79F Standard front end help

[Barbarosa]

Working on a 1979F Standard and have run into a confusing problem. Took apart the forks and now have too much space between them to get the axle right. Got the bike running, put 60+ easy miles on it knowing the front end needed attention. It went down the road straight and safe feeling but made a metallic clank on occasion when stopping that I thought might be something brake related. I knew something was amiss when I took off the L caliper and it had grind marks on the outboard side from contact with the rotor. Found the L fork tube was bad sticking in the slider while replacing seals so I got another (thanks Greg aka BA80) and began reassembly. When I got it back together there was a half inch space that shouldn’t be there. When the wheel is centered between the forks the right side spacer is against slider like it should be but the speedometer drive is a good half inch from where it needs to be to index onto the slider and tighten down. Don’t know how or what the PO did to get the wheel to even rotate, but the correct spacers etc. are there so I guess they just kept tightening the axle nut pulling the forks together till the gap was gone. Would that explain the tube running crooked ruining the L slider and grinding the caliper if that was the side that was off center the most? Don’t have history on the bike, but the triple tree appears to be a Standard with pinch bolts in the front that mount blinkers, the sliders are 79F with clamp and axle opening at the bottom, and the tubes take 37x49x8 seals. The tubes and sliders are equidistant the entire length so bent parts is not likely. Anyone ever run into a problem like this or know why that half inch gap is there? Hopefully it is not operator headspace.

[IanDMacDonald]

Can't put my finger on it, but there is a correct procedure (see manual) for torquing the front-end when it comes to keeping the forks straight. I'm wondering if it took the forks out of whack?

[MaximPhil]

Can't put my finger on it, but there is a correct procedure (see manual) for torquing the front-end when it comes to keeping the forks straight. I'm wondering if it took the forks out of whack?

My thoughts too Ian, Barbarossa get the manual out and loosen everything then tighten according to manual instructions.
Phil

[Barbarosa]

Was hoping someone knew if the center to center measurement on xs11 forks is exactly the same on all models. Don't think that much space could be taken up no matter what was tightened when anyway. Its right at half an inch

[motoman]

bettin' a spacer that tightens against inner bearing race has been left out on speddo drive side.

[TopCatGr58]

Hey Barbarosa,

I can't say with certainty, but both models, specials and standards use the same front wheel. I know that the position of the forks from the steering center is different between models front to back. With the Specials, the manuals talks about moving the slider in/out to position the rotor within the guides on the slider, and that can be 3/8" or more.

When you were rebuilding the forks, did you take the upper tubes and roll them see if they were true and not slightly bent?? You can loosen the triple tree clamps and then rotate the upper tube and see if the slider then moves closer or farther away from the wheel. If it does move in/out, then that could indicate a slightly bent upper tube!

Manual says tighten castle nut, then front left axle pinch bolt, then rear, while positioning the slider to provide the proper rotor/slider clearance.

T.C.

[Barbarosa]

Hey Barbarosa,

I can't say with certainty, but both models, specials and standards use the same front wheel. I know that the position of the forks from the steering center is different between models front to back. With the Specials, the manuals talks about moving the slider in/out to position the rotor within the guides on the slider, and that can be 3/8" or more.

When you were rebuilding the forks, did you take the upper tubes and roll them see if they were true and not slightly bent?? You can loosen the triple tree clamps and then rotate the upper tube and see if the slider then moves closer or farther away from the wheel. If it does move in/out, then that could indicate a slightly bent upper tube!

Manual says tighten castle nut, then front left axle pinch bolt, then rear, while positioning the slider to provide the proper rotor/slider clearance.

T.C.

Compared the wheel on the 79F to one from a 79MNS and they were the same measurement rotor to rotor. Roll tested the tubes on the floor with no noticeable wobble. These forks have the axle on the ends so I think the speedo gear should index into the slider on it's own if properly spaced. Mechanical drawings of the different fork configurations would show if there is a difference between centers but I can't find that data. Hoping someone reads this that has put one together from parts and ran into something like this. I don't know what has been done to this bike, but it was not done right and I with my limited knowledge suspect mismatched parts were somehow installed.

[Ranger_xs1100]

measurement

Was hoping someone knew if the center to center measurement on xs11 forks is exactly the same on all models. Don't think that much space could be taken up no matter what was tightened when anyway. Its right at half an inch

Barbarosa,
If it helps....
I measured the distance between the forks , just above the fork boot, on my 78e, 79f, and 80lg.
All were within .02 inches at about 5.87 inches.

[Barbarosa]

Same for 80SG so it is apparent that xs11 forks are centered the same. Thanks for contributing to my OCD Bob. That was cool on so many levels. PROBLEM SOLVED. The 79f is now sporting an 80 MNS triple tree, thanks Greg, and just about ready for a test ride. It must have been the tree because everything lined right up after the transplant. Keeping the square headlight so I made some spacers to take up the slack in the ears.

[3Phase]

You may not like the handling using a Special triple tree with Standard forks.

The Special forks have a leading axle, the Standards don't so the steering geometry will be wrong, as if you hit something and moved the front axle back a few inches/degrees.

The bobber folks like to go the other way and use Special forks in Standard trees to make it more like a chopper.

[BA80]

Same for 80SG so it is apparent that xs11 forks are centered the same. Thanks for contributing to my OCD Bob. That was cool on so many levels. PROBLEM SOLVED. The 79f is now sporting an 80 MNS triple tree, thanks Greg, and just about ready for a test ride. It must have been the tree because everything lined right up after the transplant. Keeping the square headlight so I made some spacers to take up the slack in the ears.

if you put the MNS triple tree on there and used the standard forks the trailing will be wrong. The steering will be twitchy and it won't handle well.

I thought I explained the difference between standard and special front ends.

[kboehringer]

F disassembly in Georgia

Barbarosa,

I recently purchased an F for the purpose of snatching the few common parts I will keep as spares for my three specials. There are several parts on this machine that will not support my specials including the trees.

I have not yet pulled the motor out of the frame but intend to do so in the next few days. Once the motor is out, the remainder of the bike (including trees) was headed for the dump.

It may be a week or so (certainly no more than two) before I am ready to haul the carcass off to the dump. If you want the trees you can have them for the cost of postage.

Kurt

[BA80]

Barbarosa,

I recently purchased an F for the purpose of snatching the few common parts I will keep as spares for my three specials. There are several parts on this machine that will not support my specials including the trees.

I have not yet pulled the motor out of the frame but intend to do so in the next few days. Once the motor is out, the remainder of the bike (including trees) was headed for the dump.

It may be a week or so (certainly no more than two) before I am ready to haul the carcass off to the dump. If you want the trees you can have them for the cost of postage.

Kurt

I don't suppose you have a title for it do you Kurt?

[kboehringer]

No title......

I don't suppose you have a title for it do you Kurt?

NO. Not required (or even issued here) in Georgia for anything this old but basically a yard ornament for any state requiring a title.

[TopCatGr58]

You may not like the handling using a Special triple tree with Standard forks.

The Special forks have a leading axle, the Standards don't so the steering geometry will be wrong, as if you hit something and moved the front axle back a few inches/degrees.

The bobber folks like to go the other way and use Special forks in Standard trees to make it more like a chopper.

Hey Barbarosa,

To sorta quote Fredintoon, the side car guys also liked using the special trees on the standards because it does reduce the trail a little and makes the steering a little lighter/easier vs. the stock configuration. Some folks complain that the OEM steering feels very heavy with these bikes. They have ~6 inches of trail stock. I did exactly what Scott/3Phase talked about, I hit a car headon and bent my frame neck straight back, and unknowingly reduced my trail to a little over 2"! :EEK: The steering was rather light, but also had a little tendency to oversteer, took a little getting used to, but I did and rode it for 8 years, this way, then another 8 years after it's first rebuild 2000-2008 until I finally learned about my bent frame! I finally fixed it this past year when I did my second rebuild and frame swap back to OEM.

But the amount of trail reduction you'll see with this tree swap is probably very little, like maybe an inch to about 5". You can determine the trail using a laser pointer lined up with the steering neck shining on the ground next to the front wheel, and then drop a line straight down from the axle, and measure the distance between them.

T.C.