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

I recently replaced the steering head bearings on the project TTR.

Following on from publishing I received some helpful advice that would have made the job easier:

Just reading your thread and the trauma of sometimes removing an outer bearing race which will be scrap. Just a blob of weld on the inner bearing surface from an arc welder and probably all other types and it will drop out when it cools and contracts. 

One thing... you mention using old bearings as drifts to drive in the new ones and to do this is well known but you also report difficulty in removing the old part afterwards. Well, if you make a cut across the old bearing first it won't be such a tight fit, can't jam and will easily pop straight out again.

This guide shows how to replacing the steering head bearings with new using an AllBalls kit 
 

Firstly remove the old outer bearing races. I used a special tool made for the job.

An alternative way of removing an outer bearing race which will be scrap is to put a blob of weld on its surface from an arc welder (and probably other types) and the race will drop out when it cools and contracts 

It is a pretty solid bit of stainless steel with four sprung "tongues" that sit under the races and allows them to be driven out with a hammer. The following pic shows the tool in place ready to drive out the top race.
 

I guess the easy bit was fitting the new inner races to the fork head on the frame. The top race is easy as it fits flush. I used a copper headed hammer to tap it in.

The bottom race is recessed so I used an old inner race to tap it home. A lot easier with a bare frame coz I could just turn it over  Not so easy with a complete bike!
 

This is where it got difficult - getting the old bottom bearing off. It was incredibly tight. I started off using a chisel to get in between the bearing and yoke to start to drive it off.

Once it had started to move it was a case of continuing to drive it off wiith the hammer and chisel. Easier with the old roller bearings removed.

Use a Dremel to cut it off if you have one - probably a lot easier!

This is the order of the parts:

This is the fiche pic:

 I guess I should have realised that if the old bearing was tight the new one would be as well - this was the case    

In retrospect I should have warmed the bearing and chilled the yoke to have made it easier. I eventually ended up whacking it on in the vice using the old inner race to protect the new bearing. Cut across the old bearing first so it won't be such a tight fit, can't jam and will easily come off again.

It would have helped having three hands to do the next bit. Having greased the bearings well, it was a case of putting the yokes back in the frame with all the washers etc all in the correct order - the workshop manual is really good for this sort of job. Needless to say I managed to mess this up and forgot to fit the new bearing seal. It took a couple of goes to get it all together in the right order with no bits left over 

Assuming that you have the forks and front wheel in, now torque up the top nut.

Job done!

Brian

Here's the TTR250 offer direct from TotallyTTRs

https://totallyttrs.com/epages/699105d9-e4cc-4b32-b236-84e72cd67f84.sf/en_GB/?ObjectPath=/Shops/699105d9-e4cc-4b32-b236-84e72cd67f84/Products/TTR-0295

It can be found as Steering Bearing and Seal Kit under AllBall kits offered for all TTR owners.

Martyn

wizz wrote:

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It lists 99-06 mine s a 4gy 94, are they the same?? 

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Yep!

AllBalls kits are manufactured in the US. They only ever imported the blue TTRs so very few US parts list the white TTRs.

Brian

Pete, this LINKY takes you to a GB supplier that specifies the requirements.

The dimensions of the taper roller bearings (top and bottom are the same size) as:-

• Inside Diameter: 25.40mm = 1 inch
• Outside Diameter: 50.29mm = 1.98 inch
• Width: 14.22mm = 0.56 inch

Martyn

You are in luck - I just measured one up and it's 52mm 

Pics and details please 

Brian

hi folks. I am fitting new bearings and I can't tell if the bottom nearing is down far enough on the shaft. there seems to be a small gap between the seal and the bottom fork bracket. can someone check their bike and let me know? checkout the attached picture for detail.

Thanks from Ireland!!

thank you Steve

 how about the gap between the cap and the frame...where I have a dab of tipex...its 4.5mm , should that gap exist or should the cap fit down flush?

Thanks again!

Can't see your picture, but there is a small gap between the forks and the frame which is the collar part of the forks, which can been seen in your first post picture.

Was there meant to be a second photo?