Ride Height Adjustment

SB-10057480-2663
Prepared By:

Kalman Takacs
Field Service Engineer
Phone (256) 241-1243
Fax (256) 832-0930
Nic Rucker
Field Service Technical Rep
Phone (256) 499-5433

Approved By:

Dan Allen
Chief Engineer

Property Name:

All LFW, BRT, and 45’ compo

Top Bus Number: All LFW, BRT, and 45’ compo
Issue:

Air bag ride height inspection.

Reason / cause:

Periodic inspection is required to maintain the proper ride height.

Solution:

Inspect and if required adjust the ride height per this work instruction.

Number of Affected Buses:

As required

Estimate Repair Time:

30 min / bus if no adjustment is required. 1 hour if adjustment is
required.

Necessary parts:

torque seal, WD-40

Necessary Tools: Usual hand tools (wrenches, sockets, screwdrivers, etc.); wire brush, torque
wrench capable for 10-70 lb.-ft.
Templates for measuring the front and rear airbag height:
 Front Suspension – T-3136 (Orange,10.00 inch Height Gauge)
 Rear Suspension – T-3137 (Green, 10.25 inch Height Gauge)
 Front Suspension – T-3279 (Yellow, 10.43 inch Height Gauge)

Work instruction number: L3/FSV-135
L4/QUA-003

Revision: C

Date: 02/02/2015

Revision: Initial

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Ride Height Adjustment

SAFETY PRECAUTIONS MUST BE FOLLOWED ACCORDING TO ACCEPTED
INDUSTRY STANDARDS AND LOCAL/PROPERTY REQUIREMENTS.
1. Park the bus on a leveled surface above a service pit.
2. (The ride height adjustment procedure can also be performed by using wheel lifts. If wheel lifts
are used, the lifting brackets underneath the wheels need to be leveled at all four locations.)
3. Place wheel chocks in front of and behind the rear wheels.
4. Release the parking brake.
5. Connect shop air to the bus air system. Check the air gauges at the dash: the air system
pressure should be at least 100 psi.
6. Check the airbag height differences at the rear axle according to the followings:
 Use the NABI airbag template (use the chart on last page to determine color of
template) and measure the rear airbag of the curbside C-frame: place the sharp end of
template underneath the top mounting plate as pictures show below. If the top surface
of the bottom of the template goes underneath the airbag and it is even with the upper
edge of the nylon spacer. Revise sentence in blue Right now just note the difference
between the airbag and the template and don’t worry about the exact heights.





Measure the front airbag of the curbside C-frame as described above.
The maximum allowed differences between the fore and aft airbag of the curbside Cframe is ¼”.
Check the airbags of the street side as described above. Note the differences between
the fore and aft airbags of the street side C-frame.

Work instruction number: L3/FSV-135
L4/QUA-003

Revision: C

Date: 02/02/2015

Revision: Initial

2/4

Ride Height Adjustment

7. Measure the front axle airbags by using the chart at the last page per bus type. Adjust the
heights of the front airbags as required by turning the front leveling valve rod up or down.

Re-check the air bag height difference at the rear again. It may have changed after the front leveling valve adjustment.

8. Go back to the rear axle. If the airbag height difference is still greater then ¼” then the upper
radius rods must to be adjusted according to the followings:
 Loosen the clamps on both ends of the upper radius rods.
 Remove dust from the threads of the radius rod heads by using a wire brush and apply
WD-40 thread penetrate spray or similar.
 If the aft airbags were shorter than the fore airbags, the upper radius rods lengths need
to be lengthened, and vice-versa. Turn the same amount of revolution and to the same
directions on both upper radius rods.
 Check the airbag heights by using the chart on the last page per bus type. If the fore
and aft airbags are within the ¼” tolerances then tighten the upper radius rod clamps
and torque them to 57-63 lb.-ft. Apply torque seal to the bolts and nuts.

Work instruction number: L3/FSV-135
L4/QUA-003

Revision: C

Date: 02/02/2015

Revision: Initial

3/4

Ride Height Adjustment

9. Now adjust the rear curbside and street side airbag heights to required measurement by
turning the curbside and street side leveling valve rods. If required move the lower end of the
rod up or down in the mounting bracket or move the entire valve body up or done in the slots of
the mounting bracket.

Re-check the front air bag height

10. For a 60’ BRT bus, adjust the middle axle just like the rear axle with the appropriate template
Note: There is only one leveling valve at the center axle
11. Check for completeness of work.
12. Record Bus Number, Date of inspection and Mileage.

BUS TYPE

FRT BAG
HEIGHT

TEMPLATE

TEMPLATE

REAR BAG
HEIGHT

TEMPLATE

ORANGE

MIDDLE
BAG
HEIGHT
N/A

45’ COMPO

10.03 IN

N/A

10.25 IN

GREEN

42’ BRT

10.03 IN

ORANGE

N/A

N/A

10.03 IN

ORANGE

40’ LFW

10.43 IN

YELLOW

N/A

N/A

10.03 IN

ORANGE

60’ BRT

10.03 IN

ORANGE

10.03 IN

ORANGE

10.03 IN

ORANGE

31’ LFW

10.43 IN

YELLOW

N/A

N/A

10.03 IN

ORANGE

Work instruction number: L3/FSV-135
L4/QUA-003

Revision: C

Date: 02/02/2015

Revision: Initial

4/4