3AJ Steering problem
 

Hi,

I've just bought a 1989 3AJ which cosmetically is in great nick, however............

........when I steer left or right the bike seems to "fall in" suddenly. Difficult to describe but steering seems normal until one is about 10 degrees from centre in either direction then seems to speed up. Quite disconcerting especially if you're not ready for it. More noticeable at walking pace as one turns the handlebars more to steer.

The front tyre looks fine and is not flattened off. The top of the forks are not quite flush with the top yike.

Any ideas?

Regards

bfgjohno

I have 2 1984 XT 600's ..... one steers fine and the other suffers from the same symptoms you describe. I haven't done anything yet, but think it might be the front forks not being "flush" at the top with the steering yoke. The one xt 600 that steers fine has the forks "flush", the other does not. This may affect the steering rake.
Just a thought... good luck!

I have an '88 3AJ sitting beside it (well, when you see a Tenere at a bargain price what are you going to do?!). Forks are set at the same position in the yoke and no problems. I've measured front axle to rear of swing arm - no difference there either.

Just a thought, but how do the headstock bearings feel? this sounds a wee bit like the notchiness I've felt on some other bikes when races have worn. It's worse on taper rollers imho, but it's easy to fix.

hi there i think you may have iffy or dry or badly adjusted head bearings as surgested, get the bike so the front wheel is of the ground and slowly move the bars from lock to lock , it should be smooth all the way if the steering is notchy or very notchy as the bars pass the striaght on position the bearings are probably tight ,worn or very dry. also while the wheel is off the ground grab the bottom of the forks, pull and push them in a forwards and backwards manner there should be no movement or noise from the bearings if there is they are too slack but you will notise this as you use the front brake .you can try to adjust any slack/ tightnass out but worn headbearings are bad news , so for 30 ish pounds from your local bearing shop put in some new ones , the old ones will have numbers on so they can match them up . your local yamaha dealer will sell you the same bearings for twice the price . if its not the bearings you may have a very iffy front tyre . zigzag.

You checked your tyre pressures?

Dropping the forks through the yokes is a quick way of speeding up the steering on a sportsbike - about an inch makes a big difference to handling. I'm not sure how this would affect a trailbike with its longer-travel suspension and looser angles, but it's certainly a possibility.

Hello bfgjohno,

Both the recommendations suggested above are good ones.

In my experience the height of the fork tubes in the clamps is very important and can result in the handling issues you describe. There is a sweet spot of about 5mm either side of stock, go byond this and handling starts to get weird.

First try returning the tubes to level in the clamps then ride. If the strange symptoms are gone you are done. If weirdness persists, proceed with checking the steering bearings as Zigzag described above.

good luck,

Pawlie

Saggy rear shock?
 

Hi bfgjohno,

I had similar handling problems when I first got my current 3AJ Tenere.
For me it turned out to be a saggy rear shock. Mine was so bad that when I lifted the back of the bike up, even though the shock's spring pre-load collar was wound to give max preload the spring was loose and could be moved up and down by about 10mm. I replaces the shock and not surprisingly the handeling problem was cured.

I would check the head race bearings first, but it might also be worth looking to see if your rear shock spring is very tired or needs more pre-load. I suppose it might be worth checking whether this front fork springs have taken a set too, i.e. has there free length reduced?

I have dropped the yokes through the forks as far as they will go until the valves in the top of the forks very nearly touch the handlebars and not noticed any change in handeling.

Good luck

Mark

Hi guys,

Lots of good ideas, thankyou. I'm not ignoring - just haven't had time to try out the suggestions yet. I'll let you now as soon as I have.

Cheers

John