What gear and speed were you driving? A look at the link tables would say if you were locked or unlocked.
Where are you reading the trans temps?
Express Van Upgrade Cooling System With a 2 Row Radiator
- Thread starter youngnretired
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Where are you reading the trans temps?
youngnretired
Senior Member
We're scheduled to be in Vegas Oct 10-14, and again on the 16th. That 16th date may slip as we don't have any scheduled meetings with anyone after the 14th
youngnretired
Senior Member
We're doing route 66 except heading to Vegas and up by Reno to visit family and meet a business associate, then back to route 66 to finish going west.
youngnretired
Senior Member
We've been on parts of it, but this will be a focused trip to travel as much of it that we can, and to stop and smell some of the roses along the way. It is the destination.
youngnretired
Senior Member
I have some real world feedback from climbing the grade to get from Cottonwood, AZ to Jerome, AZ today. Air temperature was 92 degrees.
After leaving Cottonwood and going thru several roundabouts while ascending a slight grade, transmission temps climbed from about 180 to 190. After turning off highway 89A to Jerome where the grade really starts, the transmission temperature ended up climbing to 217 by the time we reached the Gold King Mine and ghost town. In Jerome, the grade of some of their streets was quite steep with several tight switchbacks. Looks like some changes (fans, more coolers, computer programming, etc) are warranted.
Coolant temps were great. Heading up the Jerome grade, coolant temp climbed to 205, then the fan clutch would engage and the temps came right back down to the mid 190s. This took place several times.
Descending the grade went well. Used 2nd gear (4 speed auto trans) and it pretty much held 40mph with minimal breaking.
After leaving Cottonwood and going thru several roundabouts while ascending a slight grade, transmission temps climbed from about 180 to 190. After turning off highway 89A to Jerome where the grade really starts, the transmission temperature ended up climbing to 217 by the time we reached the Gold King Mine and ghost town. In Jerome, the grade of some of their streets was quite steep with several tight switchbacks. Looks like some changes (fans, more coolers, computer programming, etc) are warranted.
Coolant temps were great. Heading up the Jerome grade, coolant temp climbed to 205, then the fan clutch would engage and the temps came right back down to the mid 190s. This took place several times.
Descending the grade went well. Used 2nd gear (4 speed auto trans) and it pretty much held 40mph with minimal breaking.
You were probably climbing at 20-40mph in second or third gear.
At those speeds the torque converter will no be locked when the throttle position is high. In second gear and 90% throttle you need to be 50mph and over 65mph in third.
Sounds fairly similar to the climb we had issues on in Rocky Mountain National park. Plus we went from 5K feet to 11Kl so took more throttle than if we were lower.
At those speeds the torque converter will no be locked when the throttle position is high. In second gear and 90% throttle you need to be 50mph and over 65mph in third.
Sounds fairly similar to the climb we had issues on in Rocky Mountain National park. Plus we went from 5K feet to 11Kl so took more throttle than if we were lower.
That to me is not all that bad. I have driven in a car and a different RV. Did you come west via I40?
youngnretired
Senior Member
It was all at 20-40mph climbing the grade in mostly 3rd until we got closer to the top and the switchbacks.
Yes, we've been following I40, doing as much of the original 2 lane route 66 as possible.
Yes, we've been following I40, doing as much of the original 2 lane route 66 as possible.
You are heading to Death Valley?
youngnretired
Senior Member
We will be after going to Vegas and up by Reno first
Cool.
I just looked at it on Google maps and by using directions for bicycle you can get the total vertical up and down. About a mile long and under 500' of up. It will heat you up but not compared to some climbs.
The one we tested on in Rocky Mountain Nat park goes from Estes to a gift shop, store at 11K. It is about 24 miles with 5K of vertical up and 800 or so down. 35mph speed limit but takes over and hour to do with traffic and tight curves.
With the reprogrammed transmission we go up in 2nd gear with the converter locking at about 25mph at 95% throttle IIRC. 3000-3500 rpm. It stays a bit cooler when I run the twin electric fans than without but will make it with both water and trans under 205*. It is all above 6K feet so cooler than the OPs test most times. You can't go down without braking quite a bit even in second gear. The often have a brake temp inspection at the bottom before letting you continue to Estes and will hold you if too hot.
youngnretired
Senior Member
The turn by Cottonwood to start the climb to Jerome is probably 5-6 miles long, uphill the whole way. It's where 89A turns left at Clarkdale
I took a look and added the section from Clarksville and it came out to 5.1 miles but probably a little longer than that in reality due to routing. 1700' vertical up. I did the route with Google street view to see it in person and look for speed signs.
It looks like the first section from Clarksville to Jerome is at 50 or 55mph and after Jerome at 35mph. Both of those speeds are bad for climbing in the 4 speed Chevy but that is also a pretty common speed on steep climbs. That is the problem as it probably kept you unlocked the whole time.
At 55 you are over the 50 mph you would need even at full throttle if you are in 2nd gear and most of the curves on it were gentle so might have been able to keep it unlocked a most of the time of the time but you would have a lot of rpm going on. The van would easily pull that grade in 3rd gear but you would be under the 68 needed at full throttle and probably in and out of lockup depending on throttle position. The second section after Jerome at 35mph makes it an impossible place to get the converter locked. The trans needs 50 mph in second gear at full throttle, but a bit less if at partial throttle, and you are way under that speed. You might have been able to tickle it locked by reducing the throttle and them increasing it as the unlocked speed are lower, and used to do that. It is difficult and not very effective with lockup going in and out repeatedly.
Most of us have found that fans and more coolers help and might have gotten you up that climb, but mostly you would just delay it a bit. Is is short enough to make it before it heats would still be close I think. The warm temps also don't help, but only 5000' helps some if comparing to near 10K feet of altitude. Especially in cooler areas turning on electric fans early before you start up can cool the radiator and trans some and that really helps on short climbs or short stretch of stop and go at a town.
It looks like the first section from Clarksville to Jerome is at 50 or 55mph and after Jerome at 35mph. Both of those speeds are bad for climbing in the 4 speed Chevy but that is also a pretty common speed on steep climbs. That is the problem as it probably kept you unlocked the whole time.
At 55 you are over the 50 mph you would need even at full throttle if you are in 2nd gear and most of the curves on it were gentle so might have been able to keep it unlocked a most of the time of the time but you would have a lot of rpm going on. The van would easily pull that grade in 3rd gear but you would be under the 68 needed at full throttle and probably in and out of lockup depending on throttle position. The second section after Jerome at 35mph makes it an impossible place to get the converter locked. The trans needs 50 mph in second gear at full throttle, but a bit less if at partial throttle, and you are way under that speed. You might have been able to tickle it locked by reducing the throttle and them increasing it as the unlocked speed are lower, and used to do that. It is difficult and not very effective with lockup going in and out repeatedly.
Most of us have found that fans and more coolers help and might have gotten you up that climb, but mostly you would just delay it a bit. Is is short enough to make it before it heats would still be close I think. The warm temps also don't help, but only 5000' helps some if comparing to near 10K feet of altitude. Especially in cooler areas turning on electric fans early before you start up can cool the radiator and trans some and that really helps on short climbs or short stretch of stop and go at a town.
That is a tough question because the results users get vary so much do to use patterns and perception. Past disappointments based on vendor claims showed me that you can't trust specs, particularly for airflow. The best I found is to use a top brand like Spal and also check the amp draw for fans running. I commonly see two fans with same claimed airflow cfm but one uses 8amps and one uses 25amps even though they use the same style of motor. Good fans that cool well will have about 20-25amp use, fused at 30amps, or so and generally to get the best airflow they would have straight blades over curved. Straight blade are noisier by quite a bit though.
The two fans in the pic of my radiator and coolers are Spal 16" which were as large as I could fit. They pull about 22amps most of the time apiece.
But as I mentioned, they did not improve things enough for the tough climbs, even with the big radiator and very large trans coolers. You can also see some the bypass shrouding I did to prevent inlet are from going around the radiator.
We didn't get decent cooling on the bad hills until I reprogrammed the shift and lockup point for the transmission and added another change the made the trans able to be held in low gear and not go to second. OEM programming doesn't let that happen and every time you let up on the throttle if will shift into second gear and not downshift again until you nearly stop so horrible on steep switchbacks.
These are the fans I used
Spal fan
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youngnretired
Senior Member
Anyone give any consideration that the fluid flowing through any external (air based) cooler is just flowing too fast for any decent amount of heat transfer? Many decades ago I exchanged transmission fluid by removing a line at the radiator and having that flow to a pan, while dumping fresh fluid into the fill tube. At idle, the fluid flow was quite a bit. At 2000 or 2500 RPM, it would be a lot!
Just wondering if there would be much more cooling by parallelling fluid flow thru two external coolers instead of them being in series. Slower fluid flow should have more dwell time and heat transfer.
Just wondering if there would be much more cooling by parallelling fluid flow thru two external coolers instead of them being in series. Slower fluid flow should have more dwell time and heat transfer.
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