Comparison DT versus Norvil

Status
Not open for further replies.

plj850

Joined
May 31, 2009
Messages
377
Hi All
Have just fitted the DT head steady with the MK III spring attachment. I know there are tons of posts about the benefits from a technical viewpoint and even some comments about improved handling, numerous threads about the different headsteadies etc etc . However I have basically swapped out a Noril head steady for a DT head steady. I would be interested and I think it would be informative for other owners to read comparisons between the two from Commando owners who have had both types. (Especially as there are basically 2 types of headsteadies available the DT/CNW/Other Rose Joint (Helm Joint for all you guys the other side of the pond) and the box section Norvil/OldBrits type of Isolastic head steady)
So far my main concern is vibrations that I am getting specifically 1750-2000 quite severe vibration which the Norvil did not give me also footrest buzzing at 3500 and 5000.
The DT has definitely improved the handling but have yet to really push the bike to get a feel for how much better compared to the Norvil.
So in this case this is a direct comparison between a Norvil and a DT headsteady.(All ISO's are new last year and I checked before and after replacing the Norvil head steady with all clearances set to .008" the DT head steady was set up meticuosly the Norvil one I had needed loads of work to fit correctly initially but once I had done that it gave a very smooth ride from 3000 up and even below 3000 the vibration was not excessive.
 
One thing that could make a difference between the two as to vibration is did you have the MKIII spring assembly on the norvil headsteady ? Another thing I have found is the rubber in the replacement ISO's is stiffer than the original one's and it does not have as wide a sweet spot to quell the vibrations.
 
bill said:
One thing that could make a difference between the two as to vibration is did you have the MKIII spring assembly on the norvil headsteady ? Another thing I have found is the rubber in the replacement ISO's is stiffer than the original one's and it does not have as wide a sweet spot to quell the vibrations.
Click to expand...

Hi Bill thanks but when I mentioned the increased vibration I am reffering to the DT head steady (with the MKIII spring asembly fitted) not the Norvil head steady and more riding has confirmed what I feel is a dramatic increase in low frequency vibration around the 2000 mark.
 
Probably a silly question but have your tried varying the tension on the spring with the DT version - i thought the spring was added on the MkIII to try to control vibes at lower revs, but it needs to be adjusted to the correct tension to have the desired effect?
The other option is to remove the spring from the DT and see what effect that has, the spring being an optional extra anyway.
 
As I and ntst asked DID the norvil have the springs also??? if not the DT needs to be tried WITHOUT the springs as it IS NOT apples to apples. the springs can preload the isos and as I stated I DON'T LIKE the replacement isos as sold because of the increased hardness of the rubber and the NARROWER sweet spot in the RPM range to quell vibration. the replacements seem worst below 2,500 and above 3,500 .
 
I installed the DT with the spring, and it took a dozen or so runs to dial the spring in. The instructions say to adjust three flats at a time, and the it's a PITA.

I took the Norton up to NC last week, and it was very stable on those mountain roads - I wish I had more saddle time up there.

I played with the main ISOs first, trying to minimize vibration, then fine-tuned the the spring on the DT.

I think the rule-of-thumb on the Isolastics is:

Vibration 500-5000 RPM - both Isos too tight
Vibration 500-3000 RPM - front OK, rear too tight
Vibration 3000-5000 RPM - rear OK, front too tight
The tighter the Isos are, the more stable the bike in corners, so they should only be loose enough to dampen vibrations. I think mine are set at 3 holes from snug, which is something like .009 in my bike. (mine has the vernier conversion)

Once the Isos are dialed in, its trial-and-error on the MkIII-style spring to get the sweet spot.
 
bill said:
As I and ntst asked DID the norvil have the springs also??? if not the DT needs to be tried WITHOUT the springs as it IS NOT apples to apples. the springs can preload the isos and as I stated I DON'T LIKE the replacement isos as sold because of the increased hardness of the rubber and the NARROWER sweet spot in the RPM range to quell vibration. the replacements seem worst below 2,500 and above 3,500 .
Click to expand...

Hi thanks for the replies, no the Norvil never had the MK III Spring so I will remove spring from the DT (I see what you mean in terms of comparing apples to apples good point) I will get back to you in a couple of days .

Thanks Paul
 
BillT said:
I installed the DT with the spring, and it took a dozen or so runs to dial the spring in. The instructions say to adjust three flats at a time, and the it's a PITA.

I took the Norton up to NC last week, and it was very stable on those mountain roads - I wish I had more saddle time up there.

I played with the main ISOs first, trying to minimize vibration, then fine-tuned the the spring on the DT.

I think the rule-of-thumb on the Isolastics is:

Vibration 500-5000 RPM - both Isos too tight
Vibration 500-3000 RPM - front OK, rear too tight
Vibration 3000-5000 RPM - rear OK, front too tight
The tighter the Isos are, the more stable the bike in corners, so they should only be loose enough to dampen vibrations. I think mine are set at 3 holes from snug, which is something like .009 in my bike. (mine has the vernier conversion)

Once the Isos are dialed in, its trial-and-error on the MkIII-style spring to get the sweet spot.
Click to expand...

HI Bill checked my settings again and both ISO's set to .008 (well a 0.008 is a tight sliding fit and a 0.010 will not go so could be 0.009) So as suggested by bill and ntst for a fair comparison I will remove the MK III spring and compare the vibration between the Norvil and the DT.Then I will put it back on and try the MK III spring adjustment again although I have already used the full range of adjustment on the bolt of 12mm to 5mm as given in the instructions so will move spring back to what appears to be another spring location further back.When you say trial and error I assume you mean start with the spring at minimim tension spring at 31 mm length tension it by say 1/3rd of a turn ride the bike then keep adjusting till you find the best spring tension, thats what I tried before till I ran out of adjustment without any real improvement in the substantial vibration in quite a narrow band of 1700-2000 rpm mirrors show this up nicely.(Maybe in the other location I will see some improvement in the vibration)

Thanks Paul
 
thats what I tried before till I ran out of adjustment without any real improvement in the substantial vibration in quite a narrow band of 1700-2000 rpm mirrors show this up nicely.(Maybe in the other location I will see some improvement in the vibration)

Thanks Paul


Your working a VERY bad range to get it smooth out . I will not even try to ride or run in that low of an RPM . if your iso's are working proper than 2.500 is IMHO the lowest RPM to consider using.

If you watch a commando running in that low of an RPM it will become apparent why real fast as the motor assm will shake pretty violently if you have soft iso's.
 
BillT said:
I took the Norton up to NC last week, and it was very stable on those mountain roads - I wish I had more saddle time up there.

Bill
We need to get you up here next year in May for the three state ride we do. 2010 will be the 10th one and will be a week long event with a trip to wheels through time museum and a few day rides through the week. saturday will be the main ride that is a 200 mile loop that covers NC,TN,VA.
my place up here in TN we claim 489 turns in a 12 mile radius of the cross roads :mrgreen:

check out this link to see what we do.

http://www.britbike.com/forums/ubbthrea ... =24&page=1
Click to expand...
 
Sounds to me like the link might not be set correctly and its loading up the ISOs.

Cash
 
bill said:
thats what I tried before till I ran out of adjustment without any real improvement in the substantial vibration in quite a narrow band of 1700-2000 rpm mirrors show this up nicely.(Maybe in the other location I will see some improvement in the vibration)

Thanks Paul


Your working a VERY bad range to get it smooth out . I will not even try to ride or run in that low of an RPM . if your iso's are working proper than 2.500 is IMHO the lowest RPM to consider using.

If you watch a commando running in that low of an RPM it will become apparent why real fast as the motor assm will shake pretty violently if you have soft iso's.
Click to expand...
I know this is a bad range but I have only commented on this because the Norvil head steady I had fitted prior to swapping out with the DT did not have as severe a problem . The DT head steady has been fitted exactly as described in the instructions and I really took a lot of time to get it right so currently off the centre stand the link can be moved with the slightest touch when the bike is on the centre stand it is tight. For my purposes I use the bike a lot in London traffic so I have no choice but to spend a lot of time at pretty low rev's so assuming that my ISO's are set correctly which after 65,000 miles on my Commando and 20 odd years of ownewrship I should be able to do....if not I am in big trouble..:) When the bike is pulling fron 3,000 to 6,250 I have not noticed any major differences between the Norvil and the DT. Just a little more buzz in the pegs and bars at 3500 and 5000 but not enough to be a major problem.
Managed to give bike a run after work through some twisties and the handling is significantly better even intentionally pushing a bit hard into a couple of left handers on an empty stretch of road and and changing line enough to keep it in the right lane was not such a big deal as it was with the Norvil which really was not happy...not " a pig on rollerskates" feeling but just not great.
 
plj850 wrote;
Just a little more buzz in the pegs and bars at 3500 and 5000 but not enough to be a major problem.
Click to expand...
I too have fitted a DT headsteady, but I repaced the standard MK3 headsteady. I have noticed a slight buzz in (mainly) the right hand footrest which wasn't there before, but I have had my isolastics in bits and fitted a 1970s Craven rack onto the bike, and made these alterations all at the same time and so possibly I haven't quite got the Isolasticss in dead centrally. I took the supporting rods off the rack in case they were transmitting vibes down to the footrests, but no change, and I have to admit that I haven't tried dialing in the spring on the DT headsteady yetproperly yet.
So I am wondering if it may be the headsteady :?: I'll see if re-fitting the original headsteady alters this when I get time.

The buzz is only just noticable, so no big issue, just very similar to plj850s experience.
 
plj850 wrote;
Just a little more buzz in the pegs and bars at 3500 and 5000 but not enough to be a major problem.
Click to expand...
I too have fitted a DT headsteady, but I repaced the standard MK3 headsteady. I have noticed a slight buzz in (mainly) the right hand footrest which wasn't there before, but I have had my isolastics in bits and fitted a 1970s Craven rack onto the bike, and made these alterations all at the same time and so possibly I haven't quite got the Isolasticss in dead centrally. I took the supporting rods off the rack in case they were transmitting vibes down to the footrests, but no change, and I have to admit that I haven't tried dialing in the spring on the DT headsteady yetproperly.
So I am wondering if it may be the headsteady :?: I'll see if re-fitting the original headsteady alters this when I get time.

The buzz is only just noticable, so no big issue, just very similar to plj850s experience.
 
Status
Not open for further replies.
Back
Top