PDA

View Full Version : 90 AOD 1-2 shift slip when cold other shifts VERY good



Peterdroy66
11-11-2016, 10:39 AM
My AOD , is no question onward in its life - last spring (when colder and the car was new to me) it did usual slow to engage Rev/forward, and sometimes when cold flare after you came to a stop sign and started again.
Put a professional additive in the spring, and was MUCH MUCH better, basically felt perfect - was this the additive, warmer temperatures and or both - who knows...
Well now that it is getting colder, this morning after running say 3 minutes driving down the street to a stop sign, it flared as I started again......

I am thinking it would be worth changing the 1-2 accumulator seal/piston, any opininons - I know that if I take it to a transmission shop they will simply look at the odometer and condem it!

I think this has a good chance of fixing the problem while not being a huge deal if it does not.
It operates and feels firm and good in ALL other respects including 3-4 O/D on the highway

PR

sam jones
11-11-2016, 01:40 PM
Good morning


I would do research and talk to trusted transmission overhaul shop before coming to this conclusion. A pressure test would narrow the how far the transmission would be torn down.

I suggest you get a Mitchell Maintenance Manual and a Haynes Techbook for Ford AOD and copy necessary pages at your local library for reference.

http://www.clickclickracing.com/forums/forum.php? is a great forum for AOD maintenance.

Don't "shot gun" your way to a fix. Could be as simple as a TV cable adjustment or filter. Or as intensive as a valve body overhaul and or complete transmission overhaul.


Good Luck.

KMT
11-11-2016, 05:58 PM
Last time the AOD w/110k miles in my '90 did this, I was 1/2 qt low on fluid.

That additive may not only have helped in the way you describe, it may have also brought the level up and helped in that way too.

I second Sam's note about the TV cable. Easy to set, so if that hasn't been done in a while, I'd check it soon.

Always best to pick the low hanging fruit first ;)

Good luck.

Ken

Peterdroy66
11-13-2016, 12:31 PM
Thanks for the input guys, I agree shotgun approach is not effective, and I like low hanging fruit.
I have had other SC's do exactly the same symptom when down on fluid, so that was my initial thought back in the spring - certainly will check again.

TV, if the TV cable were out (which I have never adjusted in any other SC's) I would think that 2-3 and 3-4 shifts would be soft, but they are not, they feel really good.

Yes pressure test would be helpful, but I don't have gauges myself, nor know an transmission shop who will just do this - will ask my hot rod mechanic, but most defer to transmission specialists.

My thought in the 1st accumulator seal is that it leaks down when it sits overnight, and takes a few minutes to refill - maybe due to a worn pump and or cold fluid. Once things are warm and everything is flowing nicely it is a non-issue.

Had a 90' which had a shift kit (Baumann) and cooler, it operated perfectly well up towards 180k miles last I knew of the car in 2003.

Friend of mine has a 40k mile unit with a kit in it, I can swap in if needed, want to make this decision before it really drops in temp up here....This car is my winter SC.

PR

sam jones
11-14-2016, 12:45 AM
Good evening



if the TV cable were out (which I have never adjusted in any other SC's) I would think that 2-3 and 3-4 shifts would be soft, but they are not, they feel really good.

Yes pressure test would be helpful, but I don't have gauges myself, nor know an transmission shop who will just do this - will ask my hot rod mechanic, but most defer to transmission specialists.




PR[/QUOTE]


An early indication the TV cable might need attention is a noticeable increase in rpm and or throttling the pedal the achieve the 3-4 shift.

A DIY transmission gauge could be constructed (local hardware and hose outlet, harbor freight, ect) with the following:

- One 1/8 inch NPT Female fitting.
- One 1/8 inch NPT Male fitting.
- One 1/4 inch NPT 90 degree elbow connector.
- One 1/8 inch NPT dry pressure gauge (0-300 psi).
- High pressure hose fitting approx. 8 feet.


Using a Automatic Transmission Service Group (ATSG) manual or (Haynes Techbook FORD automatic transmission overhaul) for the AOD you would check:

- Main Line Pressure Port
Transmission selected to Reverse
Idle Pressure 75-90 psi WOT Pressure 241-290 psi

- Forward Clutch
Transmission selected to Drive
Idle Pressure 55-65 psi WOT Pressure 176-215 psi

- TV pressure
Transmission selected to Drive
Idle Pressure 0-3 psi WOT Pressure 70-91 psi



Maybe this information will help.


Good Luck.

KMT
11-14-2016, 12:52 AM
TV, if the TV cable were out (which I have never adjusted in any other SC's) I would think that 2-3 and 3-4 shifts would be soft, but they are not, they feel really good.


My recommendation was general housekeeping on a aged AOD should always involve re-setting the TV cable (takes just minutes to get done and doesn't require gauges), not a specific suggestion it may be your actual root cause ;)

If you're DIY attending to an underperforming AOD with high miles, anything you can do to bring it back to spec is in your interest, I think.

Ken

bowez
11-14-2016, 08:15 AM
Last time the AOD w/110k miles in my '90 did this, I was 1/2 qt low on fluid.

That additive may not only have helped in the way you describe, it may have also brought the level up and helped in that way too.

I second Sam's note about the TV cable. Easy to set, so if that hasn't been done in a while, I'd check it soon.

Always best to pick the low hanging fruit first ;)

Good luck.

Ken

My E4OD also is very finicky about fluid level as little as a pint down will do the same thing, but fluid level and condition are always the first things to check.

KMT
11-14-2016, 12:16 PM
My E4OD also is very finicky about fluid level as little as a pint down will do the same thing

;)

What's funny is the definition of 'down' a trans can be subject to. In one example, it would mean down from 'full' on the stick and another would be down from 'low' on the stick. 1/2 qt/pt might not matter when down from 'full', but make all the difference when down from 'low'.

Add in how it can sometimes be difficult to read an auto trans dipstick and things don't get any easier. I've also seen examples where the dipstick tube wasn't fully inserted, or the wrong tube/stick were used making it that much harder to diagnose issues, etc. Helps to make a note of the level on the stick when the trans is working right, and then stay with that later.

Ken

TbirdSCFan
11-17-2016, 11:45 PM
The level of fluid will make a difference in the "stall" when coming to a stop. Just make sure its filled to the top mark when level and at operating temperature. The NEXT thing you should know though.. is if your fluid is topped off correctly, and you still have the delayed engagement in D or R, that is due to wear on the Boost valve. There is a Sonnax replacement part for that. Since its part of the valve body, you can replace it w/o pulling the trans. :cool:

Peterdroy66
11-18-2016, 12:00 AM
Somewhat on speculation, but I decided to drop the pan and get the low servo out - have to determine which one of 3 possible lengths it is and replace it.
Ready to pull the servo piston out tomorrow.
will look into the sonnax boost valve, but I kind of want to change the servo piston and put it back together on Sat AM, we'll see.

Shift kits are great, but would be a waste of $, if the servo does not correct my problem.

just wish trans pans had a drain hole!

PR

KMT
11-18-2016, 12:16 AM
just wish trans pans had a drain hole!

PR

A harbor freight siphon pump [ http://www.harborfreight.com/fluid-siphon-pump-93290.html ] should be able to get most of the fluid out of pan via the dipstick tube first, before dropping the pan and taking a bath...

sam jones
11-18-2016, 05:29 AM
Somewhat on speculation, but I decided to drop the pan and get the low servo out - have to determine which one of 3 possible lengths it is and replace it.
Ready to pull the servo piston out tomorrow.
will look into the sonnax boost valve, but I kind of want to change the servo piston and put it back together on Sat AM, we'll see.

Shift kits are great, but would be a waste of $, if the servo does not correct my problem.

just wish trans pans had a drain hole!

PR

Good evening


Before dropping the pan I urge you to read the following AOD case study:

http://www.sccoa.com/forums/showthread.php?27691-AOD-Tranny-Experts-!!



As I learned the hard way you must address the condition of the valve body and inspecting and cleaning is a must. Servo bore cleaning, cover seal replacement and servo upgrades is of the

up-most importance. I am not a AOD tranny expert but I would refer this forum section to anyone "digging deep" into the AOD repairs in car repairs.

Good Luck.

Peterdroy66
12-23-2016, 11:41 PM
So far so good, have been driving city daily for two to three weeks, couple hundred miles and various temperatures.
I am pretty satisfied that changing the piston has improved/resolved the cold morning/slow engagement symptom.

Or maybe just because I got a good used Trans as a back up, it is no longer misbehaving!

Regards All

Pete

KMT
01-07-2017, 11:07 AM
Pete - still working ok?

Can you recall what length P/N that piston was?

Thanks.

Ken

Peterdroy66
01-09-2017, 10:18 AM
Still working well, have put few hundred miles on it.

The piston in my case was a "Two Groove" marked piston.
I don't think you can predict which one you will find in your trans, they are not expensive.

PEter

KMT
01-09-2017, 11:49 AM
Understood, thanks for the info.

Ken