Easy
15-30 minutes
It is a genuine item that is supplied by the original manufacturer for use with Ryobi and Homelite handheld string trimmers. This washer-clutch is a special friction disk that helps to engage the clutch by ensuring a tight fit between connected components. It provides an identical replacement for a damaged or a missing hardware that was installed on a new unit. Check the diagrams of your model for the exact location and the correct installation of this part. One durable metal washer is included. You may need a screwdriver and a wrench set to perform this repair.
Washer 638090001
OEM part for: Ryobi
Part Number: 638090001
$4.99
In Stock
Ships within 1 business day 
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Compatibility
This Washer will fit the following 522 machines. Confirm this part works with your model, and view the detailed model diagrams and repair help we have to offer.
This item works with the following types of products:
- Trimmer Parts
This part replaces obsolete part #: UP04275, 98929A
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Customer Repair Instructions ?
All our customer repair instructions are solicited directly from other customers just like you who have purchased and replaced this exact part.
Clutch discs broken
Paul - August 26, 2017
Tool Type
Trimmer
Difficulty
Easy
Time
Less than 15 minutes
Tools Used
Screwdriver, hammer
1. Found the Clutch discs were obsolete. (Homelite bc900 and many other trimmers I found in my research.)
2. I discovered while researching that the clutch parts breakdown used the same clutch washer and the same drum, but it used a different clutch which wasn't obsolete. Purchased new clutch, drum, and the two different sized washers. Parts were for Ryobi BC30.
3. Removed the clutch drum by loosening captive torx screw in end of drum, sliding off the drum.
4. Removed the clutch each of the two clutch discs by tapping a screwdriver with a hammer to spin then off.
5. Removed old clutch washers.
6. Replaced washers and clutch in order for other model trimmer.
7. Tighten clutch with adjustable plier.
8. Installed new drum.
2. I discovered while researching that the clutch parts breakdown used the same clutch washer and the same drum, but it used a different clutch which wasn't obsolete. Purchased new clutch, drum, and the two different sized washers. Parts were for Ryobi BC30.
3. Removed the clutch drum by loosening captive torx screw in end of drum, sliding off the drum.
4. Removed the clutch each of the two clutch discs by tapping a screwdriver with a hammer to spin then off.
5. Removed old clutch washers.
6. Replaced washers and clutch in order for other model trimmer.
7. Tighten clutch with adjustable plier.
8. Installed new drum.
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Bad vibration due to broken clutch
Dave - August 16, 2017
Tool Type
Trimmer
Difficulty
Easy
Time
30-60 minutes
Tools Used
Pliers, Power Drill, Socket set, Nutdriver, Spark plug socket and small rope
Remove spark plug and feed small rope into spark plug hole to stop piston from turning over.
Remove T25 screw holding clutch drum to crankshaft
Turn clutch counter clockwise to unscrew from shaft
Replace part in reverse sequence with new parts
Remove T25 screw holding clutch drum to crankshaft
Turn clutch counter clockwise to unscrew from shaft
Replace part in reverse sequence with new parts
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Clutch was defective
Burt - October 25, 2016
Tool Type
Trimmer
Difficulty
Easy
Time
Less than 15 minutes
Tools Used
Socket set, Torq driver, adjustable band wrench, rope
Parts Used
1. Removed starter pull handle
2. Removed 12 torq screws/bolts
3. Disconnected electrical connectors and throttle cable
4. Removed spark plug
5. Fed rope into cylinder to "jam" piston
6. Removed old clutch assembly and washer
7. Installed new washers and clutch assembly
8. Fed starter rope through housing
9. Aligned starter pulley
10. Reinstalled torq screws (8) and bolts (4)
11. Reconnected electrical connectors and throttle cable
12. Installed spark plug
2. Removed 12 torq screws/bolts
3. Disconnected electrical connectors and throttle cable
4. Removed spark plug
5. Fed rope into cylinder to "jam" piston
6. Removed old clutch assembly and washer
7. Installed new washers and clutch assembly
8. Fed starter rope through housing
9. Aligned starter pulley
10. Reinstalled torq screws (8) and bolts (4)
11. Reconnected electrical connectors and throttle cable
12. Installed spark plug
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Thanks for voting and helping fellow customers!
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Our customer service team are at the ready daily to answer your part and product questions. We have a dedicated staff with decades of collective experience in helping customers just like you purchase parts to repair their products.
All our part reviews are solicited directly from other customers who have purchased this exact part. While we moderate these reviews for profanity, offensive language or personally identifiable information, these reviews are posted exactly as submitted and no alterations are made by our team.
All our customer repair instructions are solicited directly from other customers just like you who have purchased and replaced this exact part. While we moderate these reviews for profanity, offensive language or personally identifiable information, these reviews are posted exactly as submitted and no alterations are made by our team.
Based on data from past customer purchasing behaviors, these parts are most commonly purchased together along with the part you are viewing. These parts may be necessary or helpful to replace to complete your current repair.
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