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Old 07-05-2009, 06:37 AM   #10
NOSIGN's Avatar
Joined: Apr 2009
Location: Melbourne, VIc
Oddometer: 94
Head stem!

Dylandr - cheers mate, I hope the powder coating holds as well as you say; I dropped an old bearing race on the frame today and it chipped the pc .

I felt like I owed it to Mezo's wall-o-fame to put in 45mins of farkin today.

Since I couldn't change-over headstems between the Suzuki and KTM, me 'ol man and I decided to get some SS sleeves machined to fit over the KTM headstem bearing contact area. This would allow the original DR taper bearings (NSK 4T-CR-0643 L) 30mm ID, to be fitted to the KTM headstem replacing the KTM TIMKEN L 49449 29mm ID bearings and to use the original Suzuki bearing races/ cups. This is what we came up with...

If I had my time again, before fitting the bottom sleeve, I would fit a 3mm spacer between the bottom clamp and sleeve. I should have listened to me Dad! This is because, as you'll see later, you'll need a spacer between the upper tripple clamp and the upper taper bearing. The bottom clamp design on the KTM differs to the Suzuki bottom clamp. The KATO bottom clamp bearing surface area is flat across the clamp. The Suzuki bottom clamp has an embosed area underneath the bottom bearing. This embosed area provides a large clearance between the bottom clamp and the frame head. With the bottom sleeve fitted as shown in the pic, once the bearing is in place, there is very little clearance (maybe 0.5mm or so) between the bottom clamp and frame. Hopefully this won't become an issue further down the track.

I may not have explained that too well, but if anyone is interested, I'll take some pics later to show you.

To fit the sleeves, the KTM headstem had to be machined. The KTM TIMKEN bearings have an ID of 29mm however the KTM headstem is shaped like an hourglass and is mainly a 28mm diameter. The surface area where the bearings sit is oversized to 29mm.

We figured that the SS sleeves should be at least 1mm thick, so the machinist machined 0.5mm from the KTM headstem diameter. Now the KTM headstem had a uniform 28mm diameter.

These are the dimensions of the sleeves

Two Stainless steal sleeves
ID = 28mm
OD = 30mm
length = 20mm top sleeve, 22mm bottom sleeve
small chamfered upper edge for the bearing to slide over the sleeve smoothly

To fit the new bearing without proper tools, I used the old KTM bearing, an alluminium sleeve and hammer combo to hit the new NSK bearing over the sleeve.

And the lower taper bearing fitted...

I used an air gun to clean the PC residue from the frame, then coated it with greese and G15 rust inhibitor in preparation for the bearing races/ cups.

Bottom clamp and stem in, upper bearing tapped in... feels like a pro fit - no free play, solid rotation

For the 32mm (spanner size) head stem bolt to be able to tighten the bearings, a 3mm spacer is required between the upper bearing and the tripple clamp. I used two of these 2mm thick spacers (4mm is still ok)...

What do you think of the frame colour? Is anyone even reading this?

And the finale! New Suzuki NSK bearings with races/ cups, KTM lower and top clamps with stem. Greased, fitted and feeling good

Note: prior to powder coating, the DR frame steering limit block was grinded off in order for the KATO bottom clamp to fit - just as LukAS did.

DR650SE ('97) current project
CBR954 ('03) daily ride
CBR900 ('96) the 'ol days
CR250 ('03), 125 ('89), 80 ('85) the 'ol days
KX80 ('92) the 'ol days
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