In addition to the whobble posts: rear wheel offset

[Vosselman]

Has anyone measured the rear wheel offset on a 2009 touring? If they got rid of the offset, this could be the reason why it does feel more stable.

On most HD's the rear wheel is offset. I think that especially on a rubber mounted swingarm/engine combination this can lead to whobble.
Especially when this whobble is more of a problem in corners/turns. The rear wheel wants to get in track with the front wheel. Due to the movement a rear wheel offset could be more of a problem on a rubbermount than on a softail.

Aligning the rearwheel in the swingarm does not solve this: rear wheel is still offset
Aligning the swingarm/engine in the main-frame does not solve this: rear wheel is still offset
Aligning rear wheel with front wheel by changing rearwheel axle or swingarm-mainframe will 'solve' the offset but now the front wheel is not in a 90 degree anymore.

My point/question: shouldn't rear wheel, swingarm, frame and front wheel be aligned?

[FLTRI]

Naw, just buy a brace for the back of the transmission and you bike will be glued to the pavement. Aren't you listening to the testamonies?

[Vosselman]

Maybe we can keep this topic 'facts' only.
That's the reason I opened a new topic instead of posting in the whobble / gizmo topic.

TIA

[tireater]

When I relaced my 05 FLHT spoked rims....I noticed the back and front hubs are reversed to create an offset...

[FLTRI]

"My point/question: shouldn't rear wheel, swingarm, frame and front wheel be aligned?

Of course, and when they are not in alignment there can and will be times when the chassis will get unstable or/and wobble.

There is 1 aspect of this particular chassis (FL) that makes it unique AND a challenge to assure a stable platform.

Unlike any other bike out there, the front forks are BEHIND the steering head rather than in front of. This effectively shortens the wheelbase for good slow-speed maneuvering. as well as a "caster" feel to straight ahead.

This chassis and its feel or handling is incredibly sensitive to anything not geometrically perfect.

The 1 thing that very few know about is the relationship of the swingarm to the steering neck. I must be absolutely perpendicular to one another. With standard design forks this relationship is important but a lot more forgiving if out a bit.

If the steering head is just a bit out of perpendicularity to the swingarm pivot the bike will always feel "disconnected", or wobble between the front and rear of the bike. This is due, in part, to the front and rear wheels moving up and down on different vectors.

So alignment is most critical AND some of the alignment is dictated by the frame's accuracy of mounting/pickup points that cannot be changed by adjustment and must be corrected with a frame maching.

[DalemanUK]

"My point/question: shouldn't rear wheel, swingarm, frame and front wheel be aligned?

This chassis and its feel or handling is incredibly sensitive to anything not geometrically perfect.

and that includes unequal front and rear suspension height changes which can alter the 'trail'. for example I can radically alter the steering characteristics of my air suspended mountain bike by changing front and rear shock unit pressures - raised rear = sharp turning with more nervous feel.

reverse effect on my '02 softail with pillion and luggage - which I believe has a few mm offset on the rear

[tireater]

I always wondered if my fork neck was perpendicular to the back wheel...after an accident I was in....
When you drive over a big crack it seems the front wheel goes right and the back wheel goes left...
Is there any way to check the neck w/o taking the bike to a frame shop...?

[HIPPO]

Race Tech has a Computrack now.

http://www.racetech.com/SubMenu.asp?cMenu=23&c=Yes&showPage=computrack



Link to other locations

http://www.gmd-computrack.com/index.php

[HIPPO]

As to the direct question,

I don't know about the 09's


What I do know is that it is a big mistake to put both wheels in a single plane when the bike is designed with the wheels offset, ie in two parallel planes. This is what many of the home grown alignment methods are either proposing or achieving. Not good.

[FLTRI]

"What I do know is that it is a big mistake to put both wheels in a single plane when the bike is designed with the wheels offset"
Do you by any chance know what happens when this is done? I always knew about the offset but never knew why or what would happen if changed.

[sandrooney]

Maybe RoadKingTrooper will chime in. I know he took out the offset on his RK.
SR

[HIPPO]

"What I do know is that it is a big mistake to put both wheels in a single plane when the bike is designed with the wheels offset"
Do you by any chance know what happens when this is done? I always knew about the offset but never knew why or what would happen if changed.

If this is done by changing the alignment settings the bike basically goes down the road sideways and the rubber mount system gets all bound up. Perhaps that is why some of the people that aligned them that way report improvements, as it might mask a problem.

This is obviously not the same as putting the wheels on the same plane via spacing.

[tireater]

Where do you find the offset for a particular model...?

[HIPPO]

You measure it.

[tireater]

I am using a cast rear wheel but have a non stock steel front laced rim...Can I still just 'measure it'...?

[HIPPO]

Sure. Precision depends on the method. Anything from string that gives you an approximate idea, to the home laser systems that are close, to professional methods.

[HIPPO]

Laced wheels add a whole dimension to any issue as the wheel itself can be purposely or accidentally laced with offset.

[Vosselman]

"What I do know is that it is a big mistake to put both wheels in a single plane when the bike is designed with the wheels offset"

If this is done by changing the alignment settings the bike basically goes down the road sideways and the rubber mount system gets all bound up. Perhaps that is why some of the people that aligned them that way report improvements, as it might mask a problem.

This is obviously not the same as putting the wheels on the same plane via spacing.

Hippo. 'aligning' front and rear wheel by 'moving' the engine/swingarm in the frame is not the way to go. As mentioned in my initial post, the wheels will be 'aligned' but now the front wheel is pointing to the left and rearwheel and frontwheel are not in line with the frame anymore.
Therefor I think the way to go is: align rearwheel in swingarm, align swingarm/engine in frame and than get rid of the offset.
I don't see any problems in getting rid off the offset. Do you?

[HIPPO]

Hippo. 'aligning' front and rear wheel by 'moving' the engine/swingarm in the frame is not the way to go. As mentioned in my initial post, the wheels will be 'aligned' but now the front wheel is pointing to the left and rearwheel and frontwheel are not in line with the frame anymore.

We are saying the same thing, basically the bike goes down the road sideways.

Therefor I think the way to go is: align rearwheel in swingarm, align swingarm/engine in frame and than get rid of the offset.
I don't see any problems in getting rid off the offset. Do you?

I just mentioned this to clarify the post.
From what one sees on custom built bikes, one might guess that by getting rid of the offset the bike would have a tendency to drift to the left due to the weight of the primary. Probably not much.

Way I look at it is that with the bike aligned as intended using the swing arm brackets as a reference I can live with it everything else being in spec.

I have not pursued it any further.

[FLTRI]

This is from the Racetech site:

"Phase One is measuring the bike. This identifies handling problems resulting from production misalignments, offsets and twists as well as problems from crash damage. Measurements are performed with an optical 3-D coordinate measuring device and a computerized system programmed specifically for motorcycles. (You might be surprised at how much standard production tolerances can affect your handling.)
- Measure: $150 (bike prepared - bodywork removed) "

In the above reference they are mainly referring to high performance street and racing bikes. The point is even those bikes have production deviations that affect handling. A Harley is no different. Production deviations such as steering head pivot to swingarm pivot perpendicularity, is probably the biggest "unseen" alignment problem plaguing HD touring bikes. The unique front fork arrangement greatly reduces the "room for error" quotient because, for whatever reason(s) production deviation results in.....yep you guessed it....a wobbler.

[surf]

The first question should be Are HD Touring Bikes designed with an offset between the front and rear wheel? Specifically the pre '09 models.

The service manual would lead you to think not. Method B in the alignment chapter is the straightedge method placing the wheels in-line.

Hippo, when you say "putting both wheels in a single plane" is that the same as having both wheels in-line?

[sandrooney]

I just did my 95 RK with a straightedge, and the rear wheel was not offset.
SR

[GLFLSTCI02]

Where do you find the offset for a particular model...?

I found it in the service manual for my bike. Stock offset that is.

Gene

[tireater]

It seemed the reversed hubs on my 05 FLHT would create at least a 1/2" offset...Not sure what the book says...
Maybe someone could post the offsets for the different years....

[Vosselman]

Sandrooney, how did you check this? With a straightedge you can always align the front and rear wheel.

But the rearwheel axle should be centered in the swingarm, measure to the pivot shaft. Than the engine should be aligned in the frame using the HD alignment tools to center the pivot shaft.
After this you can use a straightedge and check for offset.

[RoadKingTrooper]

Interesting topic, last summer I noticed the offset on my 2K RK. It was enough that the belt would occasionally rub on the tire  (new). I tried everything, aligned the tire in the swingarm per the manual, aligned the front and rear tires per the manual and while I did have to readjust the links, I was concerned about the bike not tracking the way HIPPO says. Out of frustration I had .250 machined off the outside of the rear caliper and a new spacer made .250 thicker than stock. This centered the tire in the fender and when realigned, the bike handled fine. A couple of months later Sandrooney and I took off the Dunlop and put on a new Metzler. To my astonishment the rear tire was now too far over to the right. I replaced the rear caliper and the stock spacer. Tire was centered!
Bottom line....... I am not convinced that the profile of the Dunlops is consistent and was the culprit behind my offset
Scot