Now I know why 904 was having issues

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Creedmoor

Recovering Fordaholic
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Sigh. First tranny rebuild and this is what I found.

I've owned this car (68 FB w/mild build on a teen) for about five years and have put about 9,500 miles on it before I started having tranny issues. I dropped the pan about 200 miles ago to see what I could see. No metal in pan, filter not really dirty. So, I adjusted the rear band since I was in there anyway, buttoned her up and refilled. It didn't really help. Drove it a few hundred miles and decided I had to fix it or have it fixed. Pulled tranny and opened up an automatic for the first time. Fluid was clean and nice smelling and nothing in the pan.

This is a stock '71 tranny. There were 4 brownish / black frictions and 4 steels in there that all looked OK. All frictions measured .082 and all steels measured .072.

So,with nothing in the pan or filter after nearly 10k miles, how the heck did this happen. More importantly, can I get a new front drum as this one seems to be toast?
 

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Check the servo seals, and all cast rings.
The Hi-drum(Third) and the KDband(Second) are hydraulically interconnected. When the tranny shifts into third from second, the apply pressure that is energizing Drive is also supposed to back off the KD servo, which still maintains its apply pressure, on the backside of the piston.It seems like your servo was not backing off, or not backing off fast enough.I can't see it being a hydraulic 3-2 issue, though;more like a bad band.
I suppose it could be problem with the small diameter cast ring on the servo. If that were damaged, it would fail to lock the band on hard, during the one-two shift; even with high throttle pressure adjustments.Yeah so pull the servo out next.
I can't tell from the pic, but it almost looks repairable. Chuck it in a lathe and find out I guess
 
You can get a new drum and band and they are not too expensive at all.
If I were you I would at least do a clutch frictions, bands and soft parts rebuild if you don't find anything else worn real bad.
I looks like the endplay was a little excessive from the looks of those ring land grooves.

How do the pump gears look?

For sure pull the servo like AJ mentioned and make sure it's not destroyed in there, because if it is you'll be looking for another transmission core or case to rebuild.
Might do this early on to make sure the case isn't unusable.
 
Thanks for the advice guys.

As detailed in an earlier post, my tranny troubles began with the car not wanting to move from a stop and as more throttle was applied, would suddenly grab (somewhat violently) and start moving. When car was fully warmed up after say 10 miles, the problem went away. Problem got worse so I decided to learn how to rebuild it.

This is going to be a full rebuild, frictions, steels, seals, front and rear bands, gaskets, sealing rings, probably bushings too. Will also be doing a TF-2 shift kit.

Fishy and Beast, the servo and accumulator bores are all nice 'n smooth, the pistons all look fine too. I measured the input shaft endplay at .045" before I started the teardown. That number is right in the middle of the specs. The pump looks ok and I can't fit a .0015" feeler guage between a straightedge and the pump body, inner/outer rotors. My theory is when the tranny was last apart (1989 from the inscription in the pan) the drum was already damaged and just cleaned up, a new band slapped in and reassembled. There's a lot of metal missing from that drum and there was virtually none in the pan/filter.

Pretty sure the drum is beyond resurfacing, it's worse than a badly worn brake drum or rotor. Where can I find one for a '71 tranny?

Parts cleaning question: So far I've been scrubbing and rinsing parts in kerosene, wiping dry, then blowing with air and bagging and tagging them. Some parts like the pump rotors and body are getting spayed with wd-40 before being stored. I'd think kerosene and wd-40 residue would be compatible with ATF. Some suggest a no residue cleaner like carb or brake cleaner. But then you risk rust. Opinions?? It seems like an endless amount of parts to clean....

Keep the advice coming gents.
 
Creedmoor said:
As detailed in an earlier post, my tranny troubles began with the car not wanting to move from a stop and as more throttle was applied, would suddenly grab (somewhat violently) and start moving. When car was fully warmed up after say 10 miles, the problem went away. Problem got worse so I decided to learn how to rebuild it.
Click to expand...
well, since the KD band has nothing to do with drive-away, I'm eager to see the lip seals in the fwd clutch, aka the "rear clutch".
 
AJ/FormS said:
well, since the KD band has nothing to do with drive-away, I'm eager to see the lip seals in the fwd clutch, aka the "rear clutch".
Click to expand...

Yeah, I couldn't remember who it was that made the lip seal prediction. Sorry AJ. Fwd clutch / rear clutch, the nomenclature and function juxtaposition is part of what's making this hard to keep track of. :). That said, these are the rubber seals from both clutch pistons (I'm assuming these are the infamous "lip seals"). They weren't "welded" on, but they were hard to remove. They are pretty stiff and not real soft. In the pic I had twisted them and they pretty much stayed that way. Not what healthy ones would be, right?

Take a look at the pressure plate pic. Ignore the big black mark at 7 o'clock - it's a shadow. The marks at about 2-3 o'clock look like heat marks to me. Down by the shadow mark, there are similar marks just above it. Is this piece pooched?

Any thoughts on my cleaning regimen?

Thanks guys.
 

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I was referring to the parts associated with that pressure plate when I said welded together.
That's about as close as it gets without being. :D
 
Getting to know the Mopar naming of the clutches is kinda goofy.
The first clutch that comes out of the tranny, Ma calls the Front clutch
The next one out, Ma calls the Rear clutch.
Thats all fine;front and rear.That makes sense so far. But once they are on the table, stripped and cleaned, which one was what,again?
Well, the first one out, locks the tranny in high-gear, so most guys that work on all brands,call it the hi-drum, cuz it operates hi gear and it's a drum.
And the second one out, operates in all forward gears, so we call it the forward clutch.This is the confusing one; Ma calls it the rear, but it only operates in the forward mode.

I would have expected the lip-seals, in the forward clutch, to be ruptured.Since they are not (just hard), but the clutches are cooked, and you say the pump is good, Ima guessing somebody drove it with the KD mech. disconnected.
 
Thanks AJ, that helps some, but it makes my head hurt. I've been referring to parts by their relative positions within the case - front to rear. OK, so the front (only) kick down band and drum had nothing to do with my problem - then why does it look so fried? That little bit of heat spotting is all it takes to ruin a pressure plate? A couple of the steels from that clutch pack exhibit similar marks, but the frictions look nearly new.

Regardless, it's all getting redone once, correctly. Please advise on best practices for parts cleaning.

Thanks loads.
 
It did that because hardened shrinking rubber seals don't expand out and seal until they are warm and can move.
It causes what is called "Morning sickness" and is where the car won't move or is real sluggish till it warms up.
During that slipping it can hot spot the clutches and steels like that.
Either that or someone used burned plates from a previous "repair" and didn't replace the rubber seals.
(you said the clutches looked good) but to burn a steel surface like that they would be black or at least really dark.

The amount of burn on the steel can happen in seconds when a trans slips, and I'll also guarantee you that front band was slipping, and I don't think the damage to that drum was from that band.
(another reason to suspect a half assed repair was done where the friction parts were all that was replaced.)
If that band did that to the front drum it would be a mirror image of the drum with no friction material on it at all.

Next look at the second picture down (the inside bore) where the sealing rings rode.
It was moving forward and back enough to almost completely cover the slot where the fluid is supposed to flow to apply that drum, yet you say the endplay was ok.
(Did that happen before also, confirming the fact that most of this stuff happened at some point before and was just patched up?)

Sure is looking that way.
 
In my personal trannys
-If the steels are still flat,really flat, I have cleaned them up and reused them. -The lined plates(frictions), is another story. They can look fine, but not be fine. I scratch them with the corner of a 1/8" screwdriver, a short circular scratch, parallel to the OD.If a light to moderate scratch leaves a rut, the material is toasted and is junk. Next,I put the screwdriver on the flat, and drag it,similarly, but with a lot of pressure, say 10pounds of force (hard enough to feel it in my wrist) . If nothing but oil rolls up, I reuse them.
-As to the PPs, they have to be a lot worse than yours look to be trash.If its flat I would flip it over and re-use it. The bluing, if it bothers you, is easy to buff off.
-Your brand new frictions need to be presoaked in ATF. Several hours at least,in such a way that all of the lining gets oil. This usually means flipping them. I use the tranny oilpan.
-I use RoadRanger silicon O-ring grease on all rubber parts.I also goop the lead-in chamfers liberally.This will help to get the pistons back into their bores without folding the lips of the lipseals.Do not force the pistons in.They have to go straight down. As soon as the clutches are fully assembled, I put the front end together into the pumphouse and air test it.
-If your kit includes split teflon rings, I don't use them.They are really tricky for a newbe to successfully install. The cast rings with locks are far easier to install. You can prefit those into their bores, and if there is still 50% or so of the gaps left( those things hardly wear at all),they are good. They wear more on the sides. If you are forced to use the teflon stuff; O-ring lube will help.
 
AJ/FormS said:
In my personal trannys
-If the steels are still flat,really flat, I have cleaned them up and reused them. -The lined plates(frictions), is another story. They can look fine, but not be fine. Scratch them with the corner of a 1/8" screwdriver, a short circular scratch, parallel to the OD.If a light to moderate scratch leaves a rut, the material is toasted and is junk. Next,put the screwdriver on the flat, and drag it,similarly, but with a lot of pressure, say 10pounds of force (hard enough to feel it in your wrist) . If nothing but oil rolls up, I reuse them.
As to the PPs, they have to be a lot worse than yours look to be trash.If its flat I would flip it over and re-use it. The bluing, if it bothers you, is easy to buff off.
Click to expand...

The bluing leaves hard spots in the surface that will cause uneven wear, so flip it over if the other side is uniform.
 
AJ, I'm dense or something, 'cause I don't quite understand how to use/measure the gap in the cast rings to see if they're still usable. Speaking of cast rings, these are from the governor. The rear one is a locking type while the front isn't. Shouldn't they be the same? Speaking of the governor, a question: I've stripped it down and cleaned it thoroughly, I'm assuming I don't need to separate the parking gear from the valve/weight section for further cleaning? Since this is a '71 tranny, I don't think there's a filter in there anywhere.
 

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Naw leave the gov body alone.
Those cast rings are interchangeable. The interlocking are only slightly better. Take that interlocking ring ant stick it into it's bore.Straighten it up. The gap can run anywhere on those, but as the ring wears out , it will expand to the point that the hooks are touching eachother and the ring can no longer expand.So if in your mocked up install, check the expansion room. If the gap is just as wide as it is deep, she's got thousands and thousands and thousands of miles left. From the pic those two look pretty good. Check all the others the same way.A kit is available with just the rings. They used to be in the masterkits, but One day I noticed no more. They were like $5.00, the last time I bought a bag.
As to the one without the hooks;IDK, no spec in the manual. I'll take a wild guess and say up to .040 should be ok.Those rings don't wear much,in that direction, cuz after they are installed they do not rotate much. The sides do the sealing. If you study them a bit, you will usually find one side almost new and the other side is worn.
 
Thanks AJ. That makes sense. For anybody wondering how to compress that monster spring in the front clutch, here's a cheap easy tool I came up with using mostly my puller set hardware. When I reassemble, I think I'll use shorter bolts 😏.
 

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By the way, wittrans.com has what you need. Call the number, I use them for all my builds. Great prices!

Shameless plug: I have an A&A multi-spring front clutch retainer, minus one spring (not sure where it went, I'm sure you can get another from them) I'll sell you for a deal if you want it... Didn't fit my a-500...
 
Woods, appreciate the offer but I just ordered that part. Coincidentally, from WIT. It's a reman, but I suspect there aren't any more NOS. Part was $15.29 and shipping was $22. Hope they put a new bushing in there.
 
Yes that drum comes with a new bushing.

This is the part I'm talking about:

12985BA.jpg


It goes in place of the big wound spring that's wound the opposite way of release, for when your wailing on it. I 'believe' you can install 5 .086 thick clutch/steels in it as well. It goes behind the pressure plate in the direct drum (the one that you replaced because the band burned it up).


http://www.aandatrans.com/Products/904-Aluminum-Multi-Spring-Retainer-Kit__K12985BA.aspx
 
If it came with 4 disc and 4 steels and the disc are .086 ...you can not install 5 of them..
 
70aarcuda said:
If it came with 4 disc and 4 steels and the disc are .086 ...you can not install 5 of them..
Click to expand...

Unless you machine the difference off the outer edge of the top hat.... ;) It will let the hat come up a bit inside the snap ring and give you room for #5.
 
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