New PR4 GT's installed, now have handlebar wobble below 50 mph.

[gsforster]

This is interesting to me.
I bought my 06 double dark side. Rode fine.
Put a pair of wheels with 900 miles on the bearings and PR4GT tires on.
Wobble 45-55 mph, peaked at 50mph. I am normally comfortable with my hands off the bars. No way with this. Not bad with hands on.
Picked up an 03 with very good condition PR4GT front and back. Dead smooth.
Getting up around 13,000 miles the wobble increases slightly but impressively has done all these miles without getting as bad as I would expect.
Switch to a new Dunlop sport max 2 in front because it is $55 shipped and hope to use it up quickly and a slightly used PR4GT on the previously dark side wheels. Dead smooth.
Rim run out on the wobbly tire rim combo is a mm. Round is good, no dents. Tire looks true to the rim. This should be in spec.
The variable that I want to check is wheel weights. Out of three front wheels, the wheel with stick on weights wobbles. Weight was distributed almost evenly. I would not think this could make such a difference.
Just data.

It's good data. I am going to swap out the front tire today if I get a moment at work, I have a slightly used Bridgstone T30 EVO front I'll mount and try just for diagnostic sake. What are the chances I got 2 "wobbly" front michelins? Or has my bike suddenly decided it does not like michelins anymore? I'll keep you all posted on my findings and results.

 

[gsforster]

Rear swing arm bearings ever checked?

3 yrs ago I had it out to replace the ujoint (just because of mileage not failure), and cleaned and relubed the swingarm bearings at that time. They were in pristine condition, and I followed the torquing procedure verbatim.

 

[Bmacleod]

I would loosen up the front end and do an alignment first off and see if that makes a difference. Takes much less time than changing a tire and you can then eliminate that as a cause. I would think its possible that an alignment that is out a bit could be effected more with some tires than others. I had a slight wobble with a PR4 that went away after some winter maintenance that included an alignment. Unfortunately, I did a few other, possibly related things, so I cant say for sure that was the solution. I have since changed out the PR4's and have to say that I am less a fan of them then I was before. Now that I am running another brand, I can say that although they stuck well, they seem a little on the soft side and dont give feedback to the rider as well. The term wishy-washy comes to mind (sorry, cant think of another way to describe them)

 

[Igofar]

 

[Whooshka]

Alignment always a good idea to do every couple of thousand miles. And if you give that a try see if you can raise the fork tubes in the triple clamps a bit. Even a 1/4 inch can make a big difference.

 

[Igofar]

PM sent from the
Standing by if needed.

 

[TipSTer]

You need a new front tire..!

 

[sirbike]

Well Igofar says do it so I just did it.
I am inclined to suspect that the PR4 tire profile combined with an alignment issue is more likely the cause than wheel weight not perfectly centered.
. Maybe when I wear out the sport max I’ll put that PR4 wheel back on to test it.

 

[lomita]

Section 18 common service manual

Wobble, pg 18-1

Worn Bearings, Bent Rim, or Tire

 

[Larry Fine]

Put a pair of wheels with 900 miles on the bearings and PR4GT tires on.
Wobble 45-55 mph, peaked at 50mph. I am normally comfortable with my hands off the bars. No way with this. Not bad with hands on.
Picked up an 03 with very good condition PR4GT front and back. Dead smooth.
Getting up around 13,000 miles the wobble increases slightly but impressively has done all these miles without getting as bad as I would expect.
Switch to a new Dunlop sport max 2 in front because it is $55 shipped and hope to use it up quickly and a slightly used PR4GT on the previously dark side wheels. Dead smooth.

Any overall diameter difference between wobbly and non-wobbly tires?

 

[Larry Fine]

And if you give that a try see if you can raise the fork tubes in the triple clamps a bit. Even a 1/4 inch can make a big difference.

Raising the rear would have the same effect on steering geometry, maintain cornering clearance, and be easier.

However, either adjustment would steepen the forks, decreasing stability.

 

[Whooshka]

Raising the rear would have the same effect on steering geometry, maintain cornering clearance, and be easier.

However, either adjustment would steepen the forks, decreasing stability.

Yes true. But by raising the forks I don't need to play with the rear to set my rake. I find it gives greater fine tune-ability in the rear (depending on load) because I already have the front where I want it to be for solo riding and light load. What's the old saying?... half dozen of one, 6 of the other. My forks are raised about 5-6 mm (I have bar risers) and I have not sacrificed any stability. I can take my hands off the bars and it still tracks straight.

I wonder how differently the 1100 reacts to suspension changes as opposed to the 1300. Gotta find wheel base and geometry specs.

 

[cyclenut57]

I noticed this thread and I too back in 2015 tried PR4GT's after reading all the good things about them.
I pulled them off just shy of 8k miles. Rear tire would slip out when pushing too hard on the corners if the tires were not good and warm (probably the dual compound)
and front end wobble which dissappeared when I went to the T30 Bridgestones in early 2016. I was running the 023 prior to that.
Needless to say I did not care for the PR4GT primarily due to the little front end wobble that progressively grew with more miles.
I have 12k on the t30's now and have T31's on deck waiting to go on.

 

[Larry Fine]

I'm thinking of trying Roadsmart IIIs next.

 

[lomita]

Experienced the same rear wheel slipping tendency with the BT023 tire once. Humbling. Got my attention. Something had to change. It was my riding style. Was trying to ride the ST like a cruiser.

Discovered leaning forward slightly through the turn, that very minor weight shift really transformed riding the ST and brought out the sweet spot of handling.

Wow, counter steering working like never before. The BT023 seemed sure footed once again. My confidence soared.

Am looking forward to riding the PR4-GTs. That nice deep black sticky rubber, the tread the siping. Heard they're good in rain too. One of these days, may even get to dawn the Frogg Toggs....

 

[gsforster]

Thought I'd do a follow up on this. I went through a very specific checklist of things alignment related and even things to check in rear wheel from Larry. Found nothing suspect. I even went as far as remounting a still good used front T30 Evo. Still had the same wobble maybe even a bit worse. I checked my steering head bearing preload - showed just under 2 lbs pull from straight ahead as the manual shows. Got a new lock-tab washer, and readjusted the preload. Now I have the drag around 2.5 - 2.75 lbs. Roadtested solo and 2 up(since 2 up was bringing on the wobble much more before) and now vastly reduced wobble - tiny bit that just seems to think about starting but never develops. Steering feels a bit more solid too, but the bike does not seem to hunt so not overly tight. For what it's worth the dealer near me did not have in stock that lock ring washer, and parts man said they always use all balls tapered bearing kit that likely comes with the washer. Hmmm. Maybe there is something to this idea of changing to tapered bearings....

 

[kiltman]

If you do go to tapered bearings (you may already know this) The steering head nut requires less torque than the OEM. After 600 miles check the torque again and you should then be good to go for many miles.

 

[Whooshka]

Thought I'd do a follow up on this. ..................... Hmmm. Maybe there is something to this idea of changing to tapered bearings....

Maybe you just have worn bearings. Not a tapered verses non-tapered issue.

 

[lomita]

The tapered "all balls bearing kit" works great on the steering head. Great upgrade.

 

[TerryS]

I have recently fitted a new PR4GT to the front of my 1300, to match a PT4GT rear that has done a few thousand km. I'm pleased to report that my ST likes these tyres very much, and I have no obvious instability. The PR4GT's have a more comfortable ride and steer a little quicker than the Bridgestone BT023s that were replaced.