fractured by center stand....again

ILLF8ED · Sep 14, 2015

Not looking for any cure, just commenting. I led the Delta Ride yesterday with the local Norton Owners Club branch on Sunday (yesterday). We had some older models along - '56 Domi, mid 60s Atlas and a '63 Electra. In respect for the Electra I kept speed at 50mph or below. After 70 miles and a stop for lunch I noticed my fore arms and back of hands were tingly numb. You know the feeling - tap on the back of you arm and you can feel the tingling up to your hands. Obviously due to the difference vibration frequency....I don't usually cruise at such a low speed. OK the rest of the story. After leaving to return from lunch my center stand fractured at the cross tube (again). This is the original '72 stand. Likely the different vibration frequency that got to my arms also cause the broken center stand. No, I'm not going to replace the '72 stand with a stronger 850 stand. Getting it re-welded for $25. Used 850 center stands are going for more than $150....economics versus modification here. Only the second time the stand has broken in 18 years >35,000 miles. Now that both welds have been re-done likely the stand will last forever.

Nater_Potater · Sep 14, 2015

illf8ed said:
Obviously due to the difference vibration frequency....I don't usually cruise at such a low speed.

I have noticed that, with a 22 tooth sprocket and new muffler support rubbers, I don't shift into 4th at anything under 50 mph due to the crazy low-speed vibrations.

Nathan

batrider · Sep 14, 2015

You can improve the '72 centerstand by making it more 850-like and adding braces. I did this when mine fractured and it lasted many years. However, I think it is a losing battle. The holes get wallowed out and you will need to rebush also. I went with the later centerstand and the conversion spacers (see previous threads) -- finally -- and it is much much better. The spring is mounted differently and actually holds it up so it doesn't bounce on every bump. I didn't pay anywhere near that price either.

Russ

kerinorton · Sep 14, 2015

The 850 stand isn't much better. I have reinforced both mine with a pc of 1/2 high tensile rod bent to fit inside the lower legs and cross bar. I welded them in 2 points on each of the lower legs. I modified the pivot mounts with hat bushes to prevent the flogging of the engine/gearbox frame as well. I also riveted pcs of rubber [ an old rear tyre ] to the bottom of the 850m stand to get better height and grip .

My 850 is built to go anytime I feel like riding and is not meant to look pretty like the750. I still looks ok though. { a few dents and rusty bits, but hell, its a used machine ]

Dereck

frankdamp · Sep 14, 2015

If the Isos are correctly set up, there should be NO vibration felt at the bars above 900 rpm. I probably did 15,000 miles or more on the prototypes without any handlebar vibration. If you're getting tingly hands at 50 mph, something is seriously out of whack. Even on my works 650SS, driving 50 miles or so from home to work, the vibration wasn't that bad. OTOH, on a P-11, 20 miles would be enough to require finger amputation!

Bear in mind, our prototypes didn't have head steadies and I've never ridden a Commando that had one. They might be the conduit for vibrations into the frame and handlebars.

gortnipper · Sep 15, 2015

Frank - do you have knowledge as to specufucally why ut was felt they were needed after the prototype phase?

frankdamp · Sep 15, 2015

Sorry, no I don't. I could see the big crash of the motorcycle industry approaching, even after Dennis Poore's attempt to rescue Norton/AMC. I left N-V in June 1968, just after the Commando went on the market and emigrated to the US. The head steady was later than that, I assume. I hadn't realised it was a factory installation.

ILLF8ED · Sep 16, 2015

frankdamp said:
If you're getting tingly hands at 50 mph, something is seriously out of whack. Even on my works 650SS, driving 50 miles or so from home to work, the vibration wasn't that bad. OTOH, on a P-11, 20 miles would be enough to require finger amputation!

Hi Frank,

I'm not feeling any vibration at the handlebar, just had a tingling in my lower arms and top of hands after running 70 miles at slower than normal pace. My assumption was different frequency vibration even if imperceptible. I doubt anything is wrong with the isolastics. That said how many miles should the isolastic rubbers last? I've got 35,000 miles since with the last rebuild in 1998.

Bernhard · Sep 17, 2015

illf8ed said:
frankdamp said:

Hi Frank,

I'm not feeling any vibration at the handlebar, just had a tingling in my lower arms and top of hands after running 70 miles at slower than normal pace. My assumption was different frequency vibration even if imperceptible. I doubt anything is wrong with the isolastics. That said how many miles should the isolastic rubbers last? I've got 35,000 miles since with the last rebuild in 1998.

Click to expand...

Depends on where that you brought your rubber isolastics, I believe that there was a bad batch made at one time :?:

fractured by center stand....again

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