CX500 GL500 650 Global

I was on the DOHC CB750 site a couple of minutes ago and came across this. Mike Nixon is well respected in the motorcycle world, so I would think this may be worth posting. He doesn't say if this applies to the ball bearing or tapered roller bearings or both, but I would assume that it will apply to either.



Shucking the Shakes
Assumptions can be dangerous. We assume for example that because no one has ever darted across five lanes of traffic in front of us that no one ever will. Until it happens. We presume on the future. We engage in blase acceptance of the status quo. But as the saying goes, we live and learn. Assuming that the tired old method of checking steering bearings -- you know, by jacking up the front end and grabbing the fork to feel for play -- is valid for use on modern motorcycles, is also dangerous. Because it isn't.

Sooner or later, all the larger late model Hondas and Yamahas develop a problem with the steering bearings that results in a head shake when decelerating from 40 mph and less. For want of a better term, we'll call it a "deceleration wobble."

The cause
There is a rule in motorcycle suspension technology which says that problems in handling that occur under 40 mph are due to defects in front of the steering head, while those occuring at higher speeds are found in causes aft of the steering. It's a tried and true rule of thumb, and a decel wobble obeys the pattern. Many things can cause weaves and wobbles, whether on acceleration or deceleration -- tire wear is especially critical. But decel wobbles have their own special causes, and if the front tire isn't excessively worn or the wheel badly out of balance, the cause is almost always the steering bearings. But we're not talking looseness. We're talking about something that is not addressed in any service manuals, factory or aftermarket. Whether because the frame is made of softer material or what, the steering bearing races "walk" in the frame. That is, they shift in their recesses and become out of square with the steering stem, and out of parallel with each other.

Modern motorcycle steering bearings tend to "worry" -- shift back and forth -- in their frames, especially on the heavier bikes. The resulting non-parallelness sets up torque forces in the steering which manifest themselves as attempts by the fork to correct itself, with the result: shimmy, shimmy. Again, the problem isn't looseness. Mere tightening fails to correct the problem.

The following procedure is one circulated by American Honda's District Service Reps. It is based on the above premise, as well as a procedure found in Honda Service Letter #126. Three tools are needed: a torque wrench, the special factory steering bearing nut socket (Honda's is part # 07916-3710100), and a good quality tubular 0-10 lb. spring scale. A floor jack or something similar to jack the front of the motorcycle off the floor will be handy, too.

Follow your manual's instructions for removing the top triple clamp (Honda calls this a "bridge"), so that the pair of special castlelated nuts becomes accessible. The upper one is just a locknut. Remove it and set it aside, along with the special washer. Jack the front end up off the floor, and feel the bearings as you turn the bars each side from center. If the bearings are notchy or the front end has a self-centering action, the bearings need to be replaced, no second-guessing here. After replacing them if necessary, continue. Get the front end off the floor. Turn the fork to full right lock, and with the torque wrench and special socket, tighten the bearings to 40-50 ft-lbs. The fork will be very stiff. Don't panic. It's only temporary. Now turn the fork lock-to-lock, repeatedly, at least twenty times. You will probably notice something interesting: that ridiculously high tension will loosen up; the bearings will get looser, indicating that they have squared up and settled into the frame. In some cases, you won't be able to tell, but even if you don't notice the bearings loosening up, proceed. Turn the fork to full left lock now and loosen the nut until it's just finger tight, then turn the fork to the right lock again and tighten it to 7-10 ft/lbs.

Attach your spring scale onto one fork tube, using a piece of shoestring or something similarly soft so as not to scratch the tube. With the fork assembly pointed straight ahead and the tire off the floor, slowly pull the spring scale straight ahead until the tip of the fender arcs about one inch. Note the poundage. You're looking for a 5-7 lb. pull. Five for motorcycles under 600 lbs., more for heavier machines and those with fairings. Tighten the tensioning nut as needed, a little at a time, and check with the spring scale.

After adjusting, drop the special washer back into place, and screw on the locknut, but don't tighten it. Though you probably found the locknut jammed against the tensioning nut, that's not the correct way to install it. It should be close to the tensioning nut, but not jammed against it. Leave a little space -- about 0.020&quot. Then bend the locktabs into the locknut to keep the two interlocked. The locknut's job is to isolate the torque of the bridge nut from the steering bearings. Reassemble the rest of the fork per the manual. If a test ride reveals that there is still a decel wobble, or the bike sways side to side like a rowboat (the bearings are too tight), readjust to higher or lower spec as needed. Ride safely.

Mike Nixon

very interesting reading blue.

I tried this on my 82 GL500I It did not cure the problem. I think this may only apply to bikes with tappered bearings. This is my second GL500 with the same problem. I stumbled on the cure on my first bike by accident. I crashed my first bike and had to replace the fork tubes,when I took it apart all the balls fell out so I replaced them with a Taperd bearing set, when I was done the wobble was gone. I wasn't sure if it was because the steering was tighter. Then I bought my new 82 GL500I last fall and it had the same problem. I tried the easy way out and put a fork brace on it with no improvement. Then I tried this repair of tightening the existing steering bearings. All it did was make the steering stiffer. So I finally broke down and installed the allballs bearing kit. Now it is very stabil with no wobble. It feels like a differant bike. I think with the original balls you just can't get enough torque on the steering head. Now it's both tight and smooth at the same time. I bought the kit on ebay for about $36.00 and free shipping. I feel it was well worth it. I put it off as long as I could because of the labor involved because I have the intertsate model, but the end result was worth it. Kevin

The Tapered roller bearing kits are superior to the old ball bearings kits.That said there are very high mileage CX/GLs still with the original ball bearings in.One of my CX has 86,000 miles on it however when I change my Fork oil I do a full front end service and check and re-pack the bearings using Moly grease.
After a decent amount of miles or time I suggest somewhere down the line you check and re-grease even the tapered kit.All things should be serviced at either recommended intervals from the manual or common sense,then they will last possibly hundreds of thousands of miles.


HTH

PS
My car has 250,000+ miles on it(Not all mine but it's been well maintained).

No problem I'm a Maintenance freek. I think that maybe the problem is just on the GL's, at least when I go to repack the bearings they won't fall out on me.

I have always been the final adjustment for preload with a long shot and hammer. I have never had the opportunity to tighten the nut, even when I had the official tool. Tightening the nut until the bearings are preloaded sufficiently to provide enough drag to rotate the holder.