Transmission???

[gldixon86]

So I just had my 99 gmc suburban 4l60e rebuilt. After it gets warmed up it’s still shifting super hard into 1st would that be my torque converter???
Engine seams good shifts good till it gets warmed up an then it will throw a code p1870??? But it was all rebuilt by a gm tech sooo I was thinking like I said maybe torque converter. Please help.

 

[Pinger]

error code p1870 - Google Search

 

[Jesse_Wenting]

So I just had my 99 gmc suburban 4l60e rebuilt. After it gets warmed up it’s still shifting super hard into 1st would that be my torque converter???
Engine seams good shifts good till it gets warmed up an then it will throw a code p1870??? But it was all rebuilt by a gm tech sooo I was thinking like I said maybe torque converter. Please help.

I mean if it was rebuilt by a GM tech you should be able to take it back under warranty and more or less say "I paid you to make it work, SO MAKE IT WORK"

 

[stutaeng]

I agree with @Jesse_Wenting take it back to the place or guy that rebuild it.

Did it do that before it got rebuilt? Are you sure it's not the 1-2 shift?. I had a transmission that did the same thing. After getting off the freeway it did a harsh shift 1-2. Basically the ECU detects a problem and commands maximum line pressure all the time. That's the reason for the harsh shift. If I shut if off and restart it it shifted fine, until I got on the freeway again and did the 1-2 shift again...2-3 was less harsh, but still noticeable. By the time it got to 3-4 it almost normal. But that 1-2 shift felt like I got rear-ended, LOL.

It's a problem with the TCC regulator valve in the valve body. See here:

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[Jesse_Wenting]

It's a problem with the TCC regulator valve in the valve body

So when I rebuilt my 98 4l60e, I got a bit confused about the different styles of input shafts and left an extra O-ring that prevented my TC from locking up. Realized really quickly though, corrected and have since driven it about 1200km but it feels like borrowed time lol

 

[stutaeng]

So when I rebuilt my 98 4l60e, I got a bit confused about the different styles of input shafts and left an extra O-ring that prevented my TC from locking up. Realized really quickly though, corrected and have since driven it about 1200km but it feels like borrowed time lol

'98/SBC would be the 298 mm input shaft. You did a full rebuild? What does it do?

 

[Jesse_Wenting]

'98/SBC would be the 298 mm input shaft

Correct. I left that extra o-ring here

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Was pretty obvious I wasn't getting lockup so I only put maybe 25km on it before I pulled it back out to fix my mistake.

You did a full rebuild?

Yes full rebuild, along with some Sonnax parts and a bit of preventative maintenance. The name of my truck in my signature is a link to my photo album. Scroll down a bit and you'll see a bunch of pics of the rebuild.

What does it do?

Not sure exactly when you mean so the reason for the rebuild was because lost my 3-4 clutches, post rebuild with the extra o-ring everything was fine except for the TC not locking up, after I removed the extra o-ring she's been fine for the past 1200ish KM (about 750 miles). 1-2 and 2-3 shifts can be pretty firm at times, but I wouldn't call it harsh. Pretty sure it's cause of the Sonnax boost and bands I put in.

The whole truck is sluggish above 45mph but that's a combination of a 305, 3.42 gearing and 33s lmao. Can't wait to have a 350 again, 3.73 or 4.11s, and 32s

 

[RichLo]

If its only shifting hard when you first put it in gear, your idle could be set too high which may be an indication of a vacuum leak

 

[Schurkey]

As said, this is not "your" problem, this belongs to the guy who rebuilt it for you.

I'd consider a failed or disabled accumulator.

 

[gldixon86]

I agree with @Jesse_Wenting take it back to the place or guy that rebuild it.

Did it do that before it got rebuilt? Are you sure it's not the 1-2 shift?. I had a transmission that did the same thing. After getting off the freeway it did a harsh shift 1-2. Basically the ECU detects a problem and commands maximum line pressure all the time. That's the reason for the harsh shift. If I shut if off and restart it it shifted fine, until I got on the freeway again and did the 1-2 shift again...2-3 was less harsh, but still noticeable. By the time it got to 3-4 it almost normal. But that 1-2 shift felt like I got rear-ended, LOL.

It's a problem with the TCC regulator valve in the valve body. See here:

xc_hide_links_from_guests_guests_error_hide_media

Yes it was doing it then as well. I got it rebuilt but I would assume he should have put in a new tcc solenoid could it be a torque converter??? But I’m thinking it’s what u said an maybe he just reused the old one??? I’ll have to find out