4L60/700R4 Slams Into Gear, Delayed 1-2 Shift

[Ruff Idol]

1992 C1500 with the 4L60 (not 4L60E) here. So the deal is I am already easily nauseated (especially after a cigar) and let me tell you when I throw the truck in drive or reverse it slams into gear so hard my stomach may go out the window. Also this week I just lost my 1-2 shift, or at least it's very delayed like I have to get up to 30 mph and the engine redlines then finally shifts into 2nd. Beyond 2nd it shifts OK from what I can tell especially under highway acceleration. I have not gotten around to testing the TPS but that is what I suspect is the culprit because I have dealt with hesitation/acceleration problems with my truck in the past.

Not sure if this helps but I did change the fluid & filter about a year ago. Look at the color - nice and pink but there's always this black residue on the dipstick, ever since I bought the truck. Very strange. I will say when I bought it it shifted like butter all around but ever since I did the fluid change (and snugged up some loose valve body bolts) I have been getting crisper than desirable shifts mainly from 1-2 as I stated. Is it possible I overtightened them? Or that the black stuff in the fluid is an indication the previous owner put in fresh fluid to mask a problem just to get rid of the thing?

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It's also very weird that some of the ATF (see pic above) came out more of a burnt color while the majority came out pink. (The old/burnt color is what it was entirely before I changed the fluid)

 

[1998_K1500_Sub]

1992 C1500 with the 4L60 (not 4L60E) here.

I believe 1993 was the first year for the "E" transmission.

in drive or reverse it slams into gear so hard my stomach may go out the window.

It sounds like the line pressure is very high for some reason, e.g., the pressure regulator isn't functioning correctly or the TV cable is in a "too-extended" position when the throttle is closed.

Also this week I just lost my 1-2 shift, or at least it's very delayed like I have to get up to 30 mph and the engine redlines then finally shifts into 2nd.

I had this behavior once on a 700R4. Some valves and/or the pressure regulator were sticking because of a large load of debris in the oil from a failed internal part.

I have not gotten around to testing the TPS

Don't bother, the non-E trans is controlled by the TV cable, except for...

The TCC is controlled by the ECU / TPS.

Fun fact: The very early 700R4's valve body actually controlled the TCC as well, for the record, so no external electrical input was required.

I did change the fluid & filter about a year ago. Look at the color - nice and pink but there's always this black residue on the dipstick, ever since I bought the truck.

I might assume that's clutch dust.

snugged up some loose valve body bolts

Umm... you used an inch-pound torque wrench, right???

If not, shame.

Why were those bolts loose? Some prior owner was monkeying around in the trans?

Is it possible I overtightened them?

So you didn't use a torque wrench?


Pull the dipstick and look at the oil under a bright light. If you see sparkles in the oil, i.e., from metallic particles, that's a sign of an internal part failure and a future rebuild.

Check the action of the TV cable. With the engine running, in Park, pull gently on the end of the cable (pull on that little metal retainer that's crimped onto the end) with your fingers. The cable should extend easily and retract smoothly on its own. In contrast, with the engine off, it will take quite a bit of effort to pull the cable.

IF, for some reason in the recent past, you've (unintentionally) changed the adjustment of the TV cable and tightened it, the symptoms you describe could result. Simply removing / reinstalling the bracket on the intake which retains the TV cable can, in certain situations, affect the adjustment enough to make a difference. Ask me how I know.

You might experiment a bit. Loosen the TV cable a "notch" on the adjuster and see how the shifts change. Then, tighten it up a notch (or two, if you loosened it one notch prior) and see how the shifts change. The difference should be quite noticeable. The results from this experiment may indicate you've nothing wrong with the transmission, it's simply a mis-adjusted TV cable.

If you take these steps above, report your results in this thread.

I trust others on GMT400 will comment.

 

[yevgenievich]

Jr shift kit has the spring and the spacer to help with sticking tv valve

 

[Ruff Idol]

I had this behavior once on a 700R4. Some valves and/or the pressure regulator were sticking because of a large load of debris in the oil from a failed internal part.

That would make a lot of sense seeing the black stuff. I gotta get a closer look at it to see if they are metallic specs

Why were those bolts loose? Some prior owner was monkeying around in the trans?

Yes, they mentioned to me it got a different trans, or at least a trans rebuild around 60,000 mi. Based on evidence I've seen I would argue they did not know what they were doing. For the record only a couple bolts were loose enough to make me nervous.

I should also note they sold it to me with a completely shot 305 when they lied and said it was a 350 AND was recently swapped. I do not trust they got the trans right

So you didn't use a torque wrench?

Sadly, no. Just barely snugged up with a 3/8" ratchet.

Pull the dipstick and look at the oil under a bright light. If you see sparkles in the oil, i.e., from metallic particles, that's a sign of an internal part failure and a future rebuild.

I will do this, I'm nervous that I already know the verdict because I did find quite a bit of crap on the pan magnet upon my last fluid change

Check the action of the TV cable. With the engine running, in Park, pull gently on the end of the cable (pull on that little metal retainer that's crimped onto the end) with your fingers. The cable should extend easily and retract smoothly on its own. In contrast, with the engine off, it will take quite a bit of effort to pull the cable.

This is from the top right? By the intake/throttle body?

IF, for some reason in the recent past, you've (unintentionally) changed the adjustment of the TV cable and tightened it, the symptoms you describe could result. Simply removing / reinstalling the bracket on the intake which retains the TV cable can, in certain situations, affect the adjustment enough to make a difference. Ask me how I know.

This is possible as I just had a guy swap in a motor for me a couple months back.

If you take these steps above, report your results in this thread.

I trust others on GMT400 will comment.

Definitely so, I also have a date with the trans shop and from my convo with the guy over the phone, his thoughts are concurrent with yours that it's most likely a hydraulic pressure/TV issue. I really wouldn't mind a R&R though because I'm about $10k into this truck including what I paid for it and it is rock solid reliable otherwise. Still won't be close to price of a new truck

 

[PlayingWithTBI]

Jr shift kit has the spring and the spacer to help with sticking tv valve

Yeah, I bought the kit with the TV spool and spring, when mine started with the delayed shifts. After putting it in, the trans ran great until the TV spool got stuck again a couple weeks later. It just had too much crud floating around. That trans is now sitting on a shelf in my shop.

On another note, the separator plate had worn holes where the check balls lived. I didn't replace the plate, I should have though. I pretty well knew it was on its last legs.

 

[1998_K1500_Sub]

Sadly, no. Just barely snugged up with a 3/8" ratchet.

Well, that was better than using a 3/4" drive impact wrench.

This is from the top right? By the intake/throttle body?

Yes, grab the cable at its end, near where its plastic floppy doodle attaches to the throttle body lever.

I really wouldn't mind a R&R though because I'm about $10k into this truck including what I paid for it and it is rock solid reliable otherwise.

As @PlayingWithTBI notes, stuff will simply wear out in the valve body.

With an R&R you know what you've got and the peace of mind that comes with it.

Still won't be close to price of a new truck

A trans R&R would be less than the sales tax on a new truck.

 

[Schurkey]

TV cable? Maybe.

If the harsh shifting came on suddenly, I'd be looking at the accumulator springs. Commonly broken. Sometimes the accumulator piston is broken.

Wouldn't hurt to pull the governor out, make sure the weights/springs/rods aren't sticking.

 

[Erik the Awful]

Also this week I just lost my 1-2 shift, or at least it's very delayed like I have to get up to 30 mph and the engine redlines then finally shifts into 2nd. Beyond 2nd it shifts OK from what I can tell especially under highway acceleration.

1-2 accumulator. I had the same symptoms on my 4L60, and everything looked good when I tore it down, except for a slight bit of wear in the 1-2 accumulator bore - note the scoring in the picture below. Pretty much every transmission shop eliminates the accumulator when they rebuild. Silly me, I'm keeping it. I havent' installed the transmission yet to see how it runs.

I burned up the transmission trying to adjust the TV cable to correct the shift. Since your 1-2 accumulator is acting up, pay attention to your 2-3 shift when adjusting the TV cable.

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[1998_K1500_Sub]

1-2 accumulator. I had the same symptoms on my 4L60,

Does this explain the harsh garage shift he's having as well?

The 1-2 accumulator affects the apply of the 2-4 band. That might explain the harsh 1-2 shift, but...

The garage shifts don't involve the 2-4 band:

- Drive: The forward clutch engages (to effect 1st gear)

- Reverse: The "reverse input" clutch and the "low and reverse" clutch are applied

If his TV cable's too tight, it would cause the abuse valve to actuate, yielding a harsh garage shift into Drive / forward clutch engagement. It would also give firmer-than-normal 1-2 shifts (well, all shifts) and reverse.

Or maybe he's got some other problem.

 

[Erik the Awful]

Dunno, but it seems like the 1-2 shift is a separate issue from the slamming into gear problem.