Wobble!!

[fbn ent]

'07 Nightster. I finally got it to wobble after trying numerous times. The wife says it has been wobbling around 76 MPH on sweepers since she got it back in '08 doesn't do it faster or slower. Like I said, I finally got it to do it for me (I'm heavier than her at 5'). Spokes, tires, bearings, fall away, swing arm all pass inspection. Anybody ever have this issue? What was it? Thanks.

[JohnK]

replace your fork oil, that should cure the problem

and since you've checked everything else... replace your engine mounts, and get some decent tires (anything but Dunlops) and you'll have a bike that handles better than when it rolled outta the showroom

[Maxxx]

whats the deal with dunlops?

[fbn ent]

Been running AVON for the last 25 years. I'll try the fork oil today. #15 working or #10? Thanks.

[aswracing]

Well known issue with the rear motor mount causing exactly what you're describing. More info and pix here: http://harleytechtalk.com/htt/index.php/topic,68845.msg743651.html#msg743651

[fbn ent]

Thanks. I was looking for that page. I was the OP with that question.I just lost it somehow.

[JohnK]

Been running AVON for the last 25 years. I'll try the fork oil today. #15 working or #10? Thanks.

I used 10wt Belray in the forks. Try to get the levels as even as possible side to side, otherwise you get a little difference in spring rate due to the air pocket at the top. This is the one fix that cured the high speed wobble on my Sportster after trying nearly everything else.

Replacing the Dunlops was the fix for low speed decel 'wiggle' I suspect the interrupted center rain groove was the cause of that nagging issue, and may have contributed to the high speed wobble as well.

[fbn ent]

Exactly like the pics ! WTF!!!!!!!!!!  There is a groove worn in the drive end of the "pipe" from the rubber isolator. What kinda crap is this. According to asw racing, this is a known issue. Looks to me like all the rubber mounted sportsters use the same setup but I could have missed something there as I am only going by microfiche. There should be a recall on these if it is as widespread as asw says. As it is I have no choice but to repair this the best I can for now and wait for parts to arrive which takes a couple of weeks here if there is no stock.

[fbn ent]

Just spent some time on the XLForum and found that, yes, pretty much everyone is having this issue. It is also in the Manual to check / replace mounts at 30K miles they say although I have not verified this yet (it's early). Go figure. From what I read there it looks like any rubber mount sportster is going to need new mounts around the 30K mark, some sooner. As far as a recall, I doubt it as it is a maintenance issue in the service manual.  Damn poor design/parts if you ask me.

[JohnK]

yeah, it's a good idea to replace the rubber isolators, they'll have noticeable sag when they're 'done'

I replaced with the Drag Specialties parts, they're a little harder and a lot cheaper than the OEM pieces. You'll get some handle bar buzz for a couple thousand miles but it will subside. It will improve the handling of the bike, but I don't believe it is the source of a high speed wobble... but for sure it will tighten up the rear end in the twisties.

For the record my '05 had a little wear on the pivot pin but no problem with broken retainer screws. That seems to be hit and miss 

[fbn ent]

I used 10wt Belray in the forks. Try to get the levels as even as possible side to side, otherwise you get a little difference in spring rate due to the air pocket at the top. This is the one fix that cured the high speed wobble on my Sportster after trying nearly everything else.

My '07 Service Manual doesn't specify how much oil for a Nightster. Same as a Low or......?

[JohnK]

Sorry man, can't offer you an answer for that. If you can find out if the damper rods and forks are the same length as the Low or the Custom you should have your answer. Otherwise I would remove the springs, compress the forks all the way and add oil until you end up with 5-1/2 to 6 inches of space from the top of the fork tube to the oil level. You'll have to adjust the oil level to tune the forks for optimum, but be careful raising it above the 5-1/2 inch level, you don't want to end up with hydro-lock and blown seals when hitting the heavy bumps.

[fbn ent]

Well, I put in Amsoil #10 at the volume for "all others" in the manual. Man was THAT wrong! Very soft and wouldn't handle my 200 pounds at all. Drained it again (probably didn't hurt to flush it, the old oil was pretty skunky) and put in BelRay 15 at the volume for the L models. Felt real good to me and the wife says it feels right. Went on a trip over the weekend with some bad frost heaves and corners involved and she says it feels solid up to 80mph and then has a bit of an issue in the rear. The swingarm heim joints are shot (I picked some up on the trip) so I figure that's the issue there. I will change them this week and she should be good to go for the rest of the season. I can get serious and do the mounts and set the forks at the correct level in the off season.