trans temp higher in reverse????
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Elder User
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trans temp higher in reverse????
i have a trany that is still under warranty but as i was backing up a couple of times in a row on a steep driveway i noticed that my trans temp gauge slowly raised a little bit. it barely went over 180 deg but i still could tell that it seemed to rise a little in just a matter of a few minutes
is this just the way they do in reverse???
thanks guys
is this just the way they do in reverse???
thanks guys
Senior User
Joined: Jun 2005
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From: Houston, TX
Mine does the same thing. No real air flow going over the cooler, backing a trailer or up a driveway puts a load on the tranny while the cooler is not getting airflow to cool. As soon as I go forward and pick up any speed it cools right down so I've never worried about it.
Posting Guru
Joined: Feb 2004
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From: Elverson, PA
Yep - what the other guys said - and I THINK I read that when in reverse - the fluid doesn't even flow through the coolers (but I'm not 100% sure on that)... I personally know 2 guys that killed 4R100's backing heavy trailers up hills!
I always use 4-low (without locking in the hubs - just for the gear reduction) if I have to back around on a hill - it's a LOT easier on the tranny.
I always use 4-low (without locking in the hubs - just for the gear reduction) if I have to back around on a hill - it's a LOT easier on the tranny.
Postmaster
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From: colorado
Originally Posted by CAT_man_963
- and I THINK I read that when in reverse - the fluid doesn't even flow through the coolers (but I'm not 100% sure on that)...
Lead Driver
Joined: Oct 2004
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From: Columbia, MO
Originally Posted by CAT_man_963
I always use 4-low (without locking in the hubs - just for the gear reduction) if I have to back around on a hill - it's a LOT easier on the tranny.
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Originally Posted by wlihntr
i remember reading something like that as well..like the pump does not run in reverse or it runs much slower.
Trans oil flows to the cooler in reverse. In fact, it flows a bit more in reverse because pressures are higher in reverse, so there is more flow.
The key is that there is little airflow over the coolers in reverse. Add that to most reversing is at low speed where the torque converter has high slip. High slip creates A LOT of heat in the torque converter, which doesn't get cooled well with the little airflow.
The only chance to cool in reverse is the radiator cooler. The air to oil aux cooler is almost worthless in reverse. That's why it almost always is a bad idea to bypass the radiator cooler.
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Postmaster
Joined: Nov 2003
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From: Utah County, UT
Originally Posted by Casey
The pump is connected to the engine. If the engine is running the pump is running at the same speed.
Trans oil flows to the cooler in reverse. In fact, it flows a bit more in reverse because pressures are higher in reverse, so there is more flow.
The key is that there is little airflow over the coolers in reverse. Add that to most reversing is at low speed where the torque converter has high slip. High slip creates A LOT of heat in the torque converter, which doesn't get cooled well with the little airflow.
The only chance to cool in reverse is the radiator cooler. The air to oil aux cooler is almost worthless in reverse. That's why it almost always is a bad idea to bypass the radiator cooler.
Trans oil flows to the cooler in reverse. In fact, it flows a bit more in reverse because pressures are higher in reverse, so there is more flow.
The key is that there is little airflow over the coolers in reverse. Add that to most reversing is at low speed where the torque converter has high slip. High slip creates A LOT of heat in the torque converter, which doesn't get cooled well with the little airflow.
The only chance to cool in reverse is the radiator cooler. The air to oil aux cooler is almost worthless in reverse. That's why it almost always is a bad idea to bypass the radiator cooler.
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The primary reason for the increase in trany temp is from the 2.18 reverse gear ratio. That is why it is recomended that if you have 4X4 you use low range to protect the trany. The reason for the failure of 4r100s when backing up with heavy loads is do the the use of the coast clutch which is a week link, at least that is what I've been told.
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