V-Max Speed Wobble (ran it up to 115mph and...)

[Shuriken]

In post #84, you can see that these forks have what looks like progressively wound springs of some type. What is the correct spring orientation? Tighter windings at the bottom of the fork or at the top?

 

[Fire-medic]

I'm glad you were able to take care of it.

 

[Shuriken]

Spotted a local vmax and had to stop and chat of course. I got to see in person the various mods people do to create more stability. Check this out. There are a few random bling items on there that you'll see but he said it was super stable with that replaced front-end, frame braces, aftermarket rear shocks, etc.

He didn't know all the details as the bike was fully modified before he bought it but you can see his 2-line Galfer brake lines. I am planning on the 2-line Galfer SS brake line configuration as well. Of course, I'd love to know more details about the front end swap, here. He thought it was (or remembered being told) it was from a Ninja 750. Obviously, you get the USD forks of large diameter, larger diameter brake discs, better calipers, and presumably a shorter front end to lower the bike.

From the feel of the clutch compared to my 85, it must have brand new springs or even a more aggressive clutch kit because it has a heavy clutch pull and a fast dump. This had 2005 stamped on the steering head. (and yes, his fork seals need replacing!)

I am beginning the front caliper rebuilds. What good is testing the steering head if I don't have any good front brakes? So cannot report steering head results until I get through the caliper rebuilds and swapping to stainless lines. Waiting on the mail again...

 

[Shuriken]

Alright... it's back together finally.

Test ride reveals super smooth steering but... too loose. Shimmy shake on decel at around 45. Gotta tighten er up and test again.

 

[Shuriken]

Tightened. 45mph head shake gone. Testing 10mph faster increments now...

 

[Shuriken]

There is definitely an art to getting the bearings just right. I'm finding them too tight or too loose. Definitely don't want them too loose; slightly too loose makes the bull I'm riding angrily shake its head! Working on small ring nut turns.

 

[Tom Determan]

Shame on me for saying this but have you ever considered just staying out of the VBoost ? All these problems go away if you drive the speed limit.

You're welcome to disregard this.

 

[Shuriken]

Shame on me for saying this but have you ever considered just staying out of the VBoost ? All these problems go away if you drive the speed limit.

You're welcome to disregard this.

Haha... no worries.

Yeah, that would cost much less. But every time I get on the freeway or want to pass.....

 

[Shuriken]

Bike is all buttoned back together.

Took it out for more testing tonight after backing off of the head bearings a tad more.

Tooled around town as normal and passed the ton on the freeway passing a vehicle or 2.

Spent a number of rides inching up to the ton. I've done all of the deceleration tests as well with no shake on decel.

Steering is maybe still a little tight or it's just right and my shocks aren't damping. But I'm only gonna change one thing at a time.

But right now the steering is very smooth, no notchiness, and the newly rebuilt brakes, new fluid, pads and stainless lines have noticeably improved and smoothed up braking as well.

Should have done all this years ago but things get in the way...

Looking at shocks and tires right now. Have had the Metzler's for years. Need to get it right for the next tire brand.

 

[Shuriken]

150m ride revealed a lot. I need to back off torque another 1/4 turn for one thing.

However... I know the rear shocks aren't doing the job... I found evidence of prior oil leakage and that combined with the seat of the pants feel tells me it's time for new ones.

It's expensive but new shocks and tires are next....

 

[Gtista]

If I recall correctly, the proper torque for the lower steering head nut is only a couple of foot pounds. That is essentially finger tight. The top ring and retainer are just there to make sure the lower nut doesn't rotate due to steering head movement back and forth. Torquing up the lower nut doesn't seem to be a way to cure any steering issues. Seems like something else may not be right with the bike.

Over the years I have ridden many bikes, at least once up to 155 mph, and none have ever had the steering head/shakes issues this bike seems to have. I did actually have two tank slappers. First was a very worn out 1957 pre-unit Triumph 500cc Tiger with most every steering component shot. The second was a Harley Sportster when a pickup with a trailer pulled across from a side road right in front of me and I instinctively stood on both brakes and temporarily locked up both wheels. The Harley spaghetti frame lived down to the job. I did not go down, but I left a 20 yard long black snake pattern down the road before things calmed down.

Just my thoughts.
Gtista

 

[Fire-medic]

Sean Morley's YouTube video about adjusting the front end should be required reading for anyone who has replaced their steering head bearings and wishes to come up with a well-adjusted steering system.

 

[Shuriken]

I don't disagree with any of that.

I haven't pushed it back up into the higher speeds anyway. I will install new tires first!

 

[88bradb]

Bike is all buttoned back together.

Took it out for more testing tonight after backing off of the head bearings a tad more.

Tooled around town as normal and passed the ton on the freeway passing a vehicle or 2.

Spent a number of rides inching up to the ton. I've done all of the deceleration tests as well with no shake on decel.

Steering is maybe still a little tight or it's just right and my shocks aren't damping. But I'm only gonna change one thing at a time.

But right now the steering is very smooth, no notchiness, and the newly rebuilt brakes, new fluid, pads and stainless lines have noticeably improved and smoothed up braking as well.

Should have done all this years ago but things get in the way...

Looking at shocks and tires right now. Have had the Metzler's for years. Need to get it right for the next tire brand.

I have had good luck out of Metzlers on my 95. I usually get around 6-7000 out of my rear and 15,000 or so out of my front.

 

[Shuriken]

Well.... good and bad news, or not really bad, just news.

I just got everything back together again after a full carb teardown, clean, and rebuild. This totally restored the throttle response, idle, and pull off the line. Even at this elevation (over 5000ft), this bike pulls like a freight train. And..... the best part is that with fully rebuilt front brakes, it can actually stop now! Really, the power of this 40yr old V4 engine is something. I haven't ridden a bike that has the feel of a VMax.

So... this isn't a carb or brake thread, but if anyone questions the value of a full carb teardown or a full brake system rebuild, money and time can be the only issues. I'd say my front brakes may even be twice as good as they were after ditching all rubber lines and rebuilding the calipers. As far as carbs doing their job, when they are cleaned, synched, and jetted for elevation or other factors, this engine is all there.

But.... the front end is still not yet to my liking. I've backed off steering head torque and the steering is smooth and stable and very responsive at certain speeds. But now that I have a new front tire, new steering head bearings, new brakes, new fork oil and fork seals..... AND also with Progressive 412 shocks on the back (which are actually damping now), the bike does feel different. Unfortunately, I am going to have to exchange my 412s for a lighter spring, but everything feels great at low and medium speed.

No wheel wobble, or bounce, either. No head shaking right now. It just feels oversensitive at high speed. And with the rear end cleaned up with suspension that is damping, and with new fork seals, 5psi, new tire, new bearings, the bike in general feels like if you give it some small steering inputs at freeway speed and higher, the bars want to to oscillate back and forth a few times before settling down. This doesn't feel like head bearings, it actually feels like fork damping....

Maybe normal for the vmax but when I have been on other bikes..... FZ6, Suzuki Bandit, BMW GS, CBR, and even other cruisers, the steering doesn't really oscillate with high speed input, it just goes where you think it should go and stops there!

I am not describing a speed wobble, tank slapper, etc. right now. The work I have done has improved everything so far. I will double check head torque again but I've only been backing off on it since first install. So, still working at it...

 

[Fire-medic]

Try Progressive Suspension fork springs or those by Race-Tech, and their Cartridge Emulators. If you set them up properly along with the static sag, I bet you will see things being much-better. That may take multiple disassemblies to fine-tune things, but follow the directions, and you will be happy with the end results.

 

[Shuriken]

I may get to that certainly in a bit.

Today I replaced the 2008 ME880s with new tires, greased the wheel bearings and gears.

I still plan to get to the swingarm bearings soon as well. However, the bike is smooth and safe for speed limit riding.

I will do some more ride testing and post back.

 

[Shuriken]

Shinko 230 tires maybe made the front end even more sensitive.

They do hookup at the light though. It may lift the front off a few inches...

Probably time to re-think the front forks now. I gotta get some damping out of these forks....

The big clue might be this: ot highway/freeway speed, the only way I can correct the steering oscillations is by pushing forawd on the steering equally. Having gone through just about everything, how could it now not be fronk forks not damping well enough?

 

[Shuriken]

Wow!

So .... what I am experiencing is the start of the high speed weave. Pushing forward on both bars equally with force cancels the weave. I will actually have to test laying over the tank but I will not be attempting any high speed crap until I get this more sorted out.

It's interesting to see the front forks in this video operating independently of each other during the wobbles and weaving. It would seem to indicate that if the steering head bearings are properly configured if the tire is good, wheel bearings good, then improper spring tension and damping and rider weight come heavily into play.

I will change wheel bearings. However, I have work to do regarding testing of springs and damping...

 

[Shuriken]

Dropped front and rear tires to 36psi each.

Discharged all of the air from the front forks, now 0psi.

Donned a 45lb backpack.

Ride test showed noticeable reduction in weave. I tested lying close to faux tank as well as upright. Upright actually seemed a bit better but maybe just because this translates more pull to the steering head.

But at the moment, I'm operating on the hypothesis that the front end is configured for a heavier rider.

It has progressive springs but I don't know the spring rates.

I tried to call progressive twice today and get put on permahold.

Does anyone know how to match progressive fork springs to rider weight?