Front shockers 1975 Scrambler 250

[IanM]

I've just bought someone elses restored 250 Scrambler. If's a Spanish built model. Does anyone know what make the forks would be? They've been chromed so no markings on them. It's registered as 1975 year of manufacture.

[Duccout]

Jon will confirm, but they are probably Telesco.


Cheers,


Colin

[A.I.M]

If they are originals then they should be Telesco. Photos would be helpful for ID, but you can also check Martyn's post on Telesco forks to compare:
viewtopic.php?f=3&t=2619

[Jon Pegler]

I think IanM's forks may be the post 1975 Telescos, which are very similar to the photos in Martyns post but have different seal holders.
The later Telescos have a seal holder with a male thread that screws internally into the fork slider, unlike the earlier forks that screw onto an external thread on the outside of the fork slider.
The later seal holder can be very tight and may need careful removal with a large pipe wrench to get it to move.
Once unscrewed, the stanchions can be removed from the sliders.
A few items may need replacing. Seals, an O-ring under the seal holder and possibly a nylon bearing sleeve on the bottom of the stanchion, although not all Telesco stanchions are fitted with this item.
I will see if I can find a photo of the later Telesco forks to show the different seal holder. The photos show a Vento fork leg, but the later seal holder is shown and is similar to the Road/Scrambler forks.

Jon

[IanM]

Hi John, thanks for reply/info
I've taken the forks apart and they have the threaded cap at the top of the slider with an upper seal and a lower o ring that seem to be ok.
The upper guide that slots in the top of the slider is broken but both parts are present. I should be able to get a machined replacement. I think the problem with them not compressing was caused by the lower 'grip ring' ? Like a small piston ring. That's what someone else here called it, is bent and not sitting in the lower groove of the fork stanchion. I can't see a lower bearing sleeve in the lower part of the tube.Do you think it should be present? What I think may have happened is while the bike was stored on it's centre stand for 5-6 years without the front wheel supported, the forks gradually dropped and the grip ring ended up above the part of the slider where it widens a few millimeters? Then it wouldn't slide back into the lower thinner part of the slider when the bike was dropped onto its wheels and bent the ring whilst trying to get them un seized? Do you think this could be the cause? And do you know of anyone able to supply a new pair of grip rings? Thanks in advance for any help.

forks4.jpeg

fork2.jpeg

fork1.jpeg

[Jon Pegler]

Ian,
I was slightly mistaken as your Telesco forks are the pre-1975 model with the earlier seal holder.
Your photo with the dismantled components has the spacer tube positioned above the spring. It should be positioned between the lower damper arrangement and the spring, with the spring directly below the top nuts.
There is no nylon lower bearing sleeve on the pre-1975 forks, only on the later ones, so you are not missing anything there.
I don't know of anyone who can supply the small bottom piston ring you describe as a 'grip ring' .
I may have some of the parts you require if you send me a message.

Jon

[IanM]

Well it’s now a month later and I’ve found that the fork tubes were rusty on the insides. A week of leaving them full of Gunk to degrease then a day filled with rust remover made the much smoother but still not totally sorted, so honed the insides with a small brake cylinder honing tool and that seems to have done the job. I found some bronze bushes of the correct internal diameter and machined the outer diameter to match the broken one. They have graphite inserts in them that I hope will aid them sliding. Pic below. Do you think the graphite part will be ok sliding on the stanctions and not damaging them? On first assembly they leaked out of the area where to O ring sits, so I have fitted new o rings and a bit of hylomar between the slider/bush and the inside of the stanction and this seems to have done the trick. One question I now have is, should the bleed screw clamp onto the bottom of the damper tube when tightened? Or are my bleed screws too long?

[Jon Pegler]

IMGP1005.JPG

Your bleed screws look too short rather than too long.
They should screw in with an extension passing through the hole in the bottom of the damper unit.
If the screw doesn't pass through the damper, (which has to be oriented the correct way to enable it to pass through), the damper will move up and down without having any effect.

Jon

[Duccout]

Hi Ian,

It seems that you have a lathe, so you can turn down a 6mm screw so that it will fit inside the hole in the bottom of the damper unit, leaving the threaded portion that screws into the bottom of the slider.


Cheers,

Colin

[A.I.M]

I have attached a picture of my pre-75 Telesco forks. If you look carefully at the far right of the picture you will see what the screw should look like. I don't have dimensions, I'm afraid.