Triumph T120 headshake problem

[ohiorider]

Not a Guzzi question ...... more of a general question re headshake.  It's posted to TriumphRat forum, but you guys always come through with thoughts based on years of experience.  Suggestions are more than welcome!

Bob
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I purchased my 2016 T120 barely used, with slightly over 1600 miles on the odometer. I had no time to spend quality time doing a shakedown cruise, since the weather turned pretty bad the day I picked up the bike. I had the dealer roll it into their van and follow me (in car) home. Aside from a few blasts in the 35 mph zones around my neighborhood, yesterday was first time on good asphalt.

Point of comparison ...... My old BMW R100GS has always developed a right/left/right wobble in the bars IF I take pressure off the bars, especially as it slows down. Nature of the beast.  The T120, OTOH, continued the steering wobble at 60, 65, and 70mph even with a normal grip on the bars. No issues below 50mph.

I believe the bike has the original OEM tires ..... Pirelli Phantom Sport, (I think.)  I know they are tube-type, and I think that one end or the other may be a bias belted tire.

This morning, I put the bike on the center stand, put scissors jack under the sump, and got the tire off the floor. Sitting on my shop stool, tried to eyeball the wheel and tire as I rotated it, and didn't notice anything wrong. I need to put a dial indicator on it if I want to perform a real check, I suppose.

Only other thing I noticed, while slowly rotating the wheel in the direction of travel, it would hit a tight spot that lasted for several degrees of rotation, possibly 70 degrees or so. I lightly gripped the tire, and rotated until I felt the friction begin, and, using the fender as a guide, chalked the tread. Also chalked the tread where the friction stopped. Probably not the cause of anything. I've had warped rotors on other bikes that only exhibited a problem when the brakes were applied.  This issue is strictly speed-related.  Could this simply be related to a bad tire right from the factory? 

[guzzisteve]

Do a balance check, tires can be bad also.

[BRG-BIRD]

Apparently the Pirelli Phantom tires are notorious for being quite lousy tires, I’m on the Triumphrat forum myself. In fact the Enfield 650 I have has the same Pirelli tires and the front tire shakes at certain speeds, can’t wait to replace them.

[moto-uno]

  I'm assuming you've checked the tire pressures ? Can you get the front wheel in the air and check for neck bearing
play or notching of the bearings ( unlikely with that low a mileage , but maybe it smacked something hard ) . My experience
with badly balanced tires is that it's most noticeable at lower road speeds , and really requires removing them to
check . The tires should be a matched set (check the sidewalls for their description and compare to Triumph info) . I sure
wouldn't ride it too fast until corrected .   Peter

[kingoffleece]

I had THREE Michelin Pilot Actv that were defective.  Bad belt-broken or twisted.  Caused the bike to act as you describe.

[Petrus Rocks]

Wheel bearings and tires.  Tires can be worn without being noticeable

[lucky phil]

Wheel bearings and tires.  Tires can be worn without being noticeable

Yep dont discount the wheel bearings. If the bearing spacer is too short ( and I've seen them that way from the factory) it can trash the bearings fast. Easy the check with the wheel in the air esp with the calipers off.Grab the wheel and look for play. Another tell tale when they are really bad is varying front brake lever travel. One minute the travel is ok the next its coming back much further than normal.

Ciao

[Kiwi Dave]

It was quite common when I was riding Bonnevilles.  The usual issue that the rear tyre was replaced with some larger (but better looking).

Could it be the same here?

[lucky phil]

It was quite common when I was riding Bonnevilles.  The usual issue that the rear tyre was replaced with some larger (but better looking).

Could it be the same here?

2016 Bonnvilles ?

Ciao

[rocker59]

My vote is bad front tire.

[bodine99]

Rear wheel not straight, loose spokes, neck bearings, wheel brgs. mirrors, only 1 can cause weird stuff wind screen or fairing handle bar mount, tire pressure try what the tire sidewall shows for pressure. tire bead line all the way up. Keep us posted

[Dave Swanson]

Bought a used Superglide years ago bike that had new rubber.  The front end shook like it was going to fall apart.  The front wheel was out of balance.  After balancing it was perfect - transformed

[ohiorider]

Thanks for all the suggestions.  Too cool for garage time today, but will spend time exploring the potential causes on warmer days.  Couple of very light flurries ..... just a few flakes at the time.

Bob

[kirkemon]

The new T120s do not have any head shake. I doubt if she really checked this motorcycle well before purchasing, as it was used.
Yes, the Phantoms are poor tires. The T120 front rotors are crap, (Sunstars), I changed mine to the Brembo that come on the Thruxton R.

[geoff in almonte]

I have no head shake on my T120 Diamond.

However, based on your description of the symptoms. I would check the rotors for warp-age or the calipers for a sticky piston.  Wheel bearings are suspect and would check/replace them when you deep six the Pirellis.  Also make sure that the suspension is set up correctly - preload, sag, compression and rebound damping (if applicable).

Good Luck!

G

[Muzz]

My vote is bad front tire.

My vote too.

[blu guzz]

On my v85, I had a lot of vibration in the bars from the Mich. Anakee on the front, felt out of round.  In a rare example of Piaggio being proactive, they replaced the front tire for me under warranty and that cured the problem.  The original bad tire was sent back to Italy for "study". 
If you find no other reasons, it could be your problem as well. 

[ohiorider]

Not a Guzzi question ...... more of a general question re headshake.  It's posted to TriumphRat forum, but you guys always come through with thoughts based on years of experience.  Suggestions are more than welcome!

Bob
-------------------------------------------------------------------------------------------------
I purchased my 2016 T120 barely used, with slightly over 1600 miles on the odometer. I had no time to spend quality time doing a shakedown cruise, since the weather turned pretty bad the day I picked up the bike. I had the dealer roll it into their van and follow me (in car) home. Aside from a few blasts in the 35 mph zones around my neighborhood, yesterday was first time on good asphalt.

Point of comparison ...... My old BMW R100GS has always developed a right/left/right wobble in the bars IF I take pressure off the bars, especially as it slows down. Nature of the beast.  The T120, OTOH, continued the steering wobble at 60, 65, and 70mph even with a normal grip on the bars. No issues below 50mph.

I believe the bike has the original OEM tires ..... Pirelli Phantom Sport, (I think.)  I know they are tube-type, and I think that one end or the other may be a bias belted tire.

This morning, I put the bike on the center stand, put scissors jack under the sump, and got the tire off the floor. Sitting on my shop stool, tried to eyeball the wheel and tire as I rotated it, and didn't notice anything wrong. I need to put a dial indicator on it if I want to perform a real check, I suppose.

Only other thing I noticed, while slowly rotating the wheel in the direction of travel, it would hit a tight spot that lasted for several degrees of rotation, possibly 70 degrees or so. I lightly gripped the tire, and rotated until I felt the friction begin, and, using the fender as a guide, chalked the tread. Also chalked the tread where the friction stopped. Probably not the cause of anything. I've had warped rotors on other bikes that only exhibited a problem when the brakes were applied.  This issue is strictly speed-related.  Could this simply be related to a bad tire right from the factory?

May 5th, 2020

The wobble is gone! I replaced the OEM front tire with a Michelin Pilot Activ in the factory recommended size (100/90-18,) Also took the wheel to a shop that has a couple of techs that are good at truing before having the new tire mounted.

The tech's comment was, 'the wheel had slightly noticeable run out, but not so bad that it alone would cause the wobbling at 55- 60 mph.) But he tweaked it and brought it into spec. That, and the new front tire, took this bike from being 'what have I bought?' to being 'wow ... glad I bought this little gal!'

Same roads, but at 65-70+mph, not a sign of a shimmy. Although I didn't notice issues with OEM tire below 55 mph, I now think the bike feels better overall .... that perhaps the defective tire was causing the bike not to be all it could be even at slower speeds.

Now, I ordered and have in my possession the mating rear Pilot Activ tire, which I should probably have mounted. But here I am with what appears to be a perfectly good rear tire with 1800 miles on it, and the bike seems to handle fine, even with the mismatch. Now, I've ridden long enough to know that tire designers design these things to operate as a pair, so I'm torn between running the OEM rear until it wears out before installing the Pilot Activ rear. I suspect it'll bug me for a few days, I'll pop the rear wheel, take it to the shop, and have the new rear tire installed.

Anyway, I was so pleased that the problem is no more, and that my T120 feels like a real bike!

Bob

[Dave Swanson]

May 5th, 2020



Anyway, I was so pleased that the problem is no more, and that my T120 feels like a real bike!

Bob

That is great news Bob.  I was eyeballing the T120 when I drove in to pick up my buddy's new 1200XE Scrambler.  Very nice.

[Kiwi Dave]

Nothing wrong with mismatched tyres by manufacturer.  Both my Cali 1400s have a Michelin Pilot Road 4 GT on the front, and a Bridgestone BT020 on the rear.  Took a couple of combinations before I settled on this arrangment.