exhaust flow modification hd785 - hd985

7/27/2019 Exhaust Flow Modification HD785 - HD985

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Page 1 of 11Service News

W2M2005D0031

Applicable vehicles

HD785-5: #4001 and after

HD985-5: #1021 and after

Modification procedure manual for the exhaust flow route changeover

system on HD785-5/HD985-5


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1. Details of the modification

Current part Improved part

Outline of the modification is as follows.

The inner diameterA of the exhaust outlet tube from the exhaust flow route changeover

box and the inner diameterB of the exhaust inlet tube into the body are increased in order

to reduce the exhaust resistance.

For the above purpose, the exhaust flow route changeover box and the exhaust inlet tube

into the body are replaced.

153.8

For use with the HD785-5 dump trucks equipped with the exhaust flow route changeover

system, the improved parts for the system which are effective to reduce the exhaust

resistance, and therefore, implement the modification to improve the system referring to this

modification procedure manual.

155.2

202

204.7

Inner diameter of the exhaust outlet

tube from the exhaust changeover box

Inner diameter of the exhaust inlet tube

into the body

A

B

Fig. 1


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HD785-5

561-84-64700 BOX

01010-81230 BOLT Consumable parts

01643-31232 WASHER Consumable parts

561-84-64820 TUBE

561-84-64830 PLATE

561-02-61240 V-CLAMP Consumable parts

568-95-11160 BAND Consumable parts

01580-11210 NUT Consumable parts



01010-81030 BOLT Consumable parts



HD985-5

561-84-64700 BOX

01010-81230 BOLT Consumable parts01643-31232 WASHER Consumable parts

561-84-6D151 TUBE

561-84-64830 PLATE

561-02-61240 V-CLAMP Consumable parts





01010-81030 BOLT Consumable parts01580-11008 NUT Consumable parts


3. Installation procedure

3.1 Preparations

Park the vehicle on a flat place. Stop the engine, turn on the parking brake and apply chocks to the tires.

2. Table of necessary parts for modification of the exhaust flow route

changeover system

No.

1

Part No. Part name Q'ty Remarks

1

2

3

4

5

6

7

8

9

10

11

12

1

1

6

6

1

1

1

2

1

2

2

1

Remarks

1 1

No. Part No. Part name Q'ty

13

2 63 6

4 1

5 1

6 2

7 1

8 2

9 2

10 1

11 1

Numbers indicated after the part numbers in the descriptions of this manual and numbers

given in the drawings correspond to the numbers in the above table of parts.

12 1

13 1


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3.2 Removal of the exhaust flow route changeover box and reworking of the related parts

1. Remove the exhaust flow route changeover box.

2. Rework the exhaust tube (561-84-64141).

Cut 25 mm of the top end section (hatched section).

Rework (Cut the top

end section.)

Exhaust tube

(561-84-64141)

Remove

Exhaust flow route changeover box

(561-84-64101)

Cut to remove this

section.

Fig. 2

Fig. 3


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3. Rework the fire prevention cover (561-89-62513). (Add a notch.)

Add a notch.

Fig. 4


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3.3 Installation of the improved exhaust flow route changeover box

Install the improved exhaust flow route changeover box 1 (561-84-64700) and fix the

exhaust tube using the clamp 6 (561-02-61240), band 7 (568-95-11160) and band 10

(561-84-64240) and connect the exhaust tube to the changeover box.

Tightening torque for the exhaust flow route changeover box mounting bolts:

98 - 123 Nm {10 - 12.5 kgm}Tightening torque for the clamp 6 (561-02-61240): 6.9 - 8.3 Nm {0.7 - 0.85 kgm}

1

23

6

7

8 910

11

1213

Fig. 5


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3.4 Reworking the body

1.

2.

3.

Remove the exhaust tube (including the plate) welded to the body. (The hatched

section in the drawing below)

Remove the hatched section around the hole for the exhaust tube to expand the size of

the hole.

Weld the exhaust inlet tube 4 (HD785-5: 561-84-64820, HD985-5: 561-84-6D151) andthe plate 5 (561-84-64830) to the body by actually positioning the parts to.

Refer to Fig. 8, 9, 10 and 11 on pages 8 thru 11.

Remove the exhaust tube

and the plate.

Fig. 6

Remove thebe

hatched section.

Fig. 7


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Fig.

8

HD

985-5

HD

785-5


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Fig.

9

Insertion

depth

Insertion

depth:

55

Tightening

torque


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F

ig.

10

Tightening

torque


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3.5 Adjustment of the exhaust inlet tube position to weld

Carry out this work after the body mount adjustment work.

(1)

(2) Slip the plate (561-84-64830) on the tube (561-84-64820).

(3)

(4)

(5)

(6) Raising and lowering the body, check that the exhaust box operates properly.

Fix the dimensions "A" of the exhaust box (561-84-64700) to 65 mm using a jig (vice,

etc.).

After aligning the centers of the box and the tube at the contact surface weld the tube

and plate to the body by actually positioning the parts to the body.

(Front to back and side to side runout should be 2 mm or less.)

After the welding work, raise the body to remove the jig and check that the dimension

"A" is 120 mm.

Lower the body slowly to seat and check that the body and the flange surface of the

exhaust box comes to even contact without gap.

Fig. 11

Front to back and side

to side runout should be

2 mm or less

When the body is raised: 120

When the body is lowered: 65

The flange surface should come

to even contact without gap.

exhaust flow modification hd785 - hd985

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