Yamaha TRX850 Enthusiasts Forum

Quick question when fitting a yzf rear wheel to the standard swingarm and spindle. I know you need to fit new bearings with an ID to match the TRX spindle, but which internal spacer do you use, TRX or YZF?

I think you have to have a spacer machined up as the TRX one is too short and the YZF one is too fat. You need one the same length as the YZF one but the same internal and external diameters as the TRX one.

the spacer between the bearings is the trx item but the other two spacers one on the sprocket side and one on the disk side need some adjustment ,,,,trixynut might be able to tell you what size they need to be ,,,or i will take my wheel to bits and give you the sizes

steve speed wrote:the spacer between the bearings is the trx item but the other two spacers one on the sprocket side and one on the disk side need some adjustment ,,,,trixynut might be able to tell you what size they need to be ,,,or i will take my wheel to bits and give you the sizes

That's good that you can use the standard TRX spacer, it saves time and a bit of messing about.

http://www.trx850.motomaniac.net/forum/ ... lit=yzf750

That's the link to the 'How To' thread

steve speed wrote:the spacer between the bearings is the trx item but the other two spacers one on the sprocket side and one on the disk side need some adjustment ,,,,trixynut might be able to tell you what size they need to be ,,,or i will take my wheel to bits and give you the sizes

I'm going to ask a stupid question now. If the spacing between the bearings on a YZF wheel is the same as on the TRX (which they must be if the TRX internal spacer can be used) why do the external spacers need to be altered? as wouldn't it mean that the the external face of the bearings (which the external spacers also sit against) are also the same distance from the swingarm as the TRX.

|swingarm|spacer|bearing|internal spacer|Bearing|spacer|swingarm|????

Confused

They may have spec'ed a different sized bearing. Ie. same internal diameter but different external diameter and width.

I was thinking that too

Anyhoo, I've looked at the bearing sizes and it looks like the bearings needed are 6304 (20 x 52 x 15) which are 1mm wider than the standard (TRX) 6204 by 1mm (they're 20 x 47 x 14). Standard YZF bearings are 6205 (25 x 52 x 12) I think. Do the seals still fit in the wheel ok with the wider bearings fitted?

edit- I'm thinking it might be less of a mess about to just fit the whole YZF back end

AHTHUD wrote: I'm going to ask a stupid question now. If the spacing between the bearings on a YZF wheel is the same as on the TRX (which they must be if the TRX internal spacer can be used) why do the external spacers need to be altered? as wouldn't it mean that the the external face of the bearings (which the external spacers also sit against) are also the same distance from the swingarm as the TRX.

|swingarm|spacer|bearing|internal spacer|Bearing|spacer|swingarm|????

Confused

The spacers are not the same with YZF and TRX, because the swingarms do not have the same width

Kayla wrote:8<
edit- I'm thinking it might be less of a mess about to just fit the whole YZF back end

True and exactly what I did

|swingarm|spacer|bearing|internal spacer|Bearing|spacer|swingarm|????



The spacers are not the same with YZF and TRX, because the swingarms do not have the same width

[quote="Kayla"]8<

The question isn't whether the spacers are different between a YZF and TRX but why if the internal bearing spacer width is common between both wheels (as suggested) and I fitted TRX bearings and internal spacer in the YZF wheel then surely the TRX outer bearing spacers would also be the same as i haven't increased the width of any component to have to reduce the width of another:?

Isn't the rim itself wider?
Should be the reason you put it in, in the first place.

Tarwetijger wrote:Isn't the rim itself wider?
Should be the reason you put it in, in the first place.

Yep the rim is wider, but we're talking about hub width here.

Tarwetijger wrote:Isn't the hub itself wider?
Should be the reason you put it in, in the first place.

Kayla wrote:Anyhoo, I've looked at the bearing sizes and it looks like the bearings needed are 6304 (20 x 52 x 15) which are 1mm wider than the standard (TRX) 6204 by 1mm (they're 20 x 47 x 14). Standard YZF bearings are 6205 (25 x 52 x 12) I think. Do the seals still fit in the wheel ok with the wider bearings fitted?

In summary:

std. TRX bearing size - 20 x 47 x 14
std. YZF bearing size - 25 x 52 x 12
why do you need 20 x 52 x 15 then?

1. What you need to do is measure from bearing seat to bearing seat on each side. It should match the spacer length.
2. If you are using std YZF bearing size you'll need spacers that are 1 mm longer than the standard ones.
3. If you are using these bigger ones you'll need spacers that are 0.5 mm smaller.

X + Y + Z + Y + X
|spacer|bearing|internal spacer|Bearing|spacer|

devlin wrote:In summary:

std. TRX bearing size - 20 x 47 x 14
std. YZF bearing size - 25 x 52 x 12
why do you need 20 x 52 x 15 then?

The new bearing is to fit the YZF hub and TRX spindle together. The hole in the YZF hub is larger at 52mm. The TRX spindle is smaller at 20mm. The width of the bearings is pretty much incidental and can be worked around.

devlin wrote:1. What you need to do is measure from bearing seat to bearing seat on each side. It should match the spacer length.
2. If you are using std YZF bearing size you'll need spacers that are 1 mm longer than the standard ones.
3. If you are using these bigger ones you'll need spacers that are 0.5 mm smaller.

X + Y + Z + Y + X
|spacer|bearing|internal spacer|Bearing|spacer|

Assuming the YZF and TRX swingarms are the same width internally across the wheel hub, which I don't think they are. I think the YZF arm is slightly wider at that point.

I was just going to measure the length of the YZF part and have one made up to the internal and external diameters of the TRX part, but the same length as the YZF bit, assuming the TRX and YZF spacers aren't the same length. Once I've got that, I can fit the new bearings and get the wheel offered up to get it central, then measure up for external spacers. It needs to be done soon though as I'm due a new rear tyre and would like to try a 180/55.

I should add that I haven't actually measured any bearings yet, this is all just stuff I've got through matching dimensions in bearings catalogues (I am that dull.)

My internal spacer and bearings were YZF, then had the outer spacers made to fit the swing arm and the yzf wheel. If I remember correctly one side was bigger than the other, and both were top hat style, but cant remember any sizes other than they are a lot bigger than the trx. Dont forget to turn the rear dished sprocket round either or the chain doesnt run straight.

Dave E