Today I collected my bike from Maxton Engineering (UK) where I've had their suspension fitted front and back. I'll do a report on that once I've got a few enthusiastic twisty miles under my belt but in the mean time I wonder if anyone can explain the unusual front suspension design that is fitted by Honda to the CB1100, it certainly caused a raised eyebrow at Maxton although they had occassionally seen this kind of thing before. Why would Honda fit different length springs to each of the fork legs and compensate by using odd length spacers? Are all CB1100's so equipped and if so, can anyone explain the engineering criteria behind such a design?
Weird Suspension Design
- Thread starter Paulb_imp
- Start date
Today I collected my bike from Maxton Engineering (UK) where I've had their suspension fitted front and back. I'll do a report on that once I've got a few enthusiastic twisty miles under my belt but in the mean time I wonder if anyone can explain the unusual front suspension design that is fitted by Honda to the CB1100, it certainly caused a raised eyebrow at Maxton although they had occassionally seen this kind of thing before. Why would Honda fit different length springs to each of the fork legs and compensate by using odd length spacers? Are all CB1100's so equipped and if so, can anyone explain the engineering criteria behind such a design?
LakeWylieJoe_imp
Running like a top
My '86 Nighthawk S has unequal spring lengths and spacers. The fork was designed that way so one fork leg could accommodate the TRAC anti-dive mechanism, which was only installed on one side.
I have no clue why this fork is designed this way, though. Maybe it's a way of getting two complimentary spring rates into play at the same time. Whatever it is, there was no doubt some reasoning behind it. They would have used common parts on both sides unless there was a reason not to.
I'd love to hear a Honda engineer explain...
I just looked at the US parts fiche for the '14 CB1100 standard and CB1100DLX, and both show a common spring and spacer part for both fork legs. Are you sure those parts came out of your fork?
I have no clue why this fork is designed this way, though. Maybe it's a way of getting two complimentary spring rates into play at the same time. Whatever it is, there was no doubt some reasoning behind it. They would have used common parts on both sides unless there was a reason not to.
I'd love to hear a Honda engineer explain...
I just looked at the US parts fiche for the '14 CB1100 standard and CB1100DLX, and both show a common spring and spacer part for both fork legs. Are you sure those parts came out of your fork?
fritzwilliger_imp
Running like a top
Perhaps this was someone's "spring fling?"Paulb_imp said:
My two cents... spoken with "forked" tongue...!
fritz
Lord Popgun
Road warrior
Looking at the parts fiche it looks like there is only one spacer listed for all models/years. Used on both sides. So I don't know.
flynrider
Road warrior
When the '14 DLX and EX came out, it was noticed that the service manual specified different amounts of fork oil for each leg (unlike the '13 models). The pic above definitely illustrates why they require different amounts, but I'm still mystified as to the reason for this asymetrical design.
Drat! I shall have to resort to the dreaded search function, but I'm sure this oddity has already been identified on the forum. I'm not sure anyone was able to explain the reason.
PS. Fritz, you really uncoiled with that post.
PPS. Try here where our man TINK has posted an excellent how-to on replacing fork springs. His explanation for the longer spring in the left for of the DLX (and presumably the EX) is that it compensates for the extra weight.
PS. Fritz, you really uncoiled with that post.
PPS. Try here where our man TINK has posted an excellent how-to on replacing fork springs. His explanation for the longer spring in the left for of the DLX (and presumably the EX) is that it compensates for the extra weight.
rboe
Road warrior
I think this topic came up in a book on Guzzi's. It's a rather trick way to have a sophisticated suspension with one leg responsible for one behavior, the other leg for a different one.
Apparently, being off center and asymmetrical does not bother the front one wit as the triple tree and axle join the assembly as one and it acts that way. The need to have the fork be mirror matches for each other is just a bias we have in our heads.
It came up in the Guzzi book where one grade of oil was used in one fork, a different grade in the other.
These motorcycle people can be quite clever at times.
Sometimes, too clever by half, but that's another topic.
Apparently, being off center and asymmetrical does not bother the front one wit as the triple tree and axle join the assembly as one and it acts that way. The need to have the fork be mirror matches for each other is just a bias we have in our heads.
It came up in the Guzzi book where one grade of oil was used in one fork, a different grade in the other.
These motorcycle people can be quite clever at times.
Sometimes, too clever by half, but that's another topic.
Django
Road warrior
My BMW K1100 had different dampers in each front fork leg, one for pull in one leg, one for push in the other leg. However, springs were the same in both legs.
flynrider
Road warrior
Interesting. Before this, the only asymmetric forks I'd seen were the 80s Hondas with TRAC anti-dive that Joe mentioned above. Common sense would tell you that symmetry is a good thing in two parallel forks attached to the same axle, but I guess sometimes common sense is wrongRboe_imp said:I think this topic came up in a book on Guzzi's. It's a rather trick way to have a sophisticated suspension with one leg responsible for one behavior, the other leg for a different one.
Apparently, being off center and asymmetrical does not bother the front one wit as the triple tree and axle join the assembly as one and it acts that way. The need to have the fork be mirror matches for each other is just a bias we have in our heads.
It came up in the Guzzi book where one grade of oil was used in one fork, a different grade in the other.
These motorcycle people can be quite clever at times.
Sometimes, too clever by half, but that's another topic.
rboe
Road warrior
I learned in my upper division classes; common sense will be your undoing. Dang.
"Economics" is the reason for the different spring lengths in the Deluxe/EX forks...
You will find that the Standard CB1100 uses the same length springs and spacers in both fork legs.
When Honda added weight to the Deluxe/EX design the cheapest way to compensate for the added weight was to beef up one of the two fork springs.
Hench the different length spring has very little to do with engineering.
You will find that the Standard CB1100 uses the same length springs and spacers in both fork legs.
When Honda added weight to the Deluxe/EX design the cheapest way to compensate for the added weight was to beef up one of the two fork springs.
Hench the different length spring has very little to do with engineering.
After reading this thread I went to my 13/14 Honda service manual and I found the same info; standard has identical length springs while the deluxe has the different length springs.TINK_imp said:
I had no idea than any manufacturer was doing this. You learn something new every day
4 Paws_imp
Road warrior
I've learned to trust and appreciate Honda engineering. We have both the Honda Jet R&D and mfg facility here as well as the jet engine facility.
They know engineering. And accountants are not in control.
With my Ural a "one off" is a common occurrence, they just use whatever part is handy at the time.
They know engineering. And accountants are not in control.
With my Ural a "one off" is a common occurrence, they just use whatever part is handy at the time.
Motogeezer1949_imp
Road warrior
Interesting. Before this, the only asymmetric forks I'd seen were the 80s Hondas with TRAC anti-dive that Joe mentioned above. Common sense would tell you that symmetry is a good thing in two parallel forks attached to the same axle, but I guess sometimes common sense is wrongFlynrider_imp said:Interesting. Before this, the only asymmetric forks I'd seen were the 80s Hondas with TRAC anti-dive that Joe mentioned above. Common sense would tell you that symmetry is a good thing in two parallel forks attached to the same axle, but I guess sometimes common sense is wrongRboe_imp said:I think this topic came up in a book on Guzzi's. It's a rather trick way to have a sophisticated suspension with one leg responsible for one behavior, the other leg for a different one.
Apparently, being off center and asymmetrical does not bother the front one wit as the triple tree and axle join the assembly as one and it acts that way. The need to have the fork be mirror matches for each other is just a bias we have in our heads.
It came up in the Guzzi book where one grade of oil was used in one fork, a different grade in the other.
These motorcycle people can be quite clever at times.
Sometimes, too clever by half, but that's another topic.
One might think it's common sense but more like common assumption imo
Lord Popgun
Road warrior
To add to my post above, I went back and looked at the fiche for the DLX. Sure enough it lists different part numbers for the collars. I can't believe no one else looked and called me on this 
