Topic: 77 400F Doesnt feel stabil

[tuckholladay]

Semi noob here, but I'm trying to learn.  The past two days I have ridden my bike (77 CB400F) it has been feeling wobbly.  The first day I just chalked it up to being really windy and having a backpack full of groceries on.  Then yesterday I took it out for just a joy ride and it felt the same, though it was still pretty windy.  I was swaying back and forth in my lane and I didnt feel like I had as much control over it as usual and i was feeling uncomfortable going over 50mph.

I tried doing research.  Is how strait I can keep it called tracking?  The tire pressure is good and the tires do not look worn out to me at all.  I am going to try torquing all the bolts on my front forks later when I have time.  Any other suggestions of things I should look for?     

[BomberMann650]

Tire pressure was the thing to check first.  Good on you!

Check that the forks are on straight and the bars aren't bent.
If those are good, get a long board and check the front to rear wheel alignment.

Post pictures of your tires we can help ya know whats up with those.

[calj737]

You should also inspect the rear swing arm bushings and the triple tree bearings.

With the bike on the center stand, grab both forks and push/pull them. Any noticeable movement? Do the forks turn lock-to-lock smoothly, or flop over?

Same principle for the swing arm. Grab the arms, and yank sideways back and forth. Any noticeable slop?

Of course check your tire pressures. But meandering is more likely attributed to suspension bearings.

[flybox1]

A few things you can look into:
tire tread.  some are better than others.  especially over grooved or worn pavement.
notched steering stem bearings.
loose tree, fork and axle fasteners
front and rear wheel bearings.
worn swingarm bushings

[tuckholladay]

i am not noticing any play in the front fork or the swing arm if i am just trying to move them by hand on the center stand.  the forks definitely are favoring flopping over to the left side when i am sitting on the seat so the front wheel isnt touching the ground, but all the cables and wires are coming around the right side.   

[flybox1]

Did you first remove the chain, rear brake linkages, and rear shocks from the swingarm?

[tuckholladay]

nope.  ok ill be back in a while.

[tuckholladay]

front fork and swing arm dont seem to have any play, but the front fork does flop over to the left without much encouragement

[calj737]

front fork and swing arm dont seem to have any play, but the front fork does flop over to the left without much encouragement

They shouldn't "flop". Check the tension on the top nut. If it will allow you to snug up and cause the forks to barely drift to each side, then lightly release it until the forks smoothly and slowly fall over.

Flopping can be a sign of service limit or wear. The stock ball bearings often don't get serviced and greased regularly which is why many replace them with tapered bearings.

[tuckholladay]

I dont feel like I should make the top nut tighter than it already is.  Maybe I need new bearings. 

I redid the chain tension.  I checked to make sure the tires were balanced.  I'm going to test it out. 

[BomberMann650]

Following what cal said.  The manual spec says "forks should freely fall to the sides when forks are installed".

Not a very clear instruction.  But snugging the bearings would be a quick way to find if they were the issue. 

Many antique bikes had a knob to adjust the steering bearing at leisure.  Early tech version of a "steering dampener"

[calj737]

For clarification: the "top nut" is not the stem nut, it's the spammer nut beneath the top clamp. That's what determines the tension on the steering bearings.

[tuckholladay]

I figured that out now, but I need to get the wrench for it

[BomberMann650]

You can break a spanner loose with a hammer and a screwdriver/punch.

Same for tightening if you're in a pinch.

Protip; The factory toolkit has a spanner wrench in it.

[jonda500]

My CB450 had a big knob to adjust the steering damper tension (not the bearings!) - under the triple trees there was like a miniature clutch which the knob adjusted the friction level of.
John

[tuckholladay]

yea i dont have the factory tool kit.  maybe ill look into seeing how much i can get one for.

[Bodi]

It isn't super difficult to service the steering bearings. The original ball type is fine, tapered roller kits are excellent but can be a pain to install - cleaning and repacking the balls just takes normal hand tools.
You don't need to remove much, just the top triple clamp (and whatever is attached to it or in the way). Under it is the actual bearing preload nut. With bike on centre stand, undo that nut slowly... I think the weight of the front wheel coming off will drop the bike onto the back wheel but I'm not sure, if not you have to jack up the front (a jack under the oil filter housing works well) The lower balls might fall out as the stem drops down, , be ready to catch them. A magnet will pick any sticky ones out. You only need to drop the stem enough to get the lower balls out, then undo the top nut enough to get the top balls out (or take it and the top inner race right out, makes it easier to get at the balls and outer race). Then pluck those balls out. There will be one more ball in the bottom bearing - 19 bottom and 18 top IIRC. Wash the balls and races with solvent. Check for dimples or cracks in the races, "just visible" tiny dimples are tolerable but deep dimples or any cracks mean new bearings.
Butter up the lower races with chassis grease, then stick the balls into the grease on the inner race... that holds them in place. Pull up the stem to close the bottom bearing, then grease the outer top race and pop the balls in that grease, grease the inner race and drop it down the stem. Add the washer(s) and nut and tighten finger tight. Check it turns OK, tighten until the action gets stiff. back off a bit: you want it free but not loose. Replace the top triple and torque the centre nut. Check steering - the top nut tightens down on the lower nut and will increase drag, so you will probably need to loosen the lower one a hair.
Once you're happy with the steering drag, tighten the fork tube clamps. Be careful, some models have a washer in the clamp gap and without that you can overtighten and berak the clamp.

[NobleHops]

I suspect the steering head bearings too, and nothing in my experience will mess up an old bike's handling (and the rider's confidence) quicker than that. Swingarm bushings are second, as suggested.

Check this next: Put the bike on the centerstand and get a helper to put all their weight on the rear of the seat, so the front end is totally unweighted and off the ground. Now, with the lightest of touches, move the handlebar from side to side, near the center of travel. Do you feel it centering in a certain spot? I'd bet a buck you do. That's shot steering head bearings.

It's not that bad a job but you're going to get sucked in to "while we're there", or at least you should with regard to replacing the fork oil, and the difference is night and day, If you use the popular AllBalls tapered steering head kit, pay close attention to the instructions about the potential to need a spacer under the lower bearing race. Last one I did we definitely needed the thinner of the two shims beneath it, and you want ot learn this BEFORE you install that stem bearing.

N.

[NobleHops]

It isn't super difficult to service the steering bearings. The original ball type is fine, tapered roller kits are excellent but can be a pain to install - cleaning and repacking the balls just takes normal hand tools.
You don't need to remove much, just the top triple clamp (and whatever is attached to it or in the way). Under it is the actual bearing preload nut. With bike on centre stand, undo that nut slowly... I think the weight of the front wheel coming off will drop the bike onto the back wheel but I'm not sure, if not you have to jack up the front (a jack under the oil filter housing works well) The lower balls might fall out as the stem drops down, , be ready to catch them. A magnet will pick any sticky ones out. You only need to drop the stem enough to get the lower balls out, then undo the top nut enough to get the top balls out (or take it and the top inner race right out, makes it easier to get at the balls and outer race). Then pluck those balls out. There will be one more ball in the bottom bearing - 19 bottom and 18 top IIRC. Wash the balls and races with solvent. Check for dimples or cracks in the races, "just visible" tiny dimples are tolerable but deep dimples or any cracks mean new bearings.
Butter up the lower races with chassis grease, then stick the balls into the grease on the inner race... that holds them in place. Pull up the stem to close the bottom bearing, then grease the outer top race and pop the balls in that grease, grease the inner race and drop it down the stem. Add the washer(s) and nut and tighten finger tight. Check it turns OK, tighten until the action gets stiff. back off a bit: you want it free but not loose. Replace the top triple and torque the centre nut. Check steering - the top nut tightens down on the lower nut and will increase drag, so you will probably need to loosen the lower one a hair.
Once you're happy with the steering drag, tighten the fork tube clamps. Be careful, some models have a washer in the clamp gap and without that you can overtighten and berak the clamp.

This is excellent advice, but I'll just toss in that a bearing shop will have those balls, new, and if you're going this route it's short money to just replace them all.

[MoMo]

Sounds like notched steering bearing to me

[754]

Lay newspaper underneath, to catch the bearings, about 3feet by 3 feet.
If you cant find them all..and no bearing house nearby, go to a bicycle shop, get the caged crank bearings ,makes sure they are 1/4 inch...smash the cage (or pry them out). And use them.

[tuckholladay]

Lay newspaper underneath, to catch the bearings, about 3feet by 3 feet.
If you cant find them all..and no bearing house nearby, go to a bicycle shop, get the caged crank bearings ,makes sure they are 1/4 inch...smash the cage (or pry them out). And use them.

Do you know off hand how many should be in there?  I just took apart the shaft holding the front fork on and took out the bearings top and bottom.  They look good to me, but I am counting 19 from the top and 18 from the bottom, which seems strange to me. 



Before I put this back together I want to figure out how many I should have.  Also is there a special kind of grease I should be getting to repack them in?

I didn't even need a pin wrench to get the top plate off, it just came off with my hand.  I probably should have just tried tightening that down to see if that helped, but I wanted to look at the bearings. 






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[BomberMann650]

Congrats!!!  YOU CAUGHT 'EM ALL!!!

[tuckholladay]

Congrats!!!  YOU CAUGHT 'EM ALL!!!

Haha awesome.  Any suggestions of the proper grease to put in there when I seal it back up? 


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[BomberMann650]

I used Phil Woods Waterproof Bearing Grease.  A leftover I had from my time served as a bicycle repairer.

Lots of people use automotive wheel bearing grease.

Important part is to clean the bearing races and inspect them thoroughly.  Needs to be a smooth and consistent surface.