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The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> This one has me stumped
Post Info TOPIC: This one has me stumped
MarkShelley


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This one has me stumped
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Today I made a disappointing discovery. You may have seen my thread on a seized speedo drive. I have resolved that and have some 3-tab washers en route from Brian. I have now found that these will be of no use as the bits on the hub that should cause the washer to spin are not present, obviously broken off at some time. I will need to buy a new wheel to get my speedo working. I know some will say just get an electronic one, but I am not keen on them.

Anyway, this has me stumped............I went to fit the wheel tonight complete with new bearings. I had the bearings fitted by my mechanic as he charges little for this and I have been rather busy lately. For some reason it was impossible to get it back together correctly. It is clear by looking at the wear lines on the spindle exactly where the spacer on the disc side should sit and it is clearly not going far enough into the hub, which would appear to mean that the bearing is not in the correct position. There is no play in the central spacer so both bearings are the correct distance apart. The wider part of the stepped spacer is obviously made to be a snug fit in the bearing rubber seal however the spacer sits so far out that the wider part of the spacer does not even touch the seal, never mind slide into it.  I also know the spacer is not in thecorrect position because it is not possible to get the caliper square on the disc.

See pic of how far the spacer sticks out when held against the inner bearing race.

The only ways this could happen (as far as I can work out!) is if either the bearings are too wide or the bearing on the speedo drive is too far in and the disc side bearing is too far out.

Anybody got any suggestions?

I will talk it over with the chap who fitted the bearings tomorrow. It will be most unlike him if he has made an error.

 

 



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MarkShelley


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Don`t know if this will help, but here are pics looking at both bearings.

 



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rattlyolddt


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Cant think what it could be. Unless you have somehow got the spacers the wrong way round? They sometimes look like they should go one way but dont.

As for the speedo, have your mechanic weld some blobs to replace the missing bits. Takes 5 mins.

Has worked on my.dt for a year so far!!

Ed

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TTRfan


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You need to check the internal diameter of the inner bearing race and check it against the spacer.

The bearings should be different. The internal diameter of the LH bearing should be 17mm I think...... The RH one is 15mm. If the same bearings have been used then that is the likely problem.

I agree with Ed, get some ali blobs tacked on in approx the right position to drive the 3-tab washer and you should be OK. You have the pattern on the LH side to copy.

Good luck!

Brian



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MarkShelley


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rattlyolddt wrote:

Cant think what it could be. Unless you have somehow got the spacers the wrong way round? They sometimes look like they should go one way but dont.

 I have been assembling it as shown in the manual as far as I can see. The disc side spacer can only go one way, otherwise it would not slide through the bearing seal.



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MarkShelley


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Clutching at straws here but should the two bearings be identical or should the disc side have a larger internal hole?
The disc side spacer has three diameters. The largest sits against the fork leg and the middle section fits snugly through the bearing seal. Currently the smallest diameter part bears on the inner race of the bearing. It has occurred to me that if the bearing on this side had a larger hole the spacer would partly slide into the bearing and I reckon that would probably be about right to get it all to assemble correctly.

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TTRfan


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MarkShelley wrote:

Clutching at straws here but should the two bearings be identical or should the disc side have a larger internal hole?
The disc side spacer has three diameters. The largest sits against the fork leg and the middle section fits snugly through the bearing seal. Currently the smallest diameter part bears on the inner race of the bearing. It has occurred to me that if the bearing on this side had a larger hole the spacer would partly slide into the bearing and I reckon that would probably be about right to get it all to assemble correctly.

 See my earlier reply Mark. The bearings are different. The disc side bearing needs to have an internal diameter of 17mm to accomodate the spacer. Only 15mm on the speedo drive side.

Brian



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MarkShelley


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I completely missed your post Brian. This is obviously the problem! I will have to chastise my mechanic for nearly making my head head explode! One day I will get this b****y bike on the road!

Would somebody be so kind as to post a pic of what the blobs should look like to give my welder something to aim for?



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TTRfan


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MarkShelley wrote:

Would somebody be so kind as to post a pic of what the blobs should look like to give my welder something to aim for?

 Pic below shows what the hub tabs should look like wink

IMG_0028.jpg



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MarkShelley


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The same as the redundant ones on the disc side then.

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