1972/3 SF1 - seems to be missing copper washer on ceriani fork drain screw.

Paul Marx said:

So many possibilities there Paul.

Jim

412128_green_l.jpg


maxresdefault.jpg


GooGooDolls_MiraclePill_OG.jpg


goo-gone-original-8oz_front_2.jpg


 
For some reason I am now driven to have a huge assortment of metric copper washers in case I ever need one in the future - and found a large assortment for like $20.00 on line - plus I want to try the "annealing" since never done that. But alas I thank you all for backup plans of fibre or goo. I realize each would do but since I will be waiting for Borranis to come back from specialist attention I will have some time to attend to other things. I'll post on the Borranis separately as I go down that path.
 
Having taken my SF out of winter / lockdown hibernation I've found that I have the same dripping fork drain screws and have lost a good puddle each side. I've checked previous posts, the Green book and Laverdamania but found some conflicting advice on fork oil grade and quantity which I would like to confirm please.

I have a Sf 750 (0) build late 1971, first registered in France in 1972, it has the early type 35mm Ceriani forks.

1) What oil grade is recommended please (90 kg solo rider )? The Green book is generic mentioning SAE 5 -10 (which I think relates to the later 38mm forks), For 35mm forks Laverdamania suggest SAE 25-35 which sounds really heavy, but presumably depends on internal apertures etc.

2) What quantity of fork oil? again the green book and Laverdamania are different with Laverdamania recommending 170cc.

3) I nipped up the drain screws 1/2 turn which were relatively loose which seems to have stopped the dripping. Can the forks be topped up to a level? or is it simplest to drain and re-fill? What is the best process? I see from this thread that I need to move the bars, loosen the top yolk, and presumably prop the front end to allow the forks to drop fully?

I've also gathered that the drain screws should have a fibre or perhaps copper washer and I should use a good 36mm socket on the top nuts, thanks all in advance.

Cheers
Greg
 

Attachments

  • IMG_20210409_151036604~2.jpg
    IMG_20210409_151036604~2.jpg
    106.8 KB · Views: 10
Looks like you have Shauns ex SF.
You don't need to prop the front up if you do one side at a time.
I put 170 cm3 of SAE 10 in my S which has the same fork, if I remember correctly.

In view of the work involved to get as far as being able to top up with oil. Drain and start again.

Paul
 
Your questions (no doubt there will be lots of opinions though)
1. I would start with 15wt and see how it goes, it also depends on the amount of wear on the internal valves.
2. The quantity stated in manuals isn virtually always enough to cover the damper valves with about half an inch of oil fully extended, after moving the slider up and down several times to get air out of the valving. I always go with that and it will probably be close to the 170cm3 you mention. A lot of people go for the maximum amount of oil the forks can hold to gain advantage of the spring advantage of the captured air. 90kg rider has little bearing on oil weight, but on spring weight, you can do sag measurements and see if it needs new springs, tons of info on the net, dead easy to check.
3. Change the oil out, even if you don't strip the forks to check them; and start from fresh so you will also see what the old oil looks like (silver/ black I would dismantle the forks and clean them). Then you can also see what sort of washers are on the drain screws. If they aren't good you can end up with sweating that is very annoying and requires draining the forks again to fix.
 
Great thank you Paul and Tippie, that all makes sense, I'll drain re-fill with 170cc of SAE 15 to start with then rather than Laverdamanias suggestion of 25-35 and get some new washers.

As you say Paul it's Shaun's old bike and is annoying as the oil that leaked is as fresh as you like and has done little mileage since the forks had new seals. Funnily enough the primary chain adjuster sprang a leak over the winter as well, so will need attending to with new or annealed copper washers. The bike was stored in a modern garage, in an air bubble but did get below freezing at one stage which is when I think is when the leaks started. I will go over the bike and nip everything up just to make sure.

IMG_20210410_164649367~2.jpg
 
Probably too late but if the caps do get buggered I got a pair from here and am happy with the quality
 
Having taken my SF out of winter / lockdown hibernation I've found that I have the same dripping fork drain screws and have lost a good puddle each side. I've checked previous posts, the Green book and Laverdamania but found some conflicting advice on fork oil grade and quantity which I would like to confirm please.

I have a Sf 750 (0) build late 1971, first registered in France in 1972, it has the early type 35mm Ceriani forks.

1) What oil grade is recommended please (90 kg solo rider )? The Green book is generic mentioning SAE 5 -10 (which I think relates to the later 38mm forks), For 35mm forks Laverdamania suggest SAE 25-35 which sounds really heavy, but presumably depends on internal apertures etc.

2) What quantity of fork oil? again the green book and Laverdamania are different with Laverdamania recommending 170cc.

3) I nipped up the drain screws 1/2 turn which were relatively loose which seems to have stopped the dripping. Can the forks be topped up to a level? or is it simplest to drain and re-fill? What is the best process? I see from this thread that I need to move the bars, loosen the top yolk, and presumably prop the front end to allow the forks to drop fully?

I've also gathered that the drain screws should have a fibre or perhaps copper washer and I should use a good 36mm socket on the top nuts, thanks all in advance.

Cheers
Greg
I used this guide and am happy with the results, fiber washers worked for me.
 
Back
Top