Monday, February 6, 2012

GSXR1000 K5/K6 Suspension - Steering Head Bearings.

Gixers and Suspenders - Part 1

It's all going on with the K6. A few months ago I decided to carry out a service on the suspension - with around 60,000km on board, it was well overdue. The bike still felt good on the road in fairness, but I like to keep it in optimum fettle (especially with the '10 R6 on its heels). 

So on the list was change the fork oil, steering head bearings and any worn swingarm/ linkage bearings. Tyre wear was good so I assumed the shock was ok...

Three things I bought before starting any of this work were the castellated sockets for the swingarm pivot, the steering stem nut and the engine bolts/nuts (although I didn't actually need the latter). All came from Turbosuzukis in the UK in incredible time! The fit, finish and quality of these tools is second to none. Very impressed and not expensive - kudos to you guys. 

Here's the steering stem tool in action:

Tyre Wear - Pilot Powers, Road Use Only.

Where do we start?

So, first thing's first, the bike needs lifting so all suspension is hanging free. Paddock stands are ok to get the wheels out, but not when you need to remove the swingarm or triple clamps.
The only option I had available was:
  1. blocks of wood under the engine/exhaust (make sure the wood is touching the sump, not just the exhaust system)
  2. blocks under the sidestand (in its down position)
  3. a steel bar bolted to the right hand of the engine (near the front there is a large hole cast into the crankcase) long enough to reach the floor or blocks of wood
  4. scrap wood wedged under right hand rear of frame
It's not perfect, but as long as you concentrate on one end of the bike at a time, the bike should remain stable - for the next photo I actually had the entire bike balanced like this. 

Forks or Shock First?

I decided to start with the forks first. Having already ordered linkage bearings for the rear, I wanted to get the yokes out to measure up for taper roller bearings. With only the lower fairings removed, you'll find there's easily enough access to the forks, triple clamps and steering head.

Just remove the calipers, the wheel, the mudguard/fender and the forks are ready to slip out. Undo the clip-on clamp bolt, the top yoke and finally the bottom yoke (triple clamps) and the fork leg should just slide out (twist if necessary to help it along).

It's actually very quick and easy to get the forks out which just leaves the triple clamps. A 36mm nut on the top (if I remember correctly) allows the top clamp to be lifted, and this can just be moved aside leaving it attached to the ignition barrel etc.

If you haven't already done this, unbolt the steering damper, brake hose clamp and the plastic cover from underneath the triple clamp and then you can remove the adjusting/locking nuts. See the very top photo for the castellated lock nut removal (special tool). The lower triple clamp should just drop out, but mine needed a few good taps with a rubber mallet due to corrosion on the stem.

What did amaze me was that Suzuki still use ball bearing races in the steering head - I thought they'd been left back in the days of BSA's etc. So measuring up, I found the dimensions to be 30x55x17 which equates to a 32006 taper roller. Down the local bearing shop and $40 later I leave with a pair of Timken bearings - superb quality, I'm happy.

Order new seals for the bearings when you carry out this job or you'll need to take special care when removing the bearing from the steering stem. I didn't, and needless to say, it took hours with a hammer, chisel, angle grinder and a Dremel just to save the seal. What a waste of a time for a few dollars worth of seal!

A suitable drift is needed to tap the outer cones of the bearing out of the frame (there are slots in the frame to facilitate this), and I actually used a piece of flat bar similar to the makeshift stand bolted to the engine. Tap them out equally, not just from one point or you'll damage/spread the frame tube. 
As you can see, the bearings are badly worn, being heavily pitted and rusty from a lack of grease and, possibly, the odd wheelie. Just fitting new bearings will improve the front end feel a lot.

Triple clamp cleaned up and ready for the seal and new bearings. Tap new bearing on carefully and try not to damage the cage that retains the rollers. Using the old bearing (upside down) to tap the new one on is a good method. Cutting a slot through the old bearing with an angle grinder will ensure it knocks back off easily too (once the new bearing is hit home).

If you're using a hammer and punch when fitting the new cups in the frame, tap them around equally (I use 4 different spots) and work up a rhythm as in North, South, East and West. This allows the bearing to go in square and true. If you knock it in at an angle, you can scrape aluminium from inside the frame, or spread the tube. This could result in loose, or misalignment, of the bearings. 

When a bearing is fully hit home, there will be a distinct difference in tone - normally sharper, or higher-pitched. Listen out for it and give a final few taps to be sure. Now you should be ready to apply a good quality, high melting point grease to the bearings and refit the triple clamps. 

On no account should they be over-tightened. If you're unsure of how to set up adjustable bearings, leave slightly slack until the forks are back in and check for play - then recheck. It's better to be safe and spend a little more time getting this right. Over-tightened bearings will wear out prematurely and impair the steering.