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Is the rear wheel in the middle of the swing arm?

Started by 1340evo, October 03, 2021, 07:06:31 AM

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1340evo

A question for all of you who's built your bike with new wheels, wider rims etc. The guy who built my bike I've established was not the best, so I question everything when I have it in bits. To add to this, I have the engine sprocket off now and the chain has been rubbing on the inside and not the outside as if it's being pushed outwards. The rear wheel is spoked onto Dacron rims.
If I look up between the rear mudguard, the wheel is closer on the left than it is on the right by 3/16" or so, but I am going to a bit of tin there. If I measure from outside of the swing arm it also shows the same but I'm measuring on the arm where it starts to bend and of course the swing arm itself depends on how its mounted to the gearbox and in turn the isolation bushes.
I can throw this forward to the front wheel, but just a slight turn on the steering will get it in line and the level still reads correct.
So, how to check it? are there any measurements I can take around the hub to see where it should sit on the axle at all?

thumper 823

Perhaps i missed it, how wide is the tire?
Next
Even stupid Harley has been known to run tires  NOT behind each other,
but to  the rear off to one side 
D Troop 3/5, - C/16 ,162AHC, Mekong delta.
Rising from the Ashes  UHIH

1340evo

October 03, 2021, 09:01:21 AM #2 Last Edit: October 03, 2021, 09:08:00 AM by 1340evo
The tyre is a 150/80 16...

I guess I can take the wheel out and measure the hub position from the rim both sides and the work out where it should sit having measured the gap in the swing arm.
But, as you say above, maybe there should be an offset to one side? thats the bit I don't know ... (1989 FXR)

He's spent Thousands on some real nice bits, but his bolting it all together has been very poor to say the least :)


RTMike

How does the wheel line up to the fender and trans :potstir:

1340evo

October 03, 2021, 10:00:00 AM #4 Last Edit: October 03, 2021, 10:05:08 AM by 1340evo
I kind of thought the arm to the trans was a given?... to the fender (sorry, I called it mud guard above) its a smaller gap on the left

1340evo

Well, thith bits of cotton and weights I've established the rim to inside of the swing arm is 66mm one side and 69mm the other so 1.5mm off centre.. so maybe not worth bothering with.
I need to get it on its wheels to measure the angle of the arm to the front... FXR's are rather complicated for stuff like this!!

Deye76

October 03, 2021, 01:18:30 PM #6 Last Edit: October 03, 2021, 01:25:12 PM by Deye76
Some say the rear wheel is not centered in the swing arm on a FXR. They favor the left (belt) side. I measured my 92' FXR, it's centered.
East Tenn.<br /> 2020 Lowrider S Touring, 2014 CVO RK,  1992 FXRP

jsachs1

I can say with certainty, that on a SOFTAIL, the rear wheel is offset to the left side of the swing arm. When I set up some rollers, with slightly wider rear tires, I made a spacer to leave the sprocket where it was stock, and milled the caliper bracket to accommodate the wheel/tire combo. Handled like a dream.
John

1340evo

October 03, 2021, 01:47:35 PM #8 Last Edit: October 03, 2021, 02:31:09 PM by 1340evo
I've found the problem, or at least another issue. Having moved it over 2mm, I can now see the rear axle is bent!... and its bent about 2-3 mm which is throwing everything off!.... So a bent rear axle, Tooth missing from the engine sprocket, Keyway trashed on the tapered clutch shaft and the crank reading .016 TIR.. whats happened to this thing.. Its all adding up now.

Alread done the crank, Have changed to splined in the box, Have replaced the engine sprocket, So I hope the axle is the last thing... Wonder what happened to it to make it all lock up?.. stone or bolt in the chain maybe?

Maybe I need to check the swing arm shaft??

Burnout

Most bent axles I have seen are due to crashing.
They don't call me Ironhead Rick just because I'm "hard headed"

1340evo

its not the original axle as that's in the box of bits and is fine, its a new axle he's bought and the bike has not been crashed when he had it. I'm thinking some thing got stuck in the chain maybe.. how do you lose a tooth of a sprocket?

Rockout Rocker Products

Quote from: jsachs1 on October 03, 2021, 01:26:57 PM
I can say with certainty, that on a SOFTAIL, the rear wheel is offset to the left side of the swing arm. When I set up some rollers, with slightly wider rear tires, I made a spacer to leave the sprocket where it was stock, and milled the caliper bracket to accommodate the wheel/tire combo. Handled like a dream.
John

I always thought that, on a Softail at least.... this was on purpose due to the engine/trans weight not being centered in the frame. Heavier on the left side meant moving the rear tire slightly to the left.

www.rockout.biz Stop the top end TAPPING!!

Burnout

Quote from: 1340evo on October 04, 2021, 02:45:24 AM
how do you lose a tooth of a sprocket?

I would be very critical of any other parts that came from that source.

An XL I bought a few years ago had a bent frame, broken cases, bent swing arm, bent rear wheel (18" mag wheel).
I figure it got blasted from behind. Paid too much for that one.... 
I did recoup though it was titled, sold the frame on CL as bent for the VIN for way more $ than it was worth to me.
They don't call me Ironhead Rick just because I'm "hard headed"

1340evo

If it had been a bent bike when he started you'd not spend the type of money on it that he did?
I'm taking the swing arm off this weekend just to check it out there. Other than the front folks, I've done everything myself now so know its right.
The bike is straight when you ride it as you can take your hands off the bars and it goes in a straight line, also goes into corners the same and no issues of diving, trying to pull up etc. Maybe just a faulty part...

cheech

Quote from: Rockout Rocker Products on October 04, 2021, 04:35:31 AM
I always thought that, on a Softail at least.... this was on purpose due to the engine/trans weight not being centered in the frame. Heavier on the left side meant moving the rear tire slightly to the left.
If I remember correctly, the offset dimensions you speak of are laid out in the service manual in that regards.
Thought I seen that once in there.
Reason behind it?  :nix:

Rockout Rocker Products

Quote from: cheech on October 05, 2021, 10:12:12 AM
Quote from: Rockout Rocker Products on October 04, 2021, 04:35:31 AM
I always thought that, on a Softail at least.... this was on purpose due to the engine/trans weight not being centered in the frame. Heavier on the left side meant moving the rear tire slightly to the left.
If I remember correctly, the offset dimensions you speak of are laid out in the service manual in that regards.
Thought I seen that once in there.
Reason behind it?  :nix:

The Softails used different length spacers on the rear wheel.... right side longer than the left. Those that wanted to run a fat tire without the belt rubbing the tire would switch the spacers around. I'm guessing it made the bike list to one side but I never personally tried it.
www.rockout.biz Stop the top end TAPPING!!

1340evo

Quote from: cheech on October 05, 2021, 10:12:12 AM
Quote from: Rockout Rocker Products on October 04, 2021, 04:35:31 AM
I always thought that, on a Softail at least.... this was on purpose due to the engine/trans weight not being centered in the frame. Heavier on the left side meant moving the rear tire slightly to the left.
If I remember correctly, the offset dimensions you speak of are laid out in the service manual in that regards.
Thought I seen that once in there.
Reason behind it?  :nix:

Mine does have a wider rear rim & tyre, but I just want to ensure its all in-line. Having removed the old front sprocket (with a tooth missing) I can see the chain is polishing the inside of the sprocket but not the outside, suggesting my wheels is maybe to the left a bit relative to the engine and box... Think I have to assume if this is correct then it does line up with the front wheel?

jsachs1

Read my post #7.
Softails right side(brake side) use a narrow spacer between the wheel bearing and inboard side of the caliper. The rest of the spacing on the right side is handled by the caliper bracket(mount).
John

1340evo

Quote from: jsachs1 on October 06, 2021, 02:17:00 PM
Read my post #7.
Softails right side(brake side) use a narrow spacer between the wheel bearing and inboard side of the caliper. The rest of the spacing on the right side is handled by the caliper bracket(mount).
John

Yes I did, but mine is a FXR.
The brake caliper comes with a Ali disc you can trim to size (Jay Brake).. will work it out this weekend...

kd

It was mentioned here at least once before that the left side weight of the power train is heavier with the primary drive considered.  The offset in the rear wheel noticed by OCD people may be an essential design component.  IMO  A blueprint of the chassis layout and center line between the wheels (not the engine) is what is required before moving stuff around and changing spacers willy nilly.
KD

Appowner

That would be my suggestion too.

Now, where would one get such a blue print?

Rockout Rocker Products

The diagram in the '91/92 Softail FSM clearly shows the offset.... and gives a spec for it.

[attach=0]

[attach=1]
www.rockout.biz Stop the top end TAPPING!!

1340evo

Interesting, although the bigger gap in the pic of the front wheel does appear to be on the RHS (ie the rear wheels offset to the right), where as if you were moving the wheel over to accommodate Primary weight should it not move Left?

Rockout Rocker Products

Oops... didn't get the whole diagram. Which makes things even odder because the Heritage & Fat Boy seem opposite  :scratch:

[attach=0]
www.rockout.biz Stop the top end TAPPING!!

Burnout

This isn't making sense,
Don't they all use the same frame?
If so how, can they move the wheel around, as this will affect belt alignment.
They don't call me Ironhead Rick just because I'm "hard headed"

kd

Quote from: Burnout on October 09, 2021, 12:41:35 PM
This isn't making sense,
Don't they all use the same frame?
If so how, can they move the wheel around, as this will affect belt alignment.

The diagram is not wheel alignment in the frame.  It's front wheel alignment to the rear wheel. They are not moving the front wheel around.  The FXSTC (Custom) and FXSTS (Springer) are the tall narrow front wheel and the FLSTC/F (fat Boy) is the 16" fatty.  When the front wheel is aligned (A=B, C=D) to the rear wheel the clearance on each side of the front wheel to the straight edges is to be as stated.  If they do not meet the required dimension (offset factor), it will likely indicate a twisted frame or swingarm bushing issue of sorts. This diagram really doesn't have anything to do with the position of the rear wheel in the swingarm or frame centerline.
KD

Rockout Rocker Products

Quote from: kd on October 09, 2021, 03:04:25 PM
Quote from: Burnout on October 09, 2021, 12:41:35 PM
This isn't making sense,
Don't they all use the same frame?
If so how, can they move the wheel around, as this will affect belt alignment.

The diagram is not wheel alignment in the frame.  It's front wheel alignment to the rear wheel. They are not moving the front wheel around.  The FXSTC (Custom) and FXSTS (Springer) are the tall narrow front wheel and the FLSTC/F (fat Boy) is the 16" fatty.  When the front wheel is aligned (A=B, C=D) to the rear wheel the clearance on each side of the front wheel to the straight edges is to be as stated.  If they do not meet the required dimension (offset factor), it will likely indicate a twisted frame or swingarm bushing issue of sorts. This diagram really doesn't have anything to do with the position of the rear wheel in the swingarm or frame centerline.

This is what I said a while back... the bike is heavier on one side than the other... thus shifting the wheel in relation to the weight.
www.rockout.biz Stop the top end TAPPING!!

1340evo

All very strange. I've got mine right in the middle of the swing arm, 49.5mm each side and measuring to the rim is now .05mm one side to the other (did I tell you I had OCD  :wink: )... looking at the above post it's not that important, and I have a chain drive so may as well get it in the mid position.
I can't understand how having them off this far does not impact the handling?.. sure it must do....

1340evo

Not sure it matters that much, so long as when you are done to lines up wheel to wheel like the diagram.
Why one is to the left and one to the right is anybodys guess?... Mine is like the top one for sure ;)