Interesting Automatic Transmission Behavior (2007 Chevrolet Silverado Classic 1500 4x4))
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- Опубліковано 17 лют 2015
- While preparing my truck for a long road trip, I discovered the transmission was doing something interesting when it was in neutral with no resistance against the driven wheels! Lucky for you, I had a video camera with me!
I have noticed the inverse of this behavior when coasting to a stop in neutral. As long as the driven wheels were rotating, the engine would not return to its normal idling speed.
I have not seen this behavior from other GM 4L60E transmissions, including the one in my S10 pickup truck.
Yes I meant to say "coupling between the engine and driveline" (or driven wheels) instead of "engine and transmission". The engine and transmission are very directly connected unless someone takes them apart!
Running a vehicle when it's up on a lift like can be very dangerous, especially if the balance shifts or you get tangled up in a spinning driveshaft. Don't do this unless you're very sure of what you're doing, and willing to accept all the responsibility for any result good or bad. It's also not a good idea to run an automatic transmission for a long period without a load it can work against.
The "service engine soon" light is on as a result of a faulty gas cap that I'll replace sometime, and the ABS fault/service brake system warnings are on as a result of the front wheel sensors saying that the vehicle is standing still while the rear differential sensor says it's moving. - Авто та транспорт
My guess is the transmission expects a certain degree of resistance from the wheels in order for all of its magical inner workings (clutches/bands/planetary gearset/etc.) to reach their proper state for the gear position you select. Thus it is indeed probably "not good" to do this trick for too long!
I've never seen that on an automatic transmission. A few days ago I started my lawn tractor (which was in neutral) and since the gear oil is so thick at 25F, and the gears are so close together, it started to roll away as if it were in 1st or 2nd gear. I thought that was interesting.
nice truck you have
My understanding from what I have learned recently is that this is probably caused by the clutches not completely disengaging because of fluid viscosity. On later model transmissions they add a "Volute" to the steel clutches to reduce drag caused by this "viscosity drive/drag" symptom. My 2001 4l60e will sometimes surge ahead when first started cold in park or neutral and I assume its because of this.
It didn't come through right in the video (since I worded it incorrectly) but that''s exactly why.
normal.... i've noticed it too. also in the garage in the morning if i put my truck in neutral and start it it will lurch forward.
I'm hoping my truck does well tomorrow night. It's supposed to be around 3F when I get off at 11:30.
i had THM2004R that did this in my 1984 Hurst/Olds if you had the Lightning Rods in manual shift mode
Linkage issue or clutches not disengaging on planetary (no held member creates neutral)
Not sure why this happens, none of the clutches are engaged in neutral, its possible that with no resistance the friction of the oil in the clutches might be enough to let a small amount of movement through the transmission.
Might be a GM recall on this......there's been so many already it doesn't surprise me.
Was thinking it was the stepper motor in the cluster, until I saw the wheels moving.
Wow, just to put this to rest.. 1. Normal completely for this to happen. Planetary gears will do this, as the input shaft is never disconnected from the torque converter, the gears are disengaged from one another. No worries, and you can do this all day without issue, and nothing is wrong with the transmission, linkage, selector anything else mentioned in the other comments.
2. No damage is done by running it off the ground and in gear, and it will shift properly and with out issue, in all gears. Its just going to seem like its shifting funny because the engine load is very close to zero, which will cause it to shift quicker and at different speeds. Its more likely to be damaged by putting the transfer case in neutral and doing this, as you'll have no indication when the output shaft has stopped its rotation, and if you put it in reverse or park it'll wear it a bit (park especially, cause the locking pin to click loudly and possibly damage the mechanism)
what can cause a 2006 chevy silverado to tell me to service airbag soon
I think this is standard in automatic transmissions. I had a Honda CR-V 2004 AWD on ramps like that to fix a "juddering", and the service document said the wheels would spin.
However, I now have a Peugeot 3008 and that is FWD and a manual, and while the engine turned the wheels where rotating. They stopped when the engine was on. So I wonder if this is a common trait of all gearboxes? Maybe to prevent damage to the clutch and/or gearbox?
My dad's 3rd gen Grand Caravan does that too. Right after it got it's first transmission rebuiild at 291k miles.
I was towing a car the other day with a rollback and accidentally lifted the rear wheels off the ground when I tilted the bed. Even with a manual transmission, the driver side tire started spinning. It was pretty easy to stop by hand though.
yes that is normal for automatics, my falcon does it (BA XR6)
nah. you were just going down a virtual hill, bro.
Where's the CandyHam?
I honestly don't think there is anything to worry about because all of my vehicles seem to do the same thing. Especially when it's cold out. Although my vehicles are from the 80's, maybe new vehicles aren't supposed to do that
My Honda CBR motorcycle does that. It's probably caused by cold oil in your trans. How long was it in the shop? Maybe try it again after running it for a bit to see if continues. If you are truly worried about it, you could always just give er a trans oil change and see if theres any excessive guck in the oil.
Shift linkage might have some slop
Yup its fluid coupling
its gearbox drag, nothing unusual at all, manual gearboxes in neutral can do this too, its due to oil, sometimes one wheel can rotate but no the other
its normal. but the amount of torque transfers to the wheel is very low. you can easily hold the wheel by hand.
This is called "Drag Torque" - even when things are disconnected the fluid between the clutch plates in the packs will transfer a little power. This is just a thing with wet clutches.
What was the truck doing at the shop for i see that put of the dash is taken off?
this happened in our trailblazer.... 2003 model while it was on the ground, Then it would barely shift and you had to shift it manually at some points... they wouldnt fix it so we turned it in to the bank
In other words, let it get repo'd. A repo is repo regardless if you make them come get it or drive it to them.
Yeah, what choice did we have we couldn't afford to pay on a car we couldn't drive. They sold it at auction for 6,500 and I dont know how but somehow we owed well over 7,500 on it. Still better than paying $5000 for a new transmission, a bumper that was messed up thanks to their "Professional" towing services,paint for a fender that they put on, We now drive an 08 nissan rogue with a better warranty, LESS than 75,000 miles, better on gas and a better bank that charges less per month, everything worked out in the end except we have to pay what we "owe" the ripoff bank we bought it from, They lied to us and told us that trailblazer had a new transmission - We found out otherwise from a transmission shop. We saw the same car on the highway broke down the other day, smoking. The bumper was still messed up and the fender was still green.
I have the exact same truck exact same year and yes it is a 2007 classic. It has done this as well. I’ve had it for only one day and it has been raining so hopefully the case is the computer aren’t picking up the amount of resistance from the wheels. It was perfect when I test drove it on a dry day. No problem at all.
So if someone could please comment back to confirm this or deny it. Cause I know it had trouble with the computer in the truck with the ac before I bought it so my theory is maybe it’s with the computer cause when I got going on a somewhat not extremely wet road it was perfectly fine.
Interesting. I've noticed that when I'm letting my car (auto trans) coast in neutral, it tends to idle about 150rpm faster than when it's stopped. I wonder if this could be why. I've always assumed the ECM was just programmed that way.
My 2000 gmc sierra 4.8. I could rev it in park and the spedo would move up in mph.
A lot of automatic transmission vehicles I have had in the air, on a lift, as you did, have done the same thing. There is never a 100% decoupling inside of an automatic transmission.
+WaybackTECH Indeed. Neutral is really just the transmission backing off torque amplification as much as possible when it comes to an automatic, whereas neutral in a true standard transmission or transaxle is actually neutral. No such thing as drive to the wheels of any kind whatsoever when this happens.
I wonder why your transmission has an analog gear position indicator? my 04 fleet model which is a few years older than this also with less features came with a small digital LCD panel that lists gears and currently selected gear yet yours has the gears printed on the gauge with a series of LEDs beneath each gear position to indicate which gear you're in... I do like yours better because the solder joints on mine have become weak and dim due to heat but if mine was working correctly it would be the superior design yet its on an older truck of the same make and model and generation
Your truck's gear indicator is actually a vacuum fluorescent display. I believe the indicator in this truck is using LEDs in its gear selector display. Even as neat as I think they are, VFDs have a few problems: they require fairly complex drive circuitry, they dim as they wear out, and in sunlight they tend to wash out or show the other indicators.
73 would be nice. I literally felt the blood freeze in my fingers as I walked out to my car after work (it's really not a nice feeling).
Florida anyone? I think Florida would be nice right about now.
***** Nah, florida is nice and all but here in Vegas we just set a new record for consecutive days over 70 degrees... the previous record was 13 days in a row!
Lucky. I'm stuck here in Iowa and I'm having to deal with blood freezing temps after work (and the Buick doesn't have a working blower so...yeah).
Why don't you move out of Iowa then? Forget Florida. Warm weather. But that's about it.
Try an mess with the shift linkage that's your problem it's a Lil lose or the small blk box on the side needs to calibrate take it of and put it back on
***** well I had a similar problem once I would put it on park and will only show to go up to reverse so I messed with it for a while. But anyways nice video keep up the good we work.
Broken geers?
Is it the loose coupling from the oil in the transmission bill ?
Why is it moaning about an engine problem?
This is actually normal. With no load on the wheels/tires it will spin them. We used to use that same method to test for broken belts in tires as in neutral it won't spin the tires with power. If someone had been right there to grab the wheels it would have stopped spinning and just revved.
I'd say the transmission isn't properly decoupling from the torque converter while in neutral, or the shifter really isn't in the neutral position and needs to be adjusted. That could be a safety hazard if it happens while the wheels are on the ground which it sounds like it is. Putting a vehicle in neutral while it is coasting should cause the engine RPMs to drop and you would lose any engine braking.
Another test, put the truck in neutral and let go of the brake pedal, the truck should not creep forward at all.
Automatic transmissions are not like manual gearboxes where in Neutral, it is a 100% decoupling from the TC. Not unless you have massive amounts of wear on the clutch packs, with low fluid pressure inside of the automatic transmission as a result. There is always some degree of movement inside of the AT which transfers to the wheels.
this is normal. dont worry.
***** :-)
Ahh good old GM, The ABS is due to sensors in the front wheels, if you can spare the money get new GM wheel bearings, with sensors in them..
Where are you headed?
lol. hahaha. Thought you were trying to escape the insane cold back that way. No in August I'm going to Michigan all the way from Wyoming. Going to swing through Chicago and see where they film Chicago Fire.
It's just transmission fluid drag
right on!
That was my guess, seemed like the only explanation that makes sense.
that's why from all of my 6 cars I got, only one is automatic, they are a problem. I understand that there aren't manual cars in north America because they have to use cruise control, but you cannot accelerate very well on an automatic, specially CVT, you hit the gas, it revs a lot and you are still going at 30; but when you go to 70 (I'm talking about KM/H) and hit the gas, the thing throws you at a billion kilometers per hour!! I can use an automatic here, but manual works better on bad messy Peruvian traffic.
weird problem happening to you by the way; I hope your car is working better now.
***** thanks for the quick reply!
cruise controlled manual? wow! I never thought that ever existed, that would be cool to see...
I wish I could have at least few segments of the road that can be wide enough for a late 80's Cadillac brougham or a similar car; people don't know how much I would love to have one of those, unfortunately, making turns over and over and avoiding obstacles makes impossible to make this cars being used on my city's/cities? roads.
but you are right about normal automatic transmissions, I remember that my mother had a JDM 1996 Nissan sunny (sentra) with a classic automatic gearbox, and it ran well, but my 2005 Nissan primera is another story, and let's not talk about vision, oh man, it's easier to see through the spirit of st. Louis periscope than seeing though my windscreen, that's why I love old cars, thin pillars, oh yeah!
taunusv4power My 88 Mustang has a manual transmission with cruise control. Granted, I need to fix some wiring between the vehicle speed sensor and the ECU to use the cruise control again... lol. My wife's car has a CVT (Nissan Versa) and it accelerates on the city and highway with rather ease. I'm clear to say I've never had much of a problem with auto or manual transmissions.
Cruise control works in cars/trucks hat have a manual transmission as well, it does the same thing, operate the throttle. Generally when you have cruise control on, you're cruising on a relatively flat and straight highway, so you'd be in cruising in 5th if it's a 5 speed, you'd be in overdrive maintaining a constant speed. The difference is that if you hit a hill and need to downshift to keep up you'd hit cancel or it would automatically cancel as soon as you hit the clutch, just like when you hit the brake. With an automatic, the cruise control opens the throttle and it automatically downshifts and accelerates without you having to do anything when the speed decrease is detected as you start up the hill.