175TS Fork Strip Question

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Samurai
Posts: 137
Joined: Wed Nov 28, 2012 9:53 pm
Location: Somerset, U.K.

175TS Fork Strip Question

Postby Samurai » Sun Feb 17, 2019 8:58 pm

Hi Guys,

I've searched through all the threads that I can find on stripping the 31.5mm fork, read the overly-complicated descriptions in the Workshop Manual (which is just plain confusing), as well as the magazine reproduction in the Tech section (can't make out anything in the photographs), but I still have a dumb, basic question which I hope that you may be able to help me!

Having removed the front wheel, fork top cap and pinch bolt, how should I actually get the fork leg out of the triple-clamps (triple-tree, I think our U.S friends refer to it as)?

When I look down the forks from the top, with the cap removed, there doesn't appear to be any lip or surface to be able to drift the leg downwards? I've tried replacing the front wheel axle into the bottom of the fork and tried tapping it down with a hide mallet, to try and free the leg but no joy and it just feels as though I'm pulling against spring pressure. I don't really want to belt the axle for fear of bending it or damaging something inside the forks just because I'm missing some step in the procedure.

Do I need to unscrew the damper rod from the bottom of the fork first, or should the whole of the fork leg just pull through the headlamp ears and painted 'shrouds' attached to the triple-clamp without having to do that?

The forks were supposedly 'refurbished' and the whole front-end assembled and painted before I bought it as an unfinished project, but since getting it back on the road recently, I've found that under hard braking the forks will stick solid on full compression, necessitating me removing the wheel and using the axle to twist and eventually free off the stuck fork!

This has happened a total of three times now, twice with the right leg sticking and once with the left, so something is obviously not right and needs investigating. However, I seem to have fallen at the first hurdle, so any advice would be much appreciated.

Cheers,

Jason.

Buster
Posts: 39
Joined: Fri Dec 22, 2017 12:56 am
Location: Reading, UK.

Re: 175TS Fork Strip Question

Postby Buster » Sun Feb 17, 2019 10:31 pm

Hi Jason,
Do one leg at a time.
Open up the split in bottom steering yolk and hold it open with a wedge (screwdriver?). Screw the top nuts in a few turns and, with a soft mallet, give them a few taps and that should get it moving.
The binding may be caused by the positioning of the lower legs on the spindle, when you fitted the wheel did you bounce the forks before tightening the spindle clamp!

Samurai
Posts: 137
Joined: Wed Nov 28, 2012 9:53 pm
Location: Somerset, U.K.

Re: 175TS Fork Strip Question

Postby Samurai » Mon Feb 18, 2019 7:24 am

Hi Buster,

Many thanks for that advice it's really helpful.

I had thought of doing as you suggested with the top nuts, but wasn't sure if I would damage the threads in doing so as they are quite fine. However, you've given me more confidence and I'll have a go tonight!

With regards to bouncing the forks before tightening the axle nut, I thought I'd done this sufficiently, bit perhaps not!

Once freezes up, the forks seem to perform fine at rest, even with me grabbing the front brake and really compressing them. It seems to only bind when I've been out for a ride for a while and then usually when I've had to slow down firmly. The striction, does appear to be centred around the alloy dust covers and the gap between them and the painted shrouds they slide inside is not even.

I think that you may be right about the positioning of the forks, as both forks have bound independently of each other at different times. I reckon the chances of the same internal problem occurring on both forks within such a short space of time, means that you may well be correct.

Bevel bob
Posts: 1042
Joined: Thu Apr 15, 2010 8:01 am
Location: Bromley Kent UK.

Re: 175TS Fork Strip Question

Postby Bevel bob » Mon Feb 18, 2019 1:32 pm

The Mudguard should not pull or push the legs and may need bending or shimming with washers. The damper balls that live in the bottom of the legs were displaced on my forks and bits of them were getting in the way of the fork action. Replacement axles are not always machined correctly. If you are going to hit the top nuts to free the legs start with the nuts only loosened a turn to keep as many threads engaged as possible.

blethermaskite
Posts: 477
Joined: Thu Mar 01, 2018 1:06 am
Location: northern ireland

Re: 175TS Fork Strip Question

Postby blethermaskite » Mon Feb 18, 2019 1:36 pm

While you have the fork legs out check that they are not slightly bent, or that they have been bent and have been straightened?
Cheers,
George

ducwiz
Posts: 604
Joined: Tue May 22, 2012 12:52 pm
Location: near Frankfurt, Germany

Re: 175TS Fork Strip Question

Postby ducwiz » Mon Feb 18, 2019 6:00 pm

FYI:

ducati fork 1.jpg

ducati fork 2.jpg


cheers Hans
You do not have the required permissions to view the files attached to this post.

Ventodue
Posts: 952
Joined: Mon Mar 08, 2010 3:23 pm
Location: Montpellier, France

Re: 175TS Fork Strip Question

Postby Ventodue » Mon Feb 18, 2019 6:00 pm

As Buster and others, Jason.

Remove the wheel, attack one leg at a time, open up the top clamp very slightly - be careful, DON'T force it: it’s a rigid and brittle casting and can crack if you ask for too much. Top cap lightly screwed back in all the way and tap delicately but firmly, preferably with a copper hide mallet, so you don’t destroy its threads. Use plenty, but plenty of lube, be patient and also try rotating the leg, backwards and forwards, little by little, millimeter by millimeter. Patience is the key. Don't force anything.

You won’t do it by tapping on the axle, by the way. You need to tap the legs out from above.

The fact that the clamp was repainted before you got it may be the cause. I have seen bikes where some clown has repainted the inside of the clamp - eek! But if that's not the reason, there will most likely be corrosion between the clamp and the legs. Reinstall them with a wipe of Vaseline or similar on the inside of the clamp.

Once the forks are out, check the tubes for straightness. Your binding is very possibly due to them not working in parallel - so either bent or not properly installed. It doesn't need to be much, so look very carefully. Rolling the tubes together, one against the other, is a good way to see if one or tother is bent.

HTH

Craig

Samurai
Posts: 137
Joined: Wed Nov 28, 2012 9:53 pm
Location: Somerset, U.K.

Re: 175TS Fork Strip Question

Postby Samurai » Mon Feb 18, 2019 6:13 pm

Craig,

Great advice, I think you could be right about the paint.

It was done by the previous owners own paint shop (quite well as it happens), but has been put on with a bit too much high-build primer for my liking and whoever did it did not take the time to mask off things like screen threads in a lot of cases! I therefore would not be at all surprised if they had over-sprayed the inside of the clamp :roll:

ranton_rambler
Posts: 439
Joined: Sun Jun 04, 2017 11:33 am
Location: Stafford UK

Re: 175TS Fork Strip Question

Postby ranton_rambler » Mon Feb 18, 2019 7:43 pm

Mine were a bit sticky too, but it was because the fit between the re-chromed stanchions and sliders was a bit tight. Hopefully sorted by stripping down again and running a bit of Scotchbrite round. Won't really know until I get out on it. The fun bit is getting it all back together. I ended up taking the stem back out so I could pull the stanchions through the bottom yokes against the spring tension, like it shows in the factory manual. I bought a hydraulic fitting with same thread as top caps to convert into a tool to pull them.
Ian

Samurai
Posts: 137
Joined: Wed Nov 28, 2012 9:53 pm
Location: Somerset, U.K.

Re: 175TS Fork Strip Question

Postby Samurai » Tue Feb 19, 2019 1:44 pm

Thanks for the heads up about refitting Ian, I'll look into a similar fitting!

You don't happen to recall what size the thread was by any chance? If not I'll measure it up tonight if I get a chance.

I really hope that I don't have to take the steering stem out a the moment, as all the electrics and headlamp etc., are connected and working fine after a long struggle. I'm really loathed to disturb them seeing as the bike is actually up and running at long last!

However, if I need to I will :roll:

Forks came apart fairly easily once I'd carefully tapped them out a bit as Buster suggested. Inspection reveals a load of molybdenum grease has been slapped around, but NO fork oil at n evidence :o

Before I separated them I spent some time pumping the slider up and down the leg and could feel the grating noise and striction whenever the leg was in a particular point of rotation. At a certain point, the leg would happily collapse into the slider under its own weight, whereas rotating it 180 degrees would produce the stiff action.

After separating the stanchion from the slider I could see only wear on the stanchion that I would reasonably expect, but some definite wear groves on the inner edge of the slider's internal face.

The damper rod appeared Ok, although the rubber O-rings seal is pretty hard and slightly pushed to one side. I'm not sure if there is meant to be a small amount of lateral play in that seal or whether it's just home hard with age?

I can't see any corresponding grooves on the stanchion surface, so the damage may have been historic and the leg replaced? I've not out a straight edge up to the leg yet (ran out of time last night), but from the manipulation results, I guess there is a very slight bend in it which must match the wear on the slider, hence the ease with which it collapses down on one face and the striction on the opposite side?

The other question I have is that the stanchion measures 30.1mm on the upper section but 30mm on the portion that actually goes into the slider? Is this standard for a '31.5mm' fork, as I see on Nigel Lacey's site that the early 125/175s have '30mm' fork seals?

I'll measure up the seal I removed tonight, but I just wanted to double check with someone more knowledgeable, in case the previous owner had fitted the wrong one, but it didn't look obviously loose on the leg?


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