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TRANSMISSION THERAPYРуководство по ремонту АКПП

Familiar Failures and

Faithful Fixes for the by Larry Frash

Mazda FN4A-EL and Ford 4F27E

T
he FN4A-EL/4F27E was first
introduced in the 1999 Mazda Always check this
Protégé. These transmissions bushing for wear
are used in a variety of Mazdas, and
in the Ford Focus. Overall, this has
been a fairly dependable unit, and
is reasonably easy to rebuild when
it does wear out. But ever since the
first one rolled off the assembly line,
these transmissions have continued to
experience a few common problems.
In this edition of Transmission Therapy
we’ll cover three of the most common
wear problems known to cause major
failures in these transmissions.

Stator Support Bushing Worn stator support bushings allow converter apply pressure to cross leak
Wear into the release circuit causing lockup slippage
The stator support bushings support
Figure 1
the turbine shaft (figures 1 and 2), but
they also separate the TCC apply and
release pressures. With lockup released,
converter charge pressure is delivered
Always check this
between the converter clutch and the
bushing for wear
apply surface (the front converter
cover). This hydraulic pressure is called
converter release pressure, and that
pressure is what keeps the converter
clutch from applying.
When conditions are right for
lockup to apply, the converter release
pressure is exhausted. Converter clutch
apply pressure is always applied to the
back of the torque converter clutch; the
only thing that keeps it from applying
is the release pressure. Once the release
pressure exhausts, converter clutch
apply pressure is able to apply the
converter clutch.
When the stator support bushings Worn stator support bushings allow converter apply pressure to cross leak
are worn, they can allow converter into the release circuit causing lockup slippage
apply pressure to leak into the release Figure 2
side of the converter. When this occurs,

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 AKPPHELP.RU Hard coat
Once Руководство
the thin по ремонту АКПП
anodized alu-
hard coat anod- minum cover
ized surface (Mazda appli-
wears through, cations)
the rings will
wear into the
aluminum

Figure 3 Figure 4

Pressed on
steel sleeve
(Ford applica- Mazda
tions) cases have
the cooler
return line
located in
the case

The Mazda
Figure 5 fitting will
not thread
converter release pressure can’t exhaust clutch ring land
into the
fast enough, so it keeps pressure on the area (figure 3). On Ford
release side of the converter clutch. This Mazda applica- cover
prevents the converter clutch from fully tions, the end cover
applying, which causes the converter is aluminum and is
clutch to slip. hard coat anodized
To avoid this problem, always around the ring
check for wear between the stator sup- land area (figure
port bushings and turbine shaft, when- 4). This hard coat-
ever you’re rebuilding one of these ing is designed to
transmissions. If you find more than prevent the rings
Figure 6
0.0015" clearance, replace the bush- from wearing into
ings. These bushings are made by the soft aluminum. Once the thin anod- EL/4F27E transmission, check the end
Omega Machine & Tool, Inc. and are ized coating wears through, the ring cover carefully to see which one is
available from a number of sources in wears into the bare aluminum, destroy- being used. Never reuse the hard coat
the aftermarket. ing the cover. anodized cover, even if there’s no sign
Once you’ve replaced the bush- The end cover used in Ford appli- of wear in the ring area. Always replace
ings, slide the stator shaft into place and cations is also made out of aluminum, the Mazda-style end cover with a Ford
recheck the clearance between the shaft but this cover has a pressed steel sleeve cover, part# XS4Z-7222-BA. This
and the bushings; while not particularly for the ring land area (figure 5). And, cover will work on all models, with a
common, it is possible for the shaft since the direct clutch rings ride against few minor modifications:
itself to wear and need replacement. the steel surface, ring land wear isn’t a The Mazda version of the FN4A-
problem on Fords. EL/4F27E transmission has the cooler
End Cover Wear So, to avoid wear in the end cover, return line located in the case (figure
It’s not uncommon to see wear in you should always use the Ford cover. 6). From there it’s routed through a
the end cover, around the top direct Whenever you rebuild an FN4A- passage to the end cover to provide

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 AKPPHELP.RU
Руководство
Familiar Failures and Faithful Fixesfor the Mazda FN4A-EL and Ford 4F27E по ремонту АКПП
Ford Cover
To adapt the Mazda Cover XS4Z-7222-BA

Ford cover for

use with a Mazda
transmission, you
must reroute
the cooler return 3/8" Fitting adaptor
YS4Z-7D273-AA
circuit. Figure 7

lube oil to the transmission. The Ford

version of this transmission has the
cooler return line threaded directly
into the end cover. Because of this, the
Ford end cover doesn’t have the cooler
return passage from the case that the
Mazda cover has (figure 7 and 8).
To adapt the Ford cover for use
with a Mazda transmission, you must
reroute the cooler return circuit. Here’s
how:
Remove the original cooler line
fitting from the Mazda case to use it as
a template to make a new fitting. The
threads are different and won’t fit the The Ford cover
Ford end cover. When you order the doesn't have the
Ford end cover, also order a 3/8" fitting cooler return passage
adapter from Ford, part# YS4Z-7D273-
AA. Install it into the Ford end cover. Figure 8
Using a piece of 3/8” cooler line,
cut and bubble flare the tubing to
match the length or the original Mazda
case fitting (figure 9). As you can see,
a bubble flare isn’t a full flare. It’s
only flared enough to hold the rubber
hose onto the line when it’s handling
pressurized fluid. Pay attention to this
when flaring the replacement line: If
you flare the tubing too much, the
flared portion of the tube will be too
sharp and will eventually cut through
the rubber hose. Cut and Bubble flare the tubing
to match the length of the original
Mazda case fitting

Figure 9

10 GEARS January / February 2006

Precesion placed.qxd 7/21/05 4:29 PM Page 19

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Руководство по ремонту АКПП

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 Familiar Failures and Faithful Fixesfor the Mazda FN4A-EL and Ford 4F27E
AKPPHELP.RU
Руководство по ремонту АКПП

Reverse clutch rings part #YS4Z-7D020-AA Direct clutch rings part #YA4Z-7D019-AA

Figure 10 Figure 11

Always check the Intermediate/Overdrive servo

for a loose pin
Shim Thickness Ford Part Number
0.062” XS4Z-7G262-FB
0.068” XS4Z-7G262-FC Figure 13
0.075” XS4Z-7G262-FD
0.083” XS4Z-7G262-FE
0.091” XS4Z-7G262-FF Any time you the original cooler return passage in the
0.098” XS4Z-7G262-FG change hard parts case. This leaves you with two options:
in a transmission, You can either plug the case passage
Figure 12 always check the or leave it open; it really doesn’t mat-
endplay. Proper ter, since there’s no oil there anyway.
Because the Ford end cover ring endplay for this transmission is 0.010" But always leave the original fitting
lands are made of steel, always use the to 0.019". Corrective shims for adjust- out of the case, so the customer or the
Ford rings. The part number for the ing endplay are available from Ford, next technician who works on the car
reverse clutch rings is YS4Z-7D020- and range from 0.062" to 0.098" (figure doesn’t think you left a hose off the
AA (figure 10). The part number for the 12). transmission.
direct clutch rings is YA4Z-7D019-AA When you bolt the end cover to the When you install the transmission
(figure 11). transmission, the Ford cover will block into the vehicle, connect the cooler

12 GEARS January / February 2006

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 AKPPHELP.RU
But the most Руководство по ремонту АКПП
If the pin gets loose enough,
it will come out of the piston,
common causing major problems

symptoms caused
by a loose servo
pin are a slip in
4th gear and 4th
gear ratio codes.

return hose to the fitting you made

for the end cover, and you’re finished:
The new end cover should work fine,
and you shouldn’t have any more wear
problems in the ring area.

Intermediate/Overdrive
Band Servo Figure 14
The intermediate/overdrive band
servo is a molded rubber piston with
a pressed-in pin (figure 13). Problems
occur when the pin becomes loose in 7…i˜ÊˆÌÊVœ“iÃÊ̜ÊÀiLՈ`ˆ˜}Ê̜ÀµÕiÊ
the piston and causes leaks between
the apply side and the release side of
Vœ˜ÛiÀÌiÀÃ]Ê
/ʘœÌʜ˜ÞÊLՈ`ÃÊ̅iÊ
the servo. Symptoms of a loose pin can LiÃÌÊiµÕˆ«“i˜Ìʈ˜Ê̅iʈ˜`ÕÃÌÀÞ]ÊÜiÊ
include:
• Ratio errors ÕÃiʈÌÊiÛiÀÞ`>Þt
• 2nd gear slip
• 2-3 flare
• 3rd gear slip
But the most common symptoms ATI’s full line of torque converter rebuilding
caused by a loose servo pin are a slip machinery is custom designed to fit your shop’s
in 4th gear and 4th gear ratio codes. If needs. ATI makes converter rebuilding easier and
the pin gets loose enough, it will come more profitable for you!
completely out of the piston, causing
œÃÌÊivviV̈ÛiʇÊ>Ê}Ài>ÌÊÀiÌÕÀ˜Êœ˜ÊޜÕÀÊ
major problems (figure 14). To avoid ˆ˜ÛiÃ̓i˜Ìt
problems from this servo, always Ài>ÌÊVÕÃ̜“iÀÊÃiÀۈVi
replace the servo with a new one during >ÃÞÊ̜ÊÕÃiÊ܈̅ʓˆ˜ˆ“Õ“ÊÃi̇ի
every rebuild.
1Ãi`ʈ˜ÊŜ«ÃÊܜÀ`‡Üˆ`i
Other than these few problem
CW3 /…iÊÃ>“iÊiµÕˆ«“i˜ÌÊ
/ÊÕÃiÃÊ̜Ê
areas, the FN4A-EL/4F27E is a fairly Converter Welder
«Àœ`ÕViʈÌÃʅˆ}…Ê«iÀvœÀ“>˜ViÊ̜ÀµÕiÊ
bulletproof transmission. Just follow Vœ˜ÛiÀÌiÀÃÊiÛiÀÞÊ`>Þt
the normal rebuild procedures, and pay
particular attention to the areas we’ve
covered here, and you shouldn’t have
any problem with these units.
www.atiauto.com 6747 Whitestone Road • Baltimore, Maryland 21207
800-284-3433 • Fax: 410-298-3579
© 2006 ATI Performance Products, Inc.

GEARS January / February 2006 13

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