Front End Knock

Andrew Shadow · Jun 2, 2013

2009 ST1300AY bought new in Dec 2012, only 5, 000 miles on it. When I rock the bike very gently on the centre stand, just barely lifting the front wheel off the floor and then gently setting it down again I hear a knock from the front end. It will knock as often as I rock it. It makes the same type of sound that a loose bearing would make. I can't find anything loose. It seems to be coming from the left caliper area. Due to the set up with the SMC there is some play as opposed to a solidly bolted caliper but I am not sure if this is the source or not. Springs inside the tubes maybe? I was alone so I couldn't rock it and listen for the location of the noise at the same time. I will get back to it with my stethascope when some one is available to help me. It doesn't do it when the front end is under load while riding or when I hit bumps- only when I rock it gently. Has anyone else noticed this?

dwalby · Jun 2, 2013

with the bike on the centerstand, grab both forks, one with each hand and rock the lower forks in the direction of the wheel travel. If you have loose steering stem bearings you will feel some play.

Igofar · Jun 3, 2013

Sounds to me like your hearing the SMC clicking due to air in the brake system. If you do your own service, remove the left front caliper, grease the needle bearings on the lower pivot point, then do a complete bleed, including the PVC, per the service manual. That should make your noise go away, if it is the SMC or air in the system.
.02

BakerBoy · Jun 3, 2013

Andrew, if it's the same noise I've heard on mine and others, it is not uncommon. It can also be heard while slightly rolling the bike back and forth and touching the brake lever--the SMC moves slightly on it's mounts (it's supposed to).

DonMac · Jun 3, 2013

The noise is possibly the brake pads moving in the caliper from contact with the rotor. My 1100 does that when coming off the center stand and I'm on the brake.

sennister · Jun 3, 2013

I would start by making sure the SMC is working. It isn't hard to test but easier with two people. Have someone turn the rear wheel while someone pushes forward on the left caliper. If there is air in the system or the piston is stuck (stuck piston was my issue a few years ago) then pushing on the caliper will not apply rear brake. This looseness will cause a rattle. I would hear it most while riding on a bumpy road through town.

If it is air, you should be able to bleed it out. If it is a stuck piston I would look at rebuilding the SMC and possibly replacing the entire assembly if there is pitting in the bore.

Andrew Shadow · Jun 3, 2013

Thanks for the ideas guys. My first thought was that I was hearing the play in the SMC as well but I had never heard this on any of ST1100's- this is my first 1300. SMC seems to be the consensus. Haven't gotten back to it as I have been finishing off some welding jobs- the motorcycle lift I will be using to check this being one of them. I am waiting for the shop manual to arrive before I try bleeding. One of the great things about this site- you know where to look for a problem before you look!

Andrew Shadow · Sep 14, 2013

I found the source of the noise. One of my rules with every motorcycle I have ever owned, regardless of new or used, is that before I ride it anywhere I always go over the wheel assembly procedure to make sure that the wheels are correctly installed and torqued. My reasoning is that I never trust anyone else with the wheel mounting procedure simply because there are only two of them and the loss of either one can be disastrous. Well I didn't do that with this bike because I wasn't up to it due to injuries I sustained in a recent car accident. A few weeks a go I had to change my tires and having now recovered enough to be able to do things again I did it myself. Upon removing the front wheel I discovered that the axle bolt, the two pich bolts on the right hand fork and one pinch bolt on the left hand fork were all finger tight. The only thing holding with any force was one left side pinch bolt. I had been up over 100 MPH several times like this! Reinforces my rule I guess.

970mike · Sep 14, 2013

Glad you found out the problem with no major problems.

broc11 · Sep 15, 2013

Andrew Shadow said:
I found the source of the noise. One of my rules with every motorcycle I have ever owned, regardless of new or used, is that before I ride it anywhere I always go over the wheel assembly procedure to make sure that the wheels are correctly installed and torqued. My reasoning is that I never trust anyone else with the wheel mounting procedure simply because there are only two of them and the loss of either one can be disastrous. Well I didn't do that with this bike because I wasn't up to it due to injuries I sustained in a recent car accident. A few weeks a go I had to change my tires and having now recovered enough to be able to do things again I did it myself. Upon removing the front wheel I discovered that the axle bolt, the two pich bolts on the right hand fork and one pinch bolt on the left hand fork were all finger tight. The only thing holding with any force was one left side pinch bolt. I had been up over 100 MPH several times like this! Reinforces my rule I guess.

Jes that's scary, I am getting some similar type noise/chatter from my st1100, I have play in the forks though catching them at the front axle,front wheel of the ground,pulling forwards and back there is some movement there,could be coming form the head bearings or the fork bushes,gona change both to be on the safe side, must be sure to see the wheels are tightened up to spec though, as you say,there is only 2 of them.
That's another reason I am so fussy that the bike is as close to 100% as possible,my life is depending on it.

broc11 · Oct 11, 2013

jfheath said:
Broc - the 1100ay may have chatter at the front end due to wear in the anti dive mechanism on the front right fork. The hole becomes elongated. But fork play and/or head bearings are well worth sorting out first.

Hi John,just rebuilt the forks yesterday,went with hyperpro springs and glad now that I did,feels like a new bike,10wt synthetic oil.rebuilt the anti dive as well,new 0 rings etc,the nylon bushing in the piston was well worn. new tapered head bearings too.
no play fore and aft in the forks now,chatter seems to be gone too.
she holds the road brilliant and isn't bogged down in the front like she was.money well spent I think.

Tom Mac 04a · Oct 12, 2013

Andrew... scary! good that you found it.

As a side note... If your re-seating the front axle and pinch bolts, don't forget there is now a proper method ( from 2008, "bounce" method ) to set the forks to prevent pulling to one side.

as follows , it allows the forks to self-realign;

(Note: Axle pinch bolts are finger loose at this point)

1. Tighten the left axle pinch bolts to 22 N-m (2.2 kgf-m, 16 lbf-ft)
Note: Indication of “Left” is if you were sitting on bike
2. Tighten Axle Bolt to 79 N-m (8.1 kgf-m, 58 lbf-ft)
3. Tighten the right axle pinch bolts to 22 N-m (2.2 kgf-m, 16 lbf-ft)
4. Now loosen the left axle pinch bolts
5. Note: During the assembly process, this is where you would be installing the brake calipers.
6. Set the bike down where the bike's weight is on the wheels. Lock the front brake and push the suspension up and down several times.
7. Tighten the left axle pinch bolts to 22 N-m (2.2 kgf-m, 16 lbf-ft)

Andrew Shadow · Oct 12, 2013

I did it per the service manual and the 2008 set up instructions I found on the internet. I am sure that they are identical but I was not able to find the 2009 set up instructions anywhere on the internet so if anybody has a link?

My service manual is the latest version with all the latest updates included and come to think of it I don't recall the fork bouncing step being part of the prcedure- have to recheck the manual for curiosity sake.

Front End Knock

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