AOD 3-4 accumulator missing @ A servo questions??

[jshoop]

I am attempting my first AOD rebuild on my 1991 LSC. There is no 3-4 accumulator. It doesn't look like anything was ever there. I don't think the tranny has ever been apart because the fill tube plug was still in the pan. Do some AOD's not have this piston or was it a factory mistake? Also, is changing from the B to the A servo a drop in affair? Could you use a used one? I am using a Brumann rebuild kit, shift kit, and boost valve. :confused:

[ November 28, 2005: Message edited by: jshoop ]

[macx]

It's correct that some AOD's didn't have
that 3-4 accum - my 89 didn't either.

TheB to A is a drop in. Just make sure
you get the rod hooked to the band.
There should be a little slot you can
stick a small screwdriver thru to push
the band into position if needed.

While you're "in" the trans, you really
should replace the 2-3 accumulator with
the late model 4R molded rubber/over steel
accumulator which doesn't wear the bore
and seals better.

I just have the A servo on a stock width
band and it has held well for several years,
I just don't do full or heavy throttle on
the 3-4 shifts.

Take a look in the tech forums if you haven't, look at Heavy Duty AOD Internals
and then RWD Interchange for some other things you may want to consider while you're in there.

Look at the other Sonnax valves Baumann offers, and also take a look at the Sonnax site.

Two things I found when I did my first AOD (I had done the other brands but never a Ford) - Installing the clutch pack pistons without the "seal protectors" is nearly impossible - I got mine done the first time but it's scarcely worth it without those. Check the links in those 2 articles, the cheapest I've seen for a set on the net is
about $65. The other thing is all the diff sizes of bushings. I ended up putting all the new ones in a cold freezer to shrink them a little, then used large sockets turned backwards on a short extension as drivers, being VERY careful to get them started straight. For ones that have to go in farther than flush, you can sand the outside of the old one a little so it's loose enuf to pull back out and use it to get the new one in. It's good to mark the depth on those that go in deeper than flush before you remove them, too.

The hardest one is the rear case bushing, of course it goes in from the inside. Takes a LONG driver handle. I made one out of my slide hammer puller handle, welding up a flat plate with a guide welded to it that the new bushing just fits over. Ruined 1 before I got the 2nd one started straight.

I got an ATSG manual (which turned out to be a reprint of the Ford service manual) but it's a little confusing the first time around. You can get a trans rebuild video from Summit, too, which might be a help.

If you have shifting problems after you put it back together, suspect the valve body. Even if you've had it all apart and cleaned it well. I ended up getting a good used one the first time from a shop, then bought a reman one the 2nd time for about $100.

The tci website has good instructions on setting the tv pressure.

Good luck!

Oh, also look at the Tech articles on removing/reinstalling, and the article about
easy H pipe removal. Should help you out.

[SilverFox]

ditto - as always good work Mark, we should teach an AOD class :cool:

[Bluegrass]

Some additional comment to a fine thread are, you can make a tool to slide up into the case to position the OD band for contact with the OD servo piston rod nose. A piece of flat stock with a curve in it and a straight handle section works good under the car.
I run the A servo with a stock width band behind a K.B. blower now for more than 3 years without a problem butt that is not to say everyone will have the same results.
I have the Baumann shift kit with upgraded piston and run the pump pressure up and have the TV set to firm besides so the OD band engagement is harsh unless you play games with the throttle and lighty load the upshift in the absence of an accumulator.
The factory removed the 3 to OD accumulator for good reason of the excess wear the band would get during the shift period.
With my throttle controlled shifting, the OD never upshifts under a power condition because it won't do so unless permitted by a reduction of throttle.
Now once OD is engaged at high enough road speed the OD in now holding all the engine power. This is the weakest point in the operation that can slip when the band gets worn and/or the servo pressure goes low for some reason.
I thought I would give a view of the AOD that when built and adjusted with some insight is a tough transmission at least for street use.
For drag strip use, this transmission needs all the help it can get internally to stay alive behind high HP engine and drag use.

Some of you know of a car that I had the pleasure of seeing run,know the owner and run the same show with, has a fully built PA unit that has more than 200 runs, last I knew, behind a K.B. blower / 331 cu/in combination laying down more than 500 hp and runs now in the 10.8 ETs in 3850 lbs. in car weight.
So this AOD is pretty good if built and set up right. ;)

[jshoop]

Thanks for all the info! I have another AOD question. How do you remove the front pump? I don't have a slide hammer and we put bolts through links in a chain, hooked another chain to it an jerked on it. My brother said he has done this successfully with Chrysler trannys. I am going to the local Autozone and renting a slide hammmer. Are there any other tricks to removing the front pump?

[jshoop]

I got the pump off!

[SilverFox]

I don't suggest using that method - there are only 2 threaded holes for metric bolts - you might rip them out/break.

I invented my own slide hammer out of threaded stock smile.gif Works every time.

But lately, I just turn the AOD on its face with a block of 2x4 under the input shaft and hit the bell with a mallet - one swing - pop! All the guts roll out quite nicely as you lay it over smile.gif tongue.gif tongue.gif

[jshoop]

I made a slide hammer out of threaded stock too! I'll have to try the other method if I do another AOD.

[SilverFox]

Where in Missouri are you? Howdy MO guy! smile.gif

[jshoop]

I'm in NE Missouri.