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Front End Bounce
I just had new tires put on my 85 Interstate front and rear and new rear brakes among other things. Since the
new tires were put on the front end wants to bounce when taking fairly tight highway off ramp. Not riding too
agressively. Going straight or thru sweepers left or right there is no problem, and there is not too much bounce
if I'm going left on an offramp but going right it the bounce gets more and more pronounced to the point I back
off on the throttle. Feels sort of like if you were driving over a bunch of smaller closely spaced speedbumps. The
guy who put the tires on pumped up my rear shock to 45psi. I had been running at 32psi. I've tried both settings
but same behaviour. The mechanic did use dyna beads for balancing. It did not exhibit this before the tire change ?
Any ideas ?

Thanks
Jim
Reply
#1 06-22-2012, 06:30 PM,
I have never used anything other than regular weights for balancing.

But concerning the use of dynabeads, I did hear of people throwing the bag into the tire and probably allowing it to destroy itself (plastic bag) I guess, and then disperse the beads as required, however it was found that the bag had not been completely opened and trapped the beads preventing normal dispersion.

Not saying this is the case but how were the beads installed into your tire, by the bag or through the valve, which I assume would be the correct method.
The only stupid questions are the one's that are not asked.

Reply
#2 06-22-2012, 06:58 PM,
Hi Tricky, the beads were installed thru the valve stem.

JimC
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#3 06-22-2012, 07:04 PM,
why he changed the shock pressures remain unclear,you might want to check the tire pressures and the front fork pressures in case he pumped them up too
1987 Aspencade 129K
1986 SEI 93K
2014 Tri-Glide HD 17K

Hancock,MD
Reply
#4 06-22-2012, 07:12 PM,
I think he bumped up the shock pressure because he runs his 86 Voyager at 50psi plus and just thought my 32psi seemed pretty low.
He did tell me that he'd done it though. There are Progressive Springs in the front so I run no air pressure there. I am intending to
replace the fork oil though as it's been a couple of years since I had the fork seals done.
Reply
#5 06-22-2012, 07:23 PM,
Take it back ! I don't care for the balancing beads. Most of the times they work, but sometimes not. This is well documented in the whole motorcycle community. On your bike, it's one of three things.... Tire balance, bum tire, or the tire bead is not seated properly to the rim. I suppose it's also possible that the front axle or caps are loose. Air pressures in shocks and forks won't cause thumping in the front when going through a tight corner.... Like I said earlier, take it back. It could be a safety issue....
Adam
'96 ST1100
Brewerton, NY
Reply
#6 06-23-2012, 03:17 AM,
Hey Neoracer, i did check the air pressure in the new tires and in fact found that the rear
had 40psi ( which is about what I normally run ) but the front was at 44psi ( I normally
run around 38 ). So I took 5 lbs pressure out of the front tire down to 39psi and that
seemed to have taken quite a bit of the bounce out of it. Not all of it though. I will
continue to play a little with shock and tire pressure combos and if that doesn't work I
will try getting the tire rebalanced the traditional way as one member suggested.

Thanks
Jim
Reply
#7 06-24-2012, 10:24 AM,
i run 35 or 36 on E3's,10 lbs front forks w/atf with progressives springs
might want to play with the front fork pressures some too,also the anti dive setting,are you using stock front springs or progressives? atf or 15w?

just some thoughts,u might want to really take a look at the road surface,have found in places where there is alot of heavy truck traffic and braking that the road surface can get "speed bumps" on them w/o really realizing it
1987 Aspencade 129K
1986 SEI 93K
2014 Tri-Glide HD 17K

Hancock,MD
Reply
#8 06-24-2012, 11:00 AM,
no disrespect to your shop, but for peace of mind,
run your finger around the rim on both sides to convince yourself that the tires bead has been set properly in the rim.
also make sure the anti-dive settings are set the same
make sure the axle is seated properly in the fork and not crooked
make sure the axle caps are seated properly
it never hurts to check over the shops work, the time spent is well worth finding that one overlooked item......
enjoying the view from the saddle....... due mainly to the people and information found within this site
Reply
#9 06-25-2012, 11:35 AM,
Neoracer,, I am running Progressives in the front, and not really sure what is in there for
shock oil but somehow I think it is probably 15W. I have not been running any air pressure
with the Progressives - Maybe I should try adding some ???

Thanks for the suggestions !

Jim
Reply
#10 06-25-2012, 09:35 PM,
bs175dths - good suggestions about double checking the shops work.

I am not familiar with the anti-dive settings ? I presume they are to
help control excessive dive on braking ? How and where do I set
it or them ? What settings do you recommend ?

Thanks for the suggestions !
Jim
Reply
#11 06-25-2012, 09:38 PM,
Look at this.

Do you not have the drivers handbook for the Interstate?


Attached Files
.jpg   dive.jpg (Size: 83.68 KB / Downloads: 282)
The only stupid questions are the one's that are not asked.

Reply
#12 06-26-2012, 04:41 AM,
i'd try to at least add some to the forks and see if it helps some.
check the antidive settings at least balance them out,although most people seem to think it makes no difference unless you are braking i still believe it does somewhat
1987 Aspencade 129K
1986 SEI 93K
2014 Tri-Glide HD 17K

Hancock,MD
Reply
#13 06-26-2012, 06:47 AM,
The front end of my bike will "hop" if I set the fork air pressure and Trac too high. It seems quite sensitive to front fork pressure.

I am running 2psi over recommended tire psi, Progressive springs, tired fork oil, air pressure just barely one bar, Trac set on softest postion when riding solo with low amount of cargo. I like the bike to transfer weight to the front tire under hard braking.


Reply
#14 06-26-2012, 06:24 PM,
I have been fooling around with front shock air pressure as a result of this thread. While adding air pressure
sure makes the bikes handle quicker it bounced even more with higher pressure i.e. 6 to 10 psi. I am
currently trying it around 2 - 3 psi/ ( I have Progressives ).

I was not aware of the Trac Anti-Dive settings until Tricky or someone mentioned them. I checked them out
and they are both set at 3. I might dial them back to 2 and see what that does.

I did feel and do a visual inspection around the rim per another members suggestion to see if the tire appeared
to be seated correctly and it does.

I am alos playing a little with rear shock pressures in conjunction with the other adjustements. If I can't get
to a satisfactory point with the bounce then I will try having the Dyna Beads removed and balanced in the old
way to see what that does. If none of that works I may see if I can get the tire replaced ?

The crazy thing is it seems fine going straight and in sweepers and not bad in left turn off ramps, it's the right
turn ramps that make it start to bounce ??? I have noticed a little wiggle in the left front caliper but the right
front caliper is solid. I even wondered if somehow when I do a right curving ramp the left caliper and brakes
somehow lay on the rotor a little more causing an intermittant interruption in the tire rotation resulting in a
bouncy condition ? Sound far fetched ?????

I'll keep you apprised of any headway !
Reply
#15 06-27-2012, 06:41 PM,


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