2004-r Manual Shifting Hesitation

[TheSilverBuick]

I have a 2004-r in my '69 Firebird, and overall it does all the things I expect of it considering the 4.56 gears in the back. It shifts are reasonable spots considering the rear gears, and the shift quality was good, it shifts firmly, even chirping the tires going into second which I expected it to do given the shift kit, but I've injured the trans, so I'm pulling it apart in the next couple weeks and would like to address an issue it's always had while I have it apart fixing another issue.

What my problem is, when shifting manually there is a decent time delay between when I move the shifter and the transmission actually changes gears, but only really noticeable on the upshifts. It seems to respond to the manual downshifts just fine, but the manual upshifts hesitate and then of course over rev's the engine from the point I was intending the shift. If I had left the shifter in Overdrive or Drive, it would have shifted a 1,000+ rpm earlier, so I wouldn't think it'd be the TV cable adjustment.

What effects the response time of the manual upshifts? Is it pump pressure? A hole in the valvebody plate? Any thoughts on additional modifications to the valvebody or pump? I don't want a full manual valvebody, but I want the hesitation gone out of the manual shifting.

[anotheridiot]

so far what I have been learning the TV cable works both with your passing gear and controls the pressure in the trans. Thats why they say you dont really need to use the lockup circuit on the converter. Are you still deep in the accelerator when you are upshifting or off the gas, shift and back on the gas? Do you have the lockup hooked up? Its supposed to lower your rpms a couple hundred when you are cruising on the highway. it that causing the little lag? Right now we are even wondering if we should be setting up the lockup circuit since we really dont expect to do much highway driving.

[68scott385]

fwiw, my trans guy, don't hurt yourself laughing...

502-933-5353

http://www.bilbreyracing.com/

I don't shift mine manually, yet, but I do regularly break heat treated input drum/hubs...time for a billet upgrade.

[TheSilverBuick]

My converter lock up is controlled by the MegaSquirt. I'm at WOT or under higher throttle and the converter is unlocked, and the delay is still there. Basically, my shift light comes on, I pull the lever for the next gear, and it's practically 1.5 seconds before it goes to the next gear, but when it finally decides to shift it shifts quick and hard, chirping the tires (at least before my recent issue). So the shift speed and firmness is good, just the lag between saying change gear and it actually going is the problem I want to solve.

Obviously setting the shift light to a much lower rpm is a crutch.

[68scott385]

What is your shift/redline rpm?

[TheSilverBuick]

fwiw, my trans guy, don't hurt yourself laughing...

502-933-5353

http://www.bilbreyracing.com/

I don't shift mine manually, yet, but I do regularly break heat treated input drum/hubs...time for a billet upgrade.

It shifts decently when left in OD or D, but the 4.56 gears with the 2004-r's convoluted governor, it's not bad, but I do tend to shift it myself, and under normal driving conditions the hesitation isn't tragic, but the WOT hesitation drives me up the wall. The L6 isn't likely to break any hard parts anytime soon and I plan to get a built up 4L60e when I get the turbo engine going.

Do you think with a phone call he'd offer up some free guidance? He doesn't have the 2004-r listed on his website.

[TheSilverBuick]

What is your shift/redline rpm?

For right or wrong I have the light set at 5,400rpm.

[68scott385]

He's not fond of the 2004r. He said it was the biggest mistake GM ever made. Then he encouraged me to buy one of his 2004r for use behind my 455bbo. He knew what I was doing and gave me a warranty. He works on anything that comes in the door but prefers racing units. IDK if he'd come off advice over the phone or not. He might be easier to talk to if you said someone suggested his service and you're in Nevada. Worst case scenario, you catch him late on Friday trying to write payroll checks and they're in a bind to get something out.


As for shift/redline, it was just to get an idea of rpm, fyi/fmi. My 455 doesn't like anything over 5000rpm and not real happy to go that high. I have no experience with domestic L6's. Was wondering if you were shifting before the governor was ready to shift.

[TheSilverBuick]

No, the 2004-r is a nicely designed transmission with the exception of the damn governor and the fact you have to drop the pan to modify it. The governor controls both part throttle shift rpm AND WOT shift point rpm, and it's based on output shaft speed like they all are. The issue (besides having to drop the pan to adjust it) is making changes to the part throttle side does effect the WOT side, and making changes to the WOT side does effect the part throttle side, so a constant balancing act. Running 4.56 gears out back though on a transmission designed to not really see gears over 3.42, means even with some dramatic mod's to the governor, it's going to shift at a way lower rpm than I'd want at WOT. I got the part throttle to be decent, and am content to shift manually at WOT. So I know at WOT the governor is already screaming "SHIFT!!!" by the time I move the shifter to the next gear, so that shouldn't be holding it up.

And the delay doesn't really seem rpm dependent. If I short shift it at 4,000rpm the time delay probably gets me to 5,000rpm before it actually shifts.

[squirrel]

Do you have a hydraulic schematic of the transmission?

[68scott385]

Do you have a hydraulic schematic of the transmission?

If you do, PLEASE share it.

[squirrel]

not easy to scan...and my shop manual is kind of wrinkled, someone let it get wet. This is the Manual 1st diagram.

[68scott385]

I'm wondering if my factory manual has those. Hmmm, need to go to the garage anyway.....

[squirrel]

this is in the 1988 Chevy full and midsize car shop manual (from Chevrolet)

[quick 52]

Not uncommon on the 2-3 shift... haven't seen it happen on the 1-2 shift... most of the time its a band release to clutch engagement... separator plate third hole under size