[MUD E1]

I've been reading about the inherent clunking most AODs have between D and OD. My AOD does it. But I haven't found anything specific to what else my AOD does: When coasting to a stop, it will shift down like normal, but will also get jerky.

It feels like the engine compression (which is slowing the vehicle down) alarms the AOD, so the AOD "disconnects" the pressure to the rear end. This causes the engine to idle down because there is nothing forcing to run fast. Then, the AOD decides to "reconnect" the pressure. This sequence cycles a few times, which causes the vehicle to jerk. It doesn't happen all the time, but is surely annoying when it does.

Does anyone have any suggestions?

Just for reference, my AOD is an low-mileage aftermarket transmission with heavy duty parts, shift kit, and wide-ratio gears. My torque converter is a Hughes (1800-2000 stall - but jerking occurs above 2000 RPM). My TV cable is set properly. I have an external tranny filter (did nothing for this problem) and Bronco has factory tranny cooler in front of radiator).

Thanks for any help.

 

[BikerPepe`]

no help.. like ever?

well... I own this rig now and she acts pretty much the same as he described back then.
it's not a big issue... and apparently has stood up for some time without being a real problem. :shrug

 

[TravisITGuy]

perhaps driving around in D vs OD unless your traveling above 55mph.

 

[JKossarides]

Any type of "clunking" could be attributed to worn u-joints, yoke issues, slip joint issues or ring and pinion issues.....when was the last time the u-joints were replaced and you lubed the slip joint shafts. I used Mobil 1 synthetic grease a couple of years ago when I rebuilt both my shafts using greaseable u-joints because I don't Off Road but if you do then go with non-greaseable as they're stronger without journal holes inside for grease.

What valve body do you have in the AOD and when was the last time you changed the fluid and filter/gasket......?

There'a also a simple shift linkage adjustment procedure in the Haynes Manual in the tranny section, Ref. Illustration "Point A" on how to, takes less the 5 minutes but the column shift linkage will be in sync with the transmission when you run thru PRNDDL.

Good Luck ~ :thumbup

 

[BikerPepe`]

kem: shifts to OD about 45 mph on the speedo. That's probably 40-42 in reality, w/31" tires. :shrug


jk: You haven't been keeping up with me. Just got the rig recently... http://www.fullsizebronco.com/forum/showthread.php?t=265226

Then figured out that it used to be owned by MUD E1/Bret down in Moses Lake, WA.
http://www.fullsizebronco.com/forum/showthread.php?t=269498

Started going back through his old threads to learn more about the rig and ran into this one. Thought I'd bring it back from the dead, since the behavior hasn't changed since 2006. Having run this long... I don't think it's a real problem, but wanted to check. :shrug

 

[JKossarides]

BikerPepe'

Post # 11 on http://www.fullsizebronco.com/forum/showthread.php?t=265226 what am I missing? lol lol

Good Luck ~ :thumbup

 

[BikerPepe`]

...when was the last time the u-joints were replaced and you lubed the slip joint shafts...

What valve body do you have in the AOD and when was the last time you changed the fluid and filter/gasket......?

There'a also a simple shift linkage adjustment procedure in the Haynes Manual in the tranny section, Ref. Illustration "Point A" on how to, takes less the 5 minutes but the column shift linkage will be in sync with the transmission when you run thru PRNDDL.

Good Luck ~ :thumbup

Well, this was why I gave that response JK.

The last time I replaced or lubed the u-joints? never, yet.
What valve body do I have in the AOD? Not a clue.
The last time I changed the fluid and filter gasket? never, yet.
and... I still need to pick up a Haynes manual for the '90. I gave the last one away with the '89... a few years back.

 

[helirich]

kem: shifts to OD about 45 mph on the speedo. That's probably 40-42 in reality, w/31" tires. :shrug

What he means is you shift it! When you start, just go to D. Then when your getting on the highway (or going faster than about 50) shift to OD. When you are slowing down, back to D. Thats what I use to do with my 88' Bronco.(AOD) No more problems.

 

[BikerPepe`]

Hmmm... interesting. OK'ey dokey! :thumbup

 

[nelbur]

I believe I have the "jerking while coasting problem" you are talking about. Mine feels like a down shift, but I am convinced that it is not. I think it is a drop in the idle rpm caused by the computer, because just a bit of throttle will restore the coasting conditions before the jerk, without any transmission shift. I have not figured out how to solve the condition so I have just lived with it.

 

[Smok3y]

Try it with overdrive off, and then again with overdrive on. If the problem still continues to happen it could be a few different things in order of likelihood:

1) check u-joints from tcase to rear axle

2) Make sure your Driveshaft flanges are tight, as well as your shackle bolts, and hanger bolts. Anything that keeps your rear axle placed should be checked. Spring plates and U-bolts as well.

3) Check the Trans mount on your trans crossmember. It could also be an engine mount issue, but I'd put my money on transmission mount since they often get neglected even more so then motor mounts.

4) Check your TV Cable (it's the Trans "Throttle Valve" cable) - often times with a shudder or jerking the TV cable is making the line pressure too high. The TV Cable may need to be loosened. Especially with a shift kit which automatically changes pressure to help control shifting, TV Cables must be properly adjusted.

5) The Planetary inside the AOD, or other gears, are starting to lose teeth and in turn are having problems meshing together during down shift.

There is also a possibility that you are having problems with the motor but I am assuming that you are correct in diagnosing that it is a trans/driveline jerking and not the motor causing it. Most of the diagnostics I said above are free to check and adjust so it won't cost money. As far as internals, that's an expensive diagnosis and an expensive fix, and I believe it to be unlikely since jerking is not usually a sign of a failing AOD (but it does happen)

Let us know once you have some time to check it out and get back to us.

 

[helirich]

5) Double check to make sure that the Transmission vacuum modulator line is properly connected, not cracked/dry rotted (it's a big thick rubber line on one end)

There is no vacuum modulator on a AOD.

 

[Smok3y]

There is no vacuum modulator on a AOD.

you're right thank you for the correction. I edited the post :thumbup

 

[Daves 88']

Mine does that while driving around town in overdrive too. I did the tv cable adjustment a few years ago, and also took it to a reputable transmission rebuilder and he said nothings wrong yet, but come back when something goes wrong. I am just thinking mine does not like driving slow in overdrive.

I remember and old girlfriend bought a 91(?) Escort new off the lot, and her manual said she had to shift in and out of overdrive according to speed.

 

[planeflyer21]

IIRC, most of the owner's manuals for vehicles state to only use overdrive when travelling 50+mph…some even higher speeds than that.

 

[dan.jones]

My 5.0 AOD bronco does this too. I thought it was a bad transmission since it's a used tranny I bought for 80 bucks. I put a bottle of lucas in it and waited for it to smoke and replace it again, but it's made it two years now. It's not my dd but it seems like the more I do drive it the more it smooths out. I did figure out the drive in D trick and it helps a lot. I had been thinking that the 3.55 gears and 33" tires was adding to the symptom some, but after reading this thread I'm guessing not.

Oh and I like your bronco a lot...reminds me of a really clean version of mine.

 

[BikerPepe`]

go big white bricks! :rockon

 

[TravisITGuy]

dan jones, the taller tires will eventually chew the AOD when in OD below 50mph.

if you think about it this the tranny doesnt talk to the computer like the e4od does so its doesnt truely know tps/throttle position when driving to give optimal line pressure. cables stretch, taller tires will also have an affect in the behavior.

 

[dan.jones]

That makes sense. Is there any chance regearing would help that or should I be planning on a different transmission? I have a set of 4.56 to go in it but I'm planning on 35's then. Plus I won't even be doing that until I swap in my 78 dana 44, but the overhaul kit for that's in the mail now so it all depends on how self motivated I can be the next few weeks. Ultimately I'd like to do a zf5 swap but mainly don't have the time right now.

 

[helirich]

That makes sense. Is there any chance regearing would help that or should I be planning on a different transmission? I have a set of 4.56 to go in it but I'm planning on 35's then. Plus I won't even be doing that until I swap in my 78 dana 44, but the overhaul kit for that's in the mail now so it all depends on how self motivated I can be the next few weeks. Ultimately I'd like to do a zf5 swap but mainly don't have the time right now.

The 4.56 gears will help the tranny last longer. Tall tires an tall gears will ware out your first gear clutches. Those gears will get you bact to stock. (with 35's) But the OD jerk is a attribute of the AOD. Just shift in and out of OD as stated. It will be fine.