FJ1100 fork conversion

[WMarshy]

Well, I dont know any difference b/c this is my only bike so they seem to work fine for me. My problem is I need more compression resistance up front, I can get my forks to compress about 4.5 inches (~114mm and maybe more) measured from free length with preload on high during normal riding. I just think the forks/springs are not up to the amount of forces from the breaking. Maybe I will agree with you more after I get the new forks in and realize I could's been breaking harder the whole time if I had better calipers.

[FJ111200]

I've not made any mods inside the forks apart from some fresh oil, can't remember what weight now, and some new progressive springs. All i know is, that it's a total positive transformation from the old XS. I can't see me going back now.
BTW, in reply to a previous post, an XS swingarm bolt which is 27mm i think, is what i fashioned onto an old 1/2 inch drive socket to remove the damping rod from the FJ forks when doing the re-build.

[crazy steve]

Thanks Phil, I'm off to EBay for a axle. If I have to, I'll shorten it a bit. One problem here is all the local bike boneyards are a couple of hours or more away from me, and all think their stuff is gold-plated...

I'm going to go with the XS stem I think but I may shorten the FJ stem, whichever looks easier. One question I didn't ask was, does the OEM fork lock still work? I would think not with the top tree being higher. And if I make some custom spacers, I'll turn out some spares if you want to get rid of those washers. Having a couple of cheap machine tools does give me a few more options. And that's one reason I'm buying two sets of forks; if a 'fit' experiment goes awry, I haven't ruined my only part.

In answer to FJ111200, Marshy pretty much put my reasons out there; when this is all done, this should look like it 'came' on the bike, not be obviously adapted. Phils' bike needs a double-take to tell it's not OEM, and that's a sign of a well-executed swap IMO. While performance is a goal, it's not the only goal for me. So retaining the stock front wheel/rotors to match the rear will keep the bike looking 'integrated'. If it were possible to do a rear wheel swap I'd probably use a more modern front, but modding a rear to fit the shaft drive would be just too much work, plus the likely issue of finding a rear tire that fits.

I am going to look into more modern brake calipers (and I just got done polishing/rebuilding mine!) and have a couple of ideas there; the late-harley four-piston units look promising, I'll know more after I do some measuring. The big problem here is nearly all 'modern' brakes use fixed calipers and floating rotors (opposite of the stock XS), so this may need a rotor swap too to work without problems. I'm a lo-buck-er just like Phil, so these need to be reasonably cheap/easily available parts.

The handling of the XS was always it's weakest point, so improving at least the front will be a big plus. Now, if you could only get rid of the 'pogo' effect from the shaft without going to chain drive....

I'm sure I'll be back with more questions for Phil, and maybe with some alternatives for install/brakes. Of course, as slow as I am at this sort of thing (tending to be perfectionist), this probably means I'll be riding my Sportster most of this summer....

'78E original owner

[bikerphil]

does the OEM fork lock still work? I would think not with the top tree being higher. And if I make some custom spacers, I'll turn out some spares if you want to get rid of those washers

No, the steering lock doesn't work anymore with the raised upper TT, but on the lower TT, the stop blocks work perfectly and didn't need any altercation at all. With your setup, YMMV.

Steve, that would be great if you had a couple extra spacers.

[WMarshy]

....
I'm going to go with the XS stem I think but I may shorten the FJ stem, whichever looks easier.

What's the issue with using the XS stem? (Correct me if Im wrong) Is it you have to just press the stem out of the FJ forks and press the XS back in, or is there something else Im missing? Wouldnt you want to keep the upper and lower tt spacing so you dont have have XSessive spacers and can keep the function of the lock? You said the bearings were the same between the two right?

....
....when this is all done, this should look like it 'came' on the bike, not be obviously adapted. Phils' bike needs a double-take to tell it's not OEM, and that's a sign of a well-executed swap IMO. While performance is a goal, it's not the only goal for me.

I totally agree!

....
I am going to look into more modern brake calipers......The big problem here is nearly all 'modern' brakes use fixed calipers and floating rotors (opposite of the stock XS), so this may need a rotor swap too to work without problems.

Thats what I was thinking... hmm, great minds think alike! We might have to make our own custom "hub" to hold a floating caliper that is a direct bolt-on where to the stock roter mounts to. This is when I wish I worked for a machine shop again... Im liking this.

[FJ111200]

You lot don't half go round the houses.

[tinman905]

If you happen to make a couple of extra spacers I would be interested

Thanks Phil, I'm off to EBay for a axle. If I have to, I'll shorten it a bit. One problem here is all the local bike boneyards are a couple of hours or more away from me, and all think their stuff is gold-plated...

I'm going to go with the XS stem I think but I may shorten the FJ stem, whichever looks easier. One question I didn't ask was, does the OEM fork lock still work? I would think not with the top tree being higher. And if I make some custom spacers, I'll turn out some spares if you want to get rid of those washers. Having a couple of cheap machine tools does give me a few more options. And that's one reason I'm buying two sets of forks; if a 'fit' experiment goes awry, I haven't ruined my only part.

In answer to FJ111200, Marshy pretty much put my reasons out there; when this is all done, this should look like it 'came' on the bike, not be obviously adapted. Phils' bike needs a double-take to tell it's not OEM, and that's a sign of a well-executed swap IMO. While performance is a goal, it's not the only goal for me. So retaining the stock front wheel/rotors to match the rear will keep the bike looking 'integrated'. If it were possible to do a rear wheel swap I'd probably use a more modern front, but modding a rear to fit the shaft drive would be just too much work, plus the likely issue of finding a rear tire that fits.

I am going to look into more modern brake calipers (and I just got done polishing/rebuilding mine!) and have a couple of ideas there; the late-harley four-piston units look promising, I'll know more after I do some measuring. The big problem here is nearly all 'modern' brakes use fixed calipers and floating rotors (opposite of the stock XS), so this may need a rotor swap too to work without problems. I'm a lo-buck-er just like Phil, so these need to be reasonably cheap/easily available parts.

The handling of the XS was always it's weakest point, so improving at least the front will be a big plus. Now, if you could only get rid of the 'pogo' effect from the shaft without going to chain drive....

I'm sure I'll be back with more questions for Phil, and maybe with some alternatives for install/brakes. Of course, as slow as I am at this sort of thing (tending to be perfectionist), this probably means I'll be riding my Sportster most of this summer....

'78E original owner

[crazy steve]

What's the issue with using the XS stem? (Correct me if Im wrong) Is it you have to just press the stem out of the FJ forks and press the XS back in, or is there something else I'm missing? Wouldn't you want to keep the upper and lower tt spacing so you don't have have XSessive spacers and can keep the function of the lock? You said the bearings were the same between the two right?

The main issue is the XS stem is welded to the lower tree, so getting it out without losing length ain't that easy...

I picked up the forks/trees/etc this afternoon and after looking the parts over briefly, have a few observations...

I didn't notice in Phil's pics that the tubes are necked down between the top and bottom trees, limiting the distance/where you can relocate the trees on the tubes. I haven't measured anything yet, but Phil's original idea of a 'spacer' for the lower bearing may be what I want to do to keep the bike at original height.

The FJ stem: Jeez, it's only pressed into the aluminum tree!? I would have expected at least a lip or c-clip so it can't pull through! Am I missing something? If I mod the stem, I'm putting something on the end to prevent pull-through. Or am I being paranoid?

The front axle: Another puzzler. Again, Phil's pics didn't show all the details, but these use a 'bolt' type axle, so when everything's tightened up, you're pulling the two ends of the forks towards each other. While this may give you a more rigid fork, it makes precision fit of the axle spacers critical to prevent/minimize fork binding. This something I'll look at much closer once I'm into the swap. It takes very little fork misalignment to cause strange handling sometimes (remember, I said I can be a perfectionist...).

The brakes: Things got interesting here. Phil reported that the FJ calipers hit on his wheel, but just for the hell of it I took one with me to see how tight it was. Well, in a 'rough fit', the stock FJ calipers just (and I mean just; about .030") clear the XS spokes. Mind you, this was just trying the calipers on the wheel/rotor. We'll see how they fit after the forks/wheel are on the bike. But I think I can pick up enough clearance by shaving the inside of the caliper, and more yet by milling a bit off the mounting tabs if needed. There may be enough variation in the machine work between the wheel/forks/calipers that Phil just got a bad 'tolerance stack', and how precisely the wheel is centered. The other interesting thing was these are rigid-mount calipers and non-floating rotors which somewhat surprised me. I went ahead and picked up a pair of calipers, and if I can make them fit I'll use them; they're really only a marginal improvement over the stockers as the pad area is only slightly larger. The XS rotors appear to be a bit thicker than the FJ, but should work fine.

More details to follow....

'78E original owner

[bikerphil]

The FJ stem: Jeez, it's only pressed into the aluminum tree!? I would have expected at least a lip or c-clip so it can't pull through! Am I missing something

There is a retaining ring at the bottom of the stem, you just can't see it. You have to press the stem out from bottom to top. Before I took on this mod, I did a bunch of reading in the "mods" section of the UK site. There's some good stuff on adapting different front ends in there, Yep, I thought about using the early FJ dual pot calipers, but the wheel clearance was way too close for my liking, so thats why I went with the "rubbish", lol, XS calipers.

[WMarshy]

Nice update Steve, I found a local lead on some FJ parts but Im not sure if he has forks b/c I havent talked with him yet. Everything sounds great, if you end up making the spacer to put under the lower bearing let us know dimensions. Also, you said the fork tube necks down in the area of the tt clamps, I dont know what the difference in lenght is between the FJ and XS spindle are, but do you think there is enough room to move the tt clamps accomidate the XS spindle length? Keep up the good work, looks like we will have plenty of detail between Phil and Steve's build to make a very nice tech tip!

[crazy steve]

Ok, a further update...

Location of the fork tubes in the trees; after measuring all this stuff, I realized Phils' bike is lowered at least some from stock; if you made me guess, I's say about 1 1/2" lower at 'static' height. The XS stem is out, if you try to use that it limits height adjustment even more. So the best solution looks to be the FJ stem with a spacer at the bottom and if you 'cheat' the taper into the lower tree, you can maintain stock height. I think what I'm going to do is build up/remachine the FJ stem and put the spacer on the lower tree, raising the lower bearing to match the XS stem. If you plan on using the FJ handlebars (I don't), you will have to drop the front of the bike to have enough fork tube sticking out above the top tree to attach the clip-ons.

Fork trail; these trees have less offset compared the stock 'Standard' trees I have, so they'll slight increase trail over stock. If you lower the front of the bike, this will bring the trail amount back down. This will also very slightly reduce wheelbase.

Brakes; well, you can forget the FJ calipers. I figured out a way to fix the wheel/caliper clearance issue, but the FJ uses a smaller rotor (11" vs 11.75") so unless you fit smaller diameter rotors, no way. I polished my OEM units, so I am using them! I did do some preliminary checking on the late Harley 4-pot calipers, and it looks like they'll fit with nothing more than a fairly simple bracket and with plenty of wheel clearance. The bigger calipers fitted to most sport bikes appear to be simply too big.

Tomorrow, I'll try to get started on the stem mod; I will have to pick up some chunks of aluminum for the lower tree spacer and the caliper mounts.

'78E original owner

[WMarshy]

Ok, a further update...

Location of the fork tubes in the trees; after measuring all this stuff, I realized Phils' bike is lowered at least some from stock; if you made me guess, I's say about 1 1/2" lower at 'static' height. The XS stem is out, if you try to use that it limits height adjustment even more. So the best solution looks to be the FJ stem with a spacer at the bottom and if you 'cheat' the taper into the lower tree, you can maintain stock height. I think what I'm going to do is build up/remachine the FJ stem and put the spacer on the lower tree, raising the lower bearing to match the XS stem. If you plan on using the FJ handlebars (I don't), you will have to drop the front of the bike to have enough fork tube sticking out above the top tree to attach the clip-ons.

Steve, could you let us know how the spacer and spindle would differ from your set up (using stock handle bars) verses using the clip-ons. Im guessing the spacer under the lower neck bearing would have to be shorter to give space for the clip-ons? Would this affect the spindle in anyway also? Thanks.

[crazy steve]

Steve, could you let us know how the spacer and spindle would differ from your set up (using stock handle bars) verses using the clip-ons. Im guessing the spacer under the lower neck bearing would have to be shorter to give space for the clip-ons? Would this affect the spindle in anyway also? Thanks.

No difference. What I'm doing different is I'm using the FJ stem (the same as Phil) but instead of putting the 'extra' stem length at the top of the neck (which is what Phil ended up doing), I'm putting mine at the bottom. This is what Phil was looking to do in his very first post with his 'race extender'. Rather than move the race down, I'm moving the bearing up on the stem and putting the spacer between the lower tree and the bearing.

To use the clip-ons, you simply slide the fork tubes higher up in the trees by whatever amount they need, roughly 3/4". I didn't pick up the clip-on bars, so I can't give that more exactly.

I'll take a few more measurements tomorrow and post them, giving the axle centerline to top of neck distances with the different combos, and this will more clearly show what I mean.

'78E original owner

[bikerphil]

Steve, sounds like a good plan. I was looking at the stock XS tree today next to an FJ upper tube, looks like the taper in the tube (forgot to mention that earlier) creates a problem.

My front wheel is about 1mm off center, seems close enough tho, the bike rides pretty straight. I wish I had access to some real tools like you do Steve.

[crazy steve]

Steve, sounds like a good plan. I was looking at the stock XS tree today next to an FJ upper tube, looks like the taper in the tube (forgot to mention that earlier) creates a problem.

My front wheel is about 1mm off center, seems close enough tho, the bike rides pretty straight. I wish I had access to some real tools like you do Steve.

Yeah, that taper is the fly in the ointment. If it wasn't for that, you could swap in the XS stem and pretty much bolt the trees onto the frame. I'm still trying to figure out why they did that...

My power tools do help, even if most of it is chinese 'stuff'; a good machinist would dispute that 'real' description. I just wish I was a better machinist; sometimes I make four to get one... my scrap bucket is always full.

If you could scare up $400, there's this:http://www.harborfreight.com/cpi/cta...emnumber=93212
This will do quite a bit as-is, and if you check some english sites, those guys do amazing things with these small lathes and some home-made tooling. This would do these stem mods no problem.

'78E original owner