What causes these symptoms?

GRWeldon

3rd Gear Poster
Joined
Oct 5, 2023
Messages
164
Location
Alabama
Country flag
I know I won't really know until I drop the pan and check accumulator pistons/springs. Aren't the 96 4R70W tranny supposed to have the updated accumulator pistoons for 1-2 and 2-3? In any case, here's what's happening:

I take off from a cold start in drive. Car starts to roll as normal, then seems as if the tranny is starved for fluid for a half second, the first re-engages and as soon as appropriate it shifts to second gear but there is a "bounce" after the engagement of second, like a back-and-forth effects like you might get when towing with a stretchy rope. Sometimes the shift from 2-3 is a bit premature. OD is fine.

This doesn't happen when I shift manually. If I'm not getting on to it with the shifter in 1st, the shift to second will happen anyway. If I'm getting on it hard, when I shift to second manually it will chirp the tire (open diff). I really don't want to be down for more than a day and would like to have parts on hand to put back in but then again, I don't want to buy anything I don't need. Doesn't really look like I'll be able to avoid be down until parts arrive, does it?
 
No, the 96 does not have the updated accumulator design. This wasn't implemented until the 1998 MY.

When you have time, read through Jerry's Thesis - it's called Ford Overdrive Transmissions 101. Lots of good info in there.


Manual shifts use a different combination of clutches to achieve the ratios for 1st and 2nd. What you're describing sounds like it could be forward clutch and/or roller clutch problems.
 
I've read (or tried to several times) Jerry's thesis. It get's a bit too technical for me. I've watched a couple of 4R70W rebuild videos on YouTube. Actually, about 5 hours worth yesterday. I think I could rebuild one. My take is that it's a broken accumulator spring. Maybe that's just wishful thinking. I'm really not set up to rebuild a transmission but I could wing it. It's a lot of effort. I have no idea how much a rebuild is.
 
Some crooked shop quoted me like 2200 for a swap to an already rebuilt transmission in 2016. So probably more than that.
(I did not need it and still don't.)
 
Don't rebuild a 96. Find a 2002 gran marquis non-police transmission. (~$200 Get a kit to rebuild it ~$150. New accumulators come with the deluxe kit.
Get a "superior tuff plate~ $50)" for the valvebody; it's already jmodded.

Read this until you understand it.
Doing that will fix all your trans problems.
 
Grog.... I keep telling you this. I'm broke! All the time! I HAVE a 96 so that's what will be rebuilt if necessary! I can't believe prices are so cheap where you are. Only place to get a $200 transmission around here is Pull-a-Part. I can't work in a yard pulling a transmission. I appreciate the sentiment and I'd love to have a PI motor and a a better trans. I seriously doubt it's in my future. Thanks for the link. BTW, the rebuild video I watched used a "superior tuff plate" I'll drill mine. It's cheaper!

Edit: I just checked the inventory of Pull-a-Part for 94-97 Thunderbirds/Cougars. There are 3 in the state of Alabama. 2 more in Georgia in Atlanta. Thunderbirds are not plentiful around here. I wish they were.
 
Last edited:
To build a 96 to last, you have to drill the plate yourself. The kit is still about $150, but you'll need to buy the overrun clutch, And put all the sonnax parts in the valvebody. Superior sells a shift improver kit wth new springs and other parts for the vb, that are already in the 2002 trans. Seal installers come in handy too. The resizer for the teflon shaft seals need to be made. I need to draw that up and post it, thinking of it. the place I got mine doesn't exist, so wtf.
 
Non-police, Mercury Gran Marquis. That's the trans to rebuild. Back in the 00's I could just run them. Now, not so much.
 
Since we're building each others cars I say manual swap :tongue:
 
Looks like ace auto salvage has a few for 250.
 
The problem with the manual swap is the $250 for a pedal. I can fix my auto a couple of times for the swap cost. :And I can build 1 auto, and use it for whichever one I break next, lol. The last 3 were swapped from the build stand, months after I built them. Put the dongle in the hole so the quart or so of lube and fluid stays in, and stick it in the trunk, and drop it off at the shop that was putting my stuff in. Then show up in the car that needed one, either limping or on a flatbed. ( his bro ran the wrecker service).
Since I got the shift schedule worked out, I'm happy with a manual. Tomorrow, I'm going to try to park Lazarus on the back porch and start pulling the engine. :)
 
Last edited:
:rofl: Yeah; I don't browse the yards around nashville either. Sorry; just trying to be helpful.
The mechanical diode($200) started being used in 98, but by 2002 they had pretty much unfucked the rest of the trans. That's why to get one of those, it already has the stuff you want. You can take a newly rebuilt 96 and destroy it, by doing the wrong things, while driving. an 02 won't die, and will actually do what you want. I'm not going to post what kills them, there are too many assholes out there.
 
Grog.... I keep telling you this. I'm broke! All the time! I HAVE a 96 so that's what will be rebuilt if necessary! I can't believe prices are so cheap where you are. Only place to get a $200 transmission around here is Pull-a-Part. I can't work in a yard pulling a transmission. I appreciate the sentiment and I'd love to have a PI motor and a a better trans. I seriously doubt it's in my future. Thanks for the link. BTW, the rebuild video I watched used a "superior tuff plate" I'll drill mine. It's cheaper!

Edit: I just checked the inventory of Pull-a-Part for 94-97 Thunderbirds/Cougars. There are 3 in the state of Alabama. 2 more in Georgia in Atlanta. Thunderbirds are not plentiful around here. I wish they were.
I have the same issue here in South Carolina rarely does a JY have a tbird and if they do its worse off than mine. so I feel your pain we are a single income family with 2 kids so money isn't plentiful. the grocery store usually gets more a week outta me than the IRS. with that being said pulling a trans from a JY isn't that bad. the Gran Marquis should be quite a bit easier to pull than a tbird and remember to bring a saw saw. cut exhaust and things that you don't need/won't work. it'll make the entire job easier it could be done in a few hours I would think. then once you have it home just save up some money little by little to get the rebuild... small steps one thing at a time so it doesn't all hit at once. for me I went a different route but only cause I grew up with a guy that owns a transmission shop and has a reputation for being the best around I was able to get the orginal trans rebuilt for 900 including a new torque converter shift kit and upgrades to internals to basicly make it a stronger trans. but I had to cause the trans went completly out. and around my house we had been acustomed to the 2yt. (2 year transmisson) every 2 years I was putting another used one in cause I didn't have the money to rebuild one... funny but sad
 
I did that thru th 00's; then I started rebuilding them lol.
 
If you have the gumption, you can message me.
The mechanical diode($200) started being used in 98, but by 2002 they had pretty much unfucked the rest of the trans.
I don't even know what a mechanical diode is!
 
It's the overrun clutch; the whole function is to freewheel in one direction, and hold in the other. Like a diode does to electricity. The one in the 96 is known, by me, to slip like a motherfucker at wot, at times it's supposed to hold. That is yet one more path to transmission destruction. I've found several, lol.
 
I've spent about 12 hours educating myself on the 4R70W. Watched the Transmission Bench 8-hour teardown, inspection and rebuild video series. Done pretty well. It's on YouTube. The guy talks so slow I had to speed it up to 1.25x speed to be able to tolerate it. Now I know for sure I can rebuild one. The price of a master rebuild kit it fairly reasonable, about $300 after shipping. That doesn't include any of the updated accumulator pistons/covers/springs so that cost would have to be added as well. Transmissionbench.com has a deluxe rebuild kit with the pistons and covers plus the Sonnax "Sure Cure" parts kit for $590 + state sales tax, shipped for free. This sounds a bit pricy to me.

I just removed the tranny from #2 as it was just hanging there. #2 is the Green 97 LX that is going to get the Towncar engine I posted a picture of. I just drained the fluid, it was semi-transparent black with a slight reddish tint. I guess I really need to tear it down so I know what "extra" parts it will need. I'd love to get a 2002 tranny to rebuild, as you suggested, and it's a good possibility that there may be one available at pull-a-part here in Montgomery. My issue is that the donor car is a LONG way from the checkout area and after walking to the car, I'm pretty much done for the day (yeah, my previous injury WAS that bad). Also the lot is made from 1-2" diameter stones that aren't very fun to lay on, let alone scoot around. I could possibly come out cheaper than a rebuild if I just grab one used and HOPE that it works well, at least for some amount of time.

Before doing anything else, next week I'm going to drop the tranny pan on #3, the White 96 that I just put back on the road and check the 1-2 accumulator piston since that one is accessible without removing the valve body. Maybe I'll get lucky and find it's in horrible shape and/or has a broken spring or two and fix it's issues. Probably not but it's worth the time to check. I think I could do it in a couple of hours and that is saving the fluid for re-use. It's bright red so I think it will be OK.

What "flavor" of transmission fluid are folks using in their daily drivers these days?
 

Attachments

  • 20240321_161832.jpg
    20240321_161832.jpg
    4.8 MB · Views: 4
I took a quick look at where I got my last kit, nd they show $481 for the deluxe kit with pistons, so the kit is ~50, and then add shipping; no, that price you quoted is about right. It's more than doubled in 8 years.
 
Don't reuse fluid; I filter and use it to clean parts, but it wears fast, so replace it for sure. In the 1-2 accumulator; If you like the slushy factory shift, put both springs in. I recommend the purple upper and no lower. If you want it to bark every 1-2 shift, use the brown top spring, no bottom. :)
 
Don't reuse fluid; I filter and use it to clean parts, but it wears fast, so replace it for sure. In the 1-2 accumulator; If you like the slushy factory shift, put both springs in. I recommend the purple upper and no lower. If you want it to bark every 1-2 shift, use the brown top spring, no bottom. :)
I think in the only J-mod I did, I used the purple upper and no lower. I was pleased with the result.
 
To do the acc piston,You need a snap ring plier that will hold in position. Unless it's broken, it wants out, so be holding it when you remove the snapring. Or you'll have a dent in your forehead, lol. PATC sells individual springs, but they come in 3s
 
Well, I pulled the tranny pan just a few minutes ago to replace the 1-2 accumulator piston. Guess what I DIDN'T find! A FILTER! Some bonehead didn't install a filter the last time the pan was off! I would suspect this would cause a starvation of fluid when the tranny was at even a slight angle. I am amazed at the stupidity. The guy I bought the car from worked on Corvettes and Mustangs! Had a 68 Mustang fastback, a 73 Stingray and an 84 Vette in his driveway when I picked up this Thunderbird. He had a lift and said he did all his own work. Unbelieveable.

I'm hoping when I put the filter back in and replace the 1-2 accumulator piston, all will be well. I might be able to update tonight...

Really y'all. I can't believe the idiocity. BTW, the pan was fairly clean. No accumulation on the bottom and very little smut on the magnet. Maybe I dodged a bullet...
 
As I get older, I'm not quite as sharp as I used to be. I have seen the same thing happen to my mother. I used to be sharp as a tack. I've looked at the transmission of my 96 from below while it's on the lift a dozen or more times. After draining the TC through that tiny little hole, I slowly pulled down the pan and actually spilled very little. The pan was fairly clean and there was a bit more smut on the magnet than I first thought, maybe a 1/16 of an inch. I could push the 1-2 accumulator up with my finger. I took out the snap ring and the cap came off followed by the piston and a bunch of fluid that I wasn't expecting that got all over my pants and shoes. Great.

The accumulator had NO SPRINGS on the top! Also, there was a mangled purple spring on the bottom. The lower O-ring on the old-style piston was broken. I'm thinking to myself, surely this will work great when I put it all back together as it's supposed to be, except I don't have ANY springs to put on top of the piston. Luck for me I just removed the 97 transmission and it was on the jack just a few feet away. I pulled it down, removed the piston that came out quite forcefully because it had TWO springs on top (none on the bottom). There was an orange and a dark spring on top. I thought I saw traces of purple on the inside spring. After washing the color was still inconclusive. If I had to call it a color, I'd say it was brown, which I know Ford made a brown one. It wouldn't take much convincing to make me think it was purple.

In any case, I had to put a spring in and I guessed that the mangled purple one out of the 96 would have been about the same diameter and length as the "brown" one out of the 97 so I used it on top of the updated accumulator piston. I cleaned up the pan from the 96, removed the stuck seal from the filter that "wasn't there" and installed the new filter. I cleaned up the pan, not really seeing that it didn't have the small, square sump on the bottom like 96-97 are supposed to have. I didn't notice until I went to put it one. Like I said, I'm not nearly as sharp as I used to be.

Well, I then took the filthy, greasy pan from the 97 to the solvent tank and cleaned it up since it was the proper pan. I reinstalled it using the reusable rubber gasket. Brought it down on the ground and reused the fluid that came out of it even though Grog told me not to. It was the proper color red and I know at least a gallon of it was new since I put it in a few weeks ago.

I didn't bother to check the fluid level at that time. I slowly pulled out of the shop in reverse and put it in drive. It almost stalled but recovered, which it has been doing since the first time I drove it. This tranny has some issues, I know. So I drive down my long driveway in D and it seemed like it was acting normally. I pulled on to the street and the shift from first to second seemed like a normal shift. I drove out of my subdivision on to the main road and nailed it. No slipping, good shift from 1-2 and a squawk from the single tire (open differential) and proceeded to go through the gears normally. I cruised about 80 for a mile or so (country county road) and turned around in a church driveway. I slowed to a stop before pulling out, then proceeded forward like a granny. Disappointingly, the shift was almost the same as before the piston change, with a bit of engagement in first, a little slip, then first again before shifting to second with the same rocking motion forward and back like when you shift a manual while idling and the car lurches forward, jerks back the lurches forward again. The duration of the rocking was maybe a third of a second then normal progression to 2-3, then 3-4.

I get it home and park and check the fluid while the car is level and in running in park. It doesn't even show on the dipstick. I'm pretty sure it isn't much more than a quart low. The nearest part store is 25 miles away and while I think I could drive it there with no issues, I'm just going to use one of my other vehicles to go in to town for the Mercon V.

I'm a bit bummed, but I'd say it has to be better for the tranny using the deep pan with a filter that also acts as a pickup tube. What MORON would ever run a transmission without a filter (if so equipped).

One thing this tranny is doing that has me puzzled. If you shift from drive to 2, it stalls. If you shift from D to 1, all is fine. Shift from 1 to 2 and it stalls. I am not experienced enough with transmissions to even guess what might cause this but it seems as if a clutch is engaging when it shouldn't? Any guesses?
 

Attachments

  • 20240402_152055.jpg
    20240402_152055.jpg
    3.5 MB · Views: 4
  • 20240402_152148.jpg
    20240402_152148.jpg
    3.7 MB · Views: 4
That's the tc clutch not disengaging; theres a mech lockout in 1st and reverse. Will it downshift to first from od if you don't put it in 2d?
 
That's the tc clutch not disengaging; theres a mech lockout in 1st and reverse. Will it downshift to first from od if you don't put it in 2d?
I want to clarify that the behavior I mentioned, stalling when shifted to 2, this happens when I'm not moving with my foot on the brake.

Not sure exactly what you are asking with your question. First, I wouldn't shift from OD to 1st, however, I have downshifted from D to 2 with no issues but I have accidently left it in 2 while coming to a stop and the engine stalls.

If the TC clutch is not disengaging, is that a transmission servo thing or is it a TC thing? In other words, would replacing the TC fix this behavior if the TC clutch is not disengaging...or to put it another way, what would fix this behavior?
 

Similar threads

Back
Top