steering dampener and tire questions for a 72 interstate.

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10drum

10drum

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Ok, I've read through some of the previous post about steering dampeners. I'm one who believes in stock (as it was designed), except for Lucas wiring.

This 72 Interstate I've been getting back on the road, is dialed in pretty good. However, it does develop a slight shake at speeds under 40mph while slowing down, and only if I loosen my grip. It seems as if the road may contribute to the shake, because it doesn't do it very often. I will be replacing the tires next spring, the K81's that are on the bike, are in great shape, but they are 10 years old. I wired a 74 commando for a friend a couple of years ago, and his had a dampener. I didn't ride it any, just wired it. I rebuilt the front tubes, and the triple tree seems solid and rotates smoothly. I've thought about installing the cNw front end, just because it looks so damn cool. I love the volt meter and indicator lights. I probably won't.

Anyway,

Should I wait till I install new tires, or is the design of the bike susceptible to shake? I plan to pull clean and/or replace the isolastic suspension this winter, if that would have any effect. Would new head bearings be a better first step? I don't ride hard or fast. It seems stable most of the time.

Thanks for all replies.

Phil
 
You nailed it when you asked: "is the design of the bike susceptible to shake"?
There has to be when a very long list of different reasons are offered up as the solution to the problem.
I would go so far as to call it a design flaw. Or multiple design flaws.
Prepare for the barrage of contradictory advice.
 
While I run with dampener , I did go through process of new wheels both ends , new tires , new bearings & axles, then replaced steering head bearings and tried different bars , ended up trying the dampener and now ride with more confidence .... that I didn't get before even after all the changes , think mine has 6 settings and mostly it kept in the third position ... I suspect all these hand built bikes vary to some degree and respond differently to each rider and setup so if you not happy after the basics have been upgraded you may benefit from fitting a dampener ..... if no help you can always move it along ...
 
10drum said:
Ok, I've read through some of the previous post about steering dampeners. I'm one who believes in stock (as it was designed), except for Lucas wiring.

This 72 Interstate I've been getting back on the road, is dialed in pretty good. However, it does develop a slight shake at speeds under 40mph while slowing down, and only if I loosen my grip. It seems as if the road may contribute to the shake, because it doesn't do it very often. I will be replacing the tires next spring, the K81's that are on the bike, are in great shape, but they are 10 years old. I wired a 74 commando for a friend a couple of years ago, and his had a dampener. I didn't ride it any, just wired it. I rebuilt the front tubes, and the triple tree seems solid and rotates smoothly. I've thought about installing the cNw front end, just because it looks so damn cool. I love the volt meter and indicator lights. I probably won't.

Anyway,

Should I wait till I install new tires, or is the design of the bike susceptible to shake? I plan to pull clean and/or replace the isolastic suspension this winter, if that would have any effect. Would new head bearings be a better first step? I don't ride hard or fast. It seems stable most of the time.

Thanks for all replies.

Phil
Click to expand...
There are many factors that can cause instability.
Tires are certainly one of them. At ten years old they should be replaced anyway.
According to Bridgestone motorcycle tire have a shelf life of 5 years.
Since you are planning on replacing those anyway, start there, check the bearings while you are there.
The steering stem bearing are something that can be checked by you, and do not necessarily need to be replaced just because of age.
I am sure there are lots of other items that can be easy to check, a few include checking every bolt you can reach for tightness, alignment of the rear wheel, swingarm bushings.
I did want to point out there is no such thing as a steering dampener, there are steering dampers.
A steering damper is a band aid and or insurance policy, it is installed to fix a symptom, front end "shake" , it does not fix the underlying problem, the cause of the "shake" .
 
Any motorcycle can go into a tank slapper if you do certain things. Sometimes you only have to inadvertently lock the front brake. Riding without a steering damper might be asking for trouble. With road bikes you can be lulled into a sense of security, but nasty is always there waiting with any motorcycle. The steering damper can stop the worst from happening.
 
Dan said,
-tire have a shelf life of 5 years.........yep I know, the key word is "shelf".
-steering stem bearing are something that can be checked by you.....comparatively speaking, they seem fine
-check the bearings while you are there.....done
-every bolt you can reach for tightness, alignment of the rear wheel, swingarm bushings....done
-damper.....a dulling or deadening influence
-or
-dampener......To deaden, restrain, or depress....seems like six of one, or half a dozen of the other.

It seems to only do it when I'm slowing down below 40, from 50 or 60, on smoother surfaces. Riding season is nearing an end, so I'll probably work on the isolastics this winter, install tires in the spring, see how it does then. This bike does not to handle as well as an OIF Triumph, but it handles better than the 60's Triumphs. The ride is the smoothest of any bike I've owned. It's like, what? was that a railroad track? It's a great bike.


Thanks for the replies.
 
10drum said:
It seems to only do it when I'm slowing down
Click to expand...
Then the engine is in a load mode rather than pulling. Pulling will raise the front end slightly, coast will pull the front end down so less trail.+ less stable or caster

The other thing I have found is while many look to the front end for trouble but if you put the bike on the center stand and go to the rear and grab the rear frame loop and push side to side you will very likely see the front tire swing side to side also. I call it the "tail wagging the dog". Almost guaranteed the speed at which it wobbles is a resonant frequency of the rear wheel's effect on the whole bike...Loose isolastics aid the bike chassis go into resonance, not sure on this one....
Rear wheel balance or especially a TRUE running rear rim therefore the tire and reduces the resonant drive source of energy.
 
Years ago, I had a serious problem with my 750, where it would get a tank slapper on sweeping corners at 70 mph or more. A steering damper never fixed it but replacing what appeared to be a good Avon GP fixed the problem.

Now I run TT100's. They are good but after 2000 plus miles or so I noticed the front wobbled at 30 mph when I took one hand off the bars. I mentioned this in a post just recently. The front tyre , which was worn at the sides, caused this wobble but was ok at higher speeds. This was experienced buy other experienced Norton riders here in NZ.

So long as your isolastic and swing arm systems are in perfect order, with good tyres, your commando will handle like a dream. You don't need a steering damper unless you are racing.

Replace you old font tyre at least..
 
Dynodave said,

Then the engine is in a load mode rather than pulling. Pulling will raise the front end slightly, coast will pull the front end down so less trail.+ less stable or caster.......great analogy, it really gets me thinking. Thanks

kerinorton said,

Now I run TT100's. They are good but after 2000 plus miles or so I noticed the front wobbled at 30 mph when I took one hand off the bars. The front tyre , which was worn at the sides, caused this wobble but was ok at higher speeds. This was experienced buy other experienced Norton riders here in NZ.....exactly

So long as your isolastic and swing arm systems are in perfect order, with good tyres, your commando will handle like a dream. You don't need a steering damper unless you are racing. Thanks a lot keri, I will have my isolastic in perfect order by spring, and it will have new tires.......I'm not a big fan of the TT100/K81s. My 79 is suppose to have K81's, but I like K70s best on that bike,( just for the roads I ride), however, I don't think they're available in the sizes this bike needs? I'll save tire questions for another thread.

Thanks for the replies
 
10drum said:
Dynodave said,

Then the engine is in a load mode rather than pulling. Pulling will raise the front end slightly, coast will pull the front end down so less trail.+ less stable or caster.......great analogy, it really gets me thinking. Thanks

kerinorton said,

Now I run TT100's. They are good but after 2000 plus miles or so I noticed the front wobbled at 30 mph when I took one hand off the bars. The front tyre , which was worn at the sides, caused this wobble but was ok at higher speeds. This was experienced buy other experienced Norton riders here in NZ.....exactly

So long as your isolastic and swing arm systems are in perfect order, with good tyres, your commando will handle like a dream. You don't need a steering damper unless you are racing. Thanks a lot keri, I will have my isolastic in perfect order by spring, and it will have new tires.......I'm not a big fan of the TT100/K81s. My 79 is suppose to have K81's, but I like K70s best on that bike,( just for the roads I ride), however, I don't think they're available in the sizes this bike needs? I'll save tire questions for another thread.

Thanks for the replies
Click to expand...
'You don't need a steering damper unless you are racing.'

You are much more likely to find something on a public road, which might cause you to have a tank slapper. On race tracks, the surfaces are usually closely monitored - even the small step at the edge of the bitumen is usually smoothed and blended. On the local roads where I live, the trucks leave a minor depression, the edges of which can steer your bike and put you off-balance..
The biggest joke on old bikes are the friction devices under the seat on a Vincent - if they are not tight you are unsafe at any speed.
 
First, I can say that a wheel once the tyre has worn down a bit would benefit from rebalancing.
Also the steering head races always wear an indentation in the straight aheard position. Ball races also get flattened at one point because they only wear in one plane , also applied to needle roller bearings, as the steering does not turn 360 degrees.
 
Bernard said;

Also the steering head races always wear an indentation in the straight aheard position.

I've thought about this as well. This is very noticeable on worn BMW swing arm bearings. This might explain why original head bearings on triumphs are individual balls sandwiched between two races. This would allow the balls to rotate independently in other directions. I have not had the triple tree apart on this bike. The parts book indicates that the head race bearings are housed bearings. Perhaps it would be beneficial to replace those???? Probably should've done that when I built the fork tubes. Oh well, just means more fun.

Thanks again for the replies.
 
I think if you feel you need a steering damper then get one
I'd think it to be essential on a race bike but a road bike?
I had a problem with high speed weave on my commando, I fitted one of those 7 position Kawasaki dampers but was never happy with it
Like sticking a plaster on a wound
It turned out to be rear rim /tyre choice it's never done it since I went back to a 19" back wheel and correct tyre
How many road bikes come with steering dampers?
Some do I know
And some need them,but does a commando? I'm not so sure
I know mine dosent, I'd be looking elsewhere before a last resort of a steering damper
Just my opinion
 
I always use taper roller bearings in the steering head because the impact area is so much greater. It means the loads are not so concentrated.
 
baz said:
I think if you feel you need a steering damper then get one
I'd think it to be essential on a race bike but a road bike?
I had a problem with high speed weave on my commando, I fitted one of those 7 position Kawasaki dampers but was never happy with it
Like sticking a plaster on a wound
It turned out to be rear rim /tyre choice it's never done it since I went back to a 19" back wheel and correct tyre
How many road bikes come with steering dampers?
Some do I know
And some need them,but does a commando? I'm not so sure
I know mine dosent, I'd be looking elsewhere before a last resort of a steering damper
Just my opinion
Click to expand...
The first Commandos were capable of mishandling very badly because they probably had road race steering geometry. On all Commandos the head steady affects the handling. - You need a steering damper because it is there waiting to get you when you don't expect it. A steering damper does not affect the steering if it is not wound up too tight. However if something sudden happens the hydraulic pressure uithin the damper makes the event controllable. - Better safe than sorry - especially with isolastics and a duff head steady ?
 
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If your Commando is nice and tight, you might never need the steering damper. But the day you need it, you will be glad you have it. Even a bike which is properly set up can mishandle and chuck you off. You might believe your Commando handles better than any Japanese bike, but the Japanese were not stupid or really cheap-skate.
 
Check headsteady. Stock 750 and 850 headsteadies allow too much side to side movement. A Dave Taylor, CNW or homemade link rod headsteady will eliminate the wobbles after all the other things mentioned don't help.
 
Modern Ducatis probably handle very well, but always seem to have a damper fitted. Perhaps if your bike's handling is perfect, you need the damper to stop the bike wagging it's head as you accelerate out of corners ? However Ducatis might be faster.
 
When I had my steering damper fitted and it didn't stop the high speed weave I backed the setting off to zero
Whilst it was still fitted I took the bike for its annual MOT inspection
When the tester got to the forks he asked about the damper
I told him I'd fitted it to try and cure a high speed weave but it didn't work
He said "well sir if it doesn't work it shouldn't be fitted to your motorcycle" I replied no the damper works but didn't solve the problem ! The reply was "but sir you just said it didn't work so it shouldn't be fitted to your motorcycle" we went round in circles many times!!
He grudgingly gave me the MOT with a warning to not bring a motorcycle for an MOT fitted with a device that doesn't work!!!
You couldn't make this up!
Needless to say I never use that place anymore
 
Even when backed right off, hydraulic steering dampers still work if you get the tank-slapper. If the damper moves at high speed the hydraulic part gets stiffer. If you don't get the tank-slapper and you have it backed-off, it does not work. However curing a weave is not really the reason you have it. You have it to stop the handle-bars turning into a blur. If it ever happens to you, get your hands off the bars and grab the tank, the damper will smooth out the oscillations pretty quickly. But be careful when you grab the bars again - do it without actually grabbing - open hands then slowly. are the go. If you grab the bars when they are still shaking, you will probably get launched. The steering head only has to be moving around slightly to be able to exert a lot of force. If it happens to you, it looks horrible, but it can easily be controlled.
The last big crash I had was one of those - did not get my hands off quick enough. - out of practice.
 
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