1983 R100 Front End SHAKE & SHIMMY

[Houseoffubar]

I'll throw in another for tires. I put a new front Metzler on a customers Kawasaki Concours, and it tank slapped violently, from 50, down to 25, any time you held on lightly, or let go of the bars.
I replaced the tire with the oem...no shake at all.

[chasbmw]

Shimmy at 30-40 mph is most likely to be the headstock bearings. The simple initial fix would be to clean and regrease the bearings and readjust.

How do you know when your bearings are too tight? The bike will tend to roll from side to side, keep adjusting the bearing until you remove the roll but not so loose that you have reintroduced the shimmy.

If you fit new bearings they will settle into position over the first 1000 miles, so you will need to keep readjusting them.

Don't use old manual tyre pressures, modern tyres work best with pressures in the mid 30s front, high 30s rear.

Avoid Metzler tyres as marketed for airheads.

[ME 109]

Originally Posted by supershaft

....... and jump them further than anyone I have ever rode with

Now we're talking.

Why does your broken shock mount spring to mind?

[Rob Farmer]

I've always found the biggest cause of these issues on the twinshocks to be wheel bearings that are incorrectly shimmed or bearings that haven't been shimmed for years.

[Moonshiner]

I can't add much to what's already been said here. But for me, it wasn't the steering head bearings. I bought my first '77 and rode it awhile before fixing or changing anything. I noticed a shimmy at about 35-40. Just in that range. Checked my front tire, it was cupped. Back tire was fairly worn and squared off. Rear shocks and front springs were original. Put on a pair of IKON's on the rear, adjusted for my bulk. Put Progressive springs on the front. Installed 2 new Metzelers. The thing rode then, and still does, like it's on rails. I have adjusted my steering head bearings over the years as well, and ALWAYS keep an eye on tire pressure.

[dm635]

Didn't know about bumping up tire pressure. I thought the original pressures were a little low.

[Stagehand]

I always check the battery, just in case.

[ME 109]

A think a flattened off rear tyre is way underestimated as a cause for front end shakes.
And everything else mentioned .

[supershaft]

Originally Posted by ME 109

Now we're talking.

Why does your broken shock mount spring to mind?

That and a lot of other things I have broke over the years. My problem is that I ride like I weigh 50 to 100 pounds less. I use to break frames (I almost broke a dirt bike frame in half once), bend axles, break and bend spokes, bend shocks, and the like. I have snapped a drive shaft in two and broke a FD ring gear in two (luckily that snapped in town or that could have killed me). I guess I am lucky my shock stud snapped here in town versus out on one of my local country roads were I would have probably been hauling the mail. I have had two damn scary high speed tube type flats that could have killed me too. Oh well, even in a rubber room life itself is a sexually transmitted fatal disease.

It seems like Metzelers are starting to get a bad buzz here in ADVR. I certainly don't like them but my dislike of them isn't for any handling issues I have seen them cause. I don't like them because they wear out super fast while having just average grip. If only tire wear had any correlation with tire grip like so many report. I would be running Conti Blitzes for their super grip! :)

[ME 109]

Originally Posted by supershaft

I don't like them because they wear out super fast while having just average grip.

I only run a metzeler on the front and can't agree they don't grip. At below 60 mph, machining valve covers in second and third gear curves, I trust them 100 %.
I have never had the front slip out on dry roads when going for it.
Ever had your bars go floppy for a moment 'cause the front wheel was lifted off the road by the valve covers?
and recoverd............. They grip.

[supershaft]

They grip but not any better than a lot of tires many of which last a lot longer and some of which grip better too as well as last a lot longer.

I don't trust any tire 100%. My 'race track only' Avons grip at least ten times better than Metzeler street tires and I slide them sometimes. My race Avons grip a lot better than street Avons and they grip a lot better than Metzelers I have had.

We have been through this before but I don't run crash bars on my bikes for that reason. I am pretty certain crash bars on my own bike would make me crash. I have never lifted my front tire off the ground dragging a valve cover. I have never banged into one that hard excepting maybe a near crash here and there but that is another subject IMO.

[craydds]

Originally Posted by supershaft

I am pretty certain crash bars on my own bike would make me crash. I have never lifted my front tire off the ground dragging a valve cover. I have never banged into one that hard excepting maybe a near crash here and there but that is another subject IMO.

Bought my bike, had some "crash bars" on it. My cousin, a freaky fast rider on his R100RS, said to "take them thangs off!" I have 'em in a box somewhere; I'll put them on the flea market someday for anybody that wants them. I did a track day at Arroyo Seco running my Metzlers, no tire worries and I was scraping some hard parts. Now, I have my suspension totally refurbished, should make a significant improvement. New Michelin Pilot Activs arriving by UPS tommorrow, got a new Marc Parnes wheel balancer today. New Michelins, awesome suspension set-up, what could possibly go wrong?

[100RT]

So Supershaft what is your problem, obesity or abuse?

[riceless950]

Hmmm?
Maybe improper fork alignment after spring swap.

Tires can have an effect also.

But as someone previously said. "Check Everything"

[supershaft]

Originally Posted by 100RT

So Supershaft what is your problem, obesity or abuse?

Neither! I am too tall!