I have had a persistant problem with my transmission on the 1-2 shift. It seems to want to stay in 1st too long and then when it finally decides to shift it bangs into second (almost feels like a shift kit). It has also had a slow leak but I make sure to keep it at the proper level. The car has 140K miles on it, no work has been done to the transmission other than a new seal for the tail shaft, and a new filter and fluid (every 30-40K miles). I want to finally fix this but I don't know where to start so any help on this would be appreciated.

 

First thing to do is scan for codes.

 

no codes for the trans. just some o2 codes from the headers and one for the removed egr system.

 

I know a lot of people will say that after 140K miles it is time for a rebuild, but I assume you are trying to delay that. Although I am no trans expert, here is what I would do which doesn't require removing the trans:

1. Drop the pan and check the fluid. If it is discolored, you might be SOL.
2. Replace the shift solenoids, which are only $15 each.
3. Remove the 1-2 accumulator next to the valve body. The internal piston might be worn on it's pin and cause problems. You might consider getting a Sonnax pinless piston assembly for $20.
4. If accessible, remove the servo and replace its gaskets. Also replace the servo return spring. $10 for those parts.
5. Replace the pan, put in new fluid and give it a try.

If the problem persists, have a trans shop check the line pressure; there is a tap at the side of the case for that purpose.
And/or I would get a rebuilt valve body for $150 off ebay. (Its tricky to rebuild yourself and the tools to ream for oversize valve parts are very expensive.)

If the problem still persists, you will need a rebuild, but it should be cheaper as you have already replaced some parts.

 

Mrvedit has some good advice... but at the end of the day he's suggesting a band-aid on a bullet wound.

Having been in the industry for more that 25 years I can tell you to absolutely do not go inside that transmission, do not challenge it by driving it "spiritedly" and start saving your money for a quality build. In my opinion if you go in and make pointed repairs based on a given diagnoses you will only be prolonging the inevitable and most importantly you may just create larger problems while tinkering with it.

Take it easy on it and save your $$$, get a nicely built unit by a good builder and then don't look back. The alternative is to go with a builder who offers inexpensive or cheap builds while you have high expectations and at the end of the day you have what you started with but only now you've spend big money and have to take it out and listen to why that guy didn't do his job in the first place.

Ask me how I know.

g

 

Yes I am.
If you can afford Gilbert's advice, follow it because he is right.
But if your budget is really only $100, you might try what I suggested.
However as Gilbert points out, any mistake or oversight here and you might not have a working car at all.

 

Hang on before you get all worked up thinking your trans is blowing up...

This is a relatively common issue with the 4L60E. Not common enough that it happens to everybody, but still I'm surprised more people haven't heard of it, particularly the trans gurus

Anyway, have you also noticed in the past that the torque converter doesn't stay locked at highway speeds? Maybe you don't drive highway enough to say, which is fine. I had this happen on my 98 Camaro a while back. Mostly it was just the TCC not staying locked when it was warm, but after a while it would suddenly start doing that horrible 1-2 neck-thrashing shift. Man that hurts. The TCC lockup issue drove me NUTS for over a year, as it also hurts highway mpg and I believe increases trans temps. I posted on here looking for suggestions, and people suggested the TCC solenoid, or a few other things, but nothing ever fixed it. The problem happened a lot more in the summer when it was warm outside.

What it came down to was this - the TCC valve (NOT the solenoid, but the valve itself) wears the bore in the valve body. Eventually it stops working right and it makes it do all sorts of funny things. GM went through like 3 designs of this valve, by the way. Now what the TCC valve has to do with 1-2 shift I don't quite understand, but this is all inter-related somehow.

I fixed mine and spent $100-ish in parts (minus trans fluid and filter). The answer was installing the Transgo SK-4L60E "P1870 code buster" kit. It also has several new springs and stuff. Chances are, your factory separator plate is worn, and you'll tear the seals when taking it apart anyway, so get a new plate and seals. Transgo has a hardened plate, make sure to get one for the right year you have (96+, older ones were slightly different).

I got a kit on ebay that came with the separator plate, seals, the SK-4L60E kit, and sonnax pinless accumulators and is what I'd recommend getting since it comes with pretty much everything you need. I also got a vette servo but more because it came with the new servo cover seal which is easy to break when opening it up to install the upgrades.

This totally fixed my issue, and has also fixed the issue for a few others that I have recommended this to. This can be done on pretty much any 4L60E transmission. I have this installed on my 02 Trailblazer as well. The Camaro's transmission is at 161k (the car is gone but the trans is in another Camaro now, still works great), and my Trailblazer is at 155k. My Trailblazer wasn't exhibiting the same issue yet when I got it at 112k, but I installed is as a preemptive move. It did vastly improve the TCC lockup time, before it used to kinda gradually slip into lockup. With the kit it just locks like you would expect it to. Less slip = less wear = longer life.

I'd definitely check into this before spending gobs of money on a rebuild or anything. Even if this isn't your issue and you need a new trans, well, it isn't a bad idea to have the parts upgraded anyway.

Obviously a good, strong, built trans is going to be the best, but if you just want more life out of your stock one this may be the way to go.

 

Quite frankly I am aware of excessively worn valve bores in transmissions. I am aware of those concerns. I have helped to design several components that have repaired or taken the original components to a higher level in a few units.

But, I am not in the market of merely repairing high mileage transmissions as I have to charge a good and fair market price for my services. Why would I charge someone several hundred dollars for a very specific, very pointed repair on a high mileage unit when I can build them a very, very nice transmission in the first place?

Yes, most builders here on the forums are aware of the "rebuilders" repair kits for valve bodies. Yes, I know the symptoms they repair. Yes I know they do a good job for a good price. And, in reality there have been way more components than just the TCC valve in the pump that have been updated or redesigned over the years! That transmission is still being redesigned by Hydra-Matic!

But, in my heart I cannot and will not sell someone that or a similar kit when I know the overall end play is loose by some .015" at best, the 3/4 clutches have .075" clearance and the single cage sprag has been slipping for months on end due to other components being stressed, the sunshell splines are worn excessively and so on....

Not, calling you out in a negative way... just trying to answer your question in an informative manner that everyone can relate to.

g

 

First off, I wasn't calling out anyone in particular either, just in my experience when I had TCC issues for over a year I never got the info I needed to fix the problem, so I wanted to be sure he had all the options laid out in front of him. I and a few others have had good success with that Transgo kit, so naturally I'm going to want to bring it up

I guess it partly stems from putting a lot of miles on my cars, but to me 140k isn't high mileage lol, just moderate. I've done 36k miles a year on average the past 2 years, so that 140k comes and goes pretty quick I'm aiming for at least 200k out of my Trailblazer before I have to do anything major to it, though I'd love to see that 250k mark like some have!

I don't know where he is with everything, and how much wear his trans really has (140k miles yes, but are they hard, or just easy highway like mine had been, or...?). Also, would that $100 now clear up the issues and gain him another 10, maybe 20k miles possibly if his trans is starting to get close to the end, and buy him some time to save up the big chunk of cash necessary for an all-out built unit? Maybe so. That is, $100 if he is comfortable installing it himself... Having a shop do it could be an entirely different matter, I have no idea what that could cost to have done. I've done mine with the help of a friend (we could use the lift at his work which made it 10x easier!).

That's all. No ill will toward anyone!

 

I'll have to give the trans go kit a try. I'm only trying to keep the trans going long enough to afford a T56 swap so I don't really want to spend a ton on a rebuild of a trans that I really don't want. I probably should have mentioned that before so I appologize about that. I appreciate all the great points brought up, and I agree if I were planning on keeping this trans a full rebuild would be the way to go. Thanks again for the help. I'll post up once I get it installed.

 

My tranny had the same issue when it was stock. Only after the fluid was good and hot, my 1-2 shifts were teeth chattering. It threw a code once every blue moon, 1860 or 1870. I just kept driving till she gave up the ghost. I am not sure about a "quick fix", but maybe find a donor car and pull the tranny. That's get you by till you figure out what you want to do. If it means anything to you, I just picked up my tranny from Gilbert this past week...solid unit....the guy knows his ****. My $.02

 

I'm also aware of the TCC valve (and not yet mentioned AFL valve) wearing out the valve body and causing all kinds of problems. That is why I recommended buying a rebuilt valve body on ebay. The Transgo kit seems like more of a work-around (it provides yet another TCC valve), but perhaps it will be good enough to keep you running for another year or so.
As Gilbert implies, removing the valve body might open a can of worms. Some of the issues to watch for are:
1. Check the separator plate carefully for check-ball damage. Or just get a new plate ($30).
2. Check the 3-4 accumulator bore and piston for wear; another pinless piston kit here is a good idea.
3. Reassemble with the correct gaskets; check the codes on your old gasket.
4. Make sure all the check ***** are in correct position; hold them in place with vaseline.
5. !!! Put the correct length bolts into their respective holes!!! Any mistake here and you can ruin the internal parts !!! Be super careful.
6. Check the internal wiring harness for any breaks in the wires or insulation. Removing the harness can break wires or insulation. You might need a new internal wiring harness (generally sold with new solenoids too).

I've done this a few times and it would take me 4-5 hours plus the time to deal with any surprises. So figure on 7+ hours if this is your first time. And your car may be done if you have to order and wait for parts. (I'm including time to pump out the trans fluid, jack up the car, work on the trans including work on the valve body, check all the accumulators, reassemble, add trans fluid, etc.)

If you are not comfortable with these steps, you'll need to consider a plan B. Paying a trans shop to do the work will cost you $400+ and as Gilbert says, would make no sense as your trans likely still has problems.

Thanks for your additional info SparkJJO; I'll be sure to include it the next time I try to answer a similar question.

 

I've wondered about the Transgo being just a temporary workaround as well, but so far it has been continuing to work great.

 

Good to know. How many miles/years do you have on it?

I assume the Trango HD2 kit has the same TCC replacement valve as the "Transgo SK-4L60E "P1870 code buster" kit" you mentioned. As you mentioned, Transgo says that it replaces the three variations GM has had.

I am studying and measuring three valve bodies this week - a brand new one and two used ones. I plan to learn more about how/why the Trango TCC valve is different from the last GM style.

I suspect that the "proper" way to fix the TCC valve is to install an oversized one, but this requires a special reamer that Sonnax sells for $150. Something tells me this requires some skill and practice too.

I hope my comments are useful to tpunk.

 

I know that this is usually a LS1 thread, but I have an interesting question. I've got a 1996 Chevrolet 1500 Single Cab. It's got a 305 V8, and I'm having similar issues; 281K Miles. It's obviously February, so it's fairly cool outside after letting it set overnight. One thing that I will note, is that when I start the truck and let it warm for about 5 minutes, it shifts just fine from 1-2 and all gear cycles. When I drive the vehicle at half operation temp, it'll shift hard from 1-2. But, when it's been running for about 30 minutes, it shifts flawlessly from 1-2,2-3, and back 3-2; of course TCC lockup on freeway. I've just purchased and recently received the following parts:

1-2 shift solenoid
2-3 shift solenoid
Force Motor EPC
1-2 ACC Piston and Seal

P.S.
-All parts were recommended by a family friend qualified GM transmission mechanic. After being recommended these parts, I noticed this thread about the TCC Bore being worn. I'm clueless as to the problem as the symptom are a bit different. Please, any further recommendations are welcome!

 

Well, a year since you asked and I missed it, but that gives even more time lol.

My Trailblazer now has 171k miles on it. Absolutely zero issues with the transmission or anything TCC related. My dad just used it to tow a Uhaul to Michigan and back twice recently while helping my brother move. My power steering quit on him but that's a totally separate issue

The Camaro's transmission has about 170k on it also and no issues there either. Remember this transmission came out of my old car that originally had the TCC lockup problems, hard 1-2 shifts, all that.

Given my experience with this I'm willing to say that the Transgo kit does fix it, not just temporarily patch it. And It is so much easier, cheaper, and less risky than having to ream out the bore.

 

Thanks for the update.
I've learned a lot in the last year too.
The Transgo kits (and others) replace the finicky PWM TCC valve with a simpler on/off TCC valve. It results in a firmer TCC engagement; I'm sure no one reading this forum would mind a firmer TCC and many might even prefer it.
So, let me correct my earlier post - its not a patch but a change to a more reliable part which is much less sensitive to wear in the VB.



I now understand the firm 1-2 shift too - once the PCM sets the 1870 code (TCC is slipping), it sets maximum line pressure which results in harsh shifts.

In the last year I have tested so many mods that I can R&R the valve body, fluid, etc in about 2 hours. I continue trying to help people get a bit more life out of their trans. I know it can be very intimidating the first time.