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Butcher
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 Posted: Sat Mar 31, 2018 8:57 am Post subject: Re: AT transmission shifting weirdness |
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The shaft does look better, but is it too small of a diameter that makes it useless?
Time will tell. I do understand you have limited options. |
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MarkWard
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| Posted: Sat Mar 31, 2018 11:04 am Post subject: Re: AT transmission shifting weirdness |
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I can appreciate adding an aftermarket cooler. Does it use a thermostat? With the cooler at the front, you are getting a pressure drop due to friction loss across that distance. You could be exceeding the design of the stock pump. I'd be more inclined to use an auxiliary pump to circulate the ATF independent of the ATF hydraulics.
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blackglasspirate
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| Posted: Sat Mar 31, 2018 12:03 pm Post subject: Re: AT transmission shifting weirdness |
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| Butcher wrote: |
The shaft does look better, but is it too small of a diameter that makes it useless?
Time will tell. I do understand you have limited options. |
I wondered the same thing at first but the overall change in diameter is extremely small, so it's unlikely. Certainly possible though, but as you say time will tell. Both the rebuilder, the machinist (who did the TC bushing), and the VW specialist here were all confident that it was fine and there was nothing to worry about. I guess I will find out soon enough.
| Quote: |
I can appreciate adding an aftermarket cooler. Does it use a thermostat? With the cooler at the front, you are getting a pressure drop due to friction loss across that distance. You could be exceeding the design of the stock pump. I'd be more inclined to use an auxiliary pump to circulate the ATF independent of the ATF hydraulics.
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It does not have a thermostat. It's a pretty dumb/basic system from Smartcar. The GoWesty one would have been a better option but at the time I originally installed it I was trying to save cash where I could. The pressure drop was the first thing I asked the mechanic when he recommended moving it to the front. Both he and the transmission guy don't think it would be a problem, but again, that's just taking their word for it.
There's another thread here having to do with relocating this particular cooler to the front and other people have confirmed they moved it to this location and haven't experienced any problems to date. I don't think anyone has actually run a pressure test to see how much it affects it though. I guess it's something I should look into.
I long suspected that the transmission was getting too hot and the cooler wasn't doing its job well enough. With these steep mountain passes through the Andes, bigger than stock tires, and fully loaded van, it puts a lot of stress on the trans. On longer/steeper passes I would stop and let it cool down for a little bit if I felt it was losing power or getting too hot and could feel a significant difference in power when I started again after it had cooled.
So with that in mind, moving it to the front seems like a good option as long as the pressure drop isn't too significant.
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MarkWard
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| Posted: Sun Apr 01, 2018 5:52 am Post subject: Re: AT transmission shifting weirdness |
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A few thoughts. I'd not reuse the cooler. Running parts washer through it is not enough to remove debris. A filter on the return should catch anything and after a few changes, will probably clean up if replacing the cooler is not an option.
The friction loss and pressure drop are real. I imagine you could find a friction loss calculator on the Google. Easy enough to test. Pressure gauge attached to port on transmission. Bentley has the pressure specs.
Without a temp gauge on the trans you are not really sure what temps you are hitting and how much heat the cooler removes vs stock or some of the other options out there.
A thermostat would bypass the cooler allowing instant pressure on start up instead of filling 30 feet off hose before getting pressure. It would open slowly letting the cooler system fill and come on line.
The above do not mean your bound for another failure. They are just considerations for longevity.
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Wildthings
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| Posted: Sun Apr 01, 2018 9:16 am Post subject: Re: AT transmission shifting weirdness |
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| MarkWard wrote: |
A few thoughts. I'd not reuse the cooler. Running parts washer through it is not enough to remove debris. A filter on the return should catch anything and after a few changes, will probably clean up if replacing the cooler is not an option.
The friction loss and pressure drop are real. I imagine you could find a friction loss calculator on the Google. Easy enough to test. Pressure gauge attached to port on transmission. Bentley has the pressure specs.
Without a temp gauge on the trans you are not really sure what temps you are hitting and how much heat the cooler removes vs stock or some of the other options out there.
A thermostat would bypass the cooler allowing instant pressure on start up instead of filling 30 feet off hose before getting pressure. It would open slowly letting the cooler system fill and come on line.
The above do not mean your bound for another failure. They are just considerations for longevity. |
You can't figure your friction loss if you don't know your flow rate, though you could remove a hose and time the filling of a quart jar to get an idea.
The hoses are not going to drain down after shutoff so it will take zero time to refill them.
Yes a thermostat would be nice but it probably isn't very necessary. The colder fluid in the lines is going to act as somewhat of a thermostat anyway. Loss of pressure in the lines is not an issue as far as I know, because the return from the cooler just dumps the oil back into the pan. Even if you had a couple of hundred pounds of back pressure, I don't think it would hurt anything, but could be wrong. Don't have a clue how oil is shunted to the cooler to begin with though.
I think you are trying to see problems where there are not any.
Replacing the cooler with a new one, or at least going through repeated cleaning cycles with the present one is not a bad idea. The suction filter in the tranny should do a good job of catching any crud from the cooler by itself so an extra filter shouldn't be necessary. It would be a good idea for him to pull the pan and clean the filter after a few hundred miles, maybe doing it repeatedly if there is much crud in the filter. |
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MarkWard
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| Posted: Sun Apr 01, 2018 3:32 pm Post subject: Re: AT transmission shifting weirdness |
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Didn't realize the return of the cooler was back into the pan. I thought it was plumbed into the pressure circuit, sort of an external loop. So forget what I said. If the return is open, there will be next to no pressure in the cooler circuit. Any debris will collect in the pan. I learn something everyday. Thanks wildthings.
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Butcher
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| Posted: Sun Apr 01, 2018 4:20 pm Post subject: Re: AT transmission shifting weirdness |
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I've tried to determine where the oil is taken from on a Vanagon and I believe it's from the oil pump pressure relief valve. I hope someone chimes in to confirm that.
I know that Porsche uses that transmission and they cool the oil from the torque converter drain. That by far is probably the best place to cool the oil since that is the place where the heat is generated. |
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blackglasspirate
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| Posted: Mon Apr 02, 2018 8:34 am Post subject: Re: AT transmission shifting weirdness |
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Got the new pistons today. There's definitely more of a lip/flare on the end of them than the ones that were in the transmission. Now I can see what the rebuilder was talking about. I dropped them off with him so now I wait.
Here's a pic for reference in case anyone in the future is wondering what the lip should look like (I couldn't find a good picture of this particular piston).
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Wildthings
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| Posted: Mon Apr 02, 2018 8:41 am Post subject: Re: AT transmission shifting weirdness |
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| Sounds like it's all getting close to coming together. Hope it gives you great service at this point. |
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blackglasspirate
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| Posted: Tue Apr 03, 2018 6:59 am Post subject: Re: AT transmission shifting weirdness |
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Sorry for all the posts, but I do have a question, seeing as I've never done this before.
When mating the auto section to the differential there are shims for the final drive play, right? Well, I don't have any other than what was already in there so is it going to cause major problems to reuse the shims and not properly measure it all out?
I'm honestly not even sure how the play/shims affect everything, which is why I'm asking.
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Butcher
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| Posted: Tue Apr 03, 2018 7:12 am Post subject: Re: AT transmission shifting weirdness |
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Assuming the last shop shimmed it correctly and none of the major parts were replaced, you should be fine.
I do not believe you have any other option. Shims are hard metal and are not a wear item so they are reused but normally measured to CYA. |
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blackglasspirate
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| Posted: Tue Apr 03, 2018 7:32 am Post subject: Re: AT transmission shifting weirdness |
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Awesome, thanks for the info!
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MarkWard
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| Posted: Tue Apr 03, 2018 7:40 am Post subject: Re: AT transmission shifting weirdness |
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I would follow the procedure in the manual for determining the shims required. Assuming it was done correctly last time would be a stretch. It's not that involved of a procedure to measure.
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blackglasspirate
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| Posted: Fri Apr 06, 2018 12:44 pm Post subject: Re: AT transmission shifting weirdness |
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Well we put the transmission back in and, to my dismay, we still are having problems. But the problems are different than before. So far there are no leaks and everything went together smoothly. However, once you start trying to move everything starts going to hell.
The good: reverse works fine.
The bad: from a stop D and 2 will just rev and not move forward at all. Putting it in 1 it will move forward, though it seems to have some hesitation at first. Once it is moving in 1st, I can manually shift to 2nd, and then D for 3rd. If I have my foot on the gas between those shifts it will rev up quite a bit before it gets in gear. If in D or 2 and I slow down too much or come to a stop, I have to put it in 1st again and start all over. There also seems to be a whine or some other sort of sound coming from the transmission when I accelerate.
If I were having the same problems as before I would probably blame the TC as having bad internals. However, since the problems I've having now are completely new, I'm leaning towards the rebuilder doing something wrong internally. I took it to him this morning and he test drove it and thinks it could possibly be the valve body (unlikely) but is going to come by in the morning and do some more testing.
At this point I'm not really sure what to do, but we're definitely getting tired of sleeping/cooking in a van that's jacked up on ramps!
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Wildthings
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| Posted: Fri Apr 06, 2018 7:23 pm Post subject: Re: AT transmission shifting weirdness |
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Maybe the new pistons just don't want to move?
The noise you hear could be the pressure relief in the valve body blowing off. This would be an indication that something is blocking a passage or that something is assembled wrong. |
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blackglasspirate
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| Posted: Sat Apr 07, 2018 10:02 am Post subject: Re: AT transmission shifting weirdness |
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We were taking out the valve body today to clean it and found a lot of metal particles in the pan. Not sure if they are new or we're still in the converter or other parts of the trans. The rebuilder said he didn't remove/clean the valve body.
Based on more discussions with him and his work I don't have much confidence in him and neither does the mechanic I'm staying with who removed the transmission. And so, we are going to remove the transmission again, disassemble ourselves, make sure nothing is in there wrong, clean everything, and also try to find a new converter.
Looks like we'll be spending more time on ramps...
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MarkWard
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| Posted: Sat Apr 07, 2018 10:29 am Post subject: Re: AT transmission shifting weirdness |
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I would still bypass the cooler till you get it solved. It could have debris in it. Sometimes it's easier to troubleshoot when you have less to look at.
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AndyBees
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| Posted: Sat Apr 07, 2018 11:03 am Post subject: Re: AT transmission shifting weirdness |
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Even if you have a Bentley Manual and/or other guide to disassemble and reassemble, you should take photos as you disassemble. They will most likely be helpful when going back with assembly!
Also, as I may have previously stated, a guy who worked the Ford transmission plant in Cincinnati, OH told me to use plenty of WD-40 during re-assembly. He said that's what they used on the assembly line. However, that was with dry parts straight from the kit.
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blackglasspirate
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| Posted: Sat Apr 07, 2018 11:35 am Post subject: Re: AT transmission shifting weirdness |
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Good points, I'll definitely be taking lots of pictures. We just separated the auto section from the diff and are going to town on it.
Regarding the cooler, I agree. We discussed removing and flushing it as much as possible as well.
I did find that I can get the converter rebuilt in Santiago for about $325, though it would take a week and I need to convince the mechanic to let us stay here another week for that. The rebuilder in Santiago doesn't think the converter is the problem but I'm still concerned about particles in there. Still figuring out what to do...
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MarkWard
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| Posted: Sat Apr 07, 2018 11:49 am Post subject: Re: AT transmission shifting weirdness |
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You can siphon the torque converter into a container. Look in the manual. I would expect centrifugal force to hold most of the particles to the outer edge of the shell, not circulate them.
Part of the overhaul process is using compressed air during the reassembly process at different stages. Fluid pressure tests should also be done prior to disassembly and for troubleshooting shift problems.
I don't envy your position. Good luck getting it sorted.
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