Another FZ1 swingarm, but a little different too.....

[Country Joe]

Great White,
Just something else you need to consider about the FZ1 swingarm swap is the difference in location of the dog bone attachment point of the FZ1 and the FJ swingarms.  The mounting point on the FZ1 swingarm is too far rearward compared to the FJ. You can make longer dog bones and bolt it all together, but I found that the ride and handling was far less than optimal. I cut off the lug on the bottom of the FZ swingarm, had a block machined to receive the FJ needle bearings and had it welded to the front of the swingarm cross member. It restored the suspension linkage geometry to where I ended up using the original 3XW dogbones and that left me with 5/8" of clearance under the rear tire while on the center stand. I tried the unmodified FZ1 swingarm for a couple of months and never could get it to ride well at all, even with the RPM shock. If you don't like the extra length of the FZ1 swingarm,  you really would be better off to just build a brace for the FJ swingarm and call it a day.

Joe

Yep. Thats one of the reasons I want to move the swingarm pivot back: to keep the linkage geometry correct.

When I measured the two swingarms in the jig, I used the linkage attachment lug as the common point. That's why I'm looking at approx 1.75" off the front and .5" off the rear. Lots of guys often don't understand how much difference even a half inch difference can make in suspension and handling. I've got enough "suspension  time" under my belt to understand what changing the ratios in a progressive linkage does.

Move the linkage mount or move the swingarm pivot, two ways to skin a cat.

My way just does dobke duty by keeping the swingarm length "FJ correct".

And if I end up junking the FZ1 arm, no big deal. I can alawys use more aluminum ingots.

[great white]

Picked up a used 3CV swingarm for 35 bucks today. I grabbed it so I can weld and hack on it without risking ruining the one on the bike.

So now it's a running competetion between modifying the FZ1 arm or bracing the stock FJ arm.

Or I may just do both!

Lol!

[great white]

Ever wonder what's inside that FZ1 swingarm?

Well;





Compared to the FJ arm, the aluminum is roughly twice the thickness. That, combined with the increased cross section and the internal webbing (not to mention the MASSIVE cross brace), is what makes it so much "stiffer" than the stock FJ arm.

Starting the "fishmouth" to move the pivot rearward:





I don't think I'm going to have to "slit" the sides to close the top and bottom ends down on the pivot. The OEM hits it with a "hell for strong" welding process that penetrates straight through in one pass. I had always planned to bevel the weld joint and do a multiple pass process, to ensure penetration and coverage.

I believe after I bevel the top and bottom pieces, it should be close enough that I can fill whatever gap is left with the weld.

My weld will be structurally strong when done, it just won't be as "pretty" as the OEM pass (well, TBH, the OEM weld isn't what I would call "pretty" anyways).  But it's going to be buried up inside the bike, so I could care less on appearance. Dimensional  correctness and strength is what matters here...



On a safety note here: aluminum exposure has been linked to onset of Alzheimer's disease. If you use sanding discs to remove bulk material here like I did, make sure you use a respirator of some sort so you don't inhale the Al dust.....you need to protect more than just your eyes and ears here. My Dad went out with Alzheimer's. Trust me when I say you definitely don't want to go out like that.  It hasn't been solidly linked as a primary cause, but there is evidence. Why take the chance? Respirators; use 'em! They're good for many reasons....

[aviationfred]

Here is a better view of the relocated dog bone mount with the swing arm mounted in the frame with dog bones and shock connected.

Fred

[great white]

Here is a better view of the relocated dog bone mount with the swing arm mounted in the frame with dog bones and shock connected.

Fred

I won't need to do that. What I'm doing is moving the swingarm pivot back, which corrects the linkage geometry to stock FJ. So no need to move the cross brace mount point forward.

6 of one, half dozen of the other.

Except my way also makes the swingarm the same as FJ length overall....well, it's actually still 1/2" longer than FJ length at the rear axle center point, but I'm either going to live with that or clip 1/2" off the rear of the arms as well.

[Pat Conlon]

Remind me, on the FZ1 swing arm mod, do you have to narrow the pivot tube like we have to do with the Thunder Ace mod?  IIRC on the TAce we had to reduce the width 8mm (4mm off each side) so the pivot tube would fit in the FJ frame.

The reason I asked, if it does need to be narrowed, with the FZ1 tube narrowed and with tube's new location on the box arms, due to the angle of the box arms, it looks like it's gonna be tight in getting those side caps (dust seals) to slide onto the pivot tube.

What do you need ~1/2" to get the caps seated on the ends of the tube?

[great white]

Remind me, on the FZ1 swing arm mod, do you have to narrow the pivot tube like we have to do with the Thunder Ace mod?  IIRC on the TAce we had to reduce the width 8mm (4mm off each side) so the pivot tube would fit in the FJ frame.

The reason I asked, if it does need to be narrowed, with the FZ1 tube narrowed and with tube's new location on the box arms, due to the angle of the box arms, it looks like it's gonna be tight in getting those side caps (dust seals) to slide onto the pivot tube.

What do you need ~1/2" to get the caps seated on the ends of the tube?

Won't know until I get to that point. From what I've read, 3mm off each side is required to fit the FJ frame. I have an appoinment all day tomorrow, but if we get the weather they are calling for, I won't be going and I should be to the point where I'm ready to start putting the swingarm together by the end of the day...

[great white]

I'm highly doubtful it will be an issue anyways. The taper at the front is fairly gentle and the new weld points will be almost exactly where they were oem. Maybe 1mm further out per side, tops. It's only moved back about 1.75"....

[great white]

I'm highly doubtful it will be an issue anyways. The taper at the front is fairly gentle and the new weld points will be almost exactly where they were oem. Maybe 1mm further out per side, tops. It's only moved back about 1.75"....

Correction on last: it's roughly 2mm further outboard on each side. So, roughly 5 mm less per side after it has been cut to size.

Still looks like ample room to fit the stackup of shims and seals.

[great white]

Been working on the pivot tube today.

One thing is for sure: Yamaha sure doesn't weld up the swingarm assembly in a jig that keeps the metal from warping/moving! it's pretty hard to keep welded parts from moving, the jig has to be pretty strong. Even then, it will move some.

The pivot tube is shaped almost like a banana, with the inner part of the curve where you would think it would be; on the welded side.

I'm thinking they must line bore after welding in order to get the bearings in the same plane. That would seem to make sense on a production scale: drop the sections in a jig, weld it up and let it warp a certain amount, line bore and it's out the door.


But, that could be a problem for a "home welded" swingarm like mine is going to be. with the tube already "warped", making the pivot bearing square could be trouble.

The other strange thing is even though the swingarm pivot tube ends are square to the tube, they are not square to the chassis mounting area because of that "banana" shape.....

[great white]

Almost ready for welding:







Next up is measuring for proper location and dimension, build the positioning jig to lock it all down solid, then weld 'er up and see what I get....

I will have to order new pivot bearings though, frigged up the FZ1 bearings that came with the swingarm when I removed them. These will work well enough for mock-up, but they ratchet a tiny bit so out they go!

[great white]

Well, time to get it done.

First, I level and true up a stock swingarm and drop reference points to the floor from my critical dimensions:



With that done, I grab the FZ1 arm and:



Gah! Whats that gawd awful mess all about? Well:



Yes, the pic is upside down... but you can see all my droplines from the modified FZ1 arm are bang on thier marks. Well, the linkage pivot is on the proper plane, the lines are just "in" a bit more because the FZ1 pivot mount is not as wide as the FJ pivot mount. I just measure and mark lines where the FZ1 pivot width should fall in comparison to the FJ lines.

Then weld 'er up:



That was the fastest part of the whole job! Like everything else, the prep takes the most time but thats how you get the right results on the first try!



Once cooled (welded AL holds its heat for a looong time) I slide it on and see how it looks/fits:





Oh yeah buddy! Thats what I'm taking about!

Looks great, maintains the FJ geometry (well, its 1/2" longer,  it I can live with that) and should add plenty of torsional stifness.

I welded with the bearings and pivot spacer installed to help keep the AL from shifteing too much under the heat of welding. The bearings were scrap and needed to be replaced anyways so this is a good "end of life" purpose for them.

It's not perfect though. Since the swingarm is now shorter, that effectively means it gets wider, sooner. It contacts the brake switch, and by that I mean it solidly contacts the brake switch! Thats an easy fix though. There is also now not enough room to clear the brake master. I can fix that by taking the peg   racket/plate to the mill and shaving off some AL to recess it a bit more. Only needs a couple mm at best.

But the biggest "Pee-Off" is the Kerkers no longer clear the swingarm. The LH side is close to clearing, but the RH side isn't even close to going on the bike, let alone clearing the swingarm. It's fixable, it just means more cutting and welding. Oh well, that's par for the course when modifying a bike.

The rest is all simple "busy work"; bushings and spacers for thr FJ axle and locating the FZR1000 wheel and R1 brake components.

Pretty happy with it so far.

[aviationfred]

Well, time to get it done.

But the biggest "Pee-Off" is the Kerkers no longer clear the swingarm. The LH side is close to clearing, but the RH side isn't even close to going on the bike, let alone clearing the swingarm. It's fixable, it just means more cutting and welding. Oh well, that's par for the course when modifying a bike.

The swing arm install looks great. You have some serious fabrication skills.

I had a similar issue with my FZ1 swing arm install. Even with the standard length of the swing arm. The Yoshimura slip on mufflers would not allow full movement of the swing arm without fouling.  

My solution, was getting a 4-1 full exhaust that had been hanging on the wall of another members garage for 20 years.  

Fred

[Pat Conlon]

Ran into that problem with the Cobra slip on's  when I did my YZF1000 swinger.
I did the following, each helped a little bit, but all together it made everything fit.
1) Spaced out the side plates with 1/4" spacers on the bolts between the plate and sub frame.
2) Shaved down the passenger foot peg nuts
3) on the muffler support, I used a low profile button head bolt (button head facing inside) with an acorn nut on the outside.
4) used a low profile Allen head banjo bolt on the m/c with special hose fitting to route the brake hose away from swing arm.
5) shaved the stop switch support bracket for clearance.

[Old Rider]

Looks great Great white You got good skills !