EVA Strobe Feature

Electronic Vibration Analyzer (EVA) Strobe Balance Feature

The strobe feature of the EVA assists a technician in system balancing a propshaft system. System balancing is a superior balance compared to just balancing the propshaft because it balances the entire rotating assembly from the transmission output shaft to the pinion gear.

Before you begin

Be sure to check for water inside the propshaft, especially if the vehicle has a trailer hitch. Vehicles that tow boats are more susceptible to having water in the propshaft.
Make sure the propshaft does not have undercoating applied to it, if it does remove the undercoating.
If propshaft runout has been eliminated as a cause of the first order propshaft speed related vibration then there must be a component that is out-of-balance. This component is spinning the same speed as the propshaft; it might even be the propshaft.
While the propshaft and tires are rotating, stay clear of the moving parts.

Vehicle Setup

Support the vehicle’s suspension on a hoist or jack stands. Do not lift the vehicle by the frame. The vehicle's ride height must be maintained.
Run the vehicle at the speed where the vibration is present and use the EVA’s sensor to determine if the vibration amplitude is worse at the front or rear of the propshaft.
Using a tire marker crayon, mark the end of the propshaft that had the highest amplitude reading in four equally spaced locations. Number each of the four locations.

Attach the EVA’s sensor (with the word UP facing up) to the bottom of the drive axle pinion housing or transmission output shaft housing.

Attach an inductive timing light to the EVA’s trigger wire. The loop of wire on the top of the EVA.

If you are using the EVA with the version 1.0 software cartridge as shown below, Power up the EVA and then click here to proceed.

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If you are using the EVA1 with the "Smart EVA" version 2.0 software, select Auto Mode and press the Enter key repeatedly until the live data screen is displayed and then click here to proceed.

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If you are using the EVA1 with the EVA2 cartridge, or the EVA2 as shown below, click here to proceed.

with or

Power up the EVA2. Press the down arrow to select the Normal Mode, then press Enter.

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When the live data screen is displayed as shown above, press the strobe button.

If asked, answer NO to full range. The next screen asks if you want to use a low propshaft RPM range (2100 - 2700). Typically you would answer yes unless the rear axle gear ratio is very low, like a 4.88:1 or 5.63:1 gear ratio. If you answer no, the next screen displayed asks if you want to use a high propshaft RPM range (3300 - 3900). Pick the appropriate range for your vehicle's propshaft RPM while the vibration is occurring. If you are not sure what the propshaft speed is, click here to calculate propshaft RPM.

Answer yes or No

Assuming the YES key was pressed to select the Low Range, the next screen is displayed when the sensor is not picking up any vibrations.

Point the timing light at the six-o’clock position of the propshaft.

Start the vehicle and place the transmission in direct drive (Usually third gear on an automatic transmission and fourth gear on a manual transmission). Bring the vehicle up to the speed where the vibration can be felt. Note engine RPM at this point, it will match propshaft RPM. The next screen is displayed when a vibration is picked up, but the frequency is too low. Increase the propshaft RPM to 2100 to 2700 RPM.

The next screen is displayed when a vibration is picked up, but the frequency is too high. Decrease the propshaft RPM to 2100 to 2700 RPM.

The next screen is displayed when a vibration is picked up, and the frequency is within 2100 - 2700 RPM. The signal level represents the amplitude level of the propshaft vibration. Typically a signal level of 3 or less will give good balance results..

If the EVA is sensing a vibration at this RPM range, it will trigger the timing light. Notice where the timing light is flashing, it should be on or in-between the marks you put on the propshaft. The position of the flashing light on the propshaft indicates where to put the weight. The use of hose clamps for weights is accepted by many vehicle manufacturers.
One hose clamp is approximately one ounce. Up to three hose clamps may be added to system balance the propshaft system.
Add, remove, rotate, or spread the hose clamps to come up with an acceptable system balance. The EVA will stop flashing the light or the flashing will become erratic when the propshaft is balanced.
Road test the vehicle again to verify that the vibration is corrected.

This page was last modified Thursday, March 05, 2009 09:02:37 PM