Steering head bearing replacement

I know it is a popular upgrade to change from the ball bearing type bearings to the tapered roller bearings. I'm in the middle of a fork seal job right now so I'll have the forks off the bike, now might be a good time.

What are the benefits of this upgrade? Should I go ahead and do it now? How difficult are they to replace - any special tools required? How can I tell if mine are bad? I'll definitely consult my shop manual, but I don't have it in front of me right now unfortunately.

I noticed that the current steering seems like it always wants to lock straight forward. With the wheel off the ground if I turn left or right there is a noticable stiff/springy spot that wants to return to center. Is this normal, or part of the problem with the stock setup? Seems to me it should just flow smooth left to right.

Replace them. If there is a click it will be felt cornering and that can be a little scary. If the front end is already disassembled it will take about 30 minutes. I just did my 650 last month they are the same bearing as the 900/1000. Check out my little tutorial


kzrider.com/index.php?option=com_kunena&...d=5&id=341185#341205

Hey thanks for the link, that is helpful! I actually had already found it doing a search. What tool did you use to drive your new races in?

Yeah I've noticed that cornering doesn't feel quite right lately. Just seems hard to steer.

Hard to steer and dangerous too.
I used a block of wood to get them in, the lower one goes past flush so I used a wooden dowel to drive it all the way in.

When you put the lower bearing on the stem it is tight, what I did was use a large crescent wrench and opened the jaws so I could catch the inside of the bearing then taped it on with a hammer. "DO NOT" use the outer part of the bearing while tapping with a hammer you will destroy the bearing

I also replaced my steering head bearings with the tapered ones. My 650 E would shimmy at 40 mph which made it no fun to ride. It also had a tight spot and would return to the center. I decided to check all the bearings and cables on the bike, since it looked as if no maintenance had been done on the bike for years. The ball bearings in the head were all rusty and had no lube. The tapered bearings made all the difference in the world. I did wind up and replace all the wheel bearings and most of the cables on the bike. Replaced the brake fluid which was black and checked out the front and rear brakes. Everything was quite easy to do as long as I took my time. I highly recommend the tapered bearings if anyone ever has to take the front assembly off the bike.

Tapered bearings are better because they locate the steering head both axially and laterally. Ball bearings can only do one or the other. This lets the steering "feel" the same under loading or bumps of the suspension and makes it act more consistently.

When it tries to stay centered like that its called detented. It will try to wobble while you're going down the road and will scare the crap outta you. To test the steering stem bearings elevate the front wheel. Then lightly push on one of the handle bars. It should fall all the way to the side that you pushed it. If it sticks, hangs up, is notchy, or hard to push then something is wrong. it doesn't necessarily mean the bearings are bad. it could be cables or brake lines that are tight or improperly routed.

They are all dented within a few thousand miles and have that detent click to straight ahead. Comes from hitting potholes ect. I'll throw my $0.02 in on the subject. I replaced mine on the original 78 KZ650B I've had for 32 yrs that had a lot of miles. Result was I could tell no difference. Later I replaced them in the high mile KZ1000MKII. Result was I could tell no difference. Later I got the hopped up 77 KZ650 and I replaced them, could tell no difference. Now I ride the other 77 KZ650 with 67,000 miles on it and I doubt the bearings have ever been lubed. I know they haven't in the 42,000 I've put on it. You think I'm going to bother replacing? Works just as good rusty/dry/detented as they do new/tapered for me. Admittedly I'm a strange one though as I have expensive top of the line Koni shocks on 2 of them along with the tapered bearings and one has the tapered bearings with original crap shocks, the forth has original crap shocks with 67,000 miles plus worn dry ball bearing steering. You think I can tell a difference? Nope.

Bad or not, replace the balls with rollers. Ball bearings in the steering head are one of the major causes of the dreaded "KZ Shimmy" so common on early liter bikes.

Picture this:
Tiny little indentations have been worn into the bearing races. As you make the minute steering inputs that happen thousands of times every ride, the balls want to fall into these indentations, while you are trying to force them back out. This little dance can case a pretty severe wobble.

Change them and be happy....and safe.

savedrider wrote:

I noticed that the current steering seems like it always wants to lock straight forward. With the wheel off the ground if I turn left or right there is a noticable stiff/springy spot that wants to return to center. Is this normal, or part of the problem with the stock setup? Seems to me it should just flow smooth left to right.

The symptoms you decribe above are the absolute classic sign of steering stem bearing race dimpling. The balls hammer against the races everytime you hit a bump, especially if things aren't adjusted just right and lubed well, resulting in tiny dimples in the races the balls then tend to seek and stay in the dimples. You will need to replace the bearings to correct this.
Tapered roller bearings give much more bearing surface area than ball bearings. Think of the bearing contact area of a tapered roller as a "stripe" for each roller that goes from one end of the roller to the other where the roller contacts the race. Then consider the bearing contact area of a ball as a single small "spot" for each ball where the ball contacts the race. The total contact area of the roller bearing "stripes" is much greater than that of the ball bearing "spots." This additional contact area spreads the load reducing the pounds per square inch of pressure at the contact area and eliminates the "dimpling" that is common on ball bearing steering stem races. This reduced pressure also makes tapered roller bearings last longer than ball bearings. The reason is is easy to visualize when you consider the roller bearings making contact with the full width of the bearing races compared to the ball bearings running in a single line near the center of the races. I highly recommend using tapered roller bearings when you replace the steering stem bearings. Having done so on my KZ650C1 I can attest to the fact that on my bike the roller bearings are dead smooth and feel more solid than the ball bearings. Ed

Great info guys, thanks!

In the past I used to notice a clunk at low speed over a divot or bump the the road. Haven't noticed it lately, but I always figured it was the steering head needing adjusting. Not sure why I never looked into it until now. I will post my findings once I get things torn down. I ordered the new bearings today.

Got the steering head torn down today. The upper races were badly pitted. The lowers looked ok, but still not perfect. Glad I finally took the time to check these out. The rollers will be a nice upgrade.