86ltrain

Hey guys, new to the board...I recently bought an 84 z28, 66000 original miles, stock everything...had real sloppy shifts, I changed to corvette servo and longer apply pin. I also updated my boost valves to .500 & .296 as suggested by Dana @ probuilt. I'm also running one of the sonnax springs that you put over your TV cable to up the pressures. It shifts quite nicely now, aggressive but not too crazy. My issue is too low RPM shift to 2nd and too high to 3rd...This is under full throttle, about 4500 or so to 2nd, have to lift a little going into 3rd at about 5500. My 305 runs real nice but don't like the 5500 business...Any suggestions? Possible governor issue?

MSgt Luttrell

Is the car carburated? And if so, is it the stock carburator? The TV cable has to maintain the factory ratio to throttle movement to shift properly and some after market carbs require a special TV cable bracket to run with a 700r4.

86ltrain

Yes, it is...has original Quadrajet on it...the more I drive it the more odd it seems. If I don't floor it, it goes through the gears pretty quickly...the 2-3 is too soon at low rpms, too late at high rpm???

MSgt Luttrell

Full throttle shifts are controlled by the governor, while the low throttle shifts are controlled by the TV adjustment. In theory, if everything is functioning correctly, you can adjust your TV Cable for a low throttle 1-2 gear shift at 17 MPH and everything else should fall into place. Do the initial TV adjustment, then fine tune it if the low throttle shift isn't right on 17 MPH; tightening the tension on the cable will raise the MPH that it shifts at. Make very small adjustments for the fine tuning, as a little tension makes a big difference.

Also the thing to remember here is that too soon a shift in part throttle means that your line pressure is low and that is a great way to burn up the bands.

86ltrain

I was out driving today, seems like a 17 mph shift with my car is too high...about 14-15 is what mines at and that's a pretty aggressive shift, will chirp the tires. I'm afraid to tighten the TV much more, would make for a really hard 1-2 shift Pretty sure I have 3.73 gears so maybe I should be a little under 17? I had another thought, is it possible my TV spring needs to be changed? Thanks for the help.

MSgt Luttrell

Every thing I've read about these cars, especially the Z-28s and IROCs, says the shifts on these cars stock is pretty hard; my IROC chirps the tires on the 1-2 gear shift if your foot is in the gas much at all.

86ltrain

Are you running the little spring I mentioned earlier on your TV cable up at the carb? It advances the TV valve a little at lower speeds...just wondering if I should take it off.

MSgt Luttrell

I'm not running a spring on my cable set up, what set up do you have that has a spring on it? How about a pic of your linkage set up? Ok I just did a search on this spring you mentioned and yes, it could be your problem, these transmissions shift hard with out adding any springs to make them shift harder. I'd try removing the spring and adjusting it to specs, to see if that takes care of it.

Pro Built Automatics

The 1982 - through early 1987 700R4's had shift timing problems, downshift problems, late shift in one gear and an early shift in another gear, WOT shifts at vastly different rpms, etc. Install one of my modified Shift kits for these years. I can subtract the parts you have already bought. These kits will address the shift timing problems at low rpm, at WOT, downshifts, etc. I have installed many of these kits over the years for the 1982 - through early 1987 700R4's. This fixed the above mentioned problems (when installed correctly) every time. I have these for all applications. Starting in late 1987 GM finally addressed the above problems, so these kits were no longer required.

86ltrain

I removed that spring and readjusted my tv, its way better...less abusive anyway.

86ltrain

I sent you a message Probuilt...thanks for your help everyone.