Trans issue

[TyGuy18]

Wondering if I could get some input on my trans issue.
Symptoms are as follows:
- Truck will not shift out of 1st if it is not completely warmed to full operating temp before I start driving. (stock thermostat so ~190degF) If I do start rolling before that it will rev to 4k+ then bang hard into second and continue that until it warms up

- Once warm truck will shift correctly (according to service manual shift test) unless I try to get on it a little (not even WOT). Then it will not go into OD unless i back off the throttle.

- If I put around 75mi or so within a few hours it will also not shift into OD without letting off the throttle.

Things I know: Truck sat for about 10 years before I purchased it. There was a receipt left in the center console that said the trans had been rebuilt about 10k before i purchased it. I have since driven it up from FL to MI and put a total of about 7k on it. I have tried adjusting the TV and since it preforms correctly when warm I feel that it is adjusted properly. Fluid appears and smells fresh and is filled to the proper level. Truck is mostly stock. Had to go .030 over during the rebuild of the motor due to a fried cylinder.

Things I dont know: Have not checked if it is a true SyTy trans (numbers match). Not sure what exactly was done during the rebuild. Have not tested line pressure. Dont have a trans temp gauge so I do not know actual temp of trans during any of these events

 

[TyGuy18]

Re: Trans issue

Bump... Anyone?

 

[randy merritt]

Re: Trans issue

I looked at my ATSG transmission manual, and one of the causes of your symptoms is a clogged governor screen. It would make sense that the trans would work better once it has warmed up, because the fluid would be thinner. This is just a thought. I would try and test the line pressure to verify correct TV operation, because it appears the TV can get stuck, and cycling it a few times seems to clear it out in some cases.

Here is some info on where the screen is located.

http://www.thirdgen.org/forums/transmissions-drivetrain/513971-700r4-filter.html

 

[Gnocide]

Re: Trans issue

line pressure or imminent damage

 

[KDBL1TY]

Re: Trans issue

Sounds like line pressure. Shot n the dark are u allowing the turbo to build pressure before pulling off?

 

[TyGuy18]

Re: Trans issue

I looked at my ATSG transmission manual, and one of the causes of your symptoms is a clogged governor screen. It would make sense that the trans would work better once it has warmed up, because the fluid would be thinner. This is just a thought. I would try and test the line pressure to verify correct TV operation, because it appears the TV can get stuck, and cycling it a few times seems to clear it out in some cases.

Here is some info on where the screen is located.

http://www.thirdgen.org/forums/transmissions-drivetrain/513971-700r4-filter.html

Sounds like line pressure is the consensus. I have tried "flicking" the cable a handful of times but it did not seem to help any. If I was to drop the pan, is there anything else I could/should be checking besides the governor screen? Such as valves? Preferably without disassembling the trans too much.

Sounds like line pressure. Shot n the dark are u allowing the turbo to build pressure before pulling off?

No boost being built. Too scared to cause total destruction.

 

[DaveP]

Re: Trans issue

All symptoms point to HIGH line pressure, which can be a result of incorrect TV adjustment, as well as other hardware problems.

Begin with a Line Pressure check. You need a 0-300 psi gauge, and a 1/8MPT 90deg el fitting to insert in the trans. You need a helper to keep their foot on the brake, and move the shifter as required. Put a small screw driver in the throttle stop to hold the revs at 1,000 RPM. So RPM is constant during all the tests. Disconnect the TV cable from the throttle arm.

"Min TV" means at-rest position. "Full TV" means pull the cable all the way out by hand. As you pull on the TV, the pressure rises. If the needle bounces as you increase pressure, suspect an air leak at the filter to pump connection.

Shifter in P,N,D4,D3: Min TV=75-85, Max TV = 193-256
Shifter in Reverse: Min TV = 96-109 Max TV = 248-329
Shifter in D2, D1 (Lo) Min TV = 188-212, Max TV = 188-212

Don't hold the TV at Max any longer than necessary to take the reading. Max Line builds heat rapidly.

These pressures are for a stock LHM. Mods or changes will result in different pressures, but you should get similar results. The minimum TV's for the LHM are about the same for any 4L60. The maximum TV's change depending on the LoRev and TV boost valve size. But the increase in pressure with Max TV should be close, or higher. If you see differences in the pressures between shifter positions in the same "group", Ie pressure is lower in D3 than D4, this indicates leakage in internal components.

Watch for the trends during your testing. The Line Pressure check tells you a whole lot about the health of your trans, and will lead you to why it's behaving the way yours does. I tink you're going to find low pressures at Max TV, which lead to TV valve, cable, internal linkage, issues. If you also have low line at min TV, then look at Pressure Regulator valve issues. (

You're probably going to end up with the pan off chasing this. First thing is look in the pan for dark clutch material. If you find some, the low line pressure has fried the fwd and 3-4 clutches. Might as well take it out and get it fixed if you find clutch material. Driving these with low line burns them up pretty quickly.

There's some hints. Checking the pressure is a PITA, and requires the correct gauge and set-up, but it's the absolute next thing to do if adjusting the TV cable isn't making it "right".

 

[randy merritt]

Re: Trans issue

I just talked to my trans buddy that built my trans, and he thinks it is something wrong with the TV. He suggested leaving the truck off, and flooring the gas pedal vigorously several times to see if it clears out whatever is causing the issue. If this does not help, a tear down is probably next. If anyone knows these trans, it is DaveP, so do everything he suggests. Of course do the pressure test.

My buddy told me I was wrong about the filter being clogged. He said it would act the opposite if the filter was clogged, i.e. it would shift worse hot that cold.

On a separate note, the test port is a pain in the ass to get to because of the transfer case brace. I installed a braided steel "pig tail" about 6" long onto the test port the last time I had the brace out to make it easier to access in the future.

 

[TyGuy18]

Re: Trans issue

Here's another check for proper TV adjustment. Try this when yours is warmed up and you feel it is "shifting properly".

Shifter in D4. Take off at very light throttle. It should shift into 2nd at about 5-8 MPH. When it shifts 1-2, NAIL IT!. All the way WOT. It MUST downshift into 1st. If it doesn't downshift TV is NOT correct.

I'm almost 100% certain yours will fail this test. (It will stay in 2nd).

Thanks for the replies everyone! I have a pressure gauge ordered. Hopefully be here in a few days.

Dave, I will try this when I get home today.

 

[TyGuy18]

Re: Trans issue

Finally got around to digging into this issue a little deeper. In response to this post from DaveP previously (which appears to be missing from the thread now)

DaveP Trans Response
All symptoms point to low line pressure, which can be a result of incorrect TV adjustment, as well as other hardware problems.

Begin with a Line Pressure check. You need a 0-300 psi gauge, and a 1/8MPT 90deg el fitting to insert in the trans. You need a helper to keep their foot on the brake, and move the shifter as required. Put a small screw driver in the throttle stop to hold the revs at 1,000 RPM. So RPM is constant during all the tests. Disconnect the TV cable from the throttle arm.

"Min TV" means at-rest position. "Full TV" means pull the cable all the way out by hand. As you pull on the TV, the pressure rises. If the needle bounces as you increase pressure, suspect an air leak at the filter to pump connection.

Shifter in P,N,D4,D3: Min TV=75-85, Max TV = 193-256
Shifter in Reverse: Min TV = 96-109 Max TV = 248-329
Shifter in D2, D1 (Lo) Min TV = 188-212, Max TV = 188-212

These pressures are for a stock LHM. Mods or changes will result in different pressures, but you should get similar results. The minimums for the LHM are about the same as. for any 4L60. The maximiums change depending on the LoRev boost valve size. But the increase in pressure with Max TV should be close, or higher.

Watch for the trends during your testing. The Line Pressure check tells you a whole lot about the health of your trans, and will lead you to why it's behaving the way yours does. I tink you're going to find low pressures at Max TV, which lead to TV valve, cable, internal linkage, issues. If you also have low line at min TV, then look at Pressure Regulator valve issues. (

You're probably going to end up with the pan off chasing this. First thing is look in the pan for dark clutch material. If you find some, the low line pressure has fried the fwd and 3-4 clutches. Might as well take it out and get it fixed if you find clutch material. Driving these with low line burns them up pretty quickly.

There's some hints. Checking the pressure is a PITA, and requires the correct gauge and set-up, but it's the absolute next thing to do if adjusting the TV cable isn't making it "right".

Hooked up the pressure gauge and this is what i found (along with a bad prop shaft u-joint :roll

Shifter in P,N,D4,D3: Min TV=130-140, Max TV = 180 (for these selections the needle would jump to about 220 then quickly settle to 180 when pulling TV to Max)
Shifter in Reverse: Min TV = 165 Max TV = 225
Shifter in D2, D1 (Lo) Min TV = 170, Max TV = 170

Is there something blocking the TV plunger from retracting correctly? or weak spring?

Am I looking at a tear down? What is next? Thanks for reading :tup:

 

[DaveP]

Re: Trans issue

Shifter in P,N,D4,D3: Min TV=130-140, Max TV = 180

I'm currently working on a 4L60 with the exact same symptoms. It won't shift out of 1st. I have the same pressure readings as you. MIN pressure is about 150psi, and doesn't change much. Min should be about 65-70psi.

With this high pressure, the shifts will be very late, if at all. Until the pressure is correct, it won't shift correctly.

I have had the valve body off the one I'm working on twice now. I'm convinced it is TV valve related, but everything seems in order. I've also had the Pressure Regulator Valve assembly out of the pump and checked, and it too seemed OK.

Unless the TV pressure checks correctly, it won't shift correctly.

I ran out of valve body gaskets. On the list to go to the supply house today to get more. I need to fix this heap, and get it out of here. If you figure it out before I do, please let me know. It's not internal, unless the pump slide got jammed. And I'm not aware that that can or does happen.

 

[Don W.]

Re: Trans issue

Probably the best article I've ever seen on the TV cable. So extensive it comes in sections.

http://tvmadeez.com/article/index.php

 

[TyGuy18]

Re: Trans issue

Thanks for the responses.

Based on the article you sent Don, it would seem that Dave and I are experiencing a "Long Spring Syndrome" (LSS). LSS is characterized by high line pressures at idle and has four causes, although only three are listed:
- Accelerator pedal is used to set WOT but does not fully open the throttle
- Throttle linkage that causes TV cable to return a distance shorter than required during setup
- A TV spring that is physically too long

Doing the testing procedure mentioned in previous post would eliminate the first two as the linkage was not even connected. So is it possible that my and/or Dave's springs are too long? Seems like this would be a noticeable issue immediately after rebuild. I am also assuming Dave has measured the spring in his trans.

Any ideas what to check next? I will probably drop the pan this weekend and see what it looks like inside.

 

[DaveP]

Re: Trans issue

I will post the "back story" on mine. This trans was rebuilt by my lifelong buddy in Reno about 14 years ago. It has functioned flawlessy in my neighbor's Jeep up until a few months ago. My neighbor had the radiator serviced because it was leaking. Upon reinstallation, about 5 miles later it stopped shifting. We presumed that some crud was left in the trans cooler from the radiator repairs, the radiator shop nor his mechanic thought to blow out or flush the cooler, and the crap got into the trans. All that was "changed" is some crap went into the trans through the lube circuit.

So the spring that is in there is the one that has been fine for 12 years. It does have the TransGo "Bootstrap" kit. I asked Dana about this deal and he suggested the same kit, but Rick put it in when he did the trans.

Armed with the info from the BowTieOverdrive essay Don posted, I now know how to look at the TV valve to see if it is in the correct position. So I intend to do that next. I know this is TV related, and having had the Valve Body out twice now and not really finding anything, I've been putting this off for months. I'm going to go out there tomorrow and pull the VB again, and look at the valve position.

Thanks, Don.

 

[Don W.]

Re: Trans issue

You're all welcome. I actually think I got this link from IGottaSy who posted this link back in Dec 2014. (From a quick search, there may be others.) I just happen to remember it and dredge it up. Credit where credit is due.

A quick test is with shifter in D4 leave from a dead stop at very light throttle. As soon as it shifts 1-2 floor it. Tran MUST downshift back into 1st. If not TV is incorrect.

Not sure where I found that one. It's just in my pile of notes that I try to keep. Since I have KRS disease. Can't Remember Sh#&. :rotf: I know there are other shift point tests, I just can't find those...:roll:

Just hope all this helps.

 

[DaveP]

Re: Trans issue

A quick test is with shifter in D4 leave from a dead stop at very light throttle. As soon as it shifts 1-2 floor it. Trans MUST downshift back into 1st. If not, TV is incorrect.

Not sure where I found that one.

It came from me. That's my writing style, use of upper-case and punctuation, and I know where I got it from.

I got the procedure from Bow Tie Overdrives when I installed one in my neighbor's Camaro. They insisted that I achieve the 2-1 downshift before they would sign-off on the installation, and validate the warranty.

 

[DaveP]

Re: Trans issue==Mine is fixed!

Re: Trans issue==Mine is fixed!

Ok, I spent the morning under this thing. The TV valve was jammed in an advanced throttle position. Long story short, the owner's mechanics (?) at his shop worked on it before I did. They made a mistake with the TransGo TV valve that jammed the valve.

With the info in that essay Don linked, with the Valve Body on the bench, for the first time in 20 years of messing with the 4L60 I understand how the TV system operates. I positioned the TV valve centered on the MTV passage like is depicted in the picture, and made a mental note of how far the TV plunger needs to be pushed into the bore to achieve this position at idle. I installed the VB, then adjusted the TV cable and checked the plunger travel BEFORE I installed the pan. I finished the install, fired it up with the pressure gauge on it and I had 65psi at idle. That is PERFECT for this trans.

On my test drive, the shifts were slightly late, and there was NO detent 2-1 like there needs to be. I advanced the TV cable one more click, and the 2-1 was there. It's DONE. It shifts and behaves properly.

I want to thank Don again for that link. I have saved the pdf's into my car-stuff folder. That is very good info. It was what I needed to give me confidence that I could fix it, because NOW I knew how it is supposed to work. Anyone can fix anything if they know how it is supposed to work, and not just guessing at how it works..

To the OP: I'm convinced you have a stuck TV plunger. Pull the pan, pull the VB, take it to the bench and remove the TV plunger and free it up. Or get a new one from Sonax. You could also PM Dana (Username: ProBuiltAutomatics) and ask him for his "cure" for this. IIRC, it was $6. It's probably the TransGo "bootstrap" TV valve assy.

 

[0966Sy]

I've heard of this issue in the past, I remember a conversation from a reputable trans builder to the guy with the symptom that while driving in 1st gear. That popping the throttle from closed to wide open repeatedly will sometimes free the TV valve.

 

[DaveP]

Re: Trans issue

I've heard of this issue in the past, I remember a conversation from a reputable trans builder to the guy with the symptom that while driving in 1st gear. That popping the throttle from closed to wide open repeatedly will sometimes free the TV valve.

Now that I know a lot more about this system, I doubt popping the throttle will dislodge the valve if it is stuck. At least try pulling the cable in and out rapidly at fast idle with the trans in PARK. Might be more effective, but I still doubt it. Here's why:

The MTV pressure is fed to the front side of the TV plunger to offset the increasing pressure on the TV valve so that the throttle feel doesn't become too stiff. So the pressure on both sides of the plunger is about the same. So changing the TV pressure (which it doesn't change if it's stuck at 150; it can't go much higher) by bumping the throttle or jerking the cable isn't likely to help free it.

The fluid entering the TV bushing (top picture above) comes from the TV feed orifice (blue circle bottom picture) which is being fed by the movement of the TV valve over the feed orifice. This fluid progressively increases in volume and pressure as the TV valve is activated. We've tried to illustrate these by color and transparency change.
•Part throttle port and detent port in the TV bushing. As the TV valve feeds TV fluid into the feed orifice, part of this fluid is fed to the TV plunger through a port in the TV bushing. This fluid increasingly assists in moving the plunger against TV back pressure to prevent the throttle feel from becoming too great.

 

[neildemo]

Re: Trans issue

Dave thank you for this thread and knowledgeable input. Saving this...