Bit of a forking issue

[byron]

Here are a couple of pictures of my cleaned and re assembled fork dampers.
I am in the process of re-assembling the R90S forks and I wondering if anyone can can help with the issue of the 3 wiper rings in the damper rod. Should the rings be staggered at say 120degrees or all in line.
Also any tips on fitting them into the tubes as they are slightly bigger and also springier than the originals

 

[Rob Farmer]

They need to be staggered. A recommended way of fitting is to use three fine feeler gauges to slide them over the threads in the fork tubes

 

[byron]

Thanks

They need to be staggered. A recommended way of fitting is to use three fine feeler gauges to slide them over the threads in the fork tubes

Thanks for that Rob - I am away for a few days but will show the results at the weekend.

 

[markjackson]

I cut a piece out of the side of a coke can to create a very thin ally 'funnel' to guide the piston rings in to the forks. It seemed to work OK, but I re-used the old rings, after reading a few scare stories about new ones sometimes being oversize.

 

[byron]

Another forking issue

Thanks for that idea of the feeler gauges Rob it worked a treat and I now have another ask of the knowledgeable guys here. The oil seal shown in the picture is there an easy was to fit it and also those felt seals in the plastic covers, are there any top tip for a novice who is not sure about these forking things.

Any help on these two issues gratefully received

 

[Kenny]

Use the old seal to tap in. Buy new self adhesive felt strips from Motorworks

 

[Rob Farmer]

If your forks are out. Fit the felt seal into the rubber cap and "form it" using a socket the same diameter as the forks. The curved edge on the socket makes it easier to get the felt seated into the rubber. If you try to fit a rubber boot with a new felt straight on the forks the sharp edge will just pull the felt out.

dont be tempted to put Motobins aeroshell oil in there it's rubbish and causes stichcion. A good quality 5w fork oil works well. Yamaha oils are good if you have a local dealer.

 

[byron]

Thanks again guys for coming up forking trumps and showing a dip wit the way forward. I am travelling up from sunny Dorset to Newcastle at the moment and keeping a lookout for for ice flows and penguins as I go. So I will try out the suggestions on Saturday and let you know .
Ps Anyone want some Motobins fork oil !!

 

[Rob Farmer]

Ps Anyone want some Motobins fork oil !!

PJ1 5W worked well for me.

The problem with fork oil is the viscosity varies so much from manufacturer to manufacturer. Its best to pick one and stay with the brand as you'll have a reference point for feel.

I had loads of grief with that Aeroshell and spent days and days pulling the front end apart trying to get the bottom of sticking forks. Changed to proper fork oil and the problem disappeared instantly. Ive tried it on other bikes since and its worked on them as well.

 

[Beemerboff]

One of my local shed shops is run by a Ex desert/Safari racer/winner and he only sells full synth Race suspension fluid.
It is probably made for rear shocks but it works well in forks too , as it is naturally multigrade , stays in grade longer than dino and on my old and worn forks noticeably reduced stiction and improved the action.

Only downside is that it is twice the price, but it lasts a bit longer.
Maxima and Belray both make a 5 wt which is probably closer to a 7, but it works fine for me in 36 MM Airhead forks.

 

[byron]

Yet another forking issue

Last weekend I managed to finish cleaning all the parts of the r90s forks and fitted the whole together. Here are a few photos of the process. However when I stripped the forks down they did not have all the replacement parts that the motobins rebuild kit did.

 

[byron]

Further Photos

Here are a few pictures of various parts being put together.
There are two photos of the damper mechanism, the bottom left one shows the new wiper rings installed and the top left picture the installation into the fork tube using the "Rob Farmer" technique
The blue fork slider seals pushed in easily with a large socket.
The bottom cap and the plastic bush/bump stop replaced all the old stuff.

 

[byron]

Yet another forking thing

The Clymer manual shows the type 1 forks with an oil filler plug at the top of the forks, my forks did not have this and my motobins kit had a smaller white plastic stop which seems to fit exactly over the top cap bolt. This spacer/ stop is shown in the manual. These are shown in the pictures

As you can see from the previous post they seem to fit together well and I suppose the idea of a bump stop at the top and bottom of the fork seems like a good idea.

 

[patrick]

Byron,
I think the bump stop at the top will serve to add a little pre load to the spring. My 100/7 didn't have them but when I fitted some, the stance was better and the forks came back up after braking! Amazing after 5yrs of putting up with a soft front end.

 

[Rob Farmer]

What fork springs are those?

side issue

I think your springs will destroy those rubbers in no time at all

PS

The "Rob Farmer Technique" mentioned came out of the Haynes manual so I'm not as smart as you think I am I just happened to try it and it worked well.

 

[Rob Farmer]

The fork oil viscosity variations mentioned above have been discussed before. This chart shows the manufacturers claimed viscosities against what they actually measured in a lab. There is a huge discrepancy. Some folks prefer to use ATF because it has tightest tolerance to claimed viscosities and is very consistent throughout the world. The advantage of proper fork oil is it contains seal swelling additives and is designed to reduce stichion in the forks.

http://www.mediaturbo.com/clients/marzocchi/forkoilviscosity.html

The Maxima oil Beemerboff mentions looks like one the best oil on the market for maintaining its viscosity. there are only a couple better.

 

[byron]

Resurrection of this thread

I have finally got the engine in the frame.
Sadly the photos are in reverse order
Bottom picture shows the engine safely in place, my buddy Peter helped me to move the engine.
The third photo show the frame ready prior to fitting the engine, note all the pipe insulation taped to the vunerable parts of the frame
The top two pictures show the successful installation, this engine fits into the frame by over a 100mm so is tricky to drop in.

Anyway all done now so on to the rebuilt gearbox for installation, so I shall now have to remove the swinging arm again.