A forum for owners of Yamaha TTR250 trail and enduro bikes!

Padowan wrote:

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How much end-play is acceptable on the swingarm before the bearings ought to be replaced?

My swingarm's got about 2-3mm of vertical play at the dropouts, just a little donk-donk when you waggle it up and down. I think it's the bearings that support either end of the link-arm that are slightly suspect, but it's certainly not that bad and I can't be entirely sure exactly which one(s) are to blame without taking it all off, which will probably be my next job just to take the opportunity to grease everything up. Worth worrying about at the moment, or should I get a bearing kit and replace them all?

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Some bearing manufacturers will have different internal clearance specifications. For example- one company has tested their bearings & found that C3 clearances lasts the longest with their tests & their bearings. Another company will find after testing that a C4 clearance is best for that bearing the way they built & tested it. In the end it may have more or less play then another brand, but the bearings will be made with the clearances specified for that particular type & brand of bearing so this isn't a problem.

Also for example- one company will have 38 µm minumum clearance & 61 µm maximum clearance for a C4 bearing that is 50mm. Whereas the other company will have 36 minimum clearance & 63 maximum for a C4 bearing that is 50mm. This will in turn add to the play but will still be in spec with that particular brand of bearing.

Standard clearance/acceptable play is 1mm with standard bearing. However, if you're not using Genuine bearings I think that 1-1.5 mm play should be acceptable, given how many different bearings are required for the job, maybe even 2mm play for some brands of bearings. 3mm would be too much, no matter what brand.

Radial clearance is the play between the ball and raceway perpendicular to the bearing axis. Axial clearance is the play parallel to the bearing axis and is typically at least 10 times greater than the radial clearance. Generally, internal radial clearance will be reduced 80% of the interference fit amount. That said, you have to take into account the side play in bearings aswell as up & down. Especially with interference fits.

Also the ball type bearing adds to the end result of play-part N36.  HERE This swivel bush will have alot more clearance than the roller needle bearings as it has to take the load.

All this said, it would pay to use the collar from the bearing company that supplied you the bearings as they will NOT be right for other brands of bearings unless all specs are the same as each other.

Oh & if your not using the Genuine ones with the inserts (it holds the bearing together so all those annoying needle roller bearings don't drop out) you will have a little more play than usual.

Hope that helps?

Jarrah

TTRfan wrote:

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The first rear suspension joint to wear is the lower shock bearing. It is the usual suspect!

Brian

 

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 +1

Yep, part N36.  HERE

Jarrah

Hi Brian,

I'm doing my linkage bearings now. Like a div, I used a long punch to get the link bolt out. I now have the punch stuck inside the link bolt. How can I get it out? Or am I in need of a new link bolt?

About to try heating the link bolt over the hob, no gas in the blowtorch.

EDIT: It didn't work.

EDIT 2: Brian, I'm even more of a div. THERE'S A NEW ONE IN THE KIT!  

-- Edited by Fladdem on Saturday 19th of April 2014 01:47:23 PM

So, similar setup to the one in the swing arm then? Needs drifting out from rhs to lhs?

PS: that tab may or may not exist anymore ;)

looking up from under the bike..

Yep, I thought as much, thats what ive been doing. Seems a pretty solid belt from a 3lb hammer isnt enough. She must be well rusted together, no wonder the suspension was stiff!

EDIT: 24hrs soaking in a liberal dose of wd40 and penetrene plus multiple applications of an unreasonable amount of force and its out.. ugly, but out :)

TTRfan wrote:

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v8r wrote:

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Needs drifting out from rhs to lhs?

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Yep - loosen the bolt on the RHS a bit and then put a drift on the head of it to start driving the main bolt through. Undo the bolt a bit more and repeat, etc. 

The bolt you are trying to remove is the one on the far left of the pic below:

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 Hmmm, interesting one Brian. Fitted my linkage kit today, and it's great. Strange though, all of my main bolts, the two in your picture and the main one which connects the link to the swing arm, have grease nipples in, but like your two, the new main one doesn't.......

Is that a model difference? seems like a backward step. Used the new one though as the old one was fairly badly worn.

also fitted my fleabay shocker, which appears to be fine without refurbing. Just waiting for the top shock bearing to arrive before I finally re-assemble it properly.

andyh wrote:

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Just fitted new bearing etc and all gone well apart from i still have a slight amount of play which seems to stem from the bolt in the drop link ( the lower eyes of the 'u' link) which is not bushed/bearing equipped - bolt is not in particularly poor condition but you can feel a little play when disassembled.

anyone else found this?

Andy

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Hi Andy

It doesn't matter if there is some play off the bike. When the bolt is in place and properly torqued up, the lower eyes of the link arm will clamp against the bearing collars and the bolt won't be able to move. The only movement will be betwixt the collars and bearing.

Brian

Hello, I'm doing just this job on mine but could not get the nut and bolt on the far left in the picture out and had to cut the nut, new ones are coming in at £50, does any one have any thrifty ideas? cheers

thanks for the replies, no it's 31 and 29 in the diagram