K1200LT trailing arm swap (and some other stuff)

[szurszewski]

I think a friend of mine was worried I didn't have enough to do and might go crazy now that WA has extended our safe at home order through the end of May (at least...). To "help out" he suggested it might be fun for me to do a little work on his sidecar rig. Yesterday I snuck out on the "project" R1100S, rode up to his pace and swapped the S for this beast:

 

 

It was a "little" wet out yesterday, and my silly pinlock decided to fill up with steam for whatever reason, but we eventually found our way to the garage. 

 

 

There are maybe a few pics of it around here already - I had it in the garage about a year ago as well to do a little of this and that (mostly a 12k service). At the time we talked about possibly removing the trailing arm and replacing it with a modified/shortened arm...but decided it was more work than either of us wanted to do at the time. The bike already has a steering mod from Hannigan to reduce the steering effort...but it has some drawbacks. My geometry and understanding of motorcycle steering isn't quite up to eloquently explaining that here, but if anyone is curious I can provide links to words by people smarter than I. In fact, if this works, when it's all done I'm sure my friend will post a glorious thread on ADV all about it - he's into that sort of showy stuff (just look at is shiny, shiny rig!). I'm more into the gory details (just look at the very similar yet oh so different K rig I used to ride), so this thread is really just here because I thought you all might like to watch the carnage. Hell, I'd say there's a better than fair chance that I just end up destroying his bike

 

Anyway - the original plan was to buy a salvage trailing arm, shorten it, and swap it in. He bought one on eBay, took it to his welder buddy and the buddy said, dude - I think that front hole should be round - yours is oval. Crap. My friend sent that one back and ordered another from eBay - from a 2004 K1200GT I believe. Got it, looked at it, thought - that doesn't look right - measured it, and found out it was already about 3/4" shorter...huh. After some measuring and internet research, it seems the K1200GT had a steering change mid model run, and the later ones had shorter trailing arms...and so now we're just going to see if we can swap it in and get the result he wants. If so, it will mean a $60 eBay part instead of a $60 eBay part + a bunch of money for the welder. 

 

Here's what's -hopefully- going in - 

 

 

 

but before I get to that, I have to play a little Tetris to make space to work.

 

 

[RoanokeRider]

Nice rig, just needs some stripes.

[szurszewski]

50 minutes ago, RoanokeRider said:

Nice rig, just needs some stripes.

I think this thread needs better pictures of those stripes...

[RoanokeRider]

You thinking more like this? These were designed, installed and designed by your buddy, Draper. He does nice work.

[szurszewski]

Yep - more like that is just what I was thinking. I also suspected that was his work - he seems to have a thing for stripes

 

Probably be a few days before I get into this - maybe - but I’ll try to post pics along the way so we can all see how far I go before I get stuck. 

[RoanokeRider]

I'm curious. What problem are you trying solve moving the ball joint back? You added a trail reducer to move the wheel forward and now moving it back. Doesn't that defete the trail reduction? Just curious.

[szurszewski]

 

2 hours ago, RoanokeRider said:

I'm curious. What problem are you trying solve moving the ball joint back? You added a trail reducer to move the wheel forward and now moving it back. Doesn't that defete the trail reduction? Just curious.

 

Now, you're getting above my mental and mathematical pay grade - I am essentially a hired monkey here and just dancing to the music. But, I believe the idea is to get the benefit of the trail reduction while avoiding the height change in the front ... or something like that. Or it could just be that my buddy is bored and thinks this will be a fun thing to do to the bike.

 

 

[RoanokeRider]

I have to set the record straight on the stripes. Draper did design and attach the stripes and he did a fine job. BUT, he hates the bright yellow that I picked. It took a LOT of discussion to get him to do it. He wanted to do either silver (shudder) or gray (shudder) stripes! Some people just don't have any imagination.

[szurszewski]

A quick pictorial update of the not much that's happened so far. 

 

The rig's owner stops by to check on progress...and drop off more parts

He's a movie star - do you know him? 

 

 

A lot of stuff has to be moved to get to the rear mount for the arm.

 

That's what we've been looking for - make sure to leave enough room to get some heat on there as BMW says, heat the frame to at least 200F before trying to pull the bearing.

 

 

I usually prefer a torch, but I didn't want to cook the paint on someone else's bike (who'd ever know?) - heat guns are so slow, and there's no fire! ...but after a lot of sitting and holding the heat, the bearing actually came out quite easily - hopefully going back in will be similar...

pretty dirty in there, eh? the top of a k-bike engine sure is good place to store grit...(or oil if your crank vent hose/manifold comes apart)

 

The view from the front with the arm removed

 

 

...and then this is where I should have some pics of the two different trailing arms sitting side by side. But, since they turned out to be exactly the same, or at least very very very close to exactly the same, that's no fun. One is already at the welding shop to get shortened up - hopefully it won't be too long because this thing takes up a good bit of garage space and it's not moving until it's back together. 

 

Meanwhile, I've got a few other things to do to stay busy - swap the rear shock spring, reinforce the top box latch, upgrade the rear brake rotor...seems like there were more things - I'll have to go find my list....

 

 

[szurszewski]

Well, it's been a couple of days ... ish ... but the welder finally got the trailing arm chopped down a little bit. Here's the photo I was hoping to end that last post with - two different lengths of trailing arms!

 

There was a 5/8" section taken off the back of the arm, out of the box section where the frame mounts are welded on. Sitting on the floor in person it's kind of hard to tell, but at the angle of the pic and looking at the shock mounting location, you can see a clear difference. Setting up for this pic I also noticed I'd scratched up the short arm on something - and you can see the single scratch from the same thing on the longer arm - it's this thing:

 

That's not as annoying at the screw clamps on the intake tubes that can run into the throttle body cams, but still annoying - pay attention to your clamps, people! Quick touch up of the paint on the arm, heated the frame back up, took the bearing/bushing assembly out of the freezer

 

 

threaded in the handy homebrew press (big socket, 12mm all-thread, some washers with grease between them and an M12 nut) to the far side of the assembly, and everything slides in easily.

 

In fact, with the bearing coming out of the freezer and the frame hot I could slide it in about 1/3 of the way just with hand pressure. 

 

Now we just have to hook up the shock, reattach the arm to the ball joint, and we're all done! Maybe...

shit:

 

Bringing the shock mount further back means the distance, of course, to the top mount is shorter too - too short to get the shock into the trailing arm. Oops. Considered trying to compress the shock, but there's not much room; considered grinding out the front lip around the shock mount on the arm, but that's not ideal...so it came apart again. This time, I decided to test mount EVERYTHING without putting the bearing back in. The big "press" socket made a good substitute:

 

 

Good plan because with the shock mounted further back I also ran into (<-- see what I'm doing there?) another problem - the spring now hits the frame. Or, it does if the shock is mounted one way; rotating it 180 degrees put's the frame gusset right between two coils.

 

 

I suppose that could work, and would probably not do anything worse than going THUNK on hard front compression, but it seems like a bad idea. What do to? smaller spring? Move the shock mount on the trailing arm forward a bit? Shorten the front portion of the other trailing arm instead of the back and put that one in? All possibilities. Another idea, which seemed easiest, was to trim a *tiny* bit from that frame gusset. It's only about 5mm thick, and goes back a few inches, so.... why not?

 

 

And now you'd think I'd have a pic of the shock in there happily clearing the frame...but I don't. It does indeed clear the frame, but the after pic looks almost exactly like the before - tough angle to photograph. Also, it was probably not necessary since putting weight on the front end moves the trailing arm up in the front/compresses the shock and moves it forward away from the frame anyway. Which is to say, I think, any hard hit that would have compressed the spring would also have moved the spring forward and away from the frame. 

 

The rest of the big things on the list are to remount the sidecar, replace the rear brake rotor, swap a new progressive spring onto the rear shock, add some front fender clearance for the large rear tire running up there...and... that's it! I think. Maybe? Oh - new fuel injectors...and....?

 

To celebrate splitting apart from British rule, I think I'll spend today rejoining the car and chair....

 

 

 

[AZgman]

Is that a crack in the casting the bearing goes into?

[szurszewski]

5 hours ago, AZgman said:

Is that a crack in the casting the bearing goes into?

It appears to be a casting/mold flaw that was made more apparent by the paint/coating on the frame. It’s definitely not a crack, but it does look a lot like one in the pics!

[szurszewski]

Just took the rig out for a successful test ride - which is an important qualifier as this was actually the third test ride, but more on that later - so I guess I'd better get this updated before I forget what all the heck I've done. 

 

The problem with having a bike apart for a long time is stuff tends to get added to the list. One thing that got added to this list was new, multiport fuel injectors. Much more hassle to swap on the KLT than a boxer normally, but pretty easy job if you've already pulled off the airbox.

 

Here's what the units from tills.de look like along side the stock BMW injectors:

 

 more holes means more faster?

 

Here's the link to the set of these:

 

 

Do they make all the difference they claim? I can't say - the bike feels snappy and responsive, as much as a 1500 lb moto boat can I suppose

 

Oh - this is unrelated, but I had the pic in here for some reason. You know how braided steel brake lines come with those nice plastic sleeves in fun colors? Here's what and UNsheathed braided brake line will do if left lightly rubbing on your swingarm. Fun stuff!

 

[szurszewski]

Since the front end was apart for the trailing arm swap, it seemed like a good time to address the oversized tire vs normal sized fender issue. I do really like a tire that fills up the space, but this one was overstepping that bound and starting to wear into the underside of the fender. Not ideal, but looks cool, right?

 

 

A quick "few minutes" with the Dremel and some flat aluminum stock yielded some spacers/extensions, and a little more room for the rubber. 

 

 

 

With the front end looking good, might as well do something to the back - first step, swap a fancy progressive spring onto the shock (turns out to be a hassle if you don't have the right collar for the big boy BMW shock...but a solution {paying a few bucks to someone with the right press and collar!} was found). 

 

 

After a few miles riding I can say it feels good - haven't tried it fully loaded over frost heaves yet, but it should help keep the centerstand off the pavement while underway.

 

 

 

 

Now that the bike is going to be so much faster and better handling, we might not be able to rely on simple wind resistance to slow down anymore. So our last upgrade was to replace the rear brake rotor, affectionately known on the LT forums as the "cowbell", with some EBC bling. Another easy job as long as you've got some heat - and this time I got to use fire!

 

 

A little time in the freezer for the new rotor, and the still hot ABS tone ring will just drop right on. Looks so good it's too bad you can't see it once the bike is back together

 

[szurszewski]

About the time that all got done, Kirby stopped by to check on his road rig and prod the progress along a little bit. 

 

 

While the sidecar is a fancy Hannigan affair, it pretty clearly was not originally mounted to the bike at Hannigan - there were a couple of odd things that we wanted to address as it went back together. 

 

No point in this photo, I just think it's funny - maybe this is what Hannigan means by "leaned very slightly apart"? Probably not. 

 

 

The main oddity of the setup was that instead of the front of the sidecar frame being about two inches higher than the rear of the frame, it was a good five inches higher - made for a weird look from the side for sure. In this pic you can see the sidecar sitting as it should be, and the lower mounting strut being not so close to where it mates to bike side bracket.

 

 

Well, it seems pretty obvious that horizontal strut is just turned upside down - easy fix!

 

 

...except now the upper strut is not nearly long enough to reach the bike. Should be another easy fix - just "unscrew" a bit more of the threaded rod, and it should be fine...except the threaded rod turns out to be barely threaded into the strut at all.

 

 

Though it looked a bit dodgy to me, it was obviously enough to keep the rig together ... so far... but it's also probably why the lower strut was mounted wrong and the nose of the car was so high. A quick trip to Tacoma Screw (<-- my mom, who is from Tacoma, still giggles whenever you say the name of the shop, even though she's, like, really old {no offense to all of you really old people...}) and I put Jeremiah to work sorting it out. 

 

 

...and we ended up with this:

 

 

(hand is just for scale). I think that will work, and I was able to get more rod threaded into the strut (up to the blue mark, about), so that makes me happy. 

 

Oh - sidenote: trying to support the front of the sidecar with the trim resting on your forearm, even for a few seconds, is probably not a good idea - 

 

[szurszewski]

...and that's that! Or sort of. Jeremiah and I got it all buttoned up last night, and took it for a spin. Hmm - starts up, doesn't want to idle, runs great at speed, but doesn't want to idle at a stop and doesn't really want to have any load under about 2800rpms. Bad gas? Tank was nearly empty and has been sitting for months in the garage. Added some fresh gas and fuel treatment, tried again - same results. Oh - duh - forgot to reset the TPS! Duh. Ok - do that, take it out - seems a bit better at first, then back to the same. ....hmm....maybe one of the new injectors is bad? Exhaust note/pattern is a little off and the bike computer shows fuel consumption at about 20mpg instead of 35mpg or so. 

 

Bring it back inside, pull off the body and tank, swap the old injectors back in... and then realize what was actually wrong. Ha! I was amused - enough to smile after doing two hours of useless work and knowing I'd have another hour or so of the same to put the tank and body back on. 

 

So, for fun, if you're the first person to correctly diagnose my silly mistake, I'll send you a very rare and highly collectible (<-- one of those statements, at least, is true...) sticker pack: