TheMoose

The 1~2 & 2~3 shifts are smooth & regular but when it shifts into 4th it shifts kinda hard & immeadiatly shifts into OD.
It shifts liike that at both light throttle cruising & medium throttle applications.

I'm just wondering if this is a normal shifting pattern or if this is something I need to tell my dealer about when he does my first oil change (there doing it for free the first time then I'll do my own)

XTOAK

Mine shifts exactly the same way...was very surprised the first few times when I drove it but got used to it. I asked the dealer and he said that it was normal.

bh74731

Moose, I think 4th is overdrive. What you may be feeling is the torque converter locking up. Mine does it at about 50mph.

Gunship Guy

Mine shifts the same way. Right at 50 mph too. I can set my watch to it, it's that consistent. Must be normal.

SuperGewl

Actually 4th is not overdrive. You have 4th & then overdrive with the torque converter lock up. Then just so happen to shift at about 45mph under light to medium throttle.
On the 47re Trannies when it does that shift somtimes you get a shudder because of the tranny dip stick being tie wrapped to the heater hose. Take a look at that under the hood and see if is. If so make sure that all of the exhaust clamps are real tight then put a big piece of rubber between the two and the shudder will go away.

bh74731

May be a matter of semantics. The 48RE is a four speed transmission - 3rd is direct drive and 4th is overdrive. When the torque converter locks up there is a drop in rpm as if going to another gear.

Matt400

[quote author=TheMoose link=board=20;threadid=18816;start=0#msg176466 date=1061832121]
I'm just wondering if this is a normal shifting pattern [/quote]I think what you are feeling is the converter lock up at 50mph which drops the R's way down, plants you into the seat and even note a speed increase with no additional throttle....I love it when it does that, its a reminder of how much torque is being put to the ground. If you switch overdrive off you will still get TC lock up but it won't feel the same as TC lock up with overdrive on.

Old School

Yeah Moose, mine does it too, and like Matt 400 I've come to enjoy it as well. It's also fun when someone who is not familiar with the pickup is riding with you, and it does that. When they look at me with that look (What the heck??) I just smile and say "Hummin Cummins". ;D

Goldenbear

I have about 6000 miles on the truck now and I have noticed that the shifting (48RE) has smoothed out a little since I took delivery in May. During smooth acceleration, I don't even feel it going into OD, but under hard/heavy acceleration I can feel and hear the tranny clunk into OD. It's NORMAL.

TheMoose

Yea I think you guys are right, it's the TQ lock up that I was feeling.
After a bit of driving around & paying close attention it was shifting smooth in to 2nd, 3rd, 4th & then OD & the TQ lock up is what was making the hard shift feel.

I guess it's all the torque that I'm feeling when it locks up!!!! ;D

Matt400

[quote author=TheMoose link=board=20;threadid=18816;start=0#msg178877 date=1062308230]I guess it's all the torque that I'm feeling when it locks up!!!! ;D
[/quote]Yep, when the converter locks you get an instant direct lock between the engine and rear end, feels like popping the clutch out on a manual. ;D

cp

Mine shifts very quickly through the top two gears, especially when cold.

Also, when decelerating, mine seems to drop completely out of gear at around 45 mph. The engine is at 750 rpm. Is that normal?

phox_mulder

[quote author=cp link=board=20;threadid=18816;start=0#msg179085 date=1062384646]
Also, when decelerating, mine seems to drop completely out of gear at around 45 mph. The engine is at 750 rpm. Is that normal?
[/quote]

Yes, normal.

That is the reason an exhaust brake doesn't work on a stock automatic transmission.
Torque converter unlocks when you take your foot off the go pedal.


phox