Lower Fork leg vibration- Help needed

[Dogdaze]

I have a suspension/ brake related question. Since I have owned the bike I have done about 8000 miles (has 20k on now) I noticed a slight judder through the brakes on light lever application (front brakes only, and not pulsating) never on moderate or hard braking. Well this has gotten worse over the 20 months I've had it, saw someone had a similar problem and was suggested to them that the disc bobbins could be the cause, so I duly rotated all the bobbins and cleaned up the discs and caliper pistons and even installed new pads. Still there, then thought I should perhaps grease the slider pins with copper grease, did that, much improved. Well took it out today and it's back, worse than ever! However whilst riding I applied light brake while looking through cockpit at the fork legs and noticed that the lower stanchions were vibrating a lot. That just did not seem right, came home took out the pads and they looked galled on the leading edges of all four pads, not good!! Under heavy compression of the forks the judder is not there.
My question is this, I know that there should be a small amount of free play in the lower legs, otherwise they cannot function, so how much is expected and is the shaking due to the brakes or are the brakes juddering due to the fork legs?
I don't ride off road, have road bias tyres and hardly ever brake excessively I don't abuse my bikes. And run about 33-34psi up front on the Pilot Road 4 Trails.
Sorry CW if this needs to be in the brake section..............

 

[tomatocity]

Before we get too far into a solution...

... what is the year of the Tenere
... what suspension do you have

 

[Dogdaze]

Before we get too far into a solution...

... what is the year of the Tenere
... what suspension do you have

2012 and stock suspension, rebound and compression set at half way and four groves showing on the preload (so on the 5th grove at the shoulder)

 

[silvergoose]

DogDaze, you said the bobbins were checked and rotated, Do you have acess to a dial indicator and stand? I would suggest checking the run out on the disk. The only way a brake pad can gall is to have debris or the disk vent holes nicking the pad material due to a slight run out. You stated that the judder is gone with more brake lever pressure, this would stand to reason due to the higher pressure forcing the disk to run more true.

Is it possible a slight fork seal leak has allowed a small amount of oil to reach the pad material? Does not explain the galling, but it could show up as a judder under light pressure.

Good Luck

 

[Dogdaze]

Silvergoose, unfortunately I have no access to a dial indicator and stand, I will try to have a closer look at the discs, maybe take them of the wheel and lie them on a flat surface, I looked for any leakage of fork oil, but found nothing.

 

[silvergoose]

DogDaze, Here is a method to check flatness of the disk.

First mark the disk with a marking pen, draw a line on the braking surface. Rotate the wheel and lightly pull the brake lever until you can hear the pad drag. High spots will mark the marker ink, low spots will of course be untouched. Simple, but it will give a better insight to the problem.

Good Luck

 

[taskmaster86]

Dogdaze,

Silvergoose gave a really good suggestion on how to check your brake discs.

I would also recommend you loosen and re-torque your front axle and axle pinch bolts just to make sure everything is OK there.

You said the leading edges of the brake pads look more worn than the rest, that is a very common problem in the automotive world. It usually means your brake caliper pistons are not pushing evenly on the pads and causing irregular wear and vibrations. That very well could be your problem.

I would pressure bleed your entire brake system, thoroughly clean your brake calipers and then install the brake pads, push them all the way back and have an assistant slowly squeeze the front brake lever while you watch the brake pads move. Make sure the pistons are pushing the pads evenly all the way across the brake pads and that the brake pads are moving straight across as they are being pushed out. Just don't go too far and let the pistons pop out of the calipers. If the brake calipers are not pushing the pistons and pads evenly, you either need to take apart your calipers and clean them thoroughly as well as replacing the piston seals. Alternatively, you can replace the entire caliper assembly but that would be a very last resort.

 

[Cycledude]

Have you checked the rear brake pads ? Fork bushings ?

 

[Dogdaze]

Thanks guys, I will try the suggestions and see how I get along. I will report back on progress ::008::

 

[Dogdaze]

Just an update, not being happy to leave things alone, I went ahead and stripped the calipers, cleaned everything, extended pistons out as far as I felt safe to do so, scrubbed everything, got behind the pistons with thick string and 'flossed' the whole area that could not be seen. I still see that the smaller of the pistons lag behind the larger ones on activating the brakes, not 100% sure this is normal, will go for a ride later or tomorrow and if none or minimal improvement may have to replace the seals. I may need questions answered on that procedure as the cost of doing that here at the local dealer I could buy a set of new calipers complete from the US.

Is there anything that I missed?

 

[taskmaster86]

If you have changed the brake fluid and the pistons are still not pushing out evenly, then that is your problem! The pistons must push the brake pads into the brake disc evenly. Otherwise, you will get abnormal brake wear and strange feelings through the brakes.

 

[silvergoose]

DogDaze, Ebay has a set of 2014 calipers. US costs $225.00 free shipping (us only) or best offer.

Item number 361430333131.

I do not think this is your problem, but I can be wrong, after all I have been married three times.

Good Luck

 

[Dogdaze]

Thanks Taskmaster, fluid has been flushed through, I'm expecting a rebuild in my future!! ::010::

Slivergoose, I don't think I need new calipers (don't really want to buy someone else's problems either), the bike only has 18500 miles on, but would you concur about the seals need replacing?

 

[WJBertrand]

Any resolution to this issue? I have the same problem, light application of the front brake at speed causes a visible vibration in the front fork. As I'm rolling to a stop there is a pronounced pulsation. Something's not flat. Pads look Ok, bobbins are clean, brake is releasing normally, that is I can easily spin the front wheel. I've had the wheel off and reinstalled with the correct torque values and it's still not right. The bike is a '15 ES. I'm probably going to call the dealer tomorrow.

 

[Dogdaze]

I just ordered a caliper piston seal kit, as the smaller pistons are not moving out at the same rate as the larger ones, even after thorough cleaning. I don't get pulsing through the levers, just through the lower fork legs, if I look down, once that is done and if it is still present than that leaves the discs, so will tackle the lower cost options first..............
I also retorqued all the triple tree clamps and wheel spindle and pinch bolts, but they were okay anyway.

 

[WJBertrand]

I just ordered a caliper piston seal kit, as the smaller pistons are not moving out at the same rate as the larger ones, even after thorough cleaning. I don't get pulsing through the levers, just through the lower fork legs, if I look down, once that is done and if it is still present than that leaves the discs, so will tackle the lower cost options first..............
I also retorqued all the triple tree clamps and wheel spindle and pinch bolts, but they were okay anyway.

Thanks for the update. In my case I heavily suspect one or both of the front discs are warped or have uneven thickness. Had the same exact issue on my Honda ST1300 and it turned out to be a defective right sided disk rotor that was uneven in thickness. I've got Y.E.S. so this should be covered as I don't believe they can call it a wear issue when I haven't even worn out the first set of brake pads.

 

[greg the pole]

I have a suspension/ brake related question. Since I have owned the bike I have done about 8000 miles (has 20k on now) I noticed a slight judder through the brakes on light lever application (front brakes only, and not pulsating) never on moderate or hard braking. Well this has gotten worse over the 20 months I've had it, saw someone had a similar problem and was suggested to them that the disc bobbins could be the cause, so I duly rotated all the bobbins and cleaned up the discs and caliper pistons and even installed new pads. Still there, then thought I should perhaps grease the slider pins with copper grease, did that, much improved. Well took it out today and it's back, worse than ever! However whilst riding I applied light brake while looking through cockpit at the fork legs and noticed that the lower stanchions were vibrating a lot. That just did not seem right, came home took out the pads and they looked galled on the leading edges of all four pads, not good!! Under heavy compression of the forks the judder is not there.
My question is this, I know that there should be a small amount of free play in the lower legs, otherwise they cannot function, so how much is expected and is the shaking due to the brakes or are the brakes juddering due to the fork legs?
I don't ride off road, have road bias tyres and hardly ever brake excessively I don't abuse my bikes. And run about 33-34psi up front on the Pilot Road 4 Trails.
Sorry CW if this needs to be in the brake section..............

When is the last time the forks were serviced? it's probably a disc/caliper issue, but I wouldn't rule out suspension.
Is the oil at the correct level, how are the bushings (inner/outer)/springs etc...
I try to rebuild my suspension once a year or 15k KM.
https://thetenerist.wordpress.com/2014/10/18/fork-rebuild-v3-0-including-fork-seal-and-bushing/
https://thetenerist.files.wordpress.com/2014/10/img_7865.jpg

 

[Dogdaze]

When is the last time the forks were serviced? it's probably a disc/caliper issue, but I wouldn't rule out suspension.
Is the oil at the correct level, how are the bushings (inner/outer)/springs etc...
I try to rebuild my suspension once a year or 15k KM.
https://thetenerist.wordpress.com/2014/10/18/fork-rebuild-v3-0-including-fork-seal-and-bushing/
https://thetenerist.files.wordpress.com/2014/10/img_7865.jpg

I have never done the suspension, nor I suspect the previous owner, bike is now 4 years old, but I would say it's had an easy life, zero off roading and for the most part, decent roads. I'm not heavy, only about 94kgs (managed to drop 25kg through getting old) and not heavy on the brakes. Yes, there is a that vibration thing going on the lower fork legs, but from my view, looking down the forks while braking, it's caused by the brakes. The wife has told me to get a new bike, so I really don't want to rebuild this bike just to end up selling it. I have never spent so much time fiddling with a bike as much as this one, and as the good wife said, what's the point of working on it in the garage when I should be riding it................ can't argue with good sense.

 

[greg the pole]

I have never done the suspension, nor I suspect the previous owner, bike is now 4 years old, but I would say it's had an easy life, zero off roading and for the most part, decent roads. I'm not heavy, only about 94kgs (managed to drop 25kg through getting old) and not heavy on the brakes. Yes, there is a that vibration thing going on the lower fork legs, but from my view, looking down the forks while braking, it's caused by the brakes. The wife has told me to get a new bike, so I really don't want to rebuild this bike just to end up selling it. I have never spent so much time fiddling with a bike as much as this one, and as the good wife said, what's the point of working on it in the garage when I should be riding it................ can't argue with good sense.

I wouldn't argue with that at all. Maybe my tenere should develop a shimmy....but my wife knows me far too well.
The oil in the suspension will be dirty if it's original, and retain little of it's qualities. It's always a good idea to maintain suspension. On or off road. That said, I love to wrench on my own bikes, but only when I can't ride.

Off to the dealer with your tenere.
So what's the replacement?

 

[Dogdaze]

So what's the replacement?

Was just thinking about a new S10 ES, I like the MT-09 Tracer (FJ) but just seemed small and I like the ergo's of the S10!!
But will try to resolve the brake issue first, then see how it goes.......... I will not attempt fork oil change myself, not enough tools with me and possibly cost issue here from the local dealer ::010::