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Author Topic: Instability on C5  (Read 15066 times)

gashousegorilla

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Re: Instability on C5
« Reply #180 on: August 30, 2010, 01:41:45 AM »
 Some more. That important rubber bush and notch at the front of the fender. Notice how it is not seated. Also new mounting hole loctions after fender correction.
« Last Edit: August 30, 2010, 01:57:21 AM by gashousegorilla »
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

gashousegorilla

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Re: Instability on C5
« Reply #181 on: August 30, 2010, 01:45:38 AM »
 And some more. After  a little compounding, the fender will look fine.The fender looks a little high, but the bike is on it's center stand in the first pic. Before refitting the fender, it was shifted back about 1 1/2". I  felt it looked better that way, but form must follow function. Remember, mine is one of the early bike's, The look may explain the mistake, I might make the same one. Who would think the fender structure would have such an impact on high speed  stability? ???  As a bike builder this has tought me alot, and what to look out for. I definatly think what we all learned was huge ,in all respects.

 Here's to you Ma, keep looking out for your boys ;) And yes I remember, I'll only ever have but one ;)
 Danny.
« Last Edit: August 30, 2010, 02:45:28 PM by gashousegorilla »
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

BRADEY

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Re: Instability on C5
« Reply #182 on: August 30, 2010, 08:05:45 AM »
This is great going for everybody who contributed to the thread. Now its time Kevin takes up this matter with the factory in India, so that the issue is taken care of on the assembly line itself (I know they are working under stress, but turning out top quality trouble free machines will be a wonderful feeling for them).

By the way, just noticed a strange thing, the engine is vibrating more ever since the tweeks were carried out to the rear end. Earlier I could do 75 MPH with a pillion and the bike was smooth as a HONDA, but now it starts to vibrate beyond 65 MPH

Not only that the top speed has come down from 90 MPH to 83 MPH. Is there something I must look into, or should I do the old BSA trick first  ;D
« Last Edit: August 30, 2010, 08:09:12 AM by BRADEY »

shappers

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Re: Instability on C5
« Reply #183 on: August 30, 2010, 09:50:30 AM »
Hi GHG, do my eyes decieve me or does the left hand shock in dsc00727 appear not to be perpendicular. The bit bolted to the swinging arm looks closer to the centre line than the top.

I've had a look at mine and it appears to be the same.  I'll try and do some careful measurements over the next few days.

As an additional observation you may have seen my attempt at raising the gearing using a Honda rear wheel. 

While doing this I noticed the rear mudguard appered to be out of line so undid both support bars nuts and bolts and straightened it all up with a length of wood.  A bit brutal I know but it did the job. 

Anyhow yesterday was the first time out where I got up to about 75mph true speed and lo and behold NO WEAVING.  With the caveat that I was leaning forward with arms more tucked in that usual and a relaxed grip on the bars.

Thats what I call a result!  And confirms what you all have been doing!

Cheers, Shappers.


gashousegorilla

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Re: Instability on C5
« Reply #184 on: August 30, 2010, 03:05:04 PM »
This is great going for everybody who contributed to the thread. Now its time Kevin takes up this matter with the factory in India, so that the issue is taken care of on the assembly line itself (I know they are working under stress, but turning out top quality trouble free machines will be a wonderful feeling for them).

By the way, just noticed a strange thing, the engine is vibrating more ever since the tweeks were carried out to the rear end. Earlier I could do 75 MPH with a pillion and the bike was smooth as a HONDA, but now it starts to vibrate beyond 65 MPH

Not only that the top speed has come down from 90 MPH to 83 MPH. Is there something I must look into, or should I do the old BSA trick first  ;D
Yes great indeed! But I'm not so sure the problem is that wide spread. Again mine was a early model. After this learning process, we know what to look for. A rear fender that looks a little too far back and in, as compared to other bikes. Any loosening of the fasteners in the tail, etc. Remember, this is a single, thats why they say to check those fasteners.
 Bradey I suspect why your feeling more vibration is due to the fact, that some of that flex was removed from your tail end. Why your seeing a reduction in speed? 83 is pretty damn good. I suspect it has something to do with air flow over that gorgious tail light/plate holder. ;)
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

gashousegorilla

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Re: Instability on C5
« Reply #185 on: August 30, 2010, 03:33:50 PM »
Hi GHG, do my eyes decieve me or does the left hand shock in dsc00727 appear not to be perpendicular. The bit bolted to the swinging arm looks closer to the centre line than the top.

I've had a look at mine and it appears to be the same.  I'll try and do some careful measurements over the next few days.

As an additional observation you may have seen my attempt at raising the gearing using a Honda rear wheel.  

While doing this I noticed the rear mudguard appered to be out of line so undid both support bars nuts and bolts and straightened it all up with a length of wood.  A bit brutal I know but it did the job.  

Anyhow yesterday was the first time out where I got up to about 75mph true speed and lo and behold NO WEAVING.  With the caveat that I was leaning forward with arms more tucked in that usual and a relaxed grip on the bars.

Thats what I call a result!  And confirms what you all have been doing!

Cheers, Shappers.


Thanks shappers. The verticle angle is off a little, but I don't think it's a big deal. It's not drastic. It's due to the fact that the angle changes on the lower shock mount on the swing arm, as you tighten up the rear axle. There is flex at the rear of the swing arm. You probably noticed it when you took off your back wheel. The rubber bushing at the shock mounts compensate for this.  That why you see the sliding of the bush over the spacer, well thought out.
 The off centered position of the fender, again I think is by design. Remember they must allow for the spacing of the sprocket/ brake drum. If the fender was centered, there would be a larger gap at the right side fender stay and fender, as looking at it from the rear. That would make the fender or tail section weeker, because of the greater span and more prone to oscillate, I think.The fender is part of that whole structure. That tail structure should be centered over the frame, not just the back wheel. I bet, if you put the fender back, your results might be a little better? Maybe? And what ever you do, DON"T PUT ANY LOAD ON THE FRAME THROUGH THE FENDER STAYS :D
Dan.
« Last Edit: August 30, 2010, 08:38:58 PM by gashousegorilla »
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

gashousegorilla

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Re: Instability on C5
« Reply #186 on: August 30, 2010, 10:33:35 PM »
  Boys, just a heads up on something unrelated while I'm seeing it. A misaligned, or improperly fitted front fender will tend to pull or twist a fork leg. When fitted correctly, you should see no scratching on the schroud or fender. Everything should be nice and centered. Adjust using the mounting locations on the fender and lower fork leg.Believe me i've made the mistake. ::) There is a difference of about an inch, between the front and the rear front fender stays.10 5/8 in front 9 5/8 in back. I'm removing my hidden fork brace, and mixed them up.
« Last Edit: August 30, 2010, 11:22:42 PM by gashousegorilla »
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

Ducati Scotty

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Re: Instability on C5
« Reply #187 on: September 01, 2010, 04:56:41 AM »
Yup, I got a couple little scratches on my fork shrouds too.  Re-adjusted the fender and all is well.

My C5 (2010) has a different style mount than yours GHG.  It looks like you have little tabs on the strut that the fender mounts to.  My strut has standoffs with tapped holes on the back side, the fender bolts right to it.  Must be a later design.

Scott

gashousegorilla

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Re: Instability on C5
« Reply #188 on: September 01, 2010, 05:23:56 AM »
Yup, I got a couple little scratches on my fork shrouds too.  Re-adjusted the fender and all is well.

My C5 (2010) has a different style mount than yours GHG.  It looks like you have little tabs on the strut that the fender mounts to.  My strut has standoffs with tapped holes on the back side, the fender bolts right to it.  Must be a later design.

Scott
Yea scott, I was told  that the new bikes have a better designed fender mounting system, from what it sound like, it's stronger. Should help take  some of that spring and waggle out of the tail .
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

Ducati Scotty

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Re: Instability on C5
« Reply #189 on: September 01, 2010, 02:53:53 PM »
This is great going for everybody who contributed to the thread. Now its time Kevin takes up this matter with the factory in India, so that the issue is taken care of on the assembly line itself (I know they are working under stress, but turning out top quality trouble free machines will be a wonderful feeling for them).

By the way, just noticed a strange thing, the engine is vibrating more ever since the tweeks were carried out to the rear end. Earlier I could do 75 MPH with a pillion and the bike was smooth as a HONDA, but now it starts to vibrate beyond 65 MPH

Not only that the top speed has come down from 90 MPH to 83 MPH. Is there something I must look into, or should I do the old BSA trick first  ;D

Vibrate?  Is it the chassis or the engine?

Scott

gashousegorilla

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Re: Instability on C5
« Reply #190 on: September 02, 2010, 12:34:05 AM »
Vibrate?  Is it the chassis or the engine?

Scott
I'm thinking his chassis is tighter, so he's feeling it more? I have'nt noticed a difference.Like when you have a regulator buzzing, then loosen the union on the vent and it goes away. Tuneing fork effect.
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

csbdr

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Re: Instability on C5
« Reply #191 on: September 02, 2010, 04:35:18 PM »
R80RT, you and I got our bikes from the 1st 2 containers.  neither one of us had a stabilityproblem, but I saw that you had made some of these changes and felt it was better.  Were the improvements enought to warrent taking the rear end apart?  Especially if there aren't any identifyable "problems"? I think you just did the washers on the shocks, right? or did you realign the rear fender as well.

r80rt

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Re: Instability on C5
« Reply #192 on: September 02, 2010, 05:20:20 PM »
I just put washers at the top of the shocks, didn't do anything else. It seems slightly better, nothing amazing and I doubt it was worth the effort. If I had to have the fender off for some reason I'd put the washers in just because, but I wouldn't make a special effort to do it.
« Last Edit: September 02, 2010, 05:46:24 PM by r80rt »
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Ducati Scotty

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Re: Instability on C5
« Reply #193 on: September 02, 2010, 05:35:33 PM »
I'm thinking his chassis is tighter, so he's feeling it more? I have'nt noticed a difference.Like when you have a regulator buzzing, then loosen the union on the vent and it goes away. Tuneing fork effect.

Just curious because I'm noticing something similar in the last 1500 miles or so.  I'll start another thread, this one is long enough ;)

http://www.enfieldmotorcycles.com/forum/index.php/topic,8465.0.html

Scott
« Last Edit: September 02, 2010, 07:00:26 PM by Ducati Scotty »

csbdr

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Re: Instability on C5
« Reply #194 on: September 02, 2010, 08:44:00 PM »
I just put washers at the top of the shocks, didn't do anything else. It seems slightly better, nothing amazing and I doubt it was worth the effort. If I had to have the fender off for some reason I'd put the washers in just because, but I wouldn't make a special effort to do it.

Good to know.  I'll keep it in mind if I ever put different shocks on the rear or something.