Hard shift from 1 to 2 when hot

[dlundblad]

This is on my 1997 Blazer. ~175k miles, but ~50k on the transmission after the rebuild. The PO (brother in law’s brother) told me it was done and I had no reason to doubt it. Fresh looking ATF and it shifted fine. I didn’t worry about it and haven’t messed with it since.

Just yesterday, it started only doing it when hot. Shifts fine until driving it 20 mins or so.. makes a sudden jolt when shifting. Doesnt slip though.

Any thoughts?

 

[oggb]

It will get much worse and is common for the 4L60E. My old S10 got to the point that it would chirp the tires every time it shifted 1-2. There are a LOT of different parts/etc. inside the trans that can cause this issue. I rebuilt mine, but I was just generally tired of the truck and sold it not long after. No idea how long it held up.

 

[Lubener]

I don't know if you would have codes but it is worth a check. I can tell you from my experience when I had a 97 Lesabre. I started getting harsh up shifts when good and hot shortly after putting Dex 6 in when I did a pan drop. The transmission shifted very well prior to that and assuming the original fluid was still in there when I did the change at 42k miles. I don't know if this is coinsidence or not but worth mentioning.

 

[BMWTurboDzl]

Insufficient fluid or perhaps wrong fluid.

 

[Blinker]

You will more than likely get a shift timing trouble code soon. Very common on these transmissions and the 4T65e as they start to wear. Basically the TCM has detected slippage and has increased the line pressure.

 

[Tman220]

Hard 1-2 shifts on a 4L60E is more likely than not a 1-2 accumulator piston or pin that is worn, cracked, hanging up, or the springs have broken.

They come with plastic pistons that often get worn or crack. A decent rebuilder would have upgraded to an aluminum piston.

1-2 accumulator is pretty easy to access with the pan down. Doesn't require you to drop the valve body. It would be pretty easy work for someone who DIY's a lot of things on their own vehicle.

 

[Kuato]

50k since rebuild....try some fresh fluid.

 

[clinebarger]

You will more than likely get a shift timing trouble code soon. Very common on these transmissions and the 4T65e as they start to wear. Basically the TCM has detected slippage and has increased the line pressure.

4L60E's didn't have adaptive shift strategies until 2007 with the addition of a ISS (Input Speed Senor), The PCM couldn't precisely calculate Ratio Errors without it.

4L60E Component Slip DTC's 99% of the time means that the Converter Clutch isn't applying or is slipping. This will command max line pressure but shouldn't be confused with 4T65E Max Adapt/Long Shift DTC's.

 

[dlundblad]

4L60E's didn't have adaptive shift strategies until 2007 with the addition of a ISS (Input Speed Senor), The PCM couldn't precisely calculate Ratio Errors without it.

4L60E Component Slip DTC's 99% of the time means that the Converter Clutch isn't applying or is slipping. This will command max line pressure but shouldn't be confused with 4T65E Max Adapt/Long Shift DTC's.

Somewhat OT, but do you know what transmission filter this would take? Looks like RA has 3 AC Delco options.

 

[clinebarger]

Take a picture of the trans pan. It's most likely the deep one but I'd like to know for sure.

 

[dlundblad]

 

[clinebarger]

That's a shallow pan.

*The current AC Delco kit number is TF289, The last time I bought one of these it DID have a good Filtran filter, But the gasket was cheap aftermarket Cork.
*A OE gasket has to be purchased separately.....GM# 8654799.



I highly recommend swapping to a deep pan as you have plenty of room to do so.
*Deep Pan, GM# 24240207......@ $20 on Amazon & Summit Racing
*Deep Filter Kit, Comes with a OE gasket, GM# 24208576
*Second magnet (Recommended), GM# 29535617

YOU MUST remove the Dipstick Stop to use the updated 24240207 pan as it has a built in stop. Simply remove the 10mm headed bolt, Throw the stop away & torque the bolt to 120 inch pounds.



Have you checked for DTC's yet?? If nothing shows up there, I recommend dropping the 2nd Accumulator Housing & checking for a broken spring.
*Just replace the entire assembly as OE assemblies are DIRT cheap, Yes....It will come with a plastic piston but actually performs BETTER than Aluminum 'til it wears out.........That takes @ 100,000 miles or more.
*GM 2nd Accumulator Assembly, GM# 24227711. Is the cheapest option at $11 on Amazon, It technically goes to a later model 4L60E that don't have the Outer Spring, So it only has the Inner Spring included.
*Remove the Piston from the Housing & install GM# 24209794....@ $8 on Amazon.....This is the Outer Spring for your Blazer. (Purple, Ovate)
*IF your original Inner Spring is broken, Use the Inner Spring included in the 2422711 Housing, If it's not broken.....Remove the new Inner Spring & Reuse the original.

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[dlundblad]

Thanks for the detailed info.

What are the benefits of the deeper pan?

Would 6 quarts be sufficient for the deep pan?

 

[dlundblad]

Just checked the codes. It is throwing a P1870. “Transmission component slipping.”

 

[350Rocket]

Just checked the codes. It is throwing a P1870. “Transmission component slipping.”

So sounds like the lockup is probably not engaging and causing max line pressure to be commanded based on what clinebarger said above.

 

[Blinker]

4L60E's didn't have adaptive shift strategies until 2007 with the addition of a ISS (Input Speed Senor), The PCM couldn't precisely calculate Ratio Errors without it.

4L60E Component Slip DTC's 99% of the time means that the Converter Clutch isn't applying or is slipping. This will command max line pressure but shouldn't be confused with 4T65E Max Adapt/Long Shift DTC's.

Great

 

[clinebarger]

Just checked the codes. It is throwing a P1870. “Transmission component slipping.”

The Converter Regulator Valve out of a TransGo SK4L60E Shift Kit is certainly worth a try. I've seen it fix some badly worn Valve Bodies!!

You could also try Blocking the Valve buy installing one 1/4" checkball into the Regulator Valve & another checkball into the Isolator Valve....The Spring will be between the 2 checkballs.......This is not a guaranteed fix for a heavily worn Valve Body.

I would go with the TransGo valve as the Valve Body has to be dropped & doing it twice would suck.

 

[dlundblad]

Just dropped the pan. What a pain. The transmission cross member had to be lowered too.

The 2nd accumulator springs were not broken, but it did have an aluminum piston.

I’m thinking I should add the regulator valve at this point so I’m not putting it back together only to have to tear it apart again or just skip the regulator valve and put in a new valve body.

 

[350Rocket]

Just dropped the pan. What a pain. The transmission cross member had to be lowered too.

The 2nd accumulator springs were not broken, but it did have an aluminum piston.

I’m thinking I should add the regulator valve at this point so I’m not putting it back together only to have to tear it apart again or just skip the regulator valve and put in a new valve body.

When I pulled the pan on my 05 Silverado I was annoyed that I had to bend the shifter cable bracket out of the way. My 80s GM cars with 2004R trans had nothing in the way on any of them. The truck is still easy to work on compared to most modern vehicles but I've had a few *** moments after nothing but 80s GM full size cars.

 

[clinebarger]

Just dropped the pan. What a pain. The transmission cross member had to be lowered too.

The 2nd accumulator springs were not broken, but it did have an aluminum piston.

I’m thinking I should add the regulator valve at this point so I’m not putting it back together only to have to tear it apart again or just skip the regulator valve and put in a new valve body.

You can usually sneak a shallow 13mm 1/4" drive socket on an extension in there to get the rear pan bolts out, If the mount is collapsed.....Jack the trans up a little after removing the 15mm hex nut holding the mount to the crossmember to gain access & replace the mount while you're there.

There are no NEW valve bodies, Only remanufactured & good used. The TransGo TCC Regulator Valve will fix the issue IF the issue is in fact in the valve body.