Swing arm location

[BrianG]

OK..... now I've done it!

 

I marked every bit that i thought might be a "replace exactly as disassembled" issue except this one!

 

So... what are the real assembly parameters for locating the swing-arm between the pork-chops??

 

I didn't measure their original protrusion measurements.....

[Guest Nigelstephens]

The requirement is to get the two mounting screws the same distance out on each side. I normally get to an approximation and get it nearly tight side to side. Then I measure with a vernier caliper the distance sticking out each side. Then adjust one side out and the other in to get the same measured distance. Then wind in slightly more so that there is no lateral movement. That is the screws are only just tight and the arm can move freely. Then recheck the same distance each side +/- 0.5mm and do up the locking nuts.

[Paul Minnaert]

I do it different, I measure between swingarm and porkchops.

[docc]

I used a lazer and markings on the floor.

 

I think Ratchethack has a thread on this procedure.

[Guest ratchethack]

Gents, I submit that if you set the stub axle faces equidistant from the pork chops that this is incorrect. Set this way, it may or may not wind up within published factory tolerance, unless you have the ultra-rare (or nonexistant?) Guzzi that came off the frame jig with very precise dimensions, including pork chops. FWIW, I have checked this out with a depth gauge on many V-11's, and have never found one that came from the factory with them set equal, including mine. I'd measured mine with a depth gauge before and after having the trans out and re-aligning it. IIRC, they were originally 1-2 mm unequal, and after I re-aligned it they were about half that.

 

Dunno how they do it at the Guzzi works, but I suspect they use a setup fixture. I reckon there are a few ways to do it, and some of 'em are more accurate than others. Since ultra-precision is NOT required here, and having it track "perfectly" is not critical, many are no doubt judged acceptable, including the old "string" method used forever on chain drive moto's. Seems kinda crude for a Guzzi, though.

 

The Guzzi service manual calls for alignment of the swingarm and rear wheel within an overall lateral tolerance of 3 mm. This allows a misalignment of no more than +/- 1.5 mm on each side. Mine came from Mandello set within this range, but when putting it back together after having the trans out, I came up with what I found to be a quick & easy way to get it more accurate than the Luigi's did.

 

Why? Because it's easy, and I believe it's more accurate and it tracks more accurately as a result. I figure why not give y'er superbly engineered tires and finely-tuned suspension every advantage?!

 

See procedure here:

 

http://www.v11lemans.com/forums/index.php?...p;p=46556

[Greg Field]

Ratchet:

 

I like your method

[Guest ratchethack]

Thanks, Greg.

[Guest Nigelstephens]

Thats interesting.

Perhaps I need to do mine again now.

Is the purpose of the alignment to align the wheels or to reduce stress on the UJ?

[Guest ratchethack]

Is the purpose of the alignment to align the wheels or to reduce stress on the UJ?

Nige, IMHO the objective is to align the wheels. Nothing more. That's wot the laser does.

 

Now this is just me, but looking at it from an entirely logical mechanical (yet entirely theoretical) physics perspective, the UJs operate within an acceptable range of vertical axial angles that make any horizontal axial angle considerations of within a few mm at the swingarm pivot negligible and irrelevant.

 

PARTIAL SUPPORTING EVIDENCE: For all practical purposes, shaft drive bikes have the same wheel alignment tolerance spec's as chain drive bikes. I reckon it logically follows that whether or not the wheels are aligned on a shaftie (within reason of course), the UJs are about as happy as they can be regardless.

 

But as always, I'm certainly open to discussion and/or debate on this!

[Guest Nigelstephens]

If it is primarily to align wheels Im suprised that it has to be done to such a high accuracy.

 

The Guzzi Manual states

 

"Adjusting the swing arm play (Fig. 18-02 / 18-03)

Ensure the swing fork oscillates freely without any

play.

Be sure both spindles «A» project by the same

amount.

The above-described adjustment operation should

be carried out with an 8 mm. allen wrench and a

gauge."

 

My interpretation is that measuring the projection of the stubs and that they are equal is sufficient.

[Guest ratchethack]

My interpretation is that measuring the projection of the stubs and that they are equal is sufficient.

Your interpretation may (or may not) be adequate, fine & dandy for all practical purposes, Nige. I'm not suggesting it necessarily isn't , just offering wot I believe to be a superior alternative. Unlike the equal length stub axle method, which ignores wheel alignment altogether and provides no measurement scale for alignment whatosever, the laser technique provides accurate, demonstrable, measurable verification using the wheels as the basis of reference, and accuracy can be observed directly on the dial of a vernier depth gauge.

 

BAA, TJM, & YMMV

[badmotogoozer]

Not intending to be argumentative - I have recently given Ratchet's laser method a go. Just offering my results/findings.

 

Purchased two laser levels and fabricated a jig to hold them both against rear tire exactly parallel. Set up in my lab to measure against wall just how well aligned they were and discovered that the laser beams were a) not centered perfectly in their housings and when "line" selected, it was apparent that at least one was not perpendicular (the two lasers not parallel in a parallel jig).

 

Off I go to buy two more lasers expecting two to match. Surprise! None of them produced parallel lines.

 

Thought, OK, I'll just use one laser - No. Being not perfectly centered, switching from side to side would also mean inverting even if only using the point, not the line.

 

These were not the cheapest nor the most expensive levels ($35 ea).

 

Tried it out on the bike. With everything set in place, centered the swing arm. Locating pins offset by 2mm. Laser says spot on. Off comes the laser rig, on goes my trusty standby, the flourescent light tube. Bungee it on each side of rear tire. Check offset. Off 1.5mm in same direction as pins are offset.

 

Hmmm. Set pins equidistant from chops, measure with flourescent tubes. Centered well within 1mm.

 

Result - return all levels, huck laser alignment apparatus into the recycle bin.

 

If going this route, be aware that there are some VERY large tolerances in retail laser levels.

 

cheers,

 

Rj

[Guest ratchethack]

Ryan, sorry it didn't work out for you. The calibration accuracy of the laser is critical the way you used it, as you pointed out.

 

A simple way to verify the accuracy of a single laser per my procedure is to do what I did before I considered using it. I layed it on its side on my bench and put a mark on a piece of tape where the dot hit the cabinet about 15 feet away. Flopped the laser over on its other side and aligned the marks. Any discrepancy here would be a doubling of the laser's lateral inaccuracy at that target range. In the case of mine, it was spot-on identical. That's all the lateral verification of accuracy I needed to have confidence in my procedure, in which I used different sides of the laser on different sides of the tire.

 

A valid argument might be made for using a single mis-aligned laser in "dot mode" by placing the same side of the laser against the tire on each side of the tire in my procedure. Any lateral inaccuracy would be cancelled out exactly, and alignment would not be compromised in the slightest.

 

I always considered the floursecent light tube method a big step up from the string method and have done both for many many years, but IMHO it's not as easy nor as accurate as the laser. Correctly used, 2 accurate lasers would no doubt make this faster, but is twice as fast as half a minute or so for a read on the other side worth buying another laser?? This is just me, but I don't know if I'd ever have another opportunity to make use of two lasers on any other kinda project?? If y'er going out to buy lasers (I already had one) I reckon just one's y'er cost/benefit optimum.

 

BAA TJM, & YMMV

[Guest Nigelstephens]

Is it noticable if the adjustment is off by say 2mm in one direction. I cannot see that the chops will be that different (including other components)?

 

If it was possible to get a cheap laser that was accurate I would curtainly give your technique a try. However, not owning one and unable to see an advantage of adjusting to a high precision with this method, I think I will just rely on the old equal sticking out stubs technique. Sorry Rachet.

[Guest ratchethack]

Sorry Rachet.

Por nada, mi compadre!

 

Wotever floats y'er boat, my friend -- Like today's "top o' the list" moto tires -- The world offers a veritable cornucopia o' superb alternatives these days -- Now how's a Guzzista to pick which ones he's gonna go with?!?!

Is it noticable if the adjustment is off by say 2mm in one direction. I cannot see that the chops will be that different (including other components)?

Scraping meself up after many crashes in the dirt over the years (on dirt bikes, in the dirt -- not Guzzi's!), I've discoverd several times that afterward the handling was funny. Come to examine the bike in more detail and fork checks out OK, I find the rear wheel cocked in the swingarm, and the bike makes 2 sets of tracks -- the rear track overlapping, but not entirely covering the front -- going in a straight line! Yes, THIS is noticeable in turns!

 

I doubt 2 mm offset would ever be noticeable even by the most persnickity rider -- but then again, it just might. Each taken individually, I suggest that there are many kinds of unnoticeable compromises in chassis adjustment that, when taken together, can add up to overall funny handling.

 

Aligning the swingarm with a laser can be looked at like it's either much ado about not too much, or it can be looked at as a quick, accurate, and easy way to git 'er done -- or something in between. That's all.

 

I reckon it's just an alternative that wasn't an option before the common use of lasers around the home and workshop, my friend.