Potential Corrections to 4R70W 'Thesis' - Part 1 - TCCoA Forums
 
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post #1 of 7 (permalink) Old 08-02-2003, 06:18 AM Thread Starter
 
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Potential Corrections to 4R70W 'Thesis' - Part 1

INFORMATION ONLY

I have the following updates/observations to offer concerning the AODE/4R70W transmission articles located in the technical area of this site. This is based upon '94 4R70W transmissions (pre '97).

A) Concerning the Direct Clutch Assembly:

The stock (OEM) replacement friction material measures .076"
The suggested replacement friction material - F8AZ-7B164-BA - measures .067"

The stock (OEM) replacement steels measure .068"
The suggested replacement steels - F6AZ-7B442-AA - measures .077"

The difference between the stock and upgrade friction materials is (-.009").
The difference between the stock and upgrade steels is +.009".

These are generally used in matching sets of each type to maintain proper clearances. The thickness of a combination of steel and friction plate is identical between the two types.

The stock pressure plate on a pre '97 5 plate clutch measures .378"
The stock pressure plate on a pre '97 6 plate clutch measures .220"
The suggested 6 plate pressure plate - F7AZ-7B066-AB - measures .238" **

** NOTE: The suggested pressure plate is apparently intended for use with a '97 or later direct drum, due to the increase in snap ring groove to piston clearances.
This is NOT noted in the text.
You should use the .220" pressure plate on a 6 clutch assembly on a pre '97 transmission or you will probably not be able to obtain the correct clutch pack clearance. This is generally .010 to .015 per plate on ALL clutch packs.
(i.e.: .060" to .090" on a 6 plate direct clutch.)

The completed clutch pack, including pressure plate and all steels, should measure a total of approximately 1.10" on a pre '97 and 1.28" on a '97 and later direct drum.

If you have exhausted the (A-D) snap ring possibilities, clutch pack clearances may be increased, if necessary, by machining the pressure plate an appropriate amount.
If you are really patient, this can be done carefully with a glass plate or granite lapping stone and 3M wet-or-dry abrasive sheets. It MUST be evenly thicknessed.

Further Updates Pending.

FWIW,
Greg

(edit: spelling and cleanup)

Last edited by GregFL; 08-03-2003 at 04:58 AM.
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post #2 of 7 (permalink) Old 08-02-2003, 06:30 PM
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Seeing as the steels are getting thicker and the friction discs smaller, it sounds like they were making an effort to combat heat by putting more steel in.

Are the pressure plates considered throw aways during a rebuild, or can they possibly be reused? If they can be reused, then the friction/steel changes won't affect the clutch pack measurements at all.
Of course a person building a 500hp transmission can spring for the extra plate, but for most the stock # of plates in all of the clutches should be enough.

However, on a side note: I think before any changes are made to this particular article, we should have someone consult "the man" for his thoughts/additions/permissions/blessings... maybe we could get the expanded section to cover AOD main controls too?

96 Mustang GT 5spd. w/ 248A Option (GTS). Stock for now until I get the Roush on.

97 Thunderbird 4.6L LX /w Sport Package
24k B&M Cooler, 1" lowered, Steeda UD Pulleys, Dynomax cat-back, J-mod, 3.73's, PI intake, PI cams, 03 GT MAF/Tube, SCT tuned - Gone but not forgotten.
MAMN12 Drag Racing Team [email protected] In need of updated times.
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post #3 of 7 (permalink) Old 08-03-2003, 04:20 AM Thread Starter
 
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I believe the steels were made thicker and the friction material changed in order increase the short life on the clutch packs in high mileage, highway driven cars.
The thicker steels increase short term heat absorption, and possibly dissipate it more easily into the drum and fluid.

The pressure plates are commonly reused during a rebuild. They should be smooth and not gouged. I personally recommend resurfacing them on a sheet of thick glass or a granite lapping stone with 3M wet-or-dry abrasive of about 220 grit, in an orbital pattern, in order to remove any glaze. Take it easy and only do this enough to restore the surface to a nice even crosshatch.

If you are upgrading the clutch packs to include additional clutch plates, the pressure plate HAS to be changed. They are thicker/thinner to accomodate the differing thicknesses of the packs.

Remember that the 3.8L direct clutch packs have only 5 plates from the factory, and the 6 plate upgrade is advisable. For really high HP/torque requirements, there are 8 plate upgrades available from the aftermarket. (i.e. Alto) The steels, frictions, and pressure plates in these packs are thinner than stock, however, and long term durability is questionable.

Those who are simply changing the type of material used, and not the quantity of plate sets, may omit the pressure plate upgrade. YOU MUST, however, use the matching steels with the selected friction materials.

These personal recommendations are based upon 25 years of servicing and modifying various automobiles, including Ford, Mercedes, SAAB, GM, Toyota, Peugeot, and Mazda Rotary engines (Ported & pinned 13B ). Your mileage may vary...

Greg

Last edited by GregFL; 08-03-2003 at 04:49 AM.
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post #4 of 7 (permalink) Old 08-04-2003, 12:07 AM
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That sounds like what I was thinking, thanks for the info... is 220 really the best for scuffing the plate? that's still pretty rough. I might feel safer with a 400 or so. (I build model cars too, so I have up to 1600 laying around, lol)
I also agree that 8 clutches are almost never needed - (who here makes 650hp?)
Overbuilding a tranny can sometimes cause more bad than good.

96 Mustang GT 5spd. w/ 248A Option (GTS). Stock for now until I get the Roush on.

97 Thunderbird 4.6L LX /w Sport Package
24k B&M Cooler, 1" lowered, Steeda UD Pulleys, Dynomax cat-back, J-mod, 3.73's, PI intake, PI cams, 03 GT MAF/Tube, SCT tuned - Gone but not forgotten.
MAMN12 Drag Racing Team [email protected] In need of updated times.
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post #5 of 7 (permalink) Old 08-04-2003, 02:50 AM Thread Starter
 
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Actually, you don't want it TOO smooth. This IS a friction interface.
When you hone cylinder walls, do you want them to have a glass like finish?
If it bothers you, you could probably go up to 320, but I've not had a problem.
(This relates to transmissions in general, not just Ford.)

I've got everything up to 2000 grit, but I wouldn't use it for this purpose.

FWIW, MN12 performance suggests sanding the OD and REV drums with 80 grit!
Even I won't go that far...

As for the 8 pack clutches, I wonder if they are even good for that much horsepower?
Thinning already stressed components sounds like a bad idea, and I believe the stock setup isn't too far off the mark.
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post #6 of 7 (permalink) Old 08-04-2003, 03:34 AM Thread Starter
 
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ADDITIONAL CAVEATS concerning the DIRECT DRUM

One other thing to watch out for is the direct drum piston and seals.

The piston contains a small check valve (ball & seat) and every one I have seen leaks slightly. When replacing the piston seals, carefully check this valve and insure that it is, indeed, a one way valve!

You can replace the piston, or you can try reforming the seat by tapping the ball from the back side with a nail set (one with a rounded, concave tip) and hammer. A few blows will usually restore the seat to an acceptable condition. Make sure, of course, that there is no debris in the valve before doing this - or you will imbed it into the seat, ruining it forever. Don't get carried away with this, you don't want to damage the ball (it IS hard) and you certainly don't want to loosen or drive the check valve out of the piston!

Also, the holes in the direct drum should be checked for burrs, as I have seen the inner bore of the piston scratched from this. Carefully file the edges (chamfer) the holes and check the piston for damage. Deep scratches in this area will cause pressure leaks and slippage of the direct clutch.

Of course, the sealing rings install with the flair down into the drum, so that hydraulic pressure helps them seal. DO NOT attempt to re-install the piston without some kind of seal guide/protector - you WILL damage the seals.

If you can't afford one/can't find one, you may create a makeshift installation tool with some heavy 10+ mil plastic. Just wrap an appropriately sized piece around the inner and outer circumference of the drum, and install the piston carefully - making sure not to fold back the seals upon themselves. Then, before the piston bottoms, but after it has cleared the rollover from the lugs for the steels to the piston sealing surface, remove the plastic and insure none remains in the bore. Make sure you have plenty of transmission fluid coating all parts before reassembly.

After assembly of the drum and checking the clearances, it is advisable to wet-air check the drum for leaks and proper piston movement. This one is a pain, due to all the passages in the bore, but it can be done. NEVER use over 40 PSI for this.

Besides, it's neat to watch!

Last edited by GregFL; 08-04-2003 at 07:55 PM.
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post #7 of 7 (permalink) Old 08-05-2003, 07:35 PM Thread Starter
 
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ADDITIONAL PART NUMBERS

As mentioned before:
The suggested 6 plate pressure plate - F7AZ-7B066-AB - measures .238" **

** NOTE: The suggested pressure plate is apparently intended for use with a '97 or later direct drum, due to the increase in snap ring groove to piston clearances.
This is NOT noted in the text.
You should use the .220" pressure plate on a 6 clutch assembly on a pre '97 transmission or you will probably not be able to obtain the correct clutch pack clearance.

The part Number for the .220" pre-'97 6 plate clutch assembly is:

E9SZ-7B066-A

Also, the improved intermediate clutch friction material has undergone
a part # change:

The old number is - F75Z-7B164-CA - this number is still old stock at some dealers.
The new number is - XW1Z-7B164-AA - packaged as a set of 4 plates.
Appears to be the same composite material, outwards radially grooved.

If you now have a 3 plate intermediate clutch pack (AOD/E - 3.8L 4R70W), and want to upgrade to 4 plates, you will need the matching pressure plate:

Part Number - F3LY-7B066-A
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