If you guys can take the time to read thru this, I'd appreciate it. I'm not sure what can be wrong. The problem's with my '86 700r4.
If I take off from a stop, either moderately or hard, the trans goes thru first gear fine, and completes the 1-2 shift. It will then "slip" in 2nd gear. When I say slip, the engine rev's go way up, and the car stops pulling forward. That's when I let off the gas. The trans then clunks back in, and I can step on the gas again.
This won't happen if I take off "nicely" from a stop.
It will happen both when the car is cold, and when the car is hot.
However, here's the odd part- If I row my own gears (move the stick from 1 to 2 to 3 to OD), the trans won't slip in 2nd!
The fluid level is perfect. The fluid is red, and does not smell burnt. On the last fluid change (March), the magnet in the pan had no huge chunks of metal- it was just slightly fuzzy. The filter had barely any metal inside, either. Yes, I put a new filter back in.
The TV cable is in proper adjustment. The shift linkage is also properly adjusted. The trans mount (ES Poly) is not broken. The motor mounts aren't broken. The trans case isn't broken. There are no leaks. The TCC solenoid locks/unlocks as it should, and the wires/connector are fine.
I've tried to list it all, because nothing "simple/obvious" is wrong.
"Why" would the trans act up in 2nd gear when the stick's in D or OD, but work fine when I manually shift?
This trans has done this since it was rebuilt September '99. It was rebuilt by a friend of my girlfriend's father. The rebuilder was the "transmission tech" at a nearby trade school, and he charged me minimal labor as a favor. I dropped the trans out myself, and brought it to him. He rebuilt it with a stock rebuild kit, and gave me a new TC. I then put the trans up- correctly.
I mentioned to the rebuilder that I had a B&M Shift Kit in there. When I got the trans back, I asked him if he changed anything. He told me "I left your valve body alone." (I later had to go back in and pull out a checkball that he replaced by accident.)
The transmission never did this before it was rebuilt, so I don't blame the B&M shiftkit.
Now: What if there's some metal somewhere in that valve body? Could the valves that control "automatic" upshifting inside the valvebody be sticking? Should I drop the valvebody and disassemble it?
Or, am I totally off-track here? What do you think?
I doubt the guy put the trans back together "wrong", since I have no other problems but this. His comment about "left the valve body alone" sticks in my mind...
It's rather annoying tho, to slowly pass a beater Honda, and have the trans slip- it sounds like I'm revving at the guy, asking for a race.
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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
If I take off from a stop, either moderately or hard, the trans goes thru first gear fine, and completes the 1-2 shift. It will then "slip" in 2nd gear. When I say slip, the engine rev's go way up, and the car stops pulling forward. That's when I let off the gas. The trans then clunks back in, and I can step on the gas again.
This won't happen if I take off "nicely" from a stop.
It will happen both when the car is cold, and when the car is hot.
However, here's the odd part- If I row my own gears (move the stick from 1 to 2 to 3 to OD), the trans won't slip in 2nd!
The fluid level is perfect. The fluid is red, and does not smell burnt. On the last fluid change (March), the magnet in the pan had no huge chunks of metal- it was just slightly fuzzy. The filter had barely any metal inside, either. Yes, I put a new filter back in.
The TV cable is in proper adjustment. The shift linkage is also properly adjusted. The trans mount (ES Poly) is not broken. The motor mounts aren't broken. The trans case isn't broken. There are no leaks. The TCC solenoid locks/unlocks as it should, and the wires/connector are fine.
I've tried to list it all, because nothing "simple/obvious" is wrong."Why" would the trans act up in 2nd gear when the stick's in D or OD, but work fine when I manually shift?
This trans has done this since it was rebuilt September '99. It was rebuilt by a friend of my girlfriend's father. The rebuilder was the "transmission tech" at a nearby trade school, and he charged me minimal labor as a favor. I dropped the trans out myself, and brought it to him. He rebuilt it with a stock rebuild kit, and gave me a new TC. I then put the trans up- correctly.
I mentioned to the rebuilder that I had a B&M Shift Kit in there. When I got the trans back, I asked him if he changed anything. He told me "I left your valve body alone." (I later had to go back in and pull out a checkball that he replaced by accident.)
The transmission never did this before it was rebuilt, so I don't blame the B&M shiftkit.
Now: What if there's some metal somewhere in that valve body? Could the valves that control "automatic" upshifting inside the valvebody be sticking? Should I drop the valvebody and disassemble it?
Or, am I totally off-track here? What do you think?
I doubt the guy put the trans back together "wrong", since I have no other problems but this. His comment about "left the valve body alone" sticks in my mind...
It's rather annoying tho, to slowly pass a beater Honda, and have the trans slip- it sounds like I'm revving at the guy, asking for a race.
------------------
-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
Supreme Member
I never really knew what to tell you, because I have a hard time diagnosing shift problems without being able to "feel" it for meyself. But I know you have been fighting this for awhile, and I see your pleas are getting more and more desperate, so I will take a stab in the dark.
My best guess would be that the 2-4 band is slipping. Here is why:
When a torque converter recieves insufficient pressure, it will slip under heavy load, but lockup with no or little load. ('96-97 4L60-Es are prime example). If you restore normal pressure, the TC acts normal, locks up when commanded. My theory is that the band has enough holding power to hold the Reverse Input Housing (what it clamps when applied) under light load, i.e. slow takeoff. However, under moderate or heavy load (you hauling *** ) there isn't enough holding power in the band, and the reverse input housing slips, until you let off the gas, and then it suddenly grabs.
Why doesn't it act up in manual second? Good question, and that is another reason I think it is the band. In manual first, and manual second, Line pressure increases. It does not do that for OD or D. Just 2 and 1. I think that by putting it in manual second (2), you are raising the line pressure just enough to allow the band to maintain its grip in the reverse input housing.
Now, does that mean the band is bad? No, not nessacarily, you could have a cut seal in the servo, you may have an apply pin to short, its hard to say, or the band may indeed be bad. Even though it wasn't much, you did pay the guy to do it, and it is obvious that he built it into the tranny, I think (there I go, butting into others buisness again) he has some obligation to try and help you solve it. He is a tranny tech right?
Anybody want to agree/disagree?
P.S. I'm no trans genius, I just love what I do and take it very seriously.
------------------
If you live in Southeastern US, check us out!
South East Thirdgen
"I used to have a handle on life, but then I used it as a plunger and broke it" -The Wave
ASE Master Tech + L1
Savannah, GA
'87 Trans Am-K&N,Cold air induction, SSM SFC, Boxed LCAs, 8mm Accel wires, Flowmaster, 16" GTA rims.
'97 Bonneville SSE
[This message has been edited by GMTech (edited October 04, 2000).]
My best guess would be that the 2-4 band is slipping. Here is why:
When a torque converter recieves insufficient pressure, it will slip under heavy load, but lockup with no or little load. ('96-97 4L60-Es are prime example). If you restore normal pressure, the TC acts normal, locks up when commanded. My theory is that the band has enough holding power to hold the Reverse Input Housing (what it clamps when applied) under light load, i.e. slow takeoff. However, under moderate or heavy load (you hauling *** ) there isn't enough holding power in the band, and the reverse input housing slips, until you let off the gas, and then it suddenly grabs.
Why doesn't it act up in manual second? Good question, and that is another reason I think it is the band. In manual first, and manual second, Line pressure increases. It does not do that for OD or D. Just 2 and 1. I think that by putting it in manual second (2), you are raising the line pressure just enough to allow the band to maintain its grip in the reverse input housing.
Now, does that mean the band is bad? No, not nessacarily, you could have a cut seal in the servo, you may have an apply pin to short, its hard to say, or the band may indeed be bad. Even though it wasn't much, you did pay the guy to do it, and it is obvious that he built it into the tranny, I think (there I go, butting into others buisness again) he has some obligation to try and help you solve it. He is a tranny tech right?
Anybody want to agree/disagree?
P.S. I'm no trans genius, I just love what I do and take it very seriously.
------------------
If you live in Southeastern US, check us out!
South East Thirdgen
"I used to have a handle on life, but then I used it as a plunger and broke it" -The Wave
ASE Master Tech + L1
Savannah, GA
'87 Trans Am-K&N,Cold air induction, SSM SFC, Boxed LCAs, 8mm Accel wires, Flowmaster, 16" GTA rims.
'97 Bonneville SSE
[This message has been edited by GMTech (edited October 04, 2000).]
GMTech, thanks for the reply! You might as well be a trans genius, especially since you rebuild these guys!
I really like that 2-4 band idea. The first time I asked this question, I was told it couldn't be the band, because the trans would be slipping in 4th gear.
At the time, I didn't know the trans was fine if I rowed through the gears manually, maybe that's why the person didn't consider line pressure. I didn't know that about the extra line pressure either, I hadn't read that before. Hey, wait, is that in that chart that shows a fluid pressure gauge hooked up to the test ports?? Hehe, I don't have that gauge, so I never looked at the chart!
I also can't see the band being bad.. for someone to replace everything else and leave the original band in- well, I dont' see that happening.
Your response is great! See, when I first mentioned the 2/4 band, I asked about the apply pin. I don't think they include different lengths in rebuild kits.. from the way the ATSG manual worded it, you had to order a pin if the original one didn't work. Maybe the rebuilder (man, I don't even know his name!) just re-used the original pin? Now, I'd need one of those servo-apply-pin depth gauges, right? Can one be made? Maybe I can rent one from a local trans shop. Heh, this would be a good time to get that Corvette servo- but then I wouldn't know if the pin fixed the problem or the servo. The pin just pushes the band into a "closed" position, right? Would too long of a pin damage the band, or would the servo absorb the extra length thru the fluid going into it?
I think you're right about one thing tho: Maybe I'll write up a sheet explaining this, and hand it to my girlfriend's dad to "pass it on" to the rebuilder. (grins) Heh, her dad asked me if I put the trans in wrong! Sheesh.
Hey if I bought one of those trans line pressure gauges, can the car be driven with the gauge on?
Thanks for the help! I don't see myself fixing this anytime soon, since college started back up, but I always like to have a game plan- it gets me thru the semester. "I can't wait for finals, then I can work on my car."
------------------
-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
I really like that 2-4 band idea. The first time I asked this question, I was told it couldn't be the band, because the trans would be slipping in 4th gear.
At the time, I didn't know the trans was fine if I rowed through the gears manually, maybe that's why the person didn't consider line pressure. I didn't know that about the extra line pressure either, I hadn't read that before. Hey, wait, is that in that chart that shows a fluid pressure gauge hooked up to the test ports?? Hehe, I don't have that gauge, so I never looked at the chart!
I also can't see the band being bad.. for someone to replace everything else and leave the original band in- well, I dont' see that happening.
Your response is great! See, when I first mentioned the 2/4 band, I asked about the apply pin. I don't think they include different lengths in rebuild kits.. from the way the ATSG manual worded it, you had to order a pin if the original one didn't work. Maybe the rebuilder (man, I don't even know his name!) just re-used the original pin? Now, I'd need one of those servo-apply-pin depth gauges, right? Can one be made? Maybe I can rent one from a local trans shop. Heh, this would be a good time to get that Corvette servo- but then I wouldn't know if the pin fixed the problem or the servo. The pin just pushes the band into a "closed" position, right? Would too long of a pin damage the band, or would the servo absorb the extra length thru the fluid going into it?
I think you're right about one thing tho: Maybe I'll write up a sheet explaining this, and hand it to my girlfriend's dad to "pass it on" to the rebuilder. (grins) Heh, her dad asked me if I put the trans in wrong! Sheesh.
Hey if I bought one of those trans line pressure gauges, can the car be driven with the gauge on?
Thanks for the help! I don't see myself fixing this anytime soon, since college started back up, but I always like to have a game plan- it gets me thru the semester. "I can't wait for finals, then I can work on my car."
------------------
-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
Supreme Member
I'm the one that told you it couldn't be the band previously. But there are two things to consider. First, there is more load going placed on the tranny when going from first to second, then there is going from third to fourth. When shifting from first to second, you are still trying to build momentum. When going from third to fourth, there is already significant momentum, and if the 2-4 band is slipping from load, you won't notice it *as much* as second. Second, there are two different pistons that apply the 2-4 band. In second gear, the 2nd apply piston is used, and in 4th, the 4th piston applies, both using the apply pin. So if there is a problem with the 2-4 band being caused by the 2nd apply piston, 4th won't be effected.
If the apply pin is to short, the band will slip. If the pin is to long, the band will drag, and if you don't have second gear starts and bind up in reverse, then the band will burn up, either way, not good. You will need to check the pin if you arn't sure.
If I were you (this is me now) I would pull the tranny. Put a new band in, put the proper pin in, and re-seal the entire servo asemmbly (theres five seals in there). But that would be my game plan.
But like I said, this is just a "shot in the dark" since I havn't driven it.
Yes, you can drive with a line pressure gauge hooked up, that is how it is used 50% of the time. The other 50% I use it to do a PC Solenoid function check (Electronic Transmissions).
------------------
If you live in Southeastern US, check us out!
South East Thirdgen
"I used to have a handle on life, but then I used it as a plunger and broke it" -The Wave
ASE Master Tech + L1
Savannah, GA
'87 Trans Am-K&N,Cold air induction, SSM SFC, Boxed LCAs, 8mm Accel wires, Flowmaster, 16" GTA rims.
'97 Bonneville SSE
If the apply pin is to short, the band will slip. If the pin is to long, the band will drag, and if you don't have second gear starts and bind up in reverse, then the band will burn up, either way, not good. You will need to check the pin if you arn't sure.
If I were you (this is me now) I would pull the tranny. Put a new band in, put the proper pin in, and re-seal the entire servo asemmbly (theres five seals in there). But that would be my game plan.
But like I said, this is just a "shot in the dark" since I havn't driven it.
Yes, you can drive with a line pressure gauge hooked up, that is how it is used 50% of the time. The other 50% I use it to do a PC Solenoid function check (Electronic Transmissions).
------------------
If you live in Southeastern US, check us out!
South East Thirdgen
"I used to have a handle on life, but then I used it as a plunger and broke it" -The Wave
ASE Master Tech + L1
Savannah, GA
'87 Trans Am-K&N,Cold air induction, SSM SFC, Boxed LCAs, 8mm Accel wires, Flowmaster, 16" GTA rims.
'97 Bonneville SSE
Oops, I'll definately have to check my GM manual, then! I thought there was only one piston inside the servo. I don't know if dropping the trans out to replace the band is an option.. I have no other car to get around with. I might try removing the servo and checking the pin depth. That can be done with the trans in the car, right? Oh, hm, I might have to lower the trans to get at the servo tho.
I do see your point tho; that band is probably a little thrashed right now, and should be replaced. (sigh) Can the reverse input housing wear down too?
This goes along with my idea of "Next time this trans goes, I'm converting to a manual, or I'll rebuild it myself!"
Maybe I'll pick up that pressure gauge. Someone's gotta sell one around here...
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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
I do see your point tho; that band is probably a little thrashed right now, and should be replaced. (sigh) Can the reverse input housing wear down too?
This goes along with my idea of "Next time this trans goes, I'm converting to a manual, or I'll rebuild it myself!"
Maybe I'll pick up that pressure gauge. Someone's gotta sell one around here...
------------------
-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards