Assembly instructions for the F4A4A1N2Z automatic transmission

Assembly of Automatic Transmission F4A4A1N2Z

Important warnings and general requirements

Do not reuse: gaskets, O-rings, oil seals — replace them with new ones.

For lubrication and retention of components, use exclusively:

blue petrolatum;
white petroleum jelly.

Caution: Do not use other types of grease (e.g. lithium or molybdenum-based) unless otherwise specified, as they may damage rubber seals and impair hydraulic operation.

Before installing friction elements (discs, brakes), lubricate them with automatic transmission fluid (ATF). Soak friction discs in ATF for at least 2 hours.
Do not apply sealant/adhesive to gaskets.
When replacing bushes, install the assembly as a complete unit.
During assembly, do not use fabric gloves or rags. Permitted: nylon cloth, paper towels.
Replace the working fluid (ATF) in the heat exchanger circuit.

Step-by-step assembly

1. Installation of the intermediate drive gear

Installing the drive gear with the guide — Fig. 1. Using guide MD998412 when installing the gear

use guide MD998412;
tighten the bolts to 34 ± 2 N·m.

Checking bolt tightening — Fig. 2. Checking the bolt tightening torque

2. Installation of the brake and return elements

Install:

the low/reverse engagement brake;
the return spring;
the spring retainer.

3. Replacement of the one-way clutch seal ring

Install a new seal ring in the groove of the one-way clutch inner ring.

Installing a new seal ring — Fig. 3. Position of the one-way clutch inner ring seal ring

4. Installation of the one-way clutch inner ring

Install the one-way clutch inner ring:

refer to the identification marks;
align the marks along line A‑A (see figure);
use the tools:
- spring remover screw (MD998924);
- spring compressor (MD998903);
press down on the ring and install the snap ring.

One-way clutch mark alignment diagram — Fig. 4. Aligning the identification marks along line A-A

5. Installation of the piston spring ring

Install the spring ring on the low/reverse engagement brake piston.

Fitting the spring ring to the piston — Fig. 5. Securing the spring ring on the brake piston

6. Installation of the brake disc pack

Install the brake disc pack:

4 friction discs;
3 steel discs;
snap ring.

Do not install the pressure disc at this stage.

7–8. Installation of the special tool and reaction plate

Install the special tool on the brake disc pack.
Install:
- the reaction plate;
- the snap ring (removed during disassembly).

9. Checking the reaction plate axial clearance

Check the reaction plate axial clearance:

Measuring plate clearance with the tool — Fig. 6. Measuring axial clearance with MB991631

lift the clearance measuring plate (MB991631);
permissible clearance: 0–0.16 mm;
if necessary, replace the snap ring (see step 10).

10. Installation of the auxiliary brake discs

Install:

2 friction discs;
1 auxiliary brake steel disc.

Do not install the pressure disc at this stage.

Laying the friction and steel discs — Fig. 7. Order of laying the auxiliary brake discs

11–12. Installation of the measuring plate and piston

Install the clearance measuring plate (MB991631).
Install:
- the return spring;
- the auxiliary brake piston;
- the snap ring.

Installing the return spring and piston — Fig. 8. Fitting the auxiliary brake piston

Securing the piston snap ring — Fig. 9. Installing the snap ring

13. Selecting the pressure disc (auxiliary brake)

Measure the plate travel (MB991631). Select the pressure disc according to the table (permissible clearance: 0.49–0.95 mm).

Plate travel, mm	Pressure disc thickness, mm	Identification mark
0.3–0.5	1.6	L
0.5–0.7	1.8	1
0.7–0.9	2.0	0
0.9–1.1	2.2	2
1.1–1.3	2.4	4
1.3–1.5	2.6	6

14–15. Measuring the low/reverse brake clearance

Turn the transmission upside down.
Measure the plate travel (MB991631) using a dial indicator and extension (MD998913).
Select the pressure disc according to the table (permissible brake clearance: 1.05–1.51 mm).

Measuring clearance with a dial indicator and extension — Fig. 10. Measuring plate travel with a dial indicator

Plate travel, mm	Pressure disc thickness, mm	Identification mark
0.7–0.9	1.6	L
0.9–1.1	1.8	1
1.1–1.3	2.0	0
1.3–1.5	2.2	2
1.5–1.7	2.4	4
1.7–1.9	2.6	6
1.9–2.1	2.8	8
2.1–2.3	3.0	D

16–17. Removing elements and installing the snap ring

Remove the elements installed in steps 7–17.
Install the snap ring in the groove of the output shaft bore in the transmission case.

Location of the snap ring groove — Fig. 11. Installing the snap ring in the case

18–20. Output shaft bearing preload

Install the adjusting ring (the thinnest, 1.88 mm) for the output shaft bearing preload.
Install the output shaft bearing outer race:
- use drift (MB990930) and handle (MB990938);
- do not reuse the separator mounting bolts (they had sealant on them).

Pressing in the bearing outer race — Fig. 12. Installing the bearing outer race

Tighten the separator bolts to 29 ± 2 N·m.

Tightening separator bolts with a torque wrench — Fig. 13. Checking separator bolt tightening

21–22. Installing the bearing and tightening the lock nut

Install the tapered roller bearing on the output shaft:
- use tool MD998350;
- the lock nut has a left-hand thread.

Fitting the tapered bearing to the shaft — Fig. 14. Installing the tapered roller bearing

Tighten the lock nut:

apply ATF to the new nut;
use a socket (MB990607) and a special socket (MB991625);
tighten to 170 ± 10 N·m, then loosen by 1 turn and retighten to the same torque.

Tightening the lock nut with a special socket — Fig. 15. Tightening the output shaft lock nut

23–27. Measuring shaft travel and final tightening

Measure the output shaft travel and record the result.
Remove the elements installed in steps 20–24.
Select and install the adjusting ring: thickness = shaft travel (step 25) + 1.88 mm + 0.01–0.09 mm (preload).
Repeat steps 21–24.
Stake the lock nut (in two places).