Anyone else experiencing Braking instability? What possible causes?

[ButterSmooth]

In 24,000+ miles I've learned about the characteristics/quirks of my RT's personality. One of the things I noted right from the beginning was the directional instability under hard braking. Accepting this as a characteristic of the vehicle and living with it this long may have been a mistake. The recent thread on alignment, suspension geometry and resultant bump steer has made me reconsider this as a 'normal' behavior.

I used to practice 'emergency stops' on all previous motorcycles. The Spyder's instability makes this an unwise practice, so I no longer rehearse for emergency braking. I can usually contain the path to one lane, but it is unpredictable and road irregularities can make directional control worse.

With 20,000+ miles on the current front tires there is no irregular wear, cupping or other indications of alignment or suspension issues. And, it has shot off line under heavy braking from the start. Nominal front inflation is 19.5psi.

What should I be looking at? Anybody else notice the issue?

 

[BLUEKNIGHT911]

In 24,000+ miles I've learned about the characteristics/quirks of my RT's personality. One of the things I noted right from the beginning was the directional instability under hard braking. Accepting this as a characteristic of the vehicle and living with it this long may have been a mistake. The recent thread on alignment, suspension geometry and resultant bump steer has made me reconsider this as a 'normal' behavior.

I used to practice 'emergency stops' on all previous motorcycles. The Spyder's instability makes this an unwise practice, so I no longer rehearse for emergency braking. I can usually contain the path to one lane, but it is unpredictable and road irregularities can make directional control worse.

With 20,000+ miles on the current front tires there is no irregular wear, cupping or other indications of alignment or suspension issues. And, it has shot off line under heavy braking from the start. Nominal front inflation is 19.5psi.

What should I be looking at? Anybody else notice the issue?

I have 72,000 + mi. on my 14 RT.... I have also tested the it's braking capabilities .... I think it's phenomenal .... Maybe I lucked out and am blessed with a PERFECT Spyder :clap::clap: ..... JMHO ... Mike :thumbup:

 

[Bunson]

Mine pulls hard to the left every time under harder braking. I need to check/lube the left front caliber slides. Hopefully that's it.

 

[MNF3]

Something isn’t right. I have a 2016 F3-t and it stays dead straight under hard braking.

 

[PMK]

Mine pulls hard to the left every time under harder braking. I need to check/lube the left front caliber slides. Hopefully that's it.

You may find, if your Spyder has Brembo brakes, those monoblock calipers are rigidly mounted and there are no pins the caliper slides on. Most likely you have a one of the four caliper pistons weaping fluid. The fluid contaminated the brake friction material and causes the pull to one side. The leaking side is opposite the side it pulls towards.

 

[PMK]

In 24,000+ miles I've learned about the characteristics/quirks of my RT's personality. One of the things I noted right from the beginning was the directional instability under hard braking. Accepting this as a characteristic of the vehicle and living with it this long may have been a mistake. The recent thread on alignment, suspension geometry and resultant bump steer has made me reconsider this as a 'normal' behavior.

I used to practice 'emergency stops' on all previous motorcycles. The Spyder's instability makes this an unwise practice, so I no longer rehearse for emergency braking. I can usually contain the path to one lane, but it is unpredictable and road irregularities can make directional control worse.

With 20,000+ miles on the current front tires there is no irregular wear, cupping or other indications of alignment or suspension issues. And, it has shot off line under heavy braking from the start. Nominal front inflation is 19.5psi.

What should I be looking at? Anybody else notice the issue?

There can be several contributing factors. You did not mention if your machine is stock, or has modifications of aftermarket front shocks, a firmer swaybar, oem tires, and if under normal braking effort will track straight with minimal to no input by the person at the controls.

I do know exactly what you mention. Jumping an entire lane though is unacceptable. You are correct though that bump steer, alignment, suspension firmness can all be contributing factors. Sadly, there are few free lunches regarding this, and truly optimized settings are simply a best compromise. In short simple terms, and assuming you have no leaking front caliper pistons, which seems unlikely since this has gone on for 22,000 miles, you can have this heavy braking squirm minimized or eliminated, provided the road crown or worn in gullies are not the cause. Have your alignment specialist check the steering angle sensor and steering torque sensor with BUDS2. If within specs, but away from truly nulled, reset each to 0.0 or very close. If the sensor are already at 0.0, increase toe in and complete the task resetting the sensors again. The tech accomplishing the task must understand your request, and avoid doing a simple within specs alignment. He must accomplish measurements before and after. Unless he initially sees a gross error, have him or her, note the dimensions and make a careful calculated change.

Others that post comments about how stable their machine is, most likely are setup with more or even excessive toe in. This type setup does not always wear tires, since induced toe out from bump steer lessens that excess toe in setting when ridden. Downside to the increased toe in, becomes tire scrub with reduced mpg, slower acceleration, and reduced speeds at given engine throttle settings simply because rolling resistance is increased. Again, no free lunch.

 

[Bunson]

You may find, if your Spyder has Brembo brakes, those monoblock calipers are rigidly mounted and there are no pins the caliper slides on. Most likely you have a one of the four caliper pistons weaping fluid. The fluid contaminated the brake friction material and causes the pull to one side. The leaking side is opposite the side it pulls towards.

Thanks, I do have Brembo brakes so I'll take a look.

 

[BajaRon]

The Spyder should be very stable under all braking conditions unless the road surface is an issue. You should be able to stomp on the brake and have no adverse actions. Something is not functioning correctly with your Spyder. It sounds like you're getting uneven brake application. First one side, then the other is being applied. As mentioned, there are a number of reasons for this. Check your brake pads. You may have one (the inner or outer) wearing much faster than the other. Or, one set of pads may be wearing faster than the other. This indicates that something in the caliper/pad system is hanging up. Pads should wear pretty evenly if functioning correctly. (though the rear set may wear more quickly than the fronts.) This is normal.

As mentioned, this will certainly give you the symptoms you are experiencing.

 

[ButterSmooth]

There can be several contributing factors. You did not mention if your machine is stock, or has modifications of aftermarket front shocks, a firmer swaybar, oem tires, and if under normal braking effort will track straight with minimal to no input by the person at the controls.

First, thanks for the thoughtful response. The RT is stock with the exception of Vredestein front tires 20,000 miles ago and a Yokohama on the rear. Normal stops are squeaky but straight.

I do know exactly what you mention. Jumping an entire lane though is unacceptable.

It hasn't jumped completely out of a lane, but a wheel will cross the line (either side) during the stop.

...you can have this heavy braking squirm minimized or eliminated, provided the road crown or worn in gullies are not the cause. ...

I think this is the crux of the issue. Most roads around here are heavily contoured by stud/chain wear in the Winter. My old Toyota Highlander (AWD) couldn't climb out of the grooves when it was icy, so they are bad. Add to that the 'repairs' that consist of a new strip of asphalt laid just in the grooves, complete with 1"-2" ridges at the edge. I need to seek out a newly paved, flat road and do some more testing.

The problem is aggravated because when the sudden swerve begins the Spyder body rolls excessively to the outside, invoking the bump steer characteristics. It's possible that a heavy sway bar could reduce this complication and get me back to 'within the lane.' Maybe more spring rate or preload could make a difference, too.

 

[UtahPete]

Have you checked for equal front tire pressure?

 

[PMK]

First, thanks for the thoughtful response. The RT is stock with the exception of Vredestein front tires 20,000 miles ago and a Yokohama on the rear. Normal stops are squeaky but straight.



It hasn't jumped completely out of a lane, but a wheel will cross the line (either side) during the stop.



I think this is the crux of the issue. Most roads around here are heavily contoured by stud/chain wear in the Winter. My old Toyota Highlander (AWD) couldn't climb out of the grooves when it was icy, so they are bad. Add to that the 'repairs' that consist of a new strip of asphalt laid just in the grooves, complete with 1"-2" ridges at the edge. I need to seek out a newly paved, flat road and do some more testing.

The problem is aggravated because when the sudden swerve begins the Spyder body rolls excessively to the outside, invoking the bump steer characteristics. It's possible that a heavy sway bar could reduce this complication and get me back to 'within the lane.' Maybe more spring rate or preload could make a difference, too.

Yes, retest on a more flat road surface. That will shed knowledge of how to proceed.

If you run minimum toe in, squirm can occur on flat ground, under hard braking on account of the bump steer induced toe out. Normal stops do not demonstrate this squirm. As toe in is added, or the suspension is firmed to lessen bump steer induced toe out, squirm is minimized or removed at the trade off of increased tire scrub.

If there was a possibility of a brake issue, I would focus on improper tone ring signal, or an ABS malfunction contending with one wheel, but that should show as a pull to one side, not a squirm or shimmy.

Give flat ground braking a try and see how it is. Obviously be careful doing those hard stops.

 

[fatboy]

also get it aligned we just had 4 2020 + rt done in maggie valley all were out worst was over 1/2 inch everyone noticed the difference

 

[ButterSmooth]

... As mentioned, there are a number of reasons for this. Check your brake pads. You may have one (the inner or outer) wearing much faster than the other. Or, one set of pads may be wearing faster than the other. This indicates that something in the caliper/pad system is hanging up. Pads should wear pretty evenly if functioning correctly. (though the rear set may wear more quickly than the fronts.) ...

That's a great suggestion. As soon as the weather changes from Fall to Winter I'm doin' the brakes, looking for clues.

 

[Isopedella]

That's a great suggestion. As soon as the weather changes from Fall to Winter I'm doin' the brakes, looking for clues.

Thats nuts! You hit the brakes firmly and it dives off to one side. Stuff that. Why Wait? Take ya 15 minutes to have a look at the pads.

 

[ButterSmooth]

Thats nuts! You hit the brakes firmly and it dives off to one side. Stuff that. Why Wait? Take ya 15 minutes to have a look at the pads.

I appreciate the sentiment, but it doesn't dive off to one side. Where I'm headed is unpredictable -- I think it has more to do with the road irregularities than any brake problem. But it's worth a look at them to see if there are any clues. You may be right on about the 'nuts' thing though, others have said something similar...

 

[Peter Aawen]

I appreciate the sentiment, but it doesn't dive off to one side. Where I'm headed is unpredictable -- I think it has more to do with the road irregularities than any brake problem. But it's worth a look at them to see if there are any clues. You may be right on about the 'nuts' thing though, others have said something similar...

Have you checked for worn/loose ball joints or tie rod ends?? Possibly teamed with 'not quite right' wheel alignment, but that sorta behaviour really sounds like something is worn or loose... :dontknow:

 

[Excoastie]

I had this issue on my '22 RT-L for the first few hundred miles.

I came to realize that it was my grip on the bars. I tend to clench up when there is a "stressful" situation, and emergency braking certainly qualifies.
I tested this by doing several "emergency" stops in an empty parking lot at about 40 MPH. If I could maintain my loose grip, all was well; when I clenched not so much.

Good luck!

--Exco

 

[PMK]

Did send you a PM, but failed to ask, are you a heavier rider?

 

[ButterSmooth]

Did send you a PM, but failed to ask, are you a heavier rider?

152# and I ride solo.

 

[pegasus1300]

Remember he has had this right from the beginning and he only has 24000 miles. Exco may be on to something with the grip idea, tho I think it is a brake pad problem or caliper problem.