Standard forks on a Special?

[Tim Johnson]

I am preparing to restore/customize a 79 XS 1100 SF. My fork tubes are really rusty and need to be replaced. What I am wondering is can I replace the forks entirely with those off a standard? I believe it would change the angle of rack a bit. So would this be a bad thing? I would think that steering would be improved at slow speeds, but I may be wrong and just asking for problems. Any suggestions? Oh the reason I want to use the standard forks is I have a standard for parts.

[oldnortonrider]

My guess, is it would be a good swap.
I've been riding my Special fairly regular for several years; I have
had, during this time, a Standard that's in pretty good shape, not
running. I have often thot about swapping the front ends, like what your suggesting; to draw up "that rake", on my Special. (On a car, I think it's called caster.)
I'm thinking , the fork necks are the same >> bearings, etc.
But, from there, forward, its all NOT the same.
I think, the last time, I stared, back and forth, real hard, when I had both machines parked close, the triple-trees are different.
Triple tree, sticking out further on the Special, with that offset axle going forward >> perfect rake for a hunerd miles an hour.
But, under 2-3 miles per hour, I've always known "the Special's rake" was causing me extra work.
The Standard I have, I've never ridden it . Oftentimes, have
thought about doing "that" steering geometry change.

I bet you'll get some suggestions, ideas/posts on this.

[sixtysix]

YES you can swap them, but you have to change the entire fork assy including triple tree. Since brake calipers and mountings are completely different. It will change the geometry slightly due to different wheel mounting location. Why do you need to change the triple tree? Yamaha made the tubes on a special 1mm less in diameter and they do not exchange......Never did it myself but this is what I have gleaned from this question being asked on the list before.

[oldnortonrider]

66 ;
That's , really, got my brain doin' somersaults ; about the forktubes being 1mm smaller on the Special, than on the Standard. No wonder!!!! ; I've had such a gain with the TKat forkbrace, that I've been riding with, the last 4 weeks. With my puny,puny 37mm forktubes.
IIRC , my Special's tubes are 37mm; that'd make BIG,FAT 38MM tubes for the Standard.
How could "they" (the manufacturer) have not POSSIBLY , have
had enuf engineering know-how ,>> to have not gone LARGER!, instead of smaller! in diameter.?!!
Do you reckon they rode it after they built it? Maybe, roadtested it?
These XS's IMO need at least 43mm tubes to do "justice" , to
the rest of the motorcycle.

[Stray Bullet]

i believe there is someone here who went the 'other' way... special tubes to STD trees... cant remember who, tho.

if i'm not mistaken the STD tubes are shorter than special tubes, besides being 1mm larger. this will have a negative effect on yer front end, dropping it down. additionally, i believe the special trees have a different rake to compensate for the leading axle.

i have the complete front end from an H on my SF. well, the speedo is a 78. and the fender. oh yeah, the bucket is too... <grin>

i did it cos i like the square looks, and i had already rebuilt the STD tubes.

i could be wrong about this, but other than the wheel and speedo drive (and probly the axle too), there are NO 'single' interchangeable front end parts (counting both tubes and lowers as a unit). change the forks... oops, gotta change the trees... oops gotta change the turn sigs,,, darn, where will i get the other bucket?? and the ears, calipers, headlight adjuster, fender, and and...

the only thing i'm not sure about is whether the gauge cups or gauge bracket holes will line up, allowing those to be swapped around.

if anyone else knows differently about swapping front end parts, i'd be interested in learning. i figure a backup front end is a GOOD thing to have...

[sksxs1100]

anyone know what the fork size for a 78E is?(ie. 34mm, 36,mm etc)

[Tim Johnson]

Thanks for all the info. I think I am going to try and swap out the special forks then for the std ones. I may regret it but hey, it shall be fun to find out. I am also going to have to change the brake calipers also.

While I am at it, I am going to stick the STD gas tank on it. I always wanted a larger capacity, and I guess I shall swap the gauges also. Hmmm this is going to be one confused bike.

[oldnortonrider]

An amalgam-hybrid. Your own personal mechanical ART .

[ErricZ]

Very interesting .... I have been thinking of buying a Special and putting some standard things on it, such as wheels and tank, but I like the rake of the Special ...


Where do we post about project questions? Has anyone tried to do a similar swap/conversion?

[Mike Hart]

fork tube diameter

I just measured the fork tube diameter (the upper part, the slider, just in case there's a terminology thing) on the following bikes:

• 79F = 37mm
• 79SF = 37mm
• 82XJ = 37mm

If some E owner would measure theirs, that should do it. I'm pretty sure they are also 37mm.

The lengths are different, so you can mix/match top/bottom parts to raise/lower a bike. (Bottoms go with clamps and calipers as a set, as mentioned earlier.)

You can also reduce the Trail a bit (and quicken the steering) by having the forks stick up out of the top clamp, the technique varies from model to model, which bars you have, etc.

[schneidr]

Tim,

You can get replacement fork tubes from Forking by Frank.

http://www.frankmain.qpg.com/

This is where I got the replacements for my SF. The cost was about $200.

[rockyr74]

<<You can also reduce the Trail a bit (and quicken the steering) by having the forks stick up out of the top clamp, the technique varies from model to model, which bars you have, etc.>>

Anybody tried this? I have a 80 special with "superbike" bars - about a 4" rise with a splay like an old triumph (hated the O.E. rototiller bars) and the bike just seems to handle weird at low speeds - to pull out of an intersection and turn seems like it is more work than it should be.

Thanks,

[Mike Hart]

Rocky, is your steering head bearing ok? Need lubing? Is it too tight? Sounds like too tight from what you describe. Could also be squared-off rear tire.

Raising the forks up won't cure what you say is happening, the effect of that is more noticeable at normal speeds, not taking off from a stop.

Does your bike go in a straight line easily? (if not, steering head bearing is too tight)

[Tim Johnson]

Ok now so if I am reading what Mike Hart said I can reuse my SF triple tees, and the tubes are interchangeable. So I am going to assume just from looking at the STD tubes and the special tubes, that the special tubes are indeed longer in length. Now this is a good thing for me, as I would like to put the STD bottoms on as this would change the rake and I would think improve the handling a bit. The reason I would like to use the Special tubes is that they are longer and I could then possibly add clamp on handlebars. Giving the bike a realsuper bike look and feel.

So how crazy and overly complicated am I making this? I can never seem to leave well enough alone.

[Mike Hart]

I like it, Tim. Denny Z's standard has special tubes and clip-ons!

From what I've heard, you have to change the clamps. You definitely need to go with calipers from a std if you use std bottoms. So you pretty much need the entire std front end, but use spcl tubes.