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Discussion Starter #1
Getting ready to install a 4R70W in my 66 coupe. I am installing a new Champion three row radiator, user the wider radiator for the 67-70. Do I also need a separate transmission cooler in addtion to the radiator?

 

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Just some guy
67 coupe, 69 Sportsroof, 86 hatchback
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Not unless you plan to tow a bunch of stuff or have a higher stall converter than stock that you expect to make a lot of heat.
They have a chart showing the supposed longevity added by use of an additional cooler. Unfortunately that chart was made by people in the business of selling such coolers and the info on it doesn't really show up anywhere else.
My thoughts are that if you are worried about extra heat for some reason, install a fluid temperature gauge and then you'll know if it is staying in the proper temperature range. Which I would certainly expect it to with that radiator.
 
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I’m in south Texas. I run a cooler on every trans. I don’t use the one in radiator.
 
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Just some guy
67 coupe, 69 Sportsroof, 86 hatchback
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That's OK as long as you use a thermostat. If you don't then sometimes during the year and during short drives the transmission never comes up to proper operating temperature. If if not, then doesn't boil off the condensate moisture in the transmission. Problems caused by that that I';ve personally seen are, valve body separator plates rusted and pitted sometimes clean through, dipsticks corroded so bad they come apart (mainly GM's though), and mostly, the friction material on the clutches can't take moisture and it delaminates in chunks. Pretty much anyone in the transmission business will have seen the same things. Less so in the more arid parts of the country but still.
All this damage is long term and rarely driven hobby cars can get away with quite a few of these type sins.
 

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Almost every trans shop around here requires you to install one for your warranty. But that is because of the heat. No thermostat in the discussion. For new cars, they require new cooler if it’s the plate style, or a flush if tube n fin. I’m not trying to argue with you Gypsy, or refute you, this is just what I/we do to compensate for the region we live in. Not so in other places.
 

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Getting ready to install a 4R70W in my 66 coupe. I am installing a new Champion three row radiator, user the wider radiator for the 67-70. Do I also need a separate transmission cooler in addtion to the radiator?

Not clear to me if you have a transmission cooler in the radiator, like the one in my stock '66. if you do, I agree that you may not need an external one. If you don't, then you will need some kind of external cooler.
 

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I don’t like messing w cooler lines when pulling radiator, another benefit to external cooling, but as stated above, its not for everyone.
 

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I did not use the trans oil cooler in my 3 row Champ rad. I nstead I put a two pass cooler in front of the rad on the rad support. No issues for the AOD after a lot of miles behind a 331.
 

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The 4R70W has a fluid temp sensor in the valve body and if using the US Shift/Baumann Controls controller it's easy to access and monitor fluid temp. You could monitor the temp for a while to determine whether an additional cooler is needed.
 

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Just some guy
67 coupe, 69 Sportsroof, 86 hatchback
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Good point. All modern automatics monitor the fluid temperature and have somewhat crippled operating strategies when the fluid is cold. So it's even more important that they run up to proper operating temperature. To hasten that, some new vehicles (Dodge trucks for example) even have small heaters inside the transmission to hasten them getting up to temperature. More and more Fords use a thermostat to block fluid flow to the cooler under a minimum temperature is reached. (The newest editions of the 4R70W-the 4R75W's have these) So if one keeps up with how the industry is going, blindly throwing an unregulated external cooler on just everything isn't the most well thought out way to go.
Anyone can do what they like, no skin off my nose. Personally, I've no interest in adding an external cooler to any vehicle unless I some kind of proof that particular vehicle needs it.

All that said, my personal 4R70W is in a driver F150. Because it was fitted with the optional "towing package" it also has a factory external cooler. Because I pay attention to such things and care, I have retrofitted the thermostatic control setup from a later model F150. I rarely tow with the truck and normally short trip it. It is also my "got to go!" response truck when the state calls. So often it doesn't get any kind of warmup.
 

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Discussion Starter #12
Not clear to me if you have a transmission cooler in the radiator, like the one in my stock '66. if you do, I agree that you may not need an external one. If you don't, then you will need some kind of external cooler.
I do have the transmission cooler in the radiator
 

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Discussion Starter #13
What converter are you running, full length headers going right next to trans as well?
I had the stock converter rebuilt. I found a place in Seattle that makes long tube headers that work for my 66 with the Borgeson and the 4R70W transmission. The headers are fairly pricey.
 

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In the last month I had 2 transmissions built locally as “ bench builds”. The shop builds the trans and I do the removal and replacement. One was a 4R70w and the other was a 5R55S. Both were required to have coolers, as both had factory coolers to begin with. The mustang only required a flush, but the 4R70W was in an F150 with a “plate” style cooler. We had to replace/bypass plate cooler and install a large fin n tube trans cooler. This was written into our receipt that new cooler was required for warranty. Shift kits were installed in both transmissions. The shift kit in the 5R55S eliminate the “temperature valve” as they are a known failure point. They get stuck in closed position and don’t allow coolant to flow to cooler and cool the trans. Bad design. Again, standard practice in south Texas.
 

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Just some guy
67 coupe, 69 Sportsroof, 86 hatchback
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If they charged you as part of a "shift kit" for simply moving the converter bypass valve spring from one side of the cooler bypass valve then you got ripped. Relocating a spring isn't any part of a kit. I think doing this was mentioned in an ATRA seminar ten years ago or something. Those who live in areas where the temperatures never go below 0 F can do without the bypass.
In-shop rebuilds get "hot flushes" with a special and not cheap machine. When they know that you don't have one of those at home or at your shop on many setups they will require you to replace the cooler as a blanket CYA sort of thing because they know you lack the equipment to properly flush all the debris out of the system. Many crate rebuilders are throwing out blanket warnings as part of their warranty that you must replace the cooler AND the radiator. Just because they are worried about debris in the system, it has nothing to do with the ambient temperature the vehicle is expected to be operated in.
All that said, yes, there are a rare few coolers that need to be replaced as no one can adequately flush them. Some older Mitsubishis come to mind but I'd have to search up the bulletins to say exactly which ones.
 

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No they didn’t do the spring swap, transgo has a replacement valve in the kit to eliminate this issue, at least that is my understanding from reading about the kit. Debris/ contamination is major concern w replacement jobs for sure.
 

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Just some guy
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Gotcha. I pulled out an old Superior kit and they have the same thing basically, They call it a "thermo blocker". I don't use it and prefer instead a thorough cleaning. As-built, it would be a 50-state car. Blocking the bypass would compromise the ability for it to operate well in frigid climates. OK if it's safe to assume the vehicle will never be used in such parts of the country I guess.

The dirty secret of transmission building is none of them are completely and perfectly rebuilt. They're ALL compromised. Because rebuilding one 100% takes way too long and would cost too much. And no one (outside of racers) is going to pay Ferrari money for repairs on a Focus. Not happening. So each shop makes it's own compromises according to their knowledge and experiences.

Still odd that two different shift kits would have an extra component where you can literally just move a spring from one side of the valve to the other and accomplish the same thing. I don't know, the shift kit people tend to be really on top of such things. It's not a modification that I care to use or recommend so I certainly haven't really looked into it until just today. :)
 
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