Forum Discussion
wilber1 wrote:
ShinerBock wrote:
wilber1 wrote:
Two days ago we pulled the rig in my signature up 4000 ft from Bakersfield to Tehachapi, GCWR would have been between 21,000 and 22000 lbs. Tranny temp at the bottom was 130F and when we reached the top it was 145F. OAT was between 40 and 45F. Almost all of that would have been due to several 4-5-4 shifts that took place during the climb.
When you talk about adding power, different versions of the ZF 8HP are used in everything from 200 HP four bangers to the 840 HP Dodge Demon.
I have a 2014 CTD and my temp generally stays around 170 when not towing and has gotten up to 180 when towing once. I am amazed that you can pull your 5ver up hills and maintain temps 30-40F less than what mine does when not towing.
Maybe I am pulling less weight. Maybe because it was a cool day. The hill also started about 20 miles after we began our day and the transmission might not have been up to normal operating temp when we started up the hill. I was still only showing 145 when we got to the top. I've seen mine at 180 puling the same loads up grades in the summer. My real point was that there was only about 15 degrees difference between start and finish. Of course the ambient temperature would also have been lower at the top of the hill.
My transmission is 165-170F unloaded even if it is 20F outside. The only thing that colder OAT's do to my trans is extend the time it take to reach 170F, but it will generally get there within 20 minutes of driving. So a max of 145F even if you weren't towing is odd to me.ShinerBock wrote:
wilber1 wrote:
Two days ago we pulled the rig in my signature up 4000 ft from Bakersfield to Tehachapi, GCWR would have been between 21,000 and 22000 lbs. Tranny temp at the bottom was 130F and when we reached the top it was 145F. OAT was between 40 and 45F. Almost all of that would have been due to several 4-5-4 shifts that took place during the climb.
When you talk about adding power, different versions of the ZF 8HP are used in everything from 200 HP four bangers to the 840 HP Dodge Demon.
I have a 2014 CTD and my temp generally stays around 170 when not towing and has gotten up to 180 when towing once. I am amazed that you can pull your 5ver up hills and maintain temps 30-40F less than what mine does when not towing.
Maybe I am pulling less weight. Maybe because it was a cool day. The hill also started about 20 miles after we began our day and the transmission might not have been up to normal operating temp when we started up the hill. I was still only showing 145 when we got to the top. I've seen mine at 180 puling the same loads up grades in the summer. My real point was that there was only about 15 degrees difference between start and finish. Of course the ambient temperature would also have been lower at the top of the hill.wilber1 wrote:
Two days ago we pulled the rig in my signature up 4000 ft from Bakersfield to Tehachapi, GCWR would have been between 21,000 and 22000 lbs. Tranny temp at the bottom was 130F and when we reached the top it was 145F. OAT was between 40 and 45F. Almost all of that would have been due to several 4-5-4 shifts that took place during the climb.
When you talk about adding power, different versions of the ZF 8HP are used in everything from 200 HP four bangers to the 840 HP Dodge Demon.
I have a 2014 CTD and my temp generally stays around 170 when not towing and has gotten up to 180 when towing once. I am amazed that you can pull your 5ver up hills and maintain temps 30-40F less than what mine does when not towing.- Two days ago we pulled the rig in my signature up 4000 ft from Bakersfield to Tehachapi, GCWR would have been between 21,000 and 22000 lbs. Tranny temp at the bottom was 130F and when we reached the top it was 145F. OAT was between 40 and 45F. Almost all of that would have been due to several 4-5-4 shifts that took place during the climb.
When you talk about adding power, different versions of the ZF 8HP are used in everything from 200 HP four bangers to the 840 HP Dodge Demon. - Since 2014, GM 1500's have had thermostatically controlled transmission cooling. 200 degrees F. +/- is normal operating temperature. My 2014 Silverado towing 8000 lbs in 100 degree F. ambient never got over 205 degrees F.
wilber1 wrote:
According to the comments section in the article I linked, the solenoids usually give up before the friction surfaces.
That really depends on the Transmission. Look at a 4L80E VS a 4L60E.
I have burnt up a few 60's in my 11 second F-bodies. Never any selnoid stuff, but you look at a 4T65E HD in like a Grand Prix GTP/Regal GS. It is the luck of the draw. Genearlly a shift kit will help with the life of those, but they have selnoid and hard part problems too.
Bottom line is if you want to increase cluth life you up line pressure, and you may get hard, crisp, faster shifts and a lot of the slippage goes away but other stuff could wear out depending on power levels. Most modern transmissions do a pretty good job on the stock tune with stock line pressure and clutch life isn't even a concern or hard parts for that matter until you start adding power.wilber1 wrote:
ShinerBock wrote:
wilber1 wrote:
If any clutches slip under high power, they will be toast in a short time.
True, and as I stated above this kind of slippage will not happen any time soon, but it will eventually happen. However, the slippage during constant shifts(which happens a lot when towing) and other things I stated above will cause the fluid temps to rise and decrease clutch life.
According to the comments section in the article I linked, the solenoids usually give up before the friction surfaces.
A normally aspirated engine with a narrow torque curve can be expected to do more shifting than a boosted engine with a fat torque curve. The transmission temperature probably has more to do with the engines than the transmissions.
I don't pay attention to the comments section of articles because you don't know the experience and knowledge of the person making them. Do they actually have experience or are they going of what someone else has stated? Also, are they referring to cars when they state that the solenoids go out before the clutches or is with heavy trucks towing thousands of pounds like we are discussing here? There will be a huge difference in shift slippage and clutch wear between the two.
Either way, it is neither here nor there because as we have seen in the video I posted, the ZF 8 speed can and does get hot when towing due to the reasons I stated earlier. One of them being due to slippage during constant shifts and trying to move more weight while towing. If that XF in the link I posted got up to 203F towing just 7k in the cold, I am sure it will get much hotter towing close to max (@ 11k) in the heat of summer.ShinerBock wrote:
wilber1 wrote:
If any clutches slip under high power, they will be toast in a short time.
True, and as I stated above this kind of slippage will not happen any time soon, but it will eventually happen. However, the slippage during constant shifts(which happens a lot when towing) and other things I stated above will cause the fluid temps to rise and decrease clutch life.
According to the comments section in the article I linked, the solenoids usually give up before the friction surfaces.
A normally aspirated engine with a narrow torque curve can be expected to do more shifting than a boosted engine with a fat torque curve. The transmission temperature probably has more to do with the engines than the transmissions.wilber1 wrote:
If any clutches slip under high power, they will be toast in a short time.
True, and as I stated above this kind of slippage will not happen any time soon, but it will eventually happen. However, the slippage during constant shifts(which happens a lot when towing) and other things I stated above will cause the fluid temps to rise and decrease clutch life.- If any clutches slip under high power, they will be toast in a short time.
