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Old 08-15-2012, 01:08 AM   #206
BergDonk OP
Beastly Adventurer
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Joined: Nov 2010
Location: Snowy Mountains Oz
Oddometer: 3,815
Steering Head Update

A bit of notchiness was developing in the head bearings, so time for some new bearings, and an upgrade, hopefully.

As you may recall, I fitted some KTM forks to my DR at the beginning of last year, just on 30,000 kms ago, and near the beginning of this thread. I initially fitted the KTM races to the Suzi cups, but this failed, so lathed up some bushes to go around the KTM cups and got them to equal the Suzi dimension, 52 mm OD.

They fitted up fine, top and bottom with new bearings at the time,

After some thought, and not long after I'd got it operational, I decided that when it came time, I'd try to fit the Suzi bearing to the bottom of the steering head. This seems like a good idea because the Suzi bearing is 1 mm taller, so may have a <> 10% increased load capacity, and/or, wear out slower. Its normally the bottom ones that are the problem, as they take the hammering. And because the ID is 1 mm larger, it'd fall over the shaft on the top down to the bottom, making assembly easier, as long as the bush could be fitted to get it to work.

I already had a new set of Suzi bearings unused from last time, so ordered some new KTM ones.

In the above pic, on the left on the blue rag is one of two original spacers from the stock forks. Heavy lumps of steel bushing that usually get junked for some plastic ones when they are upgraded. They proved to be very useful for this exercise.

So, disassemble front end, making use of the engine crane so not too much had to come apart.

I needed to sleeve the KTM shaft on the bottom with a 0.5 mm thick bush. Back to the lathe, and thinning down one of the original spring spacers as a bush, and boring the other to make it into a die to press the bush on over the shaft I got the Suzi race fitting snugly. You can just see the bush in the pic below.

After deciding that it should be OK, I hammered out the existing cups. What was nice was that my bushes stayed put. Meant that I had to remove the bottom one afterwards to fit the Suzi cup, but the top one could stay put for the new KTM bearing going there. Bit hard to see in the pic below, but its still there.

So all bolted back together, and good to go. And I've got a set of bearings left over for next time, one of each of the Suzi and KTM pairs. FWIW, both sets are Pyramid parts purchased on eBay. More than 30,000 kms would have been nice, but its had a bit of a flogging, so OK life, I think.

And the value of having a lathe and a good press validated once again.
shed time IS quality time
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