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Rebuilding My 4L80E Transmission

Do you think the whining could have been from being low of fluid? I recently worked on a buddy’s 4L80 that had a “whining” sound. He had bought a replacement dipstick, and the marks for full were almost an inch lower than the original dipstick.

I’ve been marking my dipsticks to where full is 1/4” above the flange the trans pan bolts to and have been having less trouble out of them.

Greg, your thoughts on this, please.
 
vr1967 said:
Do you think the whining could have been from being low of fluid? I recently worked on a buddy’s 4L80 that had a “whining” sound. He had bought a replacement dipstick, and the marks for full were almost an inch lower than the original dipstick.

I’ve been marking my dipsticks to where full is 1/4” above the flange the trans pan bolts to and have been having less trouble out of them.

Greg, your thoughts on this, please.
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That is the first thing I looked at. My fluid level was spot on. The fluid was bright Purple like it was brand new. The dipstick is the original it came with from the factory. It also has the dip stick restrictor bracket in the transmission as well.
 
I had a set back on putting the transmission together. I accidently dropped the center support, and now I have to buy a new one. They are not that expensive...it just a bit of a hassle finding one. I have all the drums reassembled, and ready to go back together. If it where not for have to replace the center support the transmission would be back together, and I would be working on putting the valve body back together.
 
Bummer man, but I don't blame you, even if I couldn't find anything wrong with it, I wouldn't trust it anymore, too much work into the project to risk it.
 
Just got back from the transmission supply store with another center support. I came complete with the piston and spring cage. I have to switch over my piston with new seals and custom spring cage I got with my rebuild kit. Need to install a new bushing as well. I have a new bushing for it in my rebuild kit.
 
1-ton said:
You got it. Headed up there around noon. They have a used one for $65, and a seal kit for it for $15.
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I figured. That’s where I always go and they always have what I need. Good guys.
 
Made some more progress today. Got the Center support in, and the intermediate clutch pack in.

In this image the center support is installed. Also shown is a Sonnax case saver. This helps support the case under high pressures.
full


In this image the intermediate clutch pack is installed along with a heavy duty snap ring that replaces the weaker stock one.
full
 
Its actually stronger to install the snap ring so the the ends are supported, meaning, put the snap ring gap between two of the close teeth. Its not as strong to leave the snap ring so the ends are unsupported like you have it there. The case saver definitely helps but I would still put the gap at about 3 o'clock in your picture.

Did you preload the center support before tightening the bolt?
 
folkenheath said:
Its actually stronger to install the snap ring so the the ends are supported, meaning, put the snap ring gap between two of the close teeth. Its not as strong to leave the snap ring so the ends are unsupported like you have it there. The case saver definitely helps but I would still put the gap at about 3 o'clock in your picture.

Did you preload the center support before tightening the bolt?
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The TransmissionBench.com video I have says the opposite that the snap ring gap should be placed in the 9 O' clock position where the gap is. Since I have the case saver there is not as much of a gap there anymore.

What is preload the center support? I have never heard that one.
 
I agree the case saver makes it better.

However, just think how it works, is it easier to bend two ends in a gap, or one solid piece? If you think about it that way you realize what is stronger. The two ends start to bend and take out the first two lugs, and then it's downhill from there.

If you have stock pressures and that case saver it likely won't matter, but I would still put it the stronger way, and that isn't it, regardless of what the video says, that short lug at 7 - 8 oclock is unsupported that way.

As for the preload, most builders say to preload the center support just to eliminate the slop before you torque the support bolt so it doesn't ever want to move after that, its already toward where it wants to go...

Like so ( a picture of an old Sessions book, its a TH400, but same procedure)...

20230424_074956.jpg
 
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My 4L80E transmission has all the drums and clutches installed. Now it is time to install the pump. I am waiting for a blind hole bearing and bushing remover kit I ordered from Amazon. It is supposed to arrive in a couple of days, then I will disassemble the pump, and put it back together with new bushings and other parts.

full
 
I don't remember needing a blind hole bushing remover to replace the bushings in the pump? I wonder if I just used a small internal 3 jaw puller? I replaced every single bushing in the whole trans, even the long center support bushing.
 
folkenheath said:
I don't remember needing a blind hole bushing remover to replace the bushings in the pump? I wonder if I just used a small internal 3 jaw puller? I replaced every single bushing in the whole trans, even the long center support bushing.
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Pullers with a sharp jaw can dig into the bushing bore. That already happened to one of the bushings I removed, so I bit the bullet and bought a blind hole puller set. It was only a $60 set from Amazon. I have to tear my transmission back down to the direct drum again. The clearance with the direct drum band and the direct drum is not correct because of the case saver.
 
Yes you are correct, you always have to be careful with any bores, I am extremely careful with that stuff, my puller has a cone where you can set the preload of where the jaws can travel to so they catch the part but don't force them too wide to scratch the bore. However, I don't even remember needing a blind hole, I just remember punching them through. So if there is a blind hold bushing I must of used my puller. I guess I'll find out when I do another one here this year.

Good job on documenting all this stuff by the way, I never seem to take the time to do that stuff.
 
I definitely found the source of my transmission whining sound. The pump bushing behind the pump torque converter seal was chewed up pretty decent. I am surprised I did not see that before, but I was concentrating on the transmission internals. Now that all the hubs and clutches are in I am concentrating on the pump. The guy that rebuilt my torque converter said the converter shaft was within specs, and all he did was polish it. I am installing all new bushings in my pump right now.

I went to my local transmission supply store, and bought a Sonnax pump stator bushing. It is wider than the stock bushing, and adds more stability to the input shaft. The Sonnax bushing is on the left and the stock replacement on the right.
full


I also drilled out the pump body pressure relief hole on the pump body behind the seal. The stock pressure relief hole was a tiny little 3/32" hole. I drilled it out to a larger 3/16" hole. In racing applications they say to take it out to 1/4", but since this is a stock heavy duty application I only took it out to 3/16". Also, early pumps like mine are known for having pressure problems at the seal relief hole.
full
 
I am glad I got this blind hole bearing and bushing puller. There was a couple of bushings in the pump I would have never gotten out cleanly without it.

full
 
How does the quality of that tool seem, does it feel like it will last or is it more of a limited use type tool?
 
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