A4LD shifts only at high rpm's

[microvibe]

Hello Everyone

I have 3 a4ld's giving me problems I'll start with the most important one.

I have a 1991 ranger 4x4 with a 4.0l that has a a4ld from a 91 explorer 4x4.
I did a tranny swap from the explorer to the ranger, the donnor tranny had been sitting for awhile so i did a filter change , installed it and it worked perfect for 1 day. I checked fluid after the tranny started acting wierd found it to be way overfilled so i brought it in for a complete flush.

Ok here is the problem, If i try to start off in OD it just revs out and goes no where, if i start out in D it will go as normal but when it come time to shift from 1-2 i have to tak erpm's up to 4000 or so then it kick over to 2nd and the shift is very firm, the shift from 2-3 is the same way and sometimes i have to manually play with shifter switchign from 2nd-3rd to get it to switch over, now once its in 3rd if i put shifter into OD it will just rev out as if its slipping put it back into 3rd and it drives fine again. Here's the wierd part as of few days ago i took it thru the gears up to 3rd like usuall then decided wth i'll try OD again put it into OD and it shifted into OD fine and drove like it suposed too. I started to slow down while in OD and once i got below 60km/h it seemed to kick out and just reved out again so i needed to put back into D if i take it above 60km/h i can pu tback into OD.

What i am wondering is anyone thinks maybe its a solonoid problem or govenor , basicly do you think its something i coudl fix without a complete rebuild.

ok tranny #2
This is the tranny that was orignal to the 91 ranger.
The problems with this one were when cold i would get delay engagement into reverse and forward gears would slip untill truck warmed up. also i dont think the 3-4 shift was working it seemed to go thru all the gears even into 4th but soon as i apply alittle gas while in OD it would rev out to about 3200rpm at 60mph before it started to pick up speed again(almost like a high stall torque converter lockup)maybe i should have rebuil this tranny. also if i drive on highway at 60mph in drive its at 3200 rpm as well so i assume that its not shifting into OD

Tranny #3
This is a 1994 explorer xlt 4x4 my favorite truck btw lol
2nd gear is gone will just rev out in 1st then seem to shift straight to 3rd, from what i read on here so far i think probably a broken band.

I know this is alot of info requested considering tis my 2nd post on the board, i am just unsure where to start with the repairs, i was going to just try to rebuild the 91 ranger tranny that ssitting in the garage for the 94 xlt but from what i read on here the 94's tranny is better, i would like to be able to backyard fix the ranger so i can park the xlt and get it fixed properly.

Thanks
Travis

 

[Glacier991]

WOW, bad luck in 3's!

As for #1 and #2, those are a wierd set of symptoms, and while it could be VB related, I'm sensing a teardown might be in order in each case.

As for #3, you present classic symptomology for a broken intermediate band. A Rebuild of only 1 any of the 3 ought to be this one. When (if) you rebuild it let me suggest some hard parts that ought to be changed out.

Wish I could be of more definitive assistance.

 

[Bent Bolt]

#1 sounds like two problems. No movement in O/D position means the O/D one way clutch probably is hooped. And the delayed shifts might be related to the vacuum modulator.
#2 could be alot of things- plugged filter,damaged o-rings on the filter,worn/damaged pump,worn/damaged center support-- the list can go on.
#3 is a broken band, as was mentioned, or maybe a damaged servo piston. Seen the piston rubber get so hard that it won't seal or so hard that a peice chunks off it. Is the heat sheild missing??

 

[Glacier991]

Wow Ben, you are a find. Delighted to have some FORD Tech help on these issues. And you are right, the servo seals I replace are usually hard as a rock.

 

[Bent Bolt]

I like to drop them on the floor to see if the rubber cracks off !!!! LOL !!!!

 

[microvibe]

thanks for the replies.

tranny#1
What do you mean by hooped? Would you know why the OD would work above 60kmh?

Here is alittle more detail on what happened. I didnt know the torque converter had got rained on when i installed the tranny so after the first day the fluid level was way overfull with alot of water in it so i got it flushed and it seems the tranny is getting better more i drive it since the flush. i was thinking maybe gunk in old fluid clogged up certain parts. also anything i can attempt to try fo repai rwhile tranny in truck?

#2
i am considering ripping this one apart just to find out what is all bad and get a better idea what these trannys are all about.

#3
if it would be servo piston can this be fixed while in truck or need to remove?

i have a 94 xlt coming in fo rparts which has excellent powertrain so my 94 xlt will get the parts truck tranny and i will be using tranny #3 to try my first rebuild, i just need to thru more of the rebuild sticky on this board an dmake a parts list of what i need. Will this 1994 xlt tranny work in my 91 ranger from what i have read i believe it will but just asking to make sure.

tommorrow i will be working on the 1994 and checking out the tranny abit more wil also look to see if heat shield is present, btw when i checked fluid levels the fluid smelled an dlooked like new no brownish colour or burnt smell that usually is associated with burnt bands

 

[Bent Bolt]

Hooped........

........as in NFG, fubar, just plain failed.

When you select O/D on the shifter, the O/D one way clutch (sprag) drives the forwad clutch drum. If the O/D sprag fails-- which is common-- there is no mechanical input from the engine to the forward clutch-- you get a neutral effect.

When you select D on the shifter, the coast clutch is applied which "overrides" the O/D sprag which means the forward clutch is being driven. The coast clutch is inside the O/D drum.

When the trans is in 3rd gear,all that happens to get 4th (O/D) is that the O/D band comes on which holds the O/D drum to the case.The O/D sprag overruns and voila!!! Overdrive !!!!

Over simplified but hopefully you get the general idea. Yes you can change the servo pistons in chassis. You will have to remove the cat converters to access them.

 

[Glacier991]

Water in a tranny is a VERY VERY bad thing. You might get lucky. I'll keep my fingers crossed for you. Generally that spells doom.

And yes a 94 will fit and work fine in a 91.

 

[microvibe]

well i decided to swap the 94 xlt tranny into the 91 ranger ( actually swaped motor and tranny ) I know the 94 xlt tranny worked great as that truck was my driver for a year before it became a write off.

I had a shop do the swap didnt have the time myself, but something doesnt seem right to me . It shifts nice and smooth but at 60mph its reving at 2600-2800 rpm if i put it into 3rd at 60mph it jumps to 3200rpm. What i would like to know is the normal rpm rang ein o/d at 60mph (stock gears, lt235/75/r15's).

also is thier any linkages that could mess with torque converter lockup or the passing gear cable not adjusted properly(it does drop out of o/d into 3rd when i step on it at 60mph) or maybe wiring differences from a 91 to 94 or the ecm is different? The mechanic di dsay he had to swap the wiring harness for the plenum from the 91 motor on to the 94 motor.

I cant see it being anything wrong with the tranny itself, is thier sensors on the motor itself that control tc lockup, they di dreuse some old sensors from the 91 engine.

i think i will buy a manual next time lol

thanks guys this site has so much good information