Bearing Head Conversion Guidelines

by Lowell Martin

vfr

This article was written by Lowell Martin and posted on the VFR List. He has graciously allowed me to post it here. While Lowell did this work on his '91 VFR750, I think it is an excellent article and offers some guidance when replacing a head bearing on a VFR.
The process for making a bearing conversion to include part numbers for a VFR is as follows.

The Honda part numbers for a '91 VFR750:

  1. Dust seal - 53214-KA4-701
  2. Upper tapered roller bearing - 91015-425-832
  3. Lower tapered roller bearing - 91016-371-0000
  4. Dust seal - 53214-371-010

Now the teardown. First you have to rig a way to support the front of the bike with the forks removed. I made up a stand out of two-by-fours that goes under the exhaust pipe (a Two Brothers Racing header). I then removed the fairing lower and lifted the front of the bike by passing a strap under the steering head and using a come-along strapped to one of the rafters in my garage and then lowered the bike onto the two-by-four stand under the engine and exhaust header. I wasn't real happy about the weight of the front of the bike being supported on the header, but no harm was done (I had the rear of the bike supported by a Two Brothers Racing single- sided swingarm stand for stability).

Following your OEM manual, remove

  1. Front wheel
  2. Upper fairing
  3. Fuel tank
  4. Front forks
  5. Steering stem

Now the removal of the old ball bearing races. For those in the steering head I used a long (maybe 12 inches) steel drift and a sledge hammer to drive out the upper and lower races. Being very careful, and placing the drift in the machined clearance space above each race, it is possible to drive them out of the steering head by tapping on one side and then the opposite side until they come free of the steering head. Take your time and do just a little at a time to avoid cocking the races in the steering head. (I didn't remove the gas tank until I had slipped once and put a nice ding in it with the sledge, so you are getting the benefit of my experience on what not to do, too!)

The biggest challenge is removing the old lower inner race (p/n 13 in my OEM shop manual for the '91 VFR at page 12-12) and lower dust seal (p/n 14 in the same figure). I used the trusty sledge and a cold chisel, again with lots of small taps as far apart on the circumference of the dust seal as I could get. Of course, the dust seal is beaten to a pulp in this process, but it being replaced anyway. The other thing to watch out for is to be sure not to mangle the threads on the top of the steering stem that the steering stem adjustment nut and lock nut screw down onto. Doing them in could ruin your whole day. I just put the steering stem down on an old towel on the workbench and held it by hand as I drove the lower inner race off of it. Once you have gotten that off, its on to reassembly, being sure to liberally grease the new bearing rollers/cages and races.

I used a set of Lisle automotive wheel bearing race drivers to drive the new races into the steering head. The Lisle drivers are aluminum, so there was no chance of damage to the new hardened steel roller bearing races. Again, the trusty sledge and patience are called for.

The biggest installation challenge was driving the new lower inner race onto the steering stem. Here I got lucky and the following is really true. The week before this job I installed a new bathroom faucet, but didn't use the brass drain fitting tube. It turned out to be the perfect diameter to contact the inner race of the new lower tapered roller bearing without touching the roller cage, so I just sawed it (the sink fitting, not the steering stem!) off with a hacksaw to an appropriate length and then placed it on top of the vice on my workbench, put the new inner race/roller carrier and dust seal on top of it, inserted the steering stem upside down through the new bearing inner race and drove the stem down over the bearing using the sledge and protecting the steering stem with a piece of aluminum. BE SURE NOT TO FORGET THE LOWER DUST SEAL! How ever you accomplish this it is absolutely imperative that you do not put any force whatsoever on the roller cage or the rollers themselves or they and the inner race will be ruined in the installation. So, having a proper diameter metal tube of something softer than the steel of the inner race is essential. I really lucked out with the brass faucet fitting, but I am sure some sort of plain brass, copper or aluminum tubing could be used.

Once you have the new lower bearing inner race/rollers and cage on the steering stem, reassembly is the reverse of disassembly per the shop manual. The Common Sevice Manual specifies 8 ft/lb as the torque on the steering stem adjustment nut, p/n 7 at p. 12-12 of my manual (note that this is much less than the 18 ft/lb of torque specified for ball bearings). I didn't have a wrench that I could use to torque that nut, so I just tightened the nut with the drift and the sledge until I sensed some resistance to turning the steering stem in the steering head. The Common Service Manual says the final preload on the steering stem bearings is set so the pull on the installed steering stem at the radius of the center of one of the forks to just start the stem moving is 4 pounds. I used a spring scale and a piece of string tied around one resinstalled fork to set this up. My initial "by feel" setting of the preload wasn't too far off, but was a little too loose. Once you have the bearing preload set, the reassembly proceeds in accordance with the shop manual. The only other trick is that you may have to flip the lock washer, p/n 6, or the lock nut, p/n 5, over to get a good combination of a tight fit between them and the tabs on the lock washer lining up so you can bend them up to secure the lock nut.

This whole thing took me about eight hours, including finding the pipe to drive the new lower bearing inner race on and making the two-by-four stand for the bike. The bike now has no headshake tendancies and handles very well (On reassembly, I also raised the front forks an additional 10 millimeters above the top triple clamps to quicken up the steering, but that is just personal choice on quickness vs. stability).

I realize this may sound a little daunting, but it really went quite well, all in all. The improvement in handling was dramatic. I am coming to believe that all of the various posts on hands off headshake in the 35-45 mph range, etc., are primarily due to improperly adjusted or worn out steering head bearings.


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