Topic: CB550 - All Balls Top Race Height Issue

[Paul E.]

TL;DR Stripped a few threads on the steering stem putting the chrome top stem nut on after installing All Balls tapered bearings. 
What have CB550 owners done to get more threading for the stem nut to engage when All Balls top race + bearing is as tall as it is?

More detailed info below.

I started torquing the stem nut down to the required specs, when all of a sudden it started spinning freely.  Uh oh.  It looks like the height of the new upper races didn't allow enough of the steering stem threading to be grabbed by the stem nut and washer.  It only grabbed about three threads, which I've now stripped.   



I've disassembled the steering stem, and am going to take it to a local machine shop and see if they can salvage the mangled threads.  But even if they are fixed, it seems like the top race not being able to sit as deep in the head tube will leave me with too little steering stem thread for the stem nut, unless I start removing components.

Top race sticking out


Searching the forum, it seems like some CB550 owners who have done the swap leave off the top dust cover seal, or grind the underside of the steering head top thread collar.  To gain a few more millimeters of thread, I could also leave off the washer under the stem nut, but that doesn't seem like a great idea.  Another option is to run the original ball bearings in the top, and tapered bearings in the bottom. 
What's worked for you guys?

Top Thread Collar - could grind out raised metal bits


With Dust Cover


For assembly, I used the thinner of the two spacers in the kit, installed under the bottom bearing.  The bottom spacer sits flush with the bottom of the neck.  And made sure the top and bottom races were hammered home as far as they could be.

Bottom Bearing with Thin Spacer


Any suggestions on how to get more steering stem thread for the stem nut to thread onto?  Or does that top nut just hang on with a few threads engaged?

 

[Paul E.]

Grabbing some calipers, it looks like the top and bottom races are the same height, 10.5mm
The top race outer diameter is 48.5mm
The bottom race outer diameter is 50mm.
So it looks like it only installs one way.

On yours, you had the top race, bearing, and scanner nut (which I'm calling a top thread coller) and did not install the dust cover seal?

For reference, this is the kit I purchased: http://www.dimecitycycles.com/vintage-cafe-racer-caferacer-bobber-brat-chopper-custom-motorcycle-steering-parts-honda-cb-cl-all-balls-steering-bearing-neck-kit-122-1011.html

[540nova]

You can also use a much thinner washer under the stem nut. That washer in the photo is too thick.


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[przjohn]

It would appear that your problem is the wrong spacer beneath the lower bearing. Bite the bullet and Get a used stem off Ebay and a new bearing kit, unless you can get the bearing and seal off without ruining them.  When installing them measure the distance between the bearings dry fit into the races in the frame to determine the correct spacer or no spacer at all.

[pjlogue]

This seems to be a common issue with allballs bearings.  The upper bearing/race is too thick.  I did my 750 and measured the old  race and bearings.  Bottoms were OK with the spacer to get correct height but the top race/bearing is much thicker than stock set up.  My upper race/bearings were in good condition so I reused them.  The brunt of force for riding is on the lower bearing/race.

-P.

[Paul E.]

przjohn, I took the existing lower ball bearing and race and measured their height.  I then took the new lower tapered bearing and dust seal and tried the two spacer washers included in the kit.  With the thinner of the two spacers, the stack of dust seal, bearing, thin spacer was equal to the old bearing height.  Wouldn't that indicate it is the correct spacer to use?

I will look into a thinner washer under the stem nut.

[scottly]

The spanner nut goes directly on top of the upper bearing, with no spacer or seal.
http://forums.sohc4.net/index.php/topic,160077.0.html

[Gene]

The spanner nut goes directly on top of the upper bearing, with no spacer or seal.
http://forums.sohc4.net/index.php/topic,160077.0.html

^^^ this.  Also, the thinner washer on the bottom.  Also - I think it was mentioned, make sure you have the correct race in each position.  I just changed over my steering bearings a little while ago - all balls tapered -  on my 550 and checked, double and triple checked. Be sure and good luck. Lots of good info on this forum, study hard before doing.  I've made my mistakes and found that research is key before action.

Lastly - a quick-freeze on the races makes them easier to put in.  It's not necessary, but I found it helpful.

[scottly]

Your top race looks like it's not fully seated in the steering head. It should be all the way down against the ledge, and the top of the race should be close to flush.

[Gene]

Your top race looks like it's not fully seated in the steering head. It should be all the way down against the ledge, and the top of the race should be close to flush.

Yes. That too.  Meant to mention it. There's a thread in here about a home-made tool - basically two washers and a long bolt/nut set-up that will pull the races into place.  I used a piece of wood and a hammer making sure all was level when striking and got it down in there.

[scottly]

Paul, do not try to seat the race by tightening the spanner nut, especially with the upper spacer and seal in place, as it only be engaging a couple of threads, and you will risk the same damage as the top nut.

[firebane]

2 washers, 2 bolts and some all thread. That top race is simply not seated in all the way. If you take out that race you should feel a small ridge where the new one should sit. Measure this depth with the depth of the race.

[Paul E.]

I had some time to take some pictures this evening to help show what's going on.

Here is my top race, it is fully seated.  The previous picture of the top race had a dark shadow line that made it look like it wasn't seated. 

Top Race
The black band underneath the race, is part of the steering tube, it's not a void the race can be pushed further into.


Top Race 2
Here you can see the race pressed against that dark band.  There's a bit of shadow due to the overhead lights, but it is fully seated.  I can't get my fingernail between the race and the tube.


Bottom Race - Snug as a Bug


Steering Lock Clearance
This shows the clearance between the steering stem, when it is inserted, and the steering lock.  Lower triple tree, thin spacer, dust seal, lower bearing.  I think if the thin spacer wasn't installed, the triple tree would come into contact with the steering lock.


Bottom Spacer Sitting Inside the Tube


Side View, Showing It Flush


Spanner Nut, No Top Bearing
This shows the amount of stem thread when I left off the top bearing.  Top race is installed.


Top Washer and Triple Tree, No Top Bearing
This looks like the amount of thread I would want, but this is without the All Balls top bearing installed. Top race is installed.


Top Race and Bearing


Spanner Nut, With Bearing Installed
A lot less thread available. 


Triple Tree, With Bearing Installed


Top Washer, With Bearing Installed
Not enough thread to really tighten the top nut, as I found out. 


Also, when I installed the races and the lower bearing, I used the all thread/washer/nuts method to press them into place.  Worked great!

[540nova]

Said it before, get yourself a much thinner top washer. There's no reason you need a washer that thick. It's 4x thicker than it needs to be. That would give you at least 3 more full threads.


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[DH]

http://forums.sohc4.net/index.php?topic=44819.0
This is for a 750, but I believe the 550 is the same.
not claiming this is the right or wrong way of doing things, just throwin it out there, (nut modification).

[Paul E.]

Hey 540nova, I have a thinner top washer on order.  It looks like without any washer, there are 6 threads above the triple tree.  With the washer, the thread count is 4.  So I might be able to pick up an extra thread with the thinner one.

DH, I looked at doing that mod.  I need to measure the height of the ridge on the underside of the spanner nut.  I seem to remember it as being pretty short, but even if it is 1.0mm, that's an additional thread for the top nut.

For reference, in scottly's image, there are 8 threads exposed above the steering stem washer.

[CycleRanger]

Top Thread Collar - could grind out raised metal bits

I actually carefully did this on my CJ360T to expose just a couple more threads when I installed tapered bearings.

[DH]

Top Thread Collar - could grind out raised metal bits

I actually carefully did this on my CJ360T to expose just a couple more threads when I installed tapered bearings.

Me too

[nicks2319]

I don't recall which size spacers I used when I did this, but +1 to no top dust cover. Also, I never torqued anything down to the point where i'd call it torqued. I tightened the spanner nut until I felt that there was an acceptable amount of resistance while turning the bars, and snugged the top nut.

[scottly]

I measured the depth of the ledge of the bearing seat on a K7 750, and it was about 8.7 mm, so the race would be about 2mm above the top of the steering head. The complete upper roller bearing is slightly (.9mm) taller than the stock ball bearing. The lower spacer on my bearing kit is about 1.4mm thicker than optimum, and with the spanner nut mounted directly onto the bearing (the inner race fits neatly into the "nubs" on the bottom of the nut), the nut was just barely fully engaging the threads. The nut is also very shallow, with only 5 threads or so; you need every bit of available engagement.

 

[Paul E.]

Thanks for all the help so far guys, it looks like progress is being made!

Scottly, it looks like your upper bearing is a lot closer to the stock upper bearing height.  I measured from the top of my steering head to the top of the bearing and it was 7mm.

Bearing Height from Steering Head


Good news, my metric thread file came today and I was able to fix the previously mangled top nut threads.  Also, thread files rock. 

I did the spanner nut mod, grinding out the metal ridges for the old bearing set.  This netted 1.0mm additional thread exposure.

I went ahead and did a dry fit of the steering stem and bearings, omitting the top dust seal that came in the All Balls kit.  It seems the general consensus is that the spanner nut keeps out the elements just fine. 

With the spanner nut tightened, I had 7 threads above the top triple tree.  The stock chrome washer is a bit thick, 3.19mm or so, so I swapped it out with the 1.5mm thick washer that came in the All Balls kit.  That washer was intended to go on the bottom of the spanner nut, where the metal ridges are, to shim out the dust seal.  Since I no longer have the ridges, or dust seal, this seemed like a good spot for it.  I was able to thread on the top nut, and feel pretty good about the amount of threads it is engaging, ~5.5mm.  I also will be torquing that top nut to "snug" and not shooting for the 57-86 ft/lbs as the manual states.

Looking at my fork ears, the additional height of the top bearing, has a 2mm gap between the top rubber and the upper triple tree.  It seems like I could put a 2mm spacer below it to close up the gap.  What have you guys used to reduce that gap?  I was thinking about grabbing some gasket material and cutting out a washer (1.75" OD 1.5" ID 1/16" thick) to act as a shim.

[scottly]

Paul, the 2mm figure I gave was to the top of the race, not the top of the bearing as assembled. Were any threads showing above the spanner nut? Don't worry about torquing the nut on top of the triple; the pinch bolt is what locks the triple to the stem.

[DH]

Looking at my fork ears, the additional height of the top bearing, has a 2mm gap between the top rubber and the upper triple tree.  It seems like I could put a 2mm spacer below it to close up the gap.  What have you guys used to reduce that gap?



If you can source them,  properly sized o-rings work well and they help seal out moisture.

[CycleRanger]

Looking at my fork ears, the additional height of the top bearing, has a 2mm gap between the top rubber and the upper triple tree.  It seems like I could put a 2mm spacer below it to close up the gap.  What have you guys used to reduce that gap?


If you can source them,  properly sized o-rings work well and they help seal out moisture.

I used a couple of 1 1/4 square cut rubber washers sourced from the plumbing isle at Home Depot.

[Paul E.]

Is the CB750 steering stem longer than the CB550 stem?  Just a wild idea, but I wonder if I could have swapped to a 750 stem, provided all the other measurements are the same, and it's just a longer version of the 550 stem.

scottly, I do see the beginnings of some thread above the spanner nut.  It's very similar to the stem threads spanner nut picture you posted.  The top thread is right at the top of the spanner nut.

That's a good idea about the square cut rubber washers.  My first thought was the brake caliper seal has the right profile, I just need to find something similar.  It sounds like a trip to the hardware store after work to check out o-rings and square cut washers. 

CycleRanger, did you have to modify the washer you found, or did it just work out of the box? 

Here's a promising looking washer: https://www.lowes.com/pd/Keeney-Mfg-Co-1-1-2-in-Rubber-Square-Cut-Washer/1082927

Thanks guys!

[CycleRanger]

CycleRanger, did you have to modify the washer you found, or did it just work out of the box? 

Here's a promising looking washer: https://www.lowes.com/pd/Keeney-Mfg-Co-1-1-2-in-Rubber-Square-Cut-Washer/1082927

Thanks guys!

That looks a lot like what I used except the ones I found were white. (and cheaper) I painted them black.