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- - sprocket carrier bearing mod ( https://www.xt660.com/showthread.php?t=24481)

Quote:

Originally Posted by Macca2801 (Post 219515)

Ahh that answers my questions...I never thought anyone would machine out 15mm and fit TWO bearings...thought everyone was doing the same mod as Hunday did in Pleiades link, where you just put the single wide bearing in.
I can see how the two bearings would fail.
Good luck finding a new swing arm and new hub... Hopefully a few wrecks around.
Matt.

Macca, so Hunday(Andy)'s mod is unlikely to cause this failure? I am poised to do this mod when I return from rotation in the Congo! Andy offers a hub swap out service for local 660 riders. Luckily we are in the same city.
How much play at the hub will indicate OEM Cush rubbers are shot?? Any pointers as I don't seem to have much play yet...
Thanks
Graeme

In Australia I am sure that there are lots of double bearing mods done as this is what is pushed by bike workshops...

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Quote:

Originally Posted by bluext660z (Post 219452)

Hello All,
Just would like to pass on some advice if you are looking at doing the bearing mod to the cush drive, from a bad & expensive experience on the weekend that destroyed my swing arm & hub after the alloy casting broke away allowing the hub to move to the outside chewing into the swing arm & hub.
My bike had the double bearing mod (2 x 6304 2rs) that machines 15 mm out of you hub & 15 mm off the spacer leaving a small amount of alloy that stops the hub moving sideways. the better way to go may have been to use the wide alternative of the same bearing (62304-2RS) & machine out only 6mm giving a lot more support. another alternative may be to install a internal retainer clip to take some of the load if there is enough room, I have not had a chance to look at it yet but will keep up to date with how I go.
This did happen while riding in steep country with other bikes, lots of erosion mounds, and going hard with good traction, I have tried to attach some photos but no luck as yet ??

i was thinking about having this mod done, but after seeing this i'll give it a miss. did you have the machine professionally machined or do it yourself?

Professionally, in a Workshop.

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Quote:

Originally Posted by Graemet (Post 219527)

As far as I know heaps have had it done it, mine has been in for about 20 000km of abuse!! Even Teknik Motorsport in Aust does it as a professional warranted install so they mustnt have had any problems.

I was just really shocked as I read all the posts about it and had never heard anyone machining out to fit TWO bearings...just fitting a SINGLE double row bearing as a replacement. This only requires about 5-7 mm to be removed from the housing and the spacer.

Matt.

Quote:

Originally Posted by Landton (Post 219502)

SKF bearing number is?

According to my SKF bearing book it's listed as a 3304...
20mm ID / 52mm OD / 22.2mm wide...

73304 what I would have thought it would have been..
7 = anglar contact...

..

Quote:

Originally Posted by Petenz (Post 219559)

According to my SKF bearing book it's listed as a 3304...
20mm ID / 52mm OD / 22.2mm wide...

73304 what I would have thought it would have been..
7 = anglar contact...

..

I have just edited my original post, as I had originally stated that I had used a SKF bearing, but on double checking, it turns out that I used a NSK Bearing.

The specification on box

NSK

3304B-2RSRTNG N

YRLN5

305

Someone correct me if I'm wrong but I think there has been a case or 2 of sprocket carriers breaking up that were still original without being modified ? Which might suggest a dodgy batch of parts similar to a few cases of gear selector problems ?

Just ringing around wreckers & have been told of a few sad stories of single standard bearing issues leaving people strandard and few options but to put the bike on a trailer.

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Hello, Just to update on the bearing modification that failed for me causing my rear sprocket hub & swingarm to be servery damaged. I have just replaced the hub & swingarm & done some measurements on the hub if you do the double bearing mod you will only have 2.5mm of aluminum left to keep your bearings in place (17.5mm - 15mm for the second bearing = 2.5mm). The double row 22mm wide bearing (3304 2RS) would leave 7.5mm of material.
If you have done the double bearing mod I would be checking to see if there are any signs of fatigue & seriously consider fitting an internal cir-clip as I did as temporary repair to my damaged hub. the cir-clip is a 54 mm bore "D1300-0540". I went to 54mm rather than 52mm because just after where the cir-clip is installed the size of the bore in the hub increases so it suits better.
You can see the piece that fractured off the hub in the second picture.