Repairing the Clarke Focus II Boost L20 Brush Deck

So your Clarke Boost making loud, rattling or chattering noises?    When properly working it should not make much noise at all.  But after many hours of use (and maybe abuse) there are parts that will wear and need to be replaced.  In this article we will go over how to take apart the Clarke Boost L20 Head Assembly and find out what needs replaced.  If you need help troubleshooting your problem feel free to contact us for more information:  501-844-1811.  And we have the parts you will need Here:

 To determine which parts need to replace first remove the brush deck from the machine.  Instructions on doing that can be found here:

Once you have the deck off the machine we can begin to take it apart.
Remove the 8 81220A 1/4-20 serrated nuts holding the flex plate assembly on.

Next remove the 4 56381989 SHOULDER BOLTS 

Now you can remove the Flex Plate Assembly.  You will see something like this.  Hopefully yours is not as bad as this one.  Right away we see it will need 2 new Flex Plates.   (Clarke's part says it is an assembly but it requires 2 of part number: 56383374)

Also in this picture we see potential causes of the rattling noise.  The Plate Driver 56381491 has 4 holes that go over 4 of the rubber isolators 56380190 and onto the Flex Plate.  The 4 holes on the Plate Driver wear out over time.  As these holes become larger this will make noise when the plate is shaking.  Notice the tight fit of the plate driver to the flex plate here on these new parts:

Broken Rubber Isolators can also be the problem.  Replace all 8 on the flex plate.
There is also the option of replacing all the rubber isolators and the nuts with this Kit:   CLARKE ISOLATOR KIT BOOST 20 56380236, 56380190   
Note:  When installing the rubber isolators make sure you use the 980614 star lock washer between the isolator and the brush head plate.   Torque the flex plate isolator nuts to 8-10 ft.-lbs.  After tightening the nuts, look at the lines on the rubber isolators and make sure they are not twisted, which indicates they are over tightened.

There could also be bearing noise coming from the:  50736A BEARING Remove the 61775A Bearing Retainer by taking off 3 84237A screws

There could also be bearing noise coming from the 56390072 MOTOR. With the Plate Driver removed plug the motor back in to the scrubber and engage the motor.  If there is bearing noise with just the motor running by itself the noise is coming from the 2 bearings inside the motor.   There are no part #'s from Clarke for these 2 bearings.  The motor will need to be replaced.  (It is possible to replace these bearing if you have the tools needed)  This is also a good time to install new carbon brushes in this motor.  You will need 1 of 56412287 MOTOR BRUSH AND SPRING KIT  To install:   First:  Remove the wire retaining nut and the rubber packing.  Next:  Remove both of the through bolts.

Remove the end plate.  Before taking all the old brushes off.  Move the brushes back and forth on their springs.  Notice how the springs unroll.  The brushes press into the "Cup" side of the spring.    

Install the new brushes and springs.  Use a paper clip to hold the brushes in place while putting the end plate back on the motor. Push brush back against the spring and insert a paper clip through the access hole in the end cover. (Remove silicone sealer from the holes) The wire must go through the holes
in the brush holder just in front of the brush to hold the brush back against the spring pressure.


Next place the end cap back on to the motor.  Remove the temporary paper clips to allow the new carbon brushes to seat onto the commutator.  Install the thru bolts and tighten.  Replace the silicon that was in the 4 holes that the paper clips went thru.    

Brush Motor Removal:  To remove the brush motor first remove the Eccentric and Shield 56380246 that is still on the brush deck.  

Next remove the 4  56001881 Screws.  Be careful these are bad to strip out.  Try using a hand impact or similar device.  They may be allen or phillips head screws.

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