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Transmission engages slowly in reverse


cdictas

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Hi Guys,

I have a transmission question. I have a 96 STS with 100K on the tranny. Lately I've noticed in the cold New England mornings when I start my car and put my car in reverse it takes several seconds for the transmission to engage. It only happens in the morning and in reverse. When my car was younger :D, this problem never occurred. Is this the begining of trouble?

Thanks,

:unsure:

Chuck

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I have a 96 Deville and HAD the same problem, check your fluid immediately its a sign that the fluid is low that shows up when the weather is cold and the fluid is thick and the sucking of the pump creates a vortex due to the increased surface tension... bbobynski set me straight on this...

If you search my name and tranny slow to reverse you should find the post

Mike

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Rerverse is engaged by applying the direct clutch and the low reverse band. It is possible that the low reverse servo is bleeding down overnight or that it has a small leak. When the fluid is cold the pressure comes up but the volume goes down. It may take longer to fill the servo. I would definately do a pressure check as it is shifted into reverse while cold. A drop of more than 10 psi in pressure followed by an increase to reverse pressure would signal an internal leak. Definately check the fluid to see if it smells burned. You will have to deal with this as it will probably just get worse. I would look in to it now so that if it is a servo seal or cracked servo it can be repaired before other damage is done.

HTH

John

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My fluid seems to be at the right level but it's foamy and therefore hard to tell--should I worry about the foamy part? My problem: gas mileage sucks cuz the tranny won't shift into 4th until about 42 (instead of the 35 it used to) amking the around town hops expensive! Thanks!

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My fluid seems to be at the right level but it's foamy and therefore hard to tell--should I worry about the foamy part? My problem: gas mileage sucks cuz the tranny won't shift into 4th until about 42 (instead of the 35 it used to) amking the around town hops expensive! Thanks!

Foaming is a sign of the ingesting air I believe, when was it changed last? It sounds like your fluid is low and possibly in need of a change, use Dextron lll. I heard somewhere when the fluid is low, it creates problems with the higher gear shifts

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To cdictas

Definately check the fluid level first. Don't borrow trouble. Sorry that wasn't clear.

To rllovett

Foamness shouldn't change the shift points. They are controlled by the PCM. Take a snapshot of an upshift and post TPS, VSS and engine VIN code. One of us can look up the shift point using the TPS in the service manual. If the shift point is correct it will be likely your problem is not in the trans. Anything that causes the need for more TPS to get to speed (reduced power output) will cause the PCM to shift the trans later. This will be most pronounced in 4th due to higher loading.

HTH

John

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To cdictas

Definately check the fluid level first. Don't borrow trouble. Sorry that wasn't clear.

To rllovett

Foamness shouldn't change the shift points. They are controlled by the PCM. Take a snapshot of an upshift and post TPS, VSS and engine VIN code. One of us can look up the shift point using the TPS in the service manual. If the shift point is correct it will be likely your problem is not in the trans. Anything that causes the need for more TPS to get to speed (reduced power output) will cause the PCM to shift the trans later. This will be most pronounced in 4th due to higher loading.

HTH

John

If its foaming because its low that's not good. And I agree the shift to 4th at 42 is not high, and its related to a whole host of issues, like you said. But, he is NOT getting a good read on his fluid level because of foaming and he needs to resolve that

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If its foaming because its low that's not good. And I agree the shift to 4th at 42 is not high, and its related to a whole host of issues, like you said. But, he is NOT getting a good read on his fluid level because of foaming and he needs to resolve that

I will tenatively agree with you if looking down into the trans it looks like the beer was poured too fast. However from the other board I knew that the Trans Temp was 43C or around 100 F. Because of this I assumed :unsure: that the foaminess was air bubbles on the stick trapped due to higher vicosity. The trans fluid will get some air in it as it comes through the rotating assy. Any air still in the fluid after scavenging will rise to the dipstick area. The colder the fluid is the longer it will retain air. More than a few bubbles on the surface of the fluid is too much. It should definately be checked again when the dipstick is too hot to touch.

John

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My fluid seems to be at the right level but it's foamy and therefore hard to tell--should I worry about the foamy part?  My problem: gas mileage sucks cuz the tranny won't shift into 4th until about 42 (instead of the 35 it used to) amking the around town hops expensive!  Thanks!

"foamy and hard to tell doesn't sound too good", that is all I am saying. I don't think his shifting at 42 is a problem, it could be light pedal/TPS causing that and its normal. His foamyness sounds excessive given that he is having a hard time reading it.... It could be due for a change as the anti-foaming component is depleted if its not running low and aeriating...

I did a little research before into tranny fluid, and anti-foaming seems to be something the manufacturers strive for, see this

RTF - Racing Transmission Fluid

RTF has been tested and proven to run up to 30° F cooler, even during extreme-heat racing sessions and repeated usage. RTF is uniquely formulated using a new oil-soluble molybdenum additive that greatly reduces internal friction and heat, yet does not affect clutch and band lock-up. It is made using base oils with extremely high viscosity index and the fluid contains a special defoamer agent that reduces fluid foaming even at 10,000 rpm. In addition, RTF contains extreme pressure additives to help control gear fatigue and fracture, actually forming a fluid cushion from metal-to-metal contact.

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