place of the original 4th gear pressure switch.

Even though it takes less than an hour, I am SO TIRED of dropping this transmission out of the car. Does anyone with knowledge of the hydraulic circuits /hydraulic flow have any tips on what could keep line pressure from increasing when the TV cable is pulled? Remember with exception to the leak, the car drove and shifted excellent on Saturday.

someone972

iTrader: (2)

Happen to make sure the TV valve moves freely while it's out? When I installed the one from Dana's kit, I accidentally put the roll pin in with the valve in the wrong spot, causing it to not move in it's proper track. Luckily I still had the valve body out when I noticed. Could potentially be why it feels harder to pull out too. Just something to check if you have the valve body off for some reason. I never ran it with the valve stuck in the wrong spot so I don't know what effect it would have.

Lurbie

iTrader: (3)

Yes, I pulled on the wire link the cable connects to before I put the pan back on, it seemed to move freely. It also shifted perfectly fine when I drove it prior to this. I would think if the valve were stuck, wouldn't it cause higher line pressure since it could only get stuck deeper into the bore?
My friend is coming over Thursday after work, and I plan to call Dana tonight after work also, but I'm puzzled. Is it possible to have over torqued the one valve body bolt that holds that pipe between the pump and auxiliary valve body? I did briefly over torque that. When I was reassembling everything, the torque wrench was set to 18 ft lb for the pump instead of 96 in lb for the valve body. Way before it reached 18 ft lb I realized something wasn't right, backed it off, reset my torque wrenches to 8 ft lb (8*12=96) and torqued it again. It turned slightly before clicking so I was confident that it was set right, but now I am second guessing every little thing that I did.

Lurbie

iTrader: (3)

Well you were right someone972. Working on it more, I noticed that I didn't have full travel. We had previously marked and measured the cable stroke. Originally idle was 1/2 inch out from where it was when disconnected and 2 inches out at wide open throttle. After this problem happened it would only pull out 1.5 inches and I couldn't get the throttle to open fully. So we dropped the pan and found the TV plunger sticking. Pulled that out, cleaned small metal dust off the plunger and out from between the ring lands, put it back in and still couldn't get full TV travel. So we dropped the valve body, pulled the TV valve and cleaned the valve and bore. We unfortunately did not see the debris that caused it to stick, but it's clean and moving smoothly now through full travel. Unfortunately we also tore the separator plate gasket so I have to wait until tomorrow night to put it back together.
I'm going to replace the filter and the 4ish quarts that came out when we dropped the pan.

someone972

iTrader: (2)

Good to hear that you got it (hopefully) sorted out. Be sure to double check that the new gasket doesn't block any passages, I forget if Dana/Trans-Go makes any modifications to it. Let us know how it goes when you get it back together

Lurbie

iTrader: (3)

Dana had also called me Thursday night and said the same thing about making sure the gasket matched the seperator plate, because he did modify both. The gaskets that Transtar sold me matched up without needing any modification though. Before we put it back together Friday night, I kept playing with the valve and found it sticking again. We couldn't see what it was, but there was a burr or something deep in the valve body. We wrapped some 2500 grit wet/dry sandpaper around a screwdriver and spent a lot of time smoothing out the bore. There were also tiny nicks on the new valve. So small you couldn't feel it on the valve with a fingernail, but could feel it catch the skin on your finger. So we very gently cleaned that with the same sandpaper, got it back together and it works fine now.