Cornering Wobble...why?

[Easterntide]

New taper bearing headset and new fork seals are now at my home.
this weekend will be putting seals in the forks and getting that sorted.
then if that makes me feel good inside i'll attack the bearings in the steerer!

Q: does the fairing have to be removed for the bearing races to go in?  Or do you just need to remove the forks and then the steerer will drop out after all else is disassembled?
i can do that on my bicycles w my eyes closed...but they don't have fairings :-)

[Arnie]

You don't NEED to remove the fairing, but it is safer to do so.

After the fork tubes have been removed and all the hardware from the top triple, the lower triple and steering stem will drop out. (make sure you've removed the brake splitter from the lower triple)
Then, you can learn the difficulty and frustration of removing the bearing cups from the steering tube.
There are a few different methods you can use - search the files here.

The "Park" tool may work for you, if you have one.
Enjoy your weekend :-)

[Easterntide]

I wussed out and didn't do them but my fork seals are done. Bike feels great at the moment. My local bike shop (bicycle) has all the park tools and I can borrow them as needed.
Maybe on the next rainy weekend.
Now waiting on my springs and valves from rpm/new to me Corbin and gl1800 shock to land :-)

[Ponty]

I was having a bit of a cornering wobble - more of an uncertainty than anything major - tendency to follow rough bits in the tarmac, etc, in my FJ 3CV I've not had it for that long and generally it has been well cared for. Rear shock was a bit sad anyway so I replaced it but the main issue was the dogbone bolts - I took everything off, including the swinging arm, to regrease them to find that they all were a bit loose and the one nearest the back wheel wasn't much more than finger tight. So if you're having this kind of wobble/tracking issue, have a look at them. In fact, have a look at them anyway! Cheers, And.

[Burns]

But is it dangerous or is it used as an indicator of 'don't go any faster'?

I
My first and cheapest option will be to drain the existing Fork oil and possibly get new springs...or valves. Not sure which is better bang for buck.
Then the BMW shock/new doglegs.

bang for the buck: springs

[Urban_Legend]

If you are going to change the head stem bearing, be sure to have a good supply of swear words ready. They do not like coming out.

[markmartin]

I had good luck using this type of cut off wheel on a Dremel tool to cut and remove the lower race. Carefully make two cuts through the bottom race and it will come right out with little effort.     They are readily available at Home Depot among other places.  1-1/4 in. x.063 in.



I used the Park removal tool that I bought from Randy to get the top race out.  The trick to using this tool is to slowly pull it down through the stem from the top until the spring steel fingers 'snap' open under the race.  The bottom of the tool will be sticking out of the stem and you can just hammer it up and the upper race will come out.

My initial mistake was that I started by inserting the Park removal tool up the stem from the bottom, not realizing that there is another lip right below the upper race.  After much pounding and no progress, I shined a flashlight up the stem to reveal the error of my ways. Luckily I didn't break anything.

If you don't already know, the Park removal tool will not work on the lower race---the bottom race is set into a step that is slightly larger in diameter than the rest of the bore--there is no lip revealed for the tool to grab.

Getting the correct amount of torque on the stem nut bearing is the tricky part.  I seem to have gotten it right but after 5000 miles, I've noticed that I get a slight wobble when I let go of the bars  -- it appears that I need to tighten it up just a smidgen more.

[mark1969]

As a quick disclaimer to start, I don't like starting new threads where old ones are (or seem) relevant..  

Anyway, after all my shenanigans with new clutch (which is great) my attention turned to why my 1990 FJ1200 didn't feel right turning into corners. I'm no road racer, but even I like to lean a bit when the road is clear and the sun is shining..

So I thought, before splashing out on new progressive springs I'll change the fork oil - which I did yesterday. All was going well as I undid the first fork cap (carefully..) and so I started on the other one. Once this was removed I noticed a small problem. Some numbnuts had put different..... yes that's right DIFFERENT springs in each fork. On the plus side (if there is one) both were progressive springs but one was approximately 5-6cm longer than the other with markedly different gauge metal and 'looser' coils.

All of which explained why one side had been more difficult to adjust the preload and why my bike felt awful turning into bends. So I changed the oil anyway, put it back together and await my new springs. When I fit the new springs I'll try and take a couple of photos of what was in there, just for fun.  

I've tried to give previous owners the benefit of the doubt, but sadly to my mind, all roads lead to a lazy bodge, which to me is unforgiveable considering how much we rely on the front end of our bikes. Not clever.  

On the plus side, I'll have a bike that inspires a bit more confidence soon, which I look forward to..  

[Capn Ron]

Shocking that a P.O. installed two different rate springs in the front end...will be worlds better when you get that sorted.   

In a *slight* defense of "previous owners"...All while growing up, my dad was known to say, "If you want it done right...do it yourself!!"  Turns out this is not at all accurate.  The saying should be, "If you want it done the way YOU want it done, do it yourself!"  It's a very important distinction. In your case, the PO had NO business rebuilding forks.  On the other hand, in some cases, decisions were made by PO's without your knowledge of the circumstances at that moment.

I once re-tapped a bottom bracket on a French bicycle for a guy who was touring across the U.S.  The proper tap and bearing cups were NOT available anywhere to keep him moving on his journey.  After a long discussion with him, he told me to go for it and tap it to accept metric bearing cups.  I cringed a bit, but did it in the interest of his journey.  I also wrote a note explaining the circumstances and shoved it into the bottom bracket before re-assembly.  Sort of an apology and explanation to the next mechanic who discovers this and exclaims, "What was that guy thinking???" 

[ribbert]

Shocking that a P.O. installed two different rate springs in the front end...will be worlds better when you get that sorted.   

You are quite right Capn about the difference it will make but one could be equally shocked at a PO adding a second clutch spring to hide a worn out clutch from a prospective buyer.

If I found a bike with a second spring added to hide a knackered clutch, I would not be happy. I would wonder what else he tried to conceal.

Noel

[mark1969]

...I also wrote a note explaining the circumstances and shoved it into the bottom bracket before re-assembly.  Sort of an apology and explanation to the next mechanic who discovers this and exclaims, "What was that guy thinking???"

Great foresight and bloody good mechanic manners there. Nice one. 

Just reminded me of this same bike...earlier on in my ownership while trying to find the reason for a front end bars wobble (on slowing down) I found a couple of loose nuts on one of the yokes, which didn't inspire confidence at the time...in the end, as it happens a new tyre sorted the problem. Guess we all bodge from time to time and it has to be said some bodges are ok and sometimes even ingenious at times! 

It does make you wonder though..

[fuel80guy]

I'm  currently waiting for an rpm shock to be built for my bike.
I have a BMW rear shock on my bike with dog bones that I'd be willing to sell you.
I'm located in ontario so shoot me a private message.
Rob

[mark1969]

I'll try and take a couple of photos of what was in there, just for fun.  

Old springs..Ok, I exaggerated. The difference is about 3-4cm, but still..



New springs - lovely.

...all roads lead to a lazy bodge, which to me is unforgiveable considering how much we rely on the front end of our bikes. Not clever.

And the reason I think it was deliberate? The preload adjusters were set completely differently (which I had forgotten) presumably in an attempt to counter the different spring lengths... 

[the fan]

It is more common than you think to run different springs in each fork leg, In fact on my bike (SV1000S) I am running a 9.0 in the left leg and 9.5 in the right.

Basically I found that the 9.0 spring allowed too much movement unless I adjusted the valving to stiff for comfort. The 9.5 transmitted too much energy. I run a 9.5/1.0 combination in my track YZF600.

There are even bikes out there that only have damping in one leg! I owned a 1996 KTM 440MXC that had a marzocci fork that had compression in one leg and rebound in the other.

Keep in mind that the forks are connected by the front axle, a light duty fork brace, the lower and upper triples. There is very little deflection if the bushings are in good shape.  If you are experiencing chassis wobble with an otherwise stock FJ I would look very closely at all chassis bearing, especially steering head, swing arm and wheel. If all of those check out my next target would be to ensure that there is sufficient damping in the shocks. Any of these can cause chassis wobbles even on a rock stable bike like the FJ.

It has been my experience that many chassis issues that a rider feels are in the fork can easily be traced to the rear of the bike, Keep in mind that the swing arm and main frame are both essentially big tuning forks attached to the little bits you hang on to.

[mark1969]

I'm not aware that people normally have 2 different springs in their forks.

I must be riding the bike wrong then. I know, I'll check everywhere else on the bike just to see if that is affecting my front end handling.

That's where I've been going wrong. Thanks for pointing it out.

Next time my lights don't work I'll check the tyre pressures.