Rebuilding Forks, Landsdowne Eccentiric Forks, Stiction

I rebuilt my 1975 850 Commando forks. The insides were rusted including the tops of springs, the top of cartridge rods etc. Oil was black too; no surprises here. The main culprit seems to have been the extremely rusted fork slider extension. Perhaps water was building there under the plastic cap between it and the seals. Who knows... Suffice it to say it was very rusty outside on top and inside. I took everything apart and took tons of pictures:

Photos here: https://1973nortoncommando850caferacer. ... suspension

Once all the gunge, rust etc and the innards were removed, the slider tubes themselves and even the brass bushings looked ok. I bought a whole Andover fork rebuild kit complete with new washers, upper and lower bushings, seals, fiber washers etc. I also purchased a new OEM non progressive springs. The cost of brand new cartridge parts was near a new set of Landsdowne's adjustable eccentric cartridges... so what was I to do. Everything was meticulously cleaned and inspected. My bushings are new. Both my sliders look ok as well, with decent shine, no pitting, no striations, etc. I also took my high speed buff wheel and fine polish, and shined them up some more. They looked pretty good and both left and right are similar in finish. I installed the Landsdowne's complete with 160ml of 10WT Honda oil. Admittedly, some of the oil did not get in there, but not much got away, say max of 15 ml. More on this later..

Both forks were fitted and everything looked good. I then started pumping them up and own by hand one at a time without the wheel and axle , just to feel things. I "felt" the Left- Compression leg was stiff and perhaps took a while to slide back down and was a little bound. The Right- Damper side would smoothly go up and smoothly slide back down. I've never had eccentric forks on my bikes. So the question is this -- Is this normal by definition. The Damper controls smooth sliding BACK to normal. The Compression takes the stiff Compression... and may have odd rebound to normal. i.e. is this EXACTLY what they are supposed to do? Or is it possibly my right Compression fork slider may also be sticking?

Or is it possible more oil leaked out the Left Compression... side? I will drain and refill shortly just to eliminate this scenario. But in any even, it was not more than 10-15 ml of loss. Before I do that, I may just strip them down again..

What is the consensus?

If anyone can send me their email I can even send you a short HD Video of the different side movements when compressed by hand and how they recover...


Thanks.
-->FJ SvenSven

mayby Tomspro [forum member]who as just fitted the lansdowne kit can answer all of your questions.
my concerns is with all the rust shown in the pictures if the sliders are servicable?

Almost all the rust was on the inside; the spring, the rod, cartridge parts etc. The only other exception was the slider extension but not the slider (stanchion) itself) . The sliders themselves and the chrome on them had not a single rust spot. I have 1-2 high res pictures of both of the sliders (stanchions) and they look near new. The bushings are brand new OEM from Andover.

Cheers.
-->FJ SvenSven

I order that this post is addressed correctly
Firstly sliders do not have chrome , sliders are the Alloy "legs" that the wheel is bolted between ..the parts that SLIDE.
Stanchions are the chrome plated steel 1.1/2 dia tubes that are clamped in the yolkes, your pictures show the Extream degree of years of poor maintenence..this rust wears the slider bore via the steel lower..very hard to guess ,and a internal bore gauge will show the "barrel" wear.

Thanks for the much needed clarification John.

To clarify my entire discussion had been about the chrome steel stanchions and not the Alloy Sliders that are the lower legs. That said, if the chrome stanchion on the left was worn... would it not be visibly obvious, with striations, scrapes, etc? Mine are shiny and seem very even in their entire length. I'd assume the 3-6 inch area around the fork seal would look worse for the wear? With a used bike of these many years.. who knows what was changed etc.

Can the Slider (Alloy lower leg bolts to wheel and axles, etc) be checked by a common high end calibrated micrometer... or is it more complex that that?
Similarly, is there a way to check to stanchion chrome part.. since visually both mine look ok and appear similar. However, one seems a bit more stick in performance?

Worst case scenario seems to be purchase a pair of new chrome steel stanchions and re-installing everything. The Sliders are lot more pricey.

Cheers.
-->FJ SvenSven

SvenSven said:

Almost all the rust was on the inside; the spring, the rod, cartridge parts etc. The only other exception was the slider extension but not the slider (stanchion) itself) . The sliders themselves and the chrome on them had not a single rust spot. I have 1-2 high res pictures of both of the sliders (stanchions) and they look near new. The bushings are brand new OEM from Andover.

Cheers.
-->FJ SvenSven

Click to expand...

Could it be that the bush is tight. I had a tight bush from Andover a few months ago ,they sent me a new one PDQ no problem. Said they had one or two that had been tight didn't have to send the old one back. First rate service with no bull. Bought loads from them no hassles .

J

john robert bould said:

I order that this post is addressed correctly .

Click to expand...

John nearly wet myself when I read your " command". Does your fork internals come with a copy of " the Magna Carta" instead of fitting instructions?

J

john robert bould said:

.......an internal bore gauge will show the "barrel" wear........

Click to expand...

You could really only mic the top of the slider bore so best to use the "T" type internal gauge

auldblue said:

Could it be that the bush is tight.
J

Click to expand...

Same here, except I didn't have sense enough to buy mine from Andover. The bushing would slide freely while out by itself, but would almost lock the stanchion in the slider once assembled. Slow and meticulous filing down of the outer sleeve diameter of the bushing eventually returned smooth sliding action. 'Took the better part of the evening.

As for measuring the ID of the slider, the proof of the pudding is in the eating. Once you have a good set of top and bottom bushings, "dry-fit" the stanchion into the slider and check for wobble at both ends of travel. Keep in mind that, as the assembly approaches full extension, any slop will be accentuated, but, since these parts wear more in line with the bike's centerline, you can get a good idea of how bad the wear is at any point by wiggling the stanchion fore-and-aft, and comparing that to how much it'll move side-to-side. It's best to do this either with the slider clamped in a vise, or with the stanchions assembled in the triple-trees. As you can imagine, the slider that carries the brake is more prone to fore-and-aft wear, due to the added rotational loads from braking. Even better, no special tools are needed for this check.

Nathan

I've run into bushes not being perfectly round after manufacture and handling so have gotten trapped upper bushes to slide so loose after hammer tapping round on stanchions, two new sets in storage bin and kept the old but tighter fitting bushes on Peel. I don't mic measure till after inking parts to see where hangs ups are to knock down. Roll stanchion against each other to see where to try to measure faults at. I've observed the slack in forks at hi speed hi load turns on Peel to see they shift fro/aft so fast axle becomes a blur but by golly had no effect on traction or aim as frequency don't seem to match-reasonate with tire sounds or fork occilation thank goodness. Still it worry's me on next Peel I hope to get fast enough on the harmonics may over lap and take us down, so have JSM compostite bushes to see if less slack possible w/o restriction. A great many forks in past decades and currently have completely difference gizmos & functions in each fork leg yet don't seem to bother any of them.

If ya keep pressing into danger zone like I have you may run into fork twist up spring back till feels like rubber bands connecting grips to axle, so must fit fork brace to rise fork oscillation to higher frequency than road traction sounds. When cycle harmonics match tire sounds, bye bye birdie.

Re: Rebuilding Forks, Landsdowne Eccentric Forks, Stiction

Mystery seems to have been ostensibly solved. I took off the left fork leg that was giving me headaches. In the process, once I removed the axle and front wheel, and loosened the Allen head bolt on the bottom that connects to the damper cartridge, the entire slider (lower leg) pulled right off into my hand. The stanchion and the spring and the upper parts just hung off the yoke! Seem the spring clip that holds the lower bushing a the end of the stanchion tube had become loose during the assembly. As a result, everything was loose and rubbing off everything inside the lower leg. With a lot of trickery and gentle tapping on a wooden bench with a help for a friend, we were able to remove things; in sequence; fork seal, paper (useless) gasket, the upper brass colored bushing, the lower steel bushing, and finally the clip. The upper bushing was scratched and the lower one was a tad tight etc...

So, I'm ordering and there installing a new stanchion, new upper and lower bushings etc. This *should* resolve this freaking mystery. Ahh... Life!

--->FJ SvenSven

SvenSven said:

So, I'm ordering and there installing a new stanchion, new upper and lower bushings etc. This *should* resolve this freaking mystery. Ahh... Life!

--->FJ SvenSven

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We have all been in your shoes at some point FJ , and will be again. Glad to hear you've nailed the sucker.

J

Re: Rebuilding Forks, Landsdowne Eccentric Forks, Stiction

It's easy to strain the clip, use external Circlip pliers insert the plier tangs between the clip gap,squeese and remove the clip..treat the clip as you would treat a piston ring ,avoid over opening the clip..when re-fitted it will be snug and hard to turn in the grove. check the clip fits first ..is the bush a bit to long? or the clip to wide.

SvenSven said:

Mystery seems to have been ostensibly solved. I took off the left fork leg that was giving me headaches. In the process, once I removed the axle and front wheel, and loosened the Allen head bolt on the bottom that connects to the damper cartridge, the entire slider (lower leg) pulled right off into my hand. The stanchion and the spring and the upper parts just hung off the yoke! Seem the spring clip that holds the lower bushing a the end of the stanchion tube had become loose during the assembly. As a result, everything was loose and rubbing off everything inside the lower leg. With a lot of trickery and gentle tapping on a wooden bench with a help for a friend, we were able to remove things; in sequence; fork seal, paper (useless) gasket, the upper brass colored bushing, the lower steel bushing, and finally the clip. The upper bushing was scratched and the lower one was a tad tight etc...

So, I'm ordering and there installing a new stanchion, new upper and lower bushings etc. This *should* resolve this freaking mystery. Ahh... Life!

--->FJ SvenSven

Click to expand...

Gracias!

Now I have finally properly installed all the working and undamaged parts including a new stanchion, new top and bottom bushings, a new retaining clip and fresh 160ml of red Honda 10W "suspension Fluid, SS-8", I can tell you the ride is MUCH better all around. Given, I had a rusty crapped out set of springs, foul watery oil along with rusted caps and leaking seals before ... it is NOT saying much. My point of references is all "goobered" up.

SvenSven
-->FJ

Excellent, We got there in the end, Now you need to play around with the adjustments , smoothly is the key, set the compression "just Biting" and the rebound to allow a controled/ complient return.