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700R-4 version 3.0

Blue85

Blue85

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This transmission may be original to the truck. It went out in 2000 with a failed torque converter and chewed up front planetary. That was my first time inside an automatic transmission, which I complicated by doing a bunch of upgrades. I used a B&M SuperTransKit, put in a newer pump, upgraded the forward sprag and ended up with a Corvette servo because the thing wouldn't shift right without it. I remember modifying some of the 4th clutch plates to fit the little aftermarket release springs and feeling like I was in uncharted waters.

To make a long story short, I had decades of solid performance, then this year it started to stay stuck in 1st gear. Metal in the oil was making the T/V stick. I hoped it would let me lead the overland trip in August as planned, but I sadly took this vehicle out after the 1st day.

After teardown, the failure mode is thrust washers.

20250920_113135.jpg

At first I thought the top one was a washer, but there's no such part in any diagrams. It turns out it's supposed to be part of a Torrington assembly, which I scored at the local driveline shop.

20250920_113158.jpg

What has me stumped right now is the amount of brass in the filter. All of the bushings look good, so I have to believe it's a brass thrust washer. It's too thick to be from bushings and all springs in the sprag are intact. I've got to go through everything and figure out which one went AWOL.

20250920_113128.jpg
 
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All of the clutches look mint, but the band is a little chewed. Since I've gone to EFI, electronic ignition, digital dash, etc, a hydraulic shifter seems silly, but since this doesn't seem to need much, I'll put it back in and run it. I already have a bunch of other changes planned and most of my wrench time seems to be keeping my kids cars going :dunno: . I always liked how it would downshift as needed in the dunes, it will go back to 1st without stopping and it offers great compression braking for descents, so I guess if it's not broken...of course it is, so I will, but you get the idea.

So here's what I have to go in:
HD sunshell
Basic Precision overhaul kit
New HD band
Replacement plastic washer
Oil filter
Forward planetary (mine is OK, but the carrier has wear from the broken plastic washer.)

While it's out, I'll do the rear main and oil pan gasket. I've been meaning to do those for probably 8 years. :whistle:
 
Everything I'm reading says the only brass washer is the reaction shaft to sun shell one and that one looks fine. Apparently, some models have brass washers in the planets, so I may have back the assembly up to look at the rear set.

EDIT: these planets have the later bat-wing style washers and measure within spec, so how could the brass be from there?

I'm talking about #8 below.

1758561771468.png
 
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Don't a lot of the bushings have some brass in them?

Is it possible that its not brass but steel that got too hot and reflects like brass? Is it magnetic?
 
Yes, the bushings are brass, but every one I've looked at looks OK. To create big flakes, they would have to be torn up. The brass-colored flakes don't stick to the magnet.

I filled and drained (siphoned) the torque converter multiple times through a rag and didn't catch any metal. I did find a small amount of brass in the teeth of a ring gear, so it seems the bits were chopped up by the gears. Other than getting stuck in 1st until it warmed up sometimes, it acted fine. Shifted normal, no weird noises and bright pink fluid, but to be fair the exhaust is kind of loud. Some of the crud I found in it was clearly plastic, and there are visible bits of that thrust washer in the filter. Other bits were found hiding out near the adjacent clutch pack.

I've gone through cleaning parts enough to have all of the rotating subassemblies back together, referencing the ATSG, Haynes and B&M books, but can't find any missing washers (other than the big broken plastic one). The output screen on the pump is clean.

Some of the diagrams make #601 look like brass, but the one I have is plastic. It seems right because it has two round tabs on it that mate with round holes on the pump.

1758562118440.png
 
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In the 4L80E, I believe that one is the selective plastic washer to set front end play, that come in different thicknesses. Sounds like it could be similar here?
 
Blue85 said:
Yes, the bushings are brass, but every one I've looked at looks OK. To create big flakes, they would have to be torn up. The brass-colored flakes don't stick to the magnet.

I filled and drained (siphoned) the torque converter multiple times through a rag and didn't catch any metal. I did find a small amount of brass in the teeth of a ring gear, so it seems the bits were chopped up by the gears. Other than getting stuck in 1st until it warmed up sometimes, it acted fine. Shifted normal, no weird noises and bright pink fluid, but to be fair the exhaust is kind of loud. Some of the crud I found in it was clearly plastic, and there are visible bits of that thrust washer in the filter. Other bits were found hiding out near the adjacent clutch pack.

I've gone through cleaning parts enough to have all of the rotating subassemblies back together, referencing the ATSG, Haynes and B&M books, but can't find any missing washers (other than the big broken plastic one). The output screen on the pump is clean.

Some of the diagrams make #601 look like brass, but the one I have is plastic. It seems right because it has two round tabs on it that mate with round holes on the pump.

View attachment 513993
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Could any from the torque converter make it's way there?
I don't believe you opened that up yet?
 
folkenheath said:
In the 4L80E, I believe that one is the selective plastic washer to set front end play, that come in different thicknesses. Sounds like it could be similar here?
Click to expand...
Yes, the selective washer sits underneath the pump. I think it's pretty much the same.
 
The washer on top of the reaction sun shell is the only brass washer in the transmission besides the small planetary pinion end washers. The only other brass would be from bushings or some errant bronze brazing debris from the converter. The brass could be old particles trapped in the cooler from a previous failure.
 
Greg Ducato said:
The washer on top of the reaction sun shell is the only brass washer in the transmission besides the small planetary pinion end washers. The only other brass would be from bushings or some errant bronze brazing debris from the converter. The brass could be old particles trapped in the cooler from a previous failure.
Click to expand...
I really appreciate you weighing in on this. I've kind of come to the same conclusion since no washer kit available has anything else. I did read that some torque converters are brazed, but mostly high end and this is a stock-type from Precision. Maybe the right move is to take it all apart again, replace the converter, flush the cooler and send it. I did those things 25 years ago and found no brass at that time.
 
Some of these pieces really look like *something*, like there must be a smoking gun somewhere. It seems possible that those straight patterns were stamped in by planetary teeth?
20250925_204012.jpg

I was always convinced the steel powder came from the input carrier assembly, after the large plastic washer on it gave way.

20250925_204543.jpg
 
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Those bits could potentially be related to upper and lower washers on the input sprag or the cage on the low sprag. If you haven't already, those items should be disassembled and checked prior to trans assembly.
 
Forward sprag is good.

20250929_175144.jpg
 
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Low-reverse roller is good.

20250929_185306.jpg

Both planetary sets are smooth and in spec (for the input planetary, that applies to the one I took out and the new/used one I bought.)
 
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I stopped at the local driveline place again. They can't flush a converter and they can't cut one open. We went down the list of all potential brass sources and his hypothesis is that the brass was stuck in the cooler all along. This is hard for me to believe since I've had the pan down multiple times (like swapping the TCC solenoid when the previous converter clutch died) and never saw anything brass. I bet the pan wasn't off for 15 years prior to this, other than a fluid change at some point. They have some kind of machine that passes hot oil through a rad cooler while burping air through in the opposite direction, or something like that. They claim that in the olden days they thought flushing with mineral spirits, brake clean and air was enough, but this new process is pulling out way more junk. I could pull my radiator and take it down there, I suppose.

If I can't find the smoking gun, I have to take the opposite approach. If I'm sure everything going in is clean, then everything will be clean.

Are there sometimes bronze bushings in a torque converter?
 
I would have to agree with the driveline shop and the info they shared with you.
There is no bushing or washer in that converter and the only bronze would be from brazing the fins if the builder made that type of upgrade.
I am out of town till next week but we can cut your converter open and inspect it in our converter shop. Hit me up next week if we can help.
 
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