Blew OD

Discussion of STOCK transmissions, drive shafts, differentials, axles, wheels, tires, power steering pumps, racks, pinions, linkage systems.

Blew OD

Postby robertbweltzien » Fri Sep 08, 2017 4:58 pm

Lost OD on the Merchant Marine yesterday. Shifting was delayed and the fluid was black. I hate to think that putting in Trick Shift had anything to do with it? I switched about 40,000 miles ago. I changed the fluid in the pan and TC this morning and checked the throttle cable, which was fine. Back to Dexron III from Walmart. There was no clutch material visible in the pan and a magnet picked up about a dime sized aggregate of metal shavings. Now 1-2 and 2-3 shifts are normal but still no OD (engine flares!). Time for a new tranny? '89 LSC with 195,000 miles, never had any tranny problems before. Did I cook the OD band?

BTW the car has to make it to Maryland next month, we're moving up there from Georgia. I don't want to have to tow it!

Bob
Medicine, Biomedicine, Mechanics and MK VIIs
User avatar
robertbweltzien
CLUB MEMBER
 
Posts: 481
Joined: Tue Oct 16, 2012 4:51 pm
Location: Connecticut

Re: Blew OD

Postby CDW6212R » Fri Sep 08, 2017 5:11 pm

It may be the OD band is all that died. Hopefully it just had too much clearance and was slipping. The Trick Shift was made to be the best fluid at the time that the AOD used.

The Mercon and Mercon V were replacements after the AOD was created, and Ford often just recommends the newest fluid for all past vehicles. That is bad if people choose to use Mercon V for sure, that's much slicker and will create more slippage. I think Mercon(and Dexron III) are fine since those are similar in lubricity to Type F, which is what decides how well the clutches grab given the available pressure. Mercon V transmissions have to have strong fluid pressure on all clutches, timed perfectly, or they slip some or a lot.

I have the Trick Shift in my 91 still, I put it in with a shift kit trying to fix a delayed shift(1/2/3), and it only helped a little. I haven't put 400 miles on it since then, the fluid is clear and I hope to save it for later. It's a $6ish fluid now, crazy how prices have jumped.

For your OD, there is no repair for the band except R&R the trans. But the OD servo has three piston choices I think, you might try to install the shortest and see how tight the band can get. With the pan off, I think you can get a thin screw driver up and push the band tight from one side. I forgot if the VB has to be out to reach it. There should not be a ton of slack in the band with it installed(the OD servo/piston/cover). If the band is worn, it's slightly possible it's from long life wear, and not the OD circuit. There's only about 1/32ndor so of material on it when new, I might be wrong to suggest this will help. I'd drive it without OD unless you can help it in some way.
Don
1991 Red Special Edition, my 2nd SE, dead paint, DWS 255/45/17's on 95 Cobra wheels, and soon; DVD/Navi/backup camera, OBDII and the 347, before custom paint.
98 Mountaineer with Continental DWS 255/55/18's, big sway bars, custom brakes. Soon to be A4WD with XP8 bumpers and wing.

ImageImage
User avatar
CDW6212R
CLUB MEMBER
 
Posts: 5377
Joined: Wed Feb 09, 2011 11:57 pm
Location: Near Dollywood in TN

Re: Blew OD

Postby robertbweltzien » Sat Sep 09, 2017 3:07 pm

Don, It does shift better from 1 to 2 and 2 to 3 with a new filter and Mercon III fluid. The fluid that came out was black as tar but strangely doesn't smell burned! I think you're right Don that the OD band just died of old age. The fix now would be a built up HD AOD or 5 speed. Thanks for the input-I'll just drive it for now with the three remaining functional gears. Do you have any suggestions for a good built up AOD? Perhaps the original unit along with a good set of clutches and bands, and a revamped valve body? Open to any advice. Meanwhile I'll have to procure another used vehicle, my friend's old Ford Focus or another Mark VII.

Bob
Medicine, Biomedicine, Mechanics and MK VIIs
User avatar
robertbweltzien
CLUB MEMBER
 
Posts: 481
Joined: Tue Oct 16, 2012 4:51 pm
Location: Connecticut

Re: Blew OD

Postby CDW6212R » Sat Sep 09, 2017 4:20 pm

I had a great AOD in my first LSC, the HD shift kit installed not a long time before I wrecked the car. I rebuilt it a few years later, but I put the thin clutches in the direct drum, all Kolene steels, the wider OD band parts from AODE/4R's, and increased the shift points by lightening the governor on the tail shaft. That was intended for my next car, but back then the 4R70W wasn't a viable upgrade. Now I don't really need it, and it is made for more rpm than a stock/mild 302. I could take it apart and redo some things, that may be the best idea but it'd leave a bunch of parts to have to sell off too.

The late 88-93 AOD's are the best place to begin a rebuild, yours should be fine given it's not yet hurt badly. Driving one much with fouled ATF is really bad for later reliability. Given the large supply of later used AODE/4R parts, I'd always try to swap the wider OD band in, plus the mechanical diode reverse drum(OD rides on that), install the extra intermediate clutch pressure plate(and the extra clutch/frction)and upgrade to a bigger OD servo/spring/piston. That's a minimum for a 302HO or better engine, less than that is a not wise, going cheap decision. Those are not expensive parts, maybe $200 extra, some new and some being used. The valve body is the critical part, you need that to be as clean and unhurt(from a bad trans) as possible, lowest mileage etc. The VB kit is owner choice, the simple correction kit(SK ...), or the HD kit for much better shift characteristics(firmer too, up to hard).

The rebuild units you find online are typically way high for a simple rebuild, or odd combinations for upgrades that are not ideal for most people, plus too high.
Don
1991 Red Special Edition, my 2nd SE, dead paint, DWS 255/45/17's on 95 Cobra wheels, and soon; DVD/Navi/backup camera, OBDII and the 347, before custom paint.
98 Mountaineer with Continental DWS 255/55/18's, big sway bars, custom brakes. Soon to be A4WD with XP8 bumpers and wing.

ImageImage
User avatar
CDW6212R
CLUB MEMBER
 
Posts: 5377
Joined: Wed Feb 09, 2011 11:57 pm
Location: Near Dollywood in TN

Re: Blew OD

Postby robertbweltzien » Sun Sep 10, 2017 10:51 am

Thanks again, Don. Whether to rebuild the existing unit or invest in a 5 speed swap. Now we have to hunker down for hurricane Irma and next month we move north to MD and CT. Again, thanks for the great info and have a blessed Sunday. I have bookmarked this entry.

Bob
Medicine, Biomedicine, Mechanics and MK VIIs
User avatar
robertbweltzien
CLUB MEMBER
 
Posts: 481
Joined: Tue Oct 16, 2012 4:51 pm
Location: Connecticut

Re: Blew OD

Postby CDW6212R » Sun Sep 10, 2017 1:09 pm

Take care, this hurricane season will be the worst in many decades. I hope this doesn't turn out as bad as the Texas damage was.
Don
1991 Red Special Edition, my 2nd SE, dead paint, DWS 255/45/17's on 95 Cobra wheels, and soon; DVD/Navi/backup camera, OBDII and the 347, before custom paint.
98 Mountaineer with Continental DWS 255/55/18's, big sway bars, custom brakes. Soon to be A4WD with XP8 bumpers and wing.

ImageImage
User avatar
CDW6212R
CLUB MEMBER
 
Posts: 5377
Joined: Wed Feb 09, 2011 11:57 pm
Location: Near Dollywood in TN

Re: Blew OD

Postby robertbweltzien » Mon Oct 02, 2017 7:39 pm

I can feel and see the RPM drop into OD, but no grab. Probably explains the smooth 1-2 and 2-3 shifts. It would seem that an OD band replacement might cure it if the drum isn't chewed. Fluid is still clean after 300 miles, also good. I might just try an OD band replacement with the pistons you guys have specified. Either way, I'll have to wait until I get that 2000 Focus on the road. Although it's sat for 3 years (owner had many DUIs) and has 140K he bought it new and is a semi-professional mechanic, as am I. Oil was changed every 3K along with other recommended maintenance. I'd like to try that while planning a five or 6 speed conversion.

Bob
Medicine, Biomedicine, Mechanics and MK VIIs
User avatar
robertbweltzien
CLUB MEMBER
 
Posts: 481
Joined: Tue Oct 16, 2012 4:51 pm
Location: Connecticut

Re: Blew OD

Postby robertbweltzien » Tue Oct 03, 2017 1:20 pm

It turns out that when the original owner had the rear main replaced, they broke the throttle cable. 15 years ago. I guess the AOD OD band lasted quite a while considering that.

Bob
Medicine, Biomedicine, Mechanics and MK VIIs
User avatar
robertbweltzien
CLUB MEMBER
 
Posts: 481
Joined: Tue Oct 16, 2012 4:51 pm
Location: Connecticut

Re: Blew OD

Postby oldschool1 » Tue Oct 03, 2017 4:16 pm

Wow.
User avatar
oldschool1
CLUB MEMBER
 
Posts: 8564
Joined: Fri Dec 26, 2008 10:01 pm
Location: Primos, Pennsylvania USA

Re: Blew OD

Postby CDW6212R » Tue Oct 03, 2017 7:38 pm

The TV cable increases the pressure throughout the trans, for all gears. I'd expect more damage to be done to 1st and 2nd than 3rd, or 4th. The OD band is the weakest for sure, with age it is kind of common to lose that sooner than other gears. Just adding the basic Sysko VB kit, and a OD servo "A" set of three parts, would be a minimum upgrade. The old OEM "A" servo parts used to cost under $60, now it looks like aftermarket choices are available, but the OEM is(was) over $100 last I checked. Any shop can do that kind of work, if they are willing to.
Don
1991 Red Special Edition, my 2nd SE, dead paint, DWS 255/45/17's on 95 Cobra wheels, and soon; DVD/Navi/backup camera, OBDII and the 347, before custom paint.
98 Mountaineer with Continental DWS 255/55/18's, big sway bars, custom brakes. Soon to be A4WD with XP8 bumpers and wing.

ImageImage
User avatar
CDW6212R
CLUB MEMBER
 
Posts: 5377
Joined: Wed Feb 09, 2011 11:57 pm
Location: Near Dollywood in TN

Re: Blew OD

Postby robertbweltzien » Tue Oct 03, 2017 7:41 pm

Thanks, Don. Maybe that old incident had nothing to do with it? I dunno. With the cable now adjusted to the "normal" position it seems to shift a little soft,1-2 at 15 mph and 2-3 at 25 mph with a light throttle. I may go back to tightening it a couple of millimeters as I had it set before. I loosened it when I changed ALL the fluid and filter because of a delayed 2-3 shift when I lost OD. I wonder if that will prolong the life of the three gears I have left? I have to make a 700 mile trip with my disabled wife this weekend.

Bob
Medicine, Biomedicine, Mechanics and MK VIIs
User avatar
robertbweltzien
CLUB MEMBER
 
Posts: 481
Joined: Tue Oct 16, 2012 4:51 pm
Location: Connecticut

Re: Blew OD

Postby CDW6212R » Tue Oct 03, 2017 8:20 pm

A little more TV is good at almost any time. I doubt you would get it so high that it'd delay shifts excessively. As you know, the extra pressure firms the shifts a little, it's an additive circuit not a full source feed. I wish Ford had not tried that idea, the external rod or cable makes possible problems more likely, than if they had left it not adjustable.

If the fluid looks really good, and the 1/2/3 work well, it should be reliable for its age. Just keep it in D and out of the "O." Have a good trip, I just learned we have a holiday next Monday. :oops:
Don
1991 Red Special Edition, my 2nd SE, dead paint, DWS 255/45/17's on 95 Cobra wheels, and soon; DVD/Navi/backup camera, OBDII and the 347, before custom paint.
98 Mountaineer with Continental DWS 255/55/18's, big sway bars, custom brakes. Soon to be A4WD with XP8 bumpers and wing.

ImageImage
User avatar
CDW6212R
CLUB MEMBER
 
Posts: 5377
Joined: Wed Feb 09, 2011 11:57 pm
Location: Near Dollywood in TN

Re: Blew OD

Postby robertbweltzien » Wed Oct 04, 2017 3:09 pm

Many thanks for the reassurances, Don. I set it a little tight and it tested out OK. Fluid is still nice and red. Have a good holiday!

Bob
Medicine, Biomedicine, Mechanics and MK VIIs
User avatar
robertbweltzien
CLUB MEMBER
 
Posts: 481
Joined: Tue Oct 16, 2012 4:51 pm
Location: Connecticut

Re: Blew OD

Postby CDW6212R » Wed Oct 04, 2017 4:34 pm

Good to hear. Let me know if you want some Ford blue ATF, my Lincoln has the Trick Shift in it, I love seeing that color on the dipstick.
Don
1991 Red Special Edition, my 2nd SE, dead paint, DWS 255/45/17's on 95 Cobra wheels, and soon; DVD/Navi/backup camera, OBDII and the 347, before custom paint.
98 Mountaineer with Continental DWS 255/55/18's, big sway bars, custom brakes. Soon to be A4WD with XP8 bumpers and wing.

ImageImage
User avatar
CDW6212R
CLUB MEMBER
 
Posts: 5377
Joined: Wed Feb 09, 2011 11:57 pm
Location: Near Dollywood in TN

Re: Blew OD

Postby robertbweltzien » Wed Oct 04, 2017 5:04 pm

Thanks Don. I will!

Bob
Medicine, Biomedicine, Mechanics and MK VIIs
User avatar
robertbweltzien
CLUB MEMBER
 
Posts: 481
Joined: Tue Oct 16, 2012 4:51 pm
Location: Connecticut


Return to Drivetrain

Who is online

Users browsing this forum: magpie-crawler and 1 guest