Cold Temps?

[CenWaSS]

So I took the SS out today and felt the urge to get on her. Funny thing is, when shifting into third gear she hit the rev limiter instead. I let off a little and she shifted hard (like normal) into third. I tried it again and the same thing happend. Except for hard acceleration she shifts just fine, no problems.

 

I was thinking she may be acting like this due to the cold temps? My trans temp doesnt even register, as the outside temps have been well below 20 deg. Could that be the problem?

 

Any ideas?

[Fireman31]

temperature may very well be the cause, but if it persists, your trans may actually be slipping......

Edited December 17, 2008 by Fireman31 (see edit history)

[misterp]

Yup I would blame the cold weather; the PCM will shift the transmission differently if ATF is below 100-degrees and in the weather you describe that takes a good 5+ minutes of easy driving to get up to temp; you will know because you'll have 4th but no lockup clutch until that temp is reached.

 

Mr. P.

Edited December 17, 2008 by Mr. P. (see edit history)

[CenWaSS]

Yup I would blame the cold weather; the PCM will shift the transmission differently if ATF is below 100-degrees and in the weather you describe that takes a good 5+ minutes of easy driving to get up to temp; you will know because you'll have 4th but no lockup clutch until that temp is reached.

 

Mr. P.

 

I guess I need to place something in front on the tranny cooler, my gauge never increased above 100 deg. With the windchill the news said it is more like 5 deg or less.

 

I was driving for over 45 minutes and temp indication barely reached just over 100 deg, like maybe 105deg?

[Black2003SS]

I was running into a similar issue on my built trans. I even took it to the trans shop to have them look at it. It started in this cold weather. The trans builder told me to not run my efans so much to let the trans heat up. He also asked me to stay out of it until it warms up because hard acceleration can cause excess wear on the clutches I guess. He said the trans is fine and after letting the trans warm up, it does shift right like it did in summer weather. I still have about 12k miles left on a 24k mile warranty from him. Mine never hit the rev limiter though, it would just feel like it was slipping. He said when the fluid was cold, it is obviously thicker/heavier and said it is harder for the trans to pump up something to shift properly. I was in a hurry and when he said everything was ok, i was good to go.

[CenWaSS]

Damn cold whether! I swear my SS felt like a 13 sec truck until I hit the rev limiter this is. I dont drive it much in the winter, but when I do I guess I'll stay out of the pedle.

[misterp]

I guess I need to place something in front on the tranny cooler, my gauge never increased above 100 deg. With the windchill the news said it is more like 5 deg or less.

 

I was driving for over 45 minutes and temp indication barely reached just over 100 deg, like maybe 105deg?

My transmission performs best at 155-ish; if you run ATF below 140-ish then water inside the transmission will never be boiled-off, you'll have moisutre trapped in there and over a little while you'll build a varnish on the face of all clutches in the transmission (bad bad bad). Also, with extreme cold (below 110) the little valves and plungers in the valve body will not move quick enough, and you'll get erratic shift behavior as a result (which is what you describe in your initial post). Both of these conditions will lead to slipping/burnt clutches. This is why even with an external transmission cooler the factory still runs the ATF through the radiator (to put heat into the ATF in the winter); I would snip a little piece of sheet metal and zip-tie it over part of the external transmission cooler for a while. The high-tech answer is to get a hydraulic oil thermostat set at 150-degrees, I would eagerly use the Tru-Cool one but it's way too hot (180-degrees).

 

Mr. P.

Edited December 19, 2008 by Mr. P. (see edit history)

[CenWaSS]

My transmission performs best at 155-ish; if you run ATF below 140-ish then water inside the transmission will never be boiled-off, you'll have moisutre trapped in there and over a little while you'll build a varnish on the face of all clutches in the transmission (bad bad bad). Also, with extreme cold (below 110) the little valves and plungers in the valve body will not move quick enough, and you'll get erratic shift behavior as a result (which is what you describe in your initial post). Both of these conditions will lead to slipping/burnt clutches. This is why even with an external transmission cooler the factory still runs the ATF through the radiator (to put heat into the ATF in the winter); I would snip a little piece of sheet metal and zip-tie it over part of the external transmission cooler for a while. The high-tech answer is to get a hydraulic oil thermostat set at 150-degrees, I would eagerly use the Tru-Cool one but it's way too hot (180-degrees).

 

Mr. P.

 

Thanks Mr P. Very good info, thanks again