Topic: '72 cb750 front wheel shakes with turn

[youssa]

Hello all,

Since this is my first post (I've been lurking for quite some time), I would like to introduce myself. My name is Davey enjoying the crazy weather here in TX and just started getting into the mechanical side of motorcycle after my last deployment. I'm not a tech genius, but I make up with determination to get my "new" cb750 going.

I bought the CB750 from a guy who gave up on her, she had a myriad of issues when I  first got her. I've done alot of the basics and now she is idling like a champ wanting to get going. The next thing that I would like to tackle is the front wheel (front brakes and forks), but I am trying to get an idea of what might cause the shakes when I turn the bike ( this is obviously when I'm pushing her). My guess would be the bearings have gone bad?

Thanks for any advice and really appreciate this community!

[flybox1]

bearings.
check each and every fastener from your upper tree to the fork lower.  torque to spec.
rear swingarm play.
old tires? properly inflated?
really loose spokes?  'ping' test them.

im sure others will chime in.....

[70CB750]

Steering stem bearings loose or needing replacement?

[youssa]

Right on thanks Flybox and 70cb, I'll probably get a checklist of sort.

[70CB750]

If you need shop manual, you can download it here too:

http://forums.sohc4.net/index.php?topic=17788.0

 Also Hondaman's book has a lot of good information:

http://forums.sohc4.net/index.php?topic=65293.0

[RJ CB450]

Before digging into the bearing, did you do tires yet? Could be a tire out of round, wheel straightness or balance as well.

All are easy to check, if you have a stand to get front wheel up.

Straightness and roundness, spin tire and watch/feel top and side.

Balance and wheel bearings, light spin, should rotate and slowdown slow and smooth.  If it slows then speeds or pendulums, out of balance.

While tree is free to move, give it a wiggle.  Make sure no axial play.  If you have a stethiscope, give a listen as you turn it for clacking or grinding.

[ekpent]

An easy test on the steering bearings is to put it on the centerstand or get the front wheel off the ground. Turn the handlebars and see if you feel a notchy-ness while turning or also see if the front wheel direction wants to index back into the same spot every time if you let the bars freewheel a little.
   If you have not serviced the front caliper yet it can be sticking, whack it with a rubber mallet if tight so it rolls easier and get that thing cleaned out well.

[Stev-o]

Welcome from Lake Travis Davey....guessing you are in the Ft Hood area?

The guys gave you good advice above, I'd go through the entire front end and upgrade it.

How old are your tires?

[jdubb1977]

Here's another thing to add to you to do list

Check the fork springs.  When I bought my bike the front end shook quite a bit.  I pulled the springs to find that the left one had broken in half and the coils on the 2 halves had overlapped by a couple of inches.  Thanks PO!  Replaced them...and no more wobbles. 

[acollin]

Tons of good advice here. For me the question would be : am I interested in riding now or later. Find the fault --- fix the fault for safety concerns. It could be something truly simple - like fork oil issues. Then ride for a bit-- believe this-- other faults will surface!!!

In the off season-- where I live its the rainy season, i would tear the front end off the bike and build it back up with new seals, bearings, etc -- measuring for alignment, spring tension-- If as you say that you want to get into the mechanical side of these bikes, there is no better way than getting your hands dirty and leaving grease prints on the pages of your manuals.

Good luck

[jdubb1977]

well said man!  i bought my bike w/ very little mechanical knowledge.  the first thing i tackled was the front end & brakes, and it made a world of difference.  have fun!

[Grnrngr]

 I wouldn't ride it at all until confirming the front wheel bearings are good. Again, front wheel needs to be off the ground, stand on one side, grab the tire at the top and try to push and pull, if there is side play, they need to be changed. I had one that was so bad, you could see the wheel moving side to side as the brake was applied, I suspect that is how the PO wrecked it. If the bike shakes when you're pushing it, something is very not right. Bearings and brake pads are cheap, many people switch to tapered headstock bearings for smoothness even tho the stock ones aren't damaged. If you really want to get to know your new baby, take the front end apart and replace  everything that can be replaced, then you'll know for sure.