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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: Udor1234 on February 15, 2024, 03:12:40 AM
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Does anyone know what the drive shaft rubber part is? And does it matter is its torn or can that rubber part be replaced?
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Consensus I've read indicates it is likely to be for vibration damping; so far, your post is the only one that I've found discussing damage to it. I haven't yet found a listing for a replacement part. It this were on my Brick, I'd consider repairing it with RTV-type silicone adhesive. The RTV adhesive also could be used to adhere it to the driveshaft and driveshaft housing but it would help if those surfaces could be cleaned with solvent and dried thoroughly. Regardless, I would allow the repair to cure for a few days before riding. Attached photo shows how the ring is seated on the shaft housing and driveshaft. Have you noticed excessive vibration when riding?
(https://www.motobrick.com/gallery/4/1601-150224101339.png)
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The rubber is in the original manufacture of the shaft and is not replaceable. Yours looks like it is on the way to failure. When that happens you will lose all drive to the rear end. Better to replace it with new or a good used shaft before it leaves you stranded.
Frank
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I highly doubt that RTV would hold up to the shear that that rubber-metal contact area is subjected to. As you can see in the cutaway diagram below, all of the power/torque to the final drive is transmitted via that rubber insert from the front half of the drive shaft to the rear half.
(https://i.imgur.com/cdawfow.jpeg)
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I highly doubt that RTV would hold up to the shear that that rubber-metal contact area is subjected to. As you can see in the cutaway diagram below, all of the power/torque to the final drive is transmitted via that rubber insert from the front half of the drive shaft to the rear half.
(https://i.imgur.com/cdawfow.jpeg)
What he said.
The rubber is probably vulcanized in place in the driveshaft and is intended to absorb torque shock from the inconsistent rotational speed of the shaft due to the universal joint(it's why the axles of front wheel drive vehicles use constant velocity joints). The amount of torque and the rotational speed changes will break whatever adhesive you try to bond it with.
Having said that, one of the strongest adhesives that I know of is 3M 5200 urethane adhesive. I have seen sailboat keels weighing well over 2 tons held firmly in place by a contact patch of less than 1 square foot of 5200 adhesive. Anyone who has attempted to break the bond this stuff makes will attest to it's strength. One of it's features is that besides being unbelievably strong, it is also flexible which can be useful.
You could give it a try, just make sure that the surfaces to be bonded are spotlessly clean and follow the directions. Get it at Home Depot or a marine store as it is mainly used in boat construction and repair. It's not terribly expensive, about $20 for a tube with enough to do your drive shaft.
https://www.3m.com/3M/en_US/p/d/b40066983/
One word of caution, NEVER use it on anything you might ever want to take apart.
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What he said.
Leave it to BMW Motorrad. Just the thing for my boots' lugged soles. :laughing4-giggles: Never seen or read of this particular failure.
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Ahh well. Lets see if there is anything on ebay.
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Data sheet with application instructions. DO NOT use alcohol for prep cleaning. No shear strength data for rubber, but it is rated at over 500#/sqin on steel. Should be able to handle the drive torque.
https://multimedia.3m.com/mws/media/2366044O/3m-marine-adhesive-sealant-5200.pdf?&fn=3M-Marine-Adhesive-Sealant-5200.pdf
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Just curious, before you go to the trouble of trying to repair it. What are the splines like??
Regards Martin.
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Never seen or read of this particular failure.
I had the rubber fail on the original driveshaft of my '85 RS in the later 80's at about 125,000 miles. Since then, I have replaced the driveshaft before it gets to 100,000 miles.
If buying a replacement driveshaft be aware that sometime during the production run of that type of shaft the spline count changed. I don't know the specific dates or number of splines involved. Count the splines on your present rear drive to be sure you get a compatible one.
Frank
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85 model year and earlier K100s are Z16 count. Z20 for 1986 on.
Per the parts catalog the manufacturing changeover date is 2/86.
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Just curious, before you go to the trouble of trying to repair it. What are the splines like??
Regards Martin.
The splines are good to reasonable.