Hello everyone.........

Sorry for the long read..............

I'm new to this forum, so if I am covering old ground, it's because I've not the time to search through over 4000 different threads here. So I offer my appologies........ At any rate, I drive an '87 Bronco II - Eddie Bauer, 2.9 V6 EFI, A4LD auto trans, Electronic (pushbutton) 4WD, air, cruise, pw, pl, and nearly a quarter million on the clock. This vehicle was purchased used. Engine was rebuilt by me approx. 15K miles ago. Trans has been rebuilt several times by professional shops for the same basic related issues. (i.e. Front seal failures and TC failures.) I have since resolved the TC and Seal failures myself as none of the "pro" shops that serviced it actually found the two problems. (i.e. TC alignment, (pilot), bushing at crank and Bell Hsg bushing bore alignment issue. - If anyone wants more info on these, I can elaborate).

Okay, before I get to my problem, there a a couple of noteworthy points I want to make. First, prior to me removing and servicing the trans myself, the trans was completely gone through and all serviceable "wear" parts were replaced at the "pro" shop just 2-1/2 to 3 months prior. The reason I serviced it this past time was due to the front seal springing a leak in my driveway and I was tired of taking it to "pros" who never solved the problem. By the way, there was less than 1/2 quart of fluid loss before I shut it down to service it. Second, this trans is not the the button-type electronic overdrive. There is a shift selector position for Overdrive on the floor console between N & D. Last, I have not been able to find information that explains in detail how this trans operates, it's electrical & hydraulic circuits, it's mechanics, it's setup and adjustments information and so on. So any links or book titles would be most appreciated. I do have a Haynes manual, but it basically is crap regarding the trans.

The problem..... Which is intermittent, is the trans does not always shift into overdrive as it should. I drive 45 miles each way to work and back so I am very familiar with this trans when it's functioning properly. Sometimes it will go for a day or two where it won't shift into overdrive. One time was for nearly 3 weeks. The time span between when it shifts properly and not also varies. Sometimes it will act up part way during my drive to or from work , (or where ever). Sometimes it acts up straight off the bat. I have tried to pinpoint something to correlate with this problem, weather, engine conditions, what-not. I've not found anything other than the following.

My left brake light, left rear running light, and left rear turn signal do not work. They have not worked since I've owned the vehicle. The front left running lights and turn signal does work fine. I have tried to fix the problem with the left rear lights , but I'm not the greatest at electrical issues. I have replaced the turnsignal/wiper switchgear in the steering column at the request of a guy who works in a local automotive electrical service shop. This did nothing to fix those issues. Next, when the trans is shifting properly and I'm driving on the expressway in overdrive, if I turn on my right turn signal, the engine picks up approx. 700 rpm and the trans "seems" to drop out of overdrive, (although I don't "feel" the downshift). Also, the rpm will not drop back to overdrive speeds the moment I stop using the turn signal. It may take a moment or so to go "back" where it was. (This does not happen with the left turn signal.) Third, cruise control functions properly when the trans is not functioning properly with respect to overdrive. I usually can't set the cruise to a speed when the transmission is funtioning properly. However, I'm not 100% sure if these are always the conditions for the cruise control issue. I will say this though, when the cruise is set and working, if I use my right turn signal, the cruise will drop out. Last, when I'm driving at speeds above 35 mph or so and just coasting/cruising along, and the transmission is not in overdrive, (regardless of whether it's a time when it's acting up or not), if I start to accelerate just a slight bit, the engine rpm will jump up approx. 700 rpm, (on my tach), and I will not feel any downshift or acceleration, nor will I see on my speedometer an increase in speed. Almost like a slippage, but definitly not a slippage. Just a downshift without the feel of a downshift. Strange at best.

Finally, my part in servicing my trans.......... Since the trans had just recently been fully gone through by a "pro" shop prior to it's last leaking spell, I decided only to service the following: I sent my bell hsg to a shop that installs and bores the TC snout bushing on center with the seal bore. (This is a known issue.) I replaced the TC, front seal, and the bell hsg seal. I also replaced the TC alignment bushing, (pilot bushing), which was very worn and actually the root cause of all of my transmission issues. I also completely rebuilt my transfercase, replaced both CV joints on my rear drive shaft, and replaced both universals on the front drive shaft. The only adjustments I made were to the shifter linkage when I re-installed the transmisson. The adjustment info came straight from my Haynes manual.

I'm open to any info and any questions. You can post here or email direct if you like toas I am allowing access to my email address here. I'd even be open to placing a phone call or two if that helps. I'm near Cincinnati, OH, but don't mind a long distance call if it solves this/these problems. I really like the truck and plan to keep it as it's a great year round vehicle for me.

Cheers,
-Jay

 

Okay, since I now have a much better understanding of how this trans functions, I'm of the belief that my problem lies in one of two places. It's either in the valve body where the overdrive spool/shuttle resides, or it's in the overdrive band servo. I'm leaning in the direction of the valve body though.

My reasoning is thus........ The overdrive circuits rely solely on hydraulics. The trans shifts properly through all other gears, reverse through 3rd, in all driving conditions. Thus leaving me to believe that the vacuum modulator and the govenor are functioning properly. If either of these were not, I'd have issues in reverse and the other forwars gears also. So I left with the cicuit that locks up the overdrive band on the overdrive drum. The only two items in play are the overdrive valve body shuttle and it's porting or the overdrive servo and it's porting. Since the problem is intermittent, I'm thinking that the valve body shuttle is sticking. Possibly a floating piece of debris.

Any thoughts or input is most welcome......

Cheers,
-Jay

 

Welcome to FTE!!!

You could check ebay for a Ford manual, I have one for 1989 but I believe they changed how the OD works between 87 & 89.

Have you checked for codes?

With the turn signal/OD operation stuff, is it possible the wiring is messed up?


Anyone else have any ideas????

 

Okay........ Still yet another problem, or the same problem getting worse. After driving to work today, the trans seemed to be working fine. As it were, I now think that my original problem was with the lock-up TC and I pretty sure that it's because of my brake light wiring problem. Anyway, it shifted fine and was dropping into overdrive like it should. The lock-up TC was even functioning as it should.

The last 3 miles of my drive home from work is on an expressway. It would not drop into overdrive. Not any form of coaxing would make it happen. !st through 3rd shifted in and out just fine. Reverse just fine. No overdrive.

I let it cool down and verified oil level. I re-adjusted the overdrive and intermediate bands per a spec I found here in this forum. Took it out for a spin. Still no overdrive.

Any ideas? I'm probably going to drop the pan and inspect the valve body, but I'm not 100% about what to look for as I have no schematic regarding the VB. Any help would be much appreciated!

Cheers,
-Jay