The "unstable" issue I cannot seem to cure
#11
02-05-2019, 02:13 PM
One thing I forgot to mention I fitted a number plate bracket on the left hand side swing arm just like loads of other do, and have done and I did this pretty soon after getting my bike so can' comment if it was there before fitting it.? Anyhow I was wondering if the low bracket with the no-plate may be causing some turbulence, probably clutching at straws here maybe.? 
#12
02-05-2019, 02:15 PM
One thing I forgot to mention I fitted a number plate bracket on the left hand side swing arm just like loads of other do, and have done and I did this pretty soon after getting my bike so can' comment if it was there before fitting it.? Anyhow I was wondering if the low bracket with the no-plate may be causing some turbulence, probably clutching at straws here maybe.?
#13
02-05-2019, 02:23 PM
Hi JWCFatboy your not alone on this one!!! I too have the feeling of my 2018 48 Special being slightly unstable at speed, seems fine at cruising speed but like you I can't pinpoint the cause. In your case you have changed out most things that could possibly cause the problem, whereas mine still has the standard shocks etc in place.
I too have been wondering if a steering damper may cure it, but not totally convinced on that one because the front end seems to be stable enough, I sort of get the feeling it's the back end that's actually unstable, and to be honest although unpleasant it never ever feels like it's going to get out of control.
A few years back I had a Dyna which scared the s**t out of me a few times due to getting into near tank slappers, but I found the cause to be the handlebars which were too wide.
Anyhow I will keep an eye on this thread to see if either your good self or someone else comes up with the answer........if there is one.
I too have been wondering if a steering damper may cure it, but not totally convinced on that one because the front end seems to be stable enough, I sort of get the feeling it's the back end that's actually unstable, and to be honest although unpleasant it never ever feels like it's going to get out of control.
A few years back I had a Dyna which scared the s**t out of me a few times due to getting into near tank slappers, but I found the cause to be the handlebars which were too wide.
Anyhow I will keep an eye on this thread to see if either your good self or someone else comes up with the answer........if there is one.
#15
02-05-2019, 04:06 PM
I doubt the brace or damper will help. The 48 has oversize thick 49mm front shock stems as well as a good thick cross over brace on top of the mudguard already... My gut says the 16" front is to blame... that is the only real difference between the older AND other Sportsters. My only other bike with a 16" front was a 750 Yamaha way back. It only came with this rim for a year.... when Yamaha changed to a 17" front... and as you may have guessed the 750 with the 16" always felt unstable ....
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JWCFatboy (02-06-2019)
#16
02-05-2019, 06:25 PM
HDF Community Team
The smaller the rim diameter, the "quicker" the turning. I recall reading an article about GP bikes many years ago, and it basically said a skateboard wheel up front would turn unbelievably, but completely unstable. I think the smaller rim could definitely be a factor. If you have Fatboys, you're probably pretty well used to wide tire handling versus something "odd."
That's why people take headers on those Razor scooters all the time, the small wheels just turn too quick and BAM, you're on your ***.
John
That's why people take headers on those Razor scooters all the time, the small wheels just turn too quick and BAM, you're on your ***.
John
Last edited by John Harper; 02-05-2019 at 06:27 PM.
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JWCFatboy (02-06-2019)
#18
02-05-2019, 07:20 PM
Grand HDF Member
changing both forks' guts either for Progressive monotubes, or Ohlins NIX-22 system for full adjustability.
good luck,
T.
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JWCFatboy (02-06-2019)
#19
02-06-2019, 12:50 AM
#20
02-06-2019, 01:00 AM
Regarding the stiffness and little travel of the Forty Eight: I stripped my front completely and replaced the fork oil with ATF. It did not actually changed anything. Then I made a break through! I decided to revalve the front shocks to take the harshness out BUT just before doing that I bought a pair of the previous gen. Sportster rear shocks (320mm). This much transformed the bike's comfort. It now rides less harsh and seems that the energy transfer to the front is much less and no need for revalving the front. Unfortunately it left the unstableness as it was.
The search for the cure goes on!!
The search for the cure goes on!!