Ok after working on it all summer I believe the car is now reliable, running well, and ready for the track. The last project was keeping the transmission cool. I have a PTC 9.5" non locking spragless converter. Issues arose on highway cruises and if a made a run temps would spike and not come back down until I exited the highway and idled. Recently I removed the ac condenser and installed the coolers shown in the attached photo. Cruising temps on a 90* day now stay at 165, rise slightly on a pull, and then come right back down. Fluid exits the trans, enters the bottom of the rad tank, exits at the top, and then enters the bottom cooler. Top line returns to trans. Here's the question/concern: Do you guys think this would give me a back pressure issue causing too high of a pressure in the converter? I've heard that too much pressure will shove the converter forward and take out the crank thrust bearing. Oh, lines in the photo are 3/8 btw. Thanks for any input.
Transmission Cooler Line Pressure
- Thread starter MNwe4
- Start date
David Husek
Turbo Buick Performance
- Joined
- Mar 16, 2007
You have a lot going on there. That setup is going to work the pump hard. Never use a tube and fin as it uses a lot of volume and doesn't cool well. I recommend using the radiator cooler with one plate and fin cooler with or without a fan. The lower cooler is a plate and fin cooler. On average a plate and fin cooler has 30% more cooling and 15 times less flow restriction than a tube and fin cooler. When shopping for a cooler, make sure it is a low pressure drop LPD cooler.
On the dyno we saw much higher pressures when using a bar and plate. How high is too high is debatable. Without measuring these pressures you're not going to know exactly what's going on
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Thanks for the replies. Here's some more info to add. Trans is a built 200-4r. Bottom cooler is a low pressure drop plate/fin from TruCool. I was concerned that it would not be enough due to my converter type and didn't want to do the job twice if I could avoid it. My plan was to use it in addition to my original large tube/fin cooler, but they both wouldn't fit, so I ran out and picked up the smaller tube/fin that you see on top. Car is together and temps are fantastic, but is there concern for trashing the crank thrust bearing? If I were to T in a pressure gauge on the feed line right before the coolers what pressure should I try to stay under?
turbobitt
Well-Known Member
- Joined
- Feb 14, 2002
There is no threshold that is known. Converter design and internal venting are a factor. With that being said I drove around for almost 10 years without a crank thrust problem running unrestricted converter feed and 210+ line pressure.
The pressure will vary greatly depending on engine load and if the converter is near max stall. I have tested as low as 5 psi and seen as high as 100+ PSI . Personally like to see somewhere around 35 psi in my TH400 during normal driving and lite load. This will keep enough pressure in the lube circuit so the internal trans bushings won't take a beating. Keep in mind this will still generate 85+ psi at WOT/Max stall. Adding coolers will raise the pressure for sure and bar and plate will further aggravate the problem.
AG.
