Author Topic: makita 6421  (Read 409 times)

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Offline pigpen60

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makita 6421
« on: September 09, 2014, 01:04:23 am »
I have a Makita 6421 in my possession that used to be a hd rental saw, and I was looking it over the other day and thought that the clutch drum bearing was bad. upon closer observation the bearing is fine but the shaft that it runs on is slightly undersized. anyone seen this before? should the bearing have a touch of grease?

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Offline 660magnum

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Re: makita 6421
« Reply #1 on: September 09, 2014, 01:23:47 am »
I have one of those type saws with a lot of time on it.

If the bearing gets bad, the clutch drum will occasionally make a ding sound at idle.

The shaft is as hard as the bearings. I doubt it is worn? Get a new bearing at the Dolmar dealer. Be careful, there are two different bearing sizes in those saws. You will have to take your old bearing in with you. The clutch drum may be worn? You could try a new one but there are two different sizes to match the different size bearings. The later, bigger, bearing lasts longer.

The shaft is the crankshaft. The chainsaw will have to be taken completely apart to to change the crankshaft$$$$$$
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Offline mdavlee .

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Re: makita 6421
« Reply #2 on: September 09, 2014, 09:58:17 am »
The bearing will be a tiny bit loose without the drum on. If there's slop with the drum and bearing then there's a problem.

Offline KilliansRedLeo

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Re: makita 6421
« Reply #3 on: September 09, 2014, 10:41:40 am »
+1 on the above. If the bell and bearing are both worn and not the crank, I would replace the bell and the bearing with the larger bearing and matching bell.
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Offline pigpen60

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Re: makita 6421
« Reply #4 on: September 09, 2014, 06:52:36 pm »
I took it to my dealer and he tried my drum/bearing on a 5105 and it was tight. he tried the 5105 drum/bearing on mine and it was loose. we both agreed the crank was wollered a bit, or not. a crank is out of the Q right now.

Offline 660magnum

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Re: makita 6421
« Reply #5 on: September 09, 2014, 07:05:57 pm »
Put some grease or oil on it when you put it back together. As you use it the chain oil will keep it oiled.

Use the saw when you need it for now.
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Offline pigpen60

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Re: makita 6421
« Reply #6 on: September 10, 2014, 09:56:27 am »
what is the reason for the larger bearing?

Offline 660magnum

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Re: makita 6421
« Reply #7 on: September 10, 2014, 10:14:25 am »
The two bearings had the same inside diameter but the newer larger bearing was bigger on the outside. Apparently they had trouble with the original bearing?
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Offline aclarke

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Re: makita 6421
« Reply #8 on: September 10, 2014, 01:34:22 pm »
Is the new bearing metal caged and passed on to the drum?

Offline 660magnum

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Re: makita 6421
« Reply #9 on: September 10, 2014, 01:38:10 pm »
The new bearing has larger needles. There are fewer needles and a more sophisticated cage.
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