Replacing the StarterRing Gear on theMotorcycle Dyno

Dynojet Research, Inc.200 Arden Dr.

Belgrade, MT 59714

Last Updated 10/12/1999

P/N 98221100

1

Starter Ring Gear ReplacementThis manual explains the replacement procedure for the starter

ring gear on a motorcycle dynamometer.

Removing the Old Ring Gear

Step 1

If your dyno is equipped with a brake, it will be necessary to remove

it before proceeding. If your dyno is not equipped with a brake,

please proceed to step 2.

Remove the caliper assembly by removing the (4) 3/8 bolts that hold

it to the frame.

You will also need to remove the brake line from the caliper.

You may now remove the rotor from the dyno shaft. Remove the

bolts from the taper lock on the inner portion of the rotor. Use

those bolts to extract the taper lock by threading them into the offset

holes in the taper lock. The taper lock may need to pried out, but it

should be free at this point. Remove the rotor and set it aside.

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Remove the Banjo Bolt

Step 2

Remove the (12), (8) if you had to perform step 1, 3/8” hex bolts on the

rear section of the frame. Remove the “C” channel section of the frame.

Step 3

Measure and take note of the drum orientation inside the frame. This

is crucial, as the dyno drum needs to be replaced in the exact same

location as it was before replacing the starter ring. Take measurements

from the face of the drum to the edge of the frame on both sides.

Step 4

Remove the bearing lock collars on both side of the drum. Loosen

the set screw and refer to the sticker on which way the collar

loosens. The right side lock collar is part of the pick up disk.

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Take this Measurement onboth sides of the drum.

Lock collar is on the insideof the pick up disk. Lock collar

Lock CollarInstructions

Step 5

Use a forklift and nylon straps capable of supporting 1000 lbs and

lift the drum and frame a few inches. Set a piece of 1/4” plywood

between the frame rails under the drum. It should be long enough

so when you remove the drum it remains on the plywood. Lower

the drum and frame down so only the drum sits on the plywood.

Step 6

Remove the (8) 5/8” nuts and lock washers from the bearings on

each side of the dyno. Remove the bearings and set them aside.

Step 7

Roll the drum assembly backwards, and be sure that it stays on the plywood.

Heat the starter ring with a propane torch to allow the ring to “grow”, try not

to burn the paint on the drum. Using a hammer and punch, hit the starter

ring on the inside face and work your way around the perimeter.

Installing the New Ring Gear

Step 1

Clean and debur the perimeter of the drum where the new ring gear

will be installed.

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Ring Gear

Note: The High Inertia Dyno has an additional sections of the frame that must be removed before proceeding. The frame section is under each bearing, remove them and set aside.

Additional framesections for HighInertia Dynos only.

Step 2Heat the new starter ring until it “grows” enough to fit over thedrum. Be sure the ring is seated at an equal distance around theperimeter of the drum, and hold it in place until it cools.

Step 3You may want to prime / paint the new ring gear and the area on thedrum surface where you were working.

Step 4Roll the drum assembly back into the frame, and be sure the bearingbolts are still in place through the holes on the inside of the frame.

Install the bearings back on the shaft on both sides of the dyno.Replace the 5/8” lock washers and nuts, BUT DO NOT TIGHTENTHEM YET.

P/N 98221100 5

Note: Manually rotate the drum and be sure that it isn’t hitting anything. At this point, you should also test the starter and be sure that it is lined up properly and doesn’t bind.

Be sure that the starter ringgear is lined up with thebendix on the starter.

Note: You should be able to slide the drum / shaft assembly back and forth as long as the bearing lock collars are loose. This will aid in getting the drum assembly back to its original location.

Note: High Inertia Only: Be sure to replace the additional frame members before replacing the bearings. Install the (12) 3/8” hex bolts towards the front of the dyno and torque to 42 lbs-ft.

Additional framesections for HighInertia Dynos only.

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Lift the drum assembly as you did in Step 5 of Section 1, andremove the plywood. Set the drum / frame down, and then tightenthe bearing bolt nuts on both sides to 150 lbs-ft.

Step 5

Replace the bearing lock collars on both sides of the dyno. Be sure

the drum is located EXACTLY in the same location as when you

removed it (reference the measurements you recorded earlier). Set

the lock collars (refer to sticker above bearing), and then tighten

down the set screws to 28 lbs-ft.

Step 6

Bolt the rear frame section back into place. There should be (12)

3/8’ hex bolts with lock washers, torque them to 42lbs-ft. If you are

reinstalling a brake, don’t install bolts in the top and bottom (2)

holes on the left side. If you have a brake continue through the next

5 steps, otherwise skip to Step 10.

Step 7

Mount the rotor / taper lock assembly to the shaft on the back left

side of the dyno. Be sure to install the key to ensure proper

alignment.

Step 8

Attach a dial indicator to the side of the dyno as shown, and check

for run out. The tolerances are +/- .005”. Tighten the taper lock

bolts to adjust the run out, and then torque to 15 ft/#’s. Tighten the

set screw at this point to keep the key in place.

Step 9

Attach the caliper assembly with (4) 3/8” hex bolts and torque themto 42lbs-ft..

Step 10

Adjust the brake as necessary to allow the rotor to spin free ofcontact. Loosen the jam nut, and use the adjustment nut to move thebrake pads in or out.

Step 11

Attach the brake line back to the caliper. You will most likely needto add fluid (DOT 5) and bleed the system of air.

Step 12

Make a final inspection and be sure that all fasteners are tight andthat the drum rotates freely.

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Dial indicator