Triumphrat

10-11-2004

A friend of mine dumped his S4 last week after his rear wheel locked up. He had shifted into 3rd and was accelerating when he heard a loud "pop" from his gearbox (he described the noise as sounding like a tire blew out), and witnesses at a store about 1/8 mile heard the noise as well as residents and another rider ahead. (They say the noise was very LOUD.) The rear wheel left three tire marks on the road approx. 4ft. long, separated by two 4ft. spaces with no mark before he fell. This happened at about 35 to 40 mph. His bike started again but had a hard time shifting into neutral or 1st. Anyone ever experience anything like this?

The dealer test drove his bike 20 miles, checked and found no DTCs and told him there is no problem. My friend rode this bike for 960 miles with no problem and does not want this to happen again.

Thanks for any input.

Mark.

Will · 10-12-2004

Did anyone look inside the transmission? If your friend accidentally stomped on the lever and dumped it back into second somehow, the skid mark pattern is the mother of all wheel hops. I don't know what kind of noise a transmission makes if you bang it down a gear without modulating the throttle or using the clutch. If your friend rode an additional 960 miles after the crash, then it must be OK.

10-12-2004

Sorry, I explained that wrong. The bike had 960 miles on it when this happened last week and the dealer still has it. They drained the oil and found no shavings or debris (small enough to fit through the drain). A tech from the dealer is going to put some miles on the bike to make sure everything is o.k.

You mentioned "stomping" on the lever... I have never tried to downshift without using my clutch, but agree that you would probably have to literally stomp on the lever.

Thanks,
Mark

MercyBeat · 10-12-2004

The loud pop could have been teeth breaking off the transmission.
I've dropped a gear by accendent.

[ This message was edited by: MercyBeat on 2004-10-12 19:19 ]

10-13-2004

what is a dTC?

anyway has your mate got pix of the skidz? That would help

I agree with Will; from the story a good mechanic would strip the gearbox (but this costs the workshop money £ - and $)

Mind you as a goofy downchange would cause similar outcome any good workshop would want to talk about sharing costs if there was no gearbox problem. Mechanics have to eat & pay rent as well!

Jon (in a negative mood)

Will · 10-13-2004

DTC stands for something like Digital Trouble Code. It is just a code that says some sensor is sensing a problem somewhere on the bike.

You know, you can downshift smoothly without the clutch when you are slowing, just as you can upshift without the clutch when you are accelerating. But, I shudder to think what would happen if you downshifted without the clutch while you were accelerating. You never did say how that happened or what an unintentional downshift means.

So, a couple of questions:

1. Did your friend get third gear fully engaged? I would be really surprised if it would pop back into second. It would be far more likely to pop into a false neutral, but strange things happen sometimes.

2. What kind of acceleration was your friend doing? Was he really caning the bike and shifted into second instead of shifting into fourth? That would put some really bad stress on a whole lot of parts from the crank all the way to the cush drive assembly.

If there were no bits in the oil, then maybe something bigger broke off. If you ride it for a while and the gearbox seems to work, check the chain and both sprockets. Also take apart the rear wheel to see if the cush drive assembly got ripped to bits. For what its worth, a Triumph transmission doesn't hit its sweet spot until it is close to 10K miles old anyway. Assuming that it hasn't got killed first.

Post what you find out- we all might learn something.

smokestack · 10-14-2004

Just a thought,
could it be possible he kicked up some sort of debris from the road, which could have bound the chain/sprocket, or wedged up in the front sprocket case area. also maybe in the rim/swingarm. Check the wheel "spokes" for nicks/gouges, The sprockets for damage etc..even brake disk/caliper.
I do alot of off-road riding where this happens now and then and it makes a Hell of a bang sometimes and will lock up if it gets in just right.
I would definitely check the internals if nothing else could be found, just for peace of mind.

punisher · 03-29-2005

Ive shifted into first from second a couple of time, but caught it before I let the clutch out. I wondered if there was any damage, but there was no loud noises, and the clutch was in the whole time. Anyone else done this? Its happened twice to me while sort of not paying attention while leaving a stoplight.

TTsixxer · 03-30-2005

That noise were the dogs engaging seond gear very abrutly. Imagine the noise when you shift from neutral to first gear but 3 times louder.

05-03-2005

Hey, I'm the guy who dumped my bike last October.
I've had my guy take everything apart... and he found.... absolutely nothing wrong. He said that there was some wood (maybe part of a stick) in the chain. That doesn't really explain my skid pattern and the fact that it took 5 mins of rocking my bike and jumping on my shifter to get it out of gear! All I remember is riding in 3rd for about 10-20 seconds at around 35-40mpg. All of a sudden, a lout POP (like a firecracker) and my rear wheel locked up. My buddy riding ahead of me heard it and turned around even before I went down. Two landscapers approx 1/4 mi away heard it and thought I blew out a tire. I've ridden it another 300miles w/o a problem... i just get scared sometimes remembering what happened w/o an answer. I have pics of the skid marks but can't find a way to post them.