I rececntly rebuilt a 4L60E in a 97 K1500 that had a P1870 DTC (Trans component slipping). It also had a really harsh 1-2 shift at times. When I was done, the 1-2 was a little rough, but not all that bad, and the 2-3 shift made a noise. Well, several hundred miles later, it's still doing it, and that P1870 DTC came back. I wasn't driving it when the code set, and it just popped up once. Any ideas?

My first thought on the shifts, is that maybe I got the accumulator springs switched, but I have no idea on the slipping code.

TIA!

------------------
Working on:
'84 Z28 LG4 305 with 200,000 original miles!
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350 (ZZ430)
using primarily GMPP parts.
Short block sitting on a stand. (Man, those Fast-Burn heads look good, (just sitting there doing nothing!LOL))

Starting to look like the Kicker poster child!

ASE Certified Master Tech

 

You have harsh shifts because the computer is increasing line pressure due to the DTC 1870. To fix it get a TransGo Shift Kit. It will take care of the worn out TCC Regulator Valve (when you put the SK in, take a look at how it wobbles ).

Not only will the SK fix that but it will also address several other weak points in the unit. It will NOT give bang shifts. On another note, there are a few different design converter clutchs used in this year and the wrong one can cause problems. With the SK installed it won't matter which one you used (as long as you didn't damage it. After the SK is installed, braindead the computer to clear out the compensation for the 1870. To do this, disconnect the battery and touch the cable ends together and then have someone step on the brakes at the same time.



[This message has been edited by transfixleo (edited June 06, 2001).]

 

Tahnks for responding. I tore into it today, and here's what I found. The separator plate, where the checkballs go, was all messed up, like they had tried pushing through the plate. It also appeared that I didn't have the gaskets lined up all that well. I have a new plate and gaskets on order.
A little more about the 1870 DTC, the harsh shifts started right after clearing out the ECM immediately after the rebuild. The DTC just came back a couple days ago, and the rebuild was about 3 weeks ago, and it had been driven about 1000 miles since.

How much does the Transgo kit that I need typically cost?

Thanks again!

 

That checkball always does that. The TransGo SK comes with a different ball for that spot. Are you in the tranny business? If so where?

 

Well, I'm an ASE certified master tech, and I do it all. I've recently started into automatic tranny's, and things have gone pretty well so far. I work at a shop in Johnstown Ohio, just in the evenings right now, until I leave my day job (Factory work). I do all the transmission and rear-end work that we get in, and I'm starting to get better at it! My latest rebuild was a Ford AODE. Pretty easy rebuild. So far, I've just done stock rebuilds, but I want to start getting into some performance stuff. I'm gonna be building up my own 700 for the Z. I've been rebuilding for the past few months, and most of them have been mopars!

Well, thanks for the tips!


------------------
Working on:
'84 Z28 LG4 305 with 200,000 original miles!
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350 (ZZ430)
using primarily GMPP parts.
Short block sitting on a stand. (Man, those Fast-Burn heads look good, (just sitting there doing nothing!LOL))

Starting to look like the Kicker poster child!

ASE Certified Master Tech

 

Transfixleo hit the nail on the head. Your harsh shifting is because once the P1870 sets, the PCM commands max line pressure via the PC Solenoid. Once it commands max line pressure, shifts are very hard, and the checkballs "peen" the spacer plate very badly. I once had a truck that the checkball went completly through the plate.

Your P1870 is 99% of the time set for the TCC Regulated Apply Valve like Leo mentioned. This is an anodized aluminum valve that slides in an aluminum valvebody. Because the valve is anodized, it shows NO wear, while the valvebody itself gets tore to ****, but you really can't see it due to the small hole. 1996 and 1997 were the worst years, 1998 GM designed a new style valve with a ring in the valve to help "float" the valve, but it didn't really help. Now, all the reman valvebodys have a skirt over the spring to keep the valve longer so it won't wobble and wear the bore as much.

As for fixing this, working at a dealer, my only option is a $400 reman valvbody, but since you don't work at a dealer, you have many options. I think a company called Sonax makes a repair kit, along with another company. One of the kits has you drill out the bore and install a sleeve kit, which I hear works great. I have also heard alot of people installing a spring between the valves to bypass the whole PWM apply and have it lock up like a 700.

I hope this helps, good luck.

------------------
If you live in Southeastern US, check us out!
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ASE Master Tech + L1
Savannah, GA

'87 Trans Am
S/D TPI retrofit including functional PassKey,
22# injectors,
Whatever chip I feel like burning,
JET AFPR, Ported Plenum,
TB Coolant Bypass, Custom Cold Air,
SSM SFC, KYB Shocks, Boxed LCAs, Wonder Bar,
8mm Accel wires,
Flowmaster Exhaust,
16" GTA rims,
Corvette Servo,
3.73 Posi
4wheel Disc Brakes
Summit 1-5/8" headers, 2.5" Dynomax catback.

Best 1/8: 9.519@72.74

'97 Bonneville SSE

[This message has been edited by GMTech (edited June 10, 2001).]

 

Sonnax does make a replacement valve but you also have to buy the reamer, each part cost @the same as the TransGo Shift Kit which comes with a redesigned valve (Hmmm, sounds allot like what GM is now doing on their 'Service' VB's! Wonder where they got the idea???) so you don't have to ream anything. It also addresses the 3-4 clutch failures, etc. where the Sonnax for twice the money only addreses the valve wear. Certain years you can get away with the spring trick but not on the C3 system. The computer tries to make it slip and when it doesn't it drops pressure- not the best thing for longevity!

 

Well, what bothers me, is that the harsh shifting began BEFORE the code set. I will look into the valve though. You say it can be felt that it is worn? Looks like I have to pull the VB back down, I had put the new plate and gaskets in, but I will pull them back apart and fix it right!

Thanks!

------------------
Working on:
'84 Z28 LG4 305 with 200,000 original miles!
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350 (ZZ430)
using primarily GMPP parts.
Short block sitting on a stand. (Man, those Fast-Burn heads look good, (just sitting there doing nothing!LOL))

Starting to look like the Kicker poster child!

ASE Certified Master Tech

 

What I do is remove the valve (you will have to remove the valvebody, since the retaining clip comes out through the case side of the valvebody) and put it in backwards (the spring land gives you something to grab on to) and sitck it in as far as you can and still hang on to it. Now wiggle it up and down. There should be almost NO deflection. If you want something to compare it to, pull the manual valve out, and move it up and down, it won't move at all, and thats how your regulated apply valve should work.

Feel confident that this is your problem, because like I said, about 90% of the P1870 (especially 1996-97) are because of the TCC regulated apply valve.

I knew that you had to ream for a Sonnax kit, but didn't know the price. I guess the TransGo kit would be the way to go. Actually, all the reman valvebodies I have seen didn't use a sleeve, just a skirted spring land making it about 15mm longer, and I think a larger OD so that the bore can be "trued up".

GM knows they have problems with these valvebodies, the part number has changed four times now. I have actually replaced the original style valvebodies w/ the "floating" valve style valvebodies, only to see them come back 30,000 miles later for the same concern (P1870, harsh shift) and ended up installing a "skirted" style valve valvebody. I wish I had pics to show you what I am talking about.

As for the harsh shift BEFORE the MIL, Since the P1870 is a Type "B" DTC, the first time it fails, the PCM will freeze shift adapts, and set a code and command max line pressure, but being a Type "B" DTC, it takes two consecutive trips w/ a failure to turn the light on. Type "A" DTCs are the only ones that will turn the MIL on the first time they set a code.

------------------
If you live in Southeastern US, check us out!
South East Thirdgen

GM Master Tech
ASE Master Tech + L1
Savannah, GA

'87 Trans Am
S/D TPI retrofit including functional PassKey,
22# injectors,
Whatever chip I feel like burning,
JET AFPR, Ported Plenum,
TB Coolant Bypass, Custom Cold Air,
SSM SFC, KYB Shocks, Boxed LCAs, Wonder Bar,
8mm Accel wires,
Flowmaster Exhaust,
16" GTA rims,
Corvette Servo,
3.73 Posi
4wheel Disc Brakes
Summit 1-5/8" headers, 2.5" Dynomax catback.

Best 1/8: 9.519@72.74

'97 Bonneville SSE

[This message has been edited by GMTech (edited June 10, 2001).]

 

Well, thanks for all the help! I put the TransGo kit in today ($34.80) and the new separator plate and gaskets, wiped out the ECM memory, and now it shifts great, but it is still making sort of a grunt on the 2-3 shift. It feels fine, and I'm really not very worried about it, but the curiosity factor gets me every time!!!! The noise started right after the rebuild, but not before I had cleared the ECM. Clearing the ECM seemed to "cause" it. Oh well.

Again, thanks!

------------------
Working on:
'84 Z28 LG4 305 with 200,000 original miles!
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350 (ZZ430)
using primarily GMPP parts.
Short block sitting on a stand. (Man, those Fast-Burn heads look good, (just sitting there doing nothing!LOL))

Starting to look like the Kicker poster child!

ASE Certified Master Tech

 

Hmmm, now I am curious. Was this noise not present after the O/H until the ECM clearing? Or was it there right after the O/H? If so, what kind of clutches did you use?

 

Immediately after the rebuild, I don't remmeber hearing the noise, and I hadn't cleared the ECM yet (Battery was still connected while the tranny was out). After a test drive, I wiped the ECM, then I started noticing the noise. It's not much of an issue, in fact the owner of the shop I work at didn't even hear it.

I used the Raybestos clutches that come in the Daaco kit. For stock rebuilds, I like these kits, they use TransTec seal kits, and Raybestos clutches, and alto steels most of the time. I'm not sure right now which Raybestos clutches they were. I may be able to figure it out.

I'm gonna warn you now, I'm gonna be aslking some very specific question pretty soon, as I'm planning to start getting the parts together for my transmission for the Z. I want that thing to be PERFECT.

Thanks for the help!

 

I don't know why it would start up after the ECM clearing. My first thought would be clutch 'chatter' from the Ray clutches. I am not a fan of those. I use Borg Warner exclusively (OK, on certain units I use Alto Power Packs).

I'll be glad to help if I can.