Cam bearing replacing

If the parts are machineable there would be a number of ways to relocate and hold them. I don't know if Ray tried to determine the hardness or not...
Chances are the parts would not be machineable without annealing them first, then rehardened before assembly. Without knowing the exact alloys, it could be a little tricky.

If this hits me, I will probably go with 4 spot welds, and then hope to grind the spot welds off if the bearings need replacing again.

Camshaft would likely be 8620 or similar and even at Rc60 it is still machinable with the correct tooling etc. but it is not something that I would want to do larger pieces on a production basis but sinking a couple of holes as described in my earlier post is not that big of deal with the proper setup.

It just seemed like welding would be the easiest and quickest way to lock the gear on the shaft to me ... Spot welds would probably have worked but I was in no mood to take any chance so it was the whole thing ... It should grind off in the future for another bearing replacing ...

Yesterday, I was a bit lazy but today, I got the bike back together and it is running AOK so far ... One issue is one of my bolts holding down cam cap #1 is stripped pretty much ... I used lots of loctite on it and I'm hoping I can ride a day or two before I try to insert an helicoil in it for the fix ...

Thanks for all the help and ideas here and thanks to Uptite George as he has helping me also ... His email address seems a little wacked out though as me emails were getting returned for some odd reason ...

PS ... Engine runs alot quieter now ...

hows the cam repair holding up? im about to tackle the same prob with a '04 TC250

Did you have any damage from the bearings letting go?

No problems from that work on my 08 TXC250...

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I've got 2 010 TC250s since then and I'm thinking very hard on changing the cam bearings on them because of the threads here about bad bearings for these models and the work is simple enough ...

not sure, I bought the bike not running. The big end and mains had failed also, the previous owner had not done an oil change in 30 hrs!!

Great ill do the same repair. I think ill do my 450 while I have the tig out. Thanks for posting the thread its been very helpfull

One of the bearings let go again on ours. This time some ball bearings got away, so the poor TXC is sitting in the garage waiting on surgery.

I am about to do the same bearing replacement. What clearance rating bearing did you guys go with? Standard 6001 or 6001 C3. I just caught mine, the bearing cage was letting go on the exhaust cam non gear side so I could just replace the outer ones but would prefer to do all 4.

Did you ever get the TXC repaired?

Glad you woke this thread up and put your repair here, so it is with a similar bike.

For those that did not see his bearing, here's Kreza's pic:

Its pretty much done. The husband got a new Husaberg TE 300, so I've been dragging my feet on repairing this one, but I need to get it back in riding shape since we have a dual sport ride coming up in the fall. Since so much of the bearing disappeared, I had a buddy split the case and inspect/clean out the bottom end. He did not find much debris, so it must have ground itself up nicely and disappeared in the oil (no huge chunks there either). George at UpTite repaired the bearing again. Last time, we had him replace all 4 with higher quality German bearings. The same one broke up the second time, so I m curious what force is acting on this bearing in particular to cause the problem.

The first one we noticed while rebuilding the bike and the bearing had not let go, but was obviously about to blow up. The second time, the symptoms were a bike that suddenly became very hard to start. We took the cover off to check valve clearance and found it to be very off. Went to remove the cams to see what shims were in there only to see the bearing blown up again.

Yours is the first case I have heard of where the same position bearing has failed with a superior replacement. This failure is in-line with what I have posted elsewhere, that there is a defect in the casting of the cam bearing journal or the cap that is causing the torquing of the cam cap to squeeze the bearing OR that the mounting of the bearing is somehow skewed off to the side and the faulty mounting of the bearing causes that bearing to fail.

I have manage to seperate my cams, made up a bit of a jig to hold in place while pressing. First marked the postition of the sprocket and shaft with a small cut off wheel to ensure I had a good visual groove for realignment. Got to 5 tonnes of pressure without budging so I applied some heat with the oxy until it cracked and out it came easily enough.

I am going with SKF brand 6001 C3 clearance rated bearings as another member Kuzmich postd that his bike had these C3 bearings on his cam. The ones I removed had no markings what so ever. These C3 clearance rated bearings might be able to handle what OHR suggested above.

Next is to work out what temperature to heat the sprockets before installation without ruining them.

So she's all good now. New bearings simple enough to put on. I heated the gears to 200 degrees Celsius and had the cams in the freezer for about an hour. Gently tapped it on in alignment and pressed the rest of the way. One spot of TIG weld between shaft and gear for peace of mind topped it off. It does help considerably when you have all the equipment to do it. I feel for those who have to pay.

I'd have to pay.....

Only one spot, will that make it unbalanced, I thought i would tell my guy 2 spots or 4....

I only fused the two together and didn't add any filler metal and being so close to the centre of the shaft I don't foresee any balance issues, particularly on a camshaft with lobes not being central.

Thought I'd resurrect this thread, as I'm going to have a go at replacing my te630 camshaft bearings this week. I did something a little different to Kreza, in that I remove both the bearings before removing the gear. I did this by busting the bearing trapped behind the gear to remove the outer race and the cage and balls. Then I cut the inner race carefully with a dremel and broke it away with a cold chisel. This made it easier to get a purchase directly on the gear.

I made up this jig to put in the press. I'll report how it goes when I get to my mates workshop next week! Wish me luck.