Progressive Fork Springs, XS1B

[Ipa62]

Hi out there. So was thinking about putting progressive fork springs in my '71 XS1B, cannot find them available and I have looked a lot. The stock springs are 23mm diameter and 400mm long, there is also a spacer that is 46mm long. Conceivably I can fit a spring that is 445-450mm in length (would replace the old spring and spacer). I did find springs on MikesXS that are 23mm x 495mm in length, don't know if this is a good idea, but has anyone ever cut a spring to fit (in this case cut off 45-50mm)? Any other ideas? Btw, I did find someone to custom make them, lots of $$$.
Another thought would be to forget about it, maybe progressive springs won't help all that much for a bike that generally has questionable handling.

 

[gggGary]

Fire up the angle grinder, whack away. I might suggest putting the spring in a vice cut right next to the vice.

 

[Ipa62]

Yeah, this was my idea, only problem is that the spring would then not have a closed end, but really not that big of deal. Thanks for your thoughts.

 

[gggGary]

springs can be easily heated and bent, cut it about a 1/2" longer than what you want, heat and bend in that last coil so it touches the one below it. (do not quench let let it air cool) then make your cut.

 

[MaxPete]

A progressive spring has two or more distinct pitches - or spacing of the coils.

One end of the spring will have the coils spaced further apart (a larger pitch) and the other end has them spaced closer together at a smaller pitch. The smaller pitch is what makes the spring "progressive".

Be sure to cut the end which has the wider spacing and don't touch the closer pitched end.

 

[Ipa62]

Yes, the idea was to cut the coarse (large pitch) end of the spring. I suppose in a perfect world one would cut an equal amount off both ends, but this is probably way more work than its worth. Thanks for all the good advice.

 

[MaxPete]

No no - cut ONLY the coarse pitch end.

The other (fine pitch) end is specially prepped for a spring seat washer (looks just like a little top hat) that goes under your fork tube end cap which is up in the triple clamp.

QUESTION: how do you know how much to cut off?

 

[Ipa62]

MaxPete, the spring (#3 in the pic) is 400 mm long, the spacer (#6) is 46mm long, the progressive spring I found (that is the same diameter) is 495mm long, so 495 - 446 = 49mm to remove, that's assuming I replace both the original spring and spacer with one progressive spring. That would mean that the new spring would be up against the cap, the washer (#5, you mentioned above) on the end of the spring would help to protect the cap. I honestly don't understand why the spacer is in there at all, maybe Yamaha was using springs already in their arsenal and 400mm was the closest fit. But then I am no expert on the matter.

 

[MaxPete]

Yup - #5 is the spring seat washer (cap) and it will go at the top of the spring where the closely spaced coils are located. As for cutting the spring - your math looks OK to me - BUT - many people feel that the XS650 is under-sprung and so if you are a bigger person, perhaps you might want to try it without cutting the spring and leaving out the spacer, as I did.

Here is my logic: my spacer was a similar length to yours but I simply left it out when I reassembled my forks on my 1976 XS650C because the progressives were actually a fair bit longer than the old linear (equally spaced coils) spring - but I wanted a stiffer front end.

The thing is that your old spring is about 45 years old and has likely collapsed quite a bit from its original length. My old springs were about 16.75" long versus the stock spring length of about...hmmmm....18" and my new progressives were about 19.75" (3" longer) but they fitted fine. However, there is NO WAY that I could have gotten the spacer in there with the new spring - so I just left it out.

The proof is in the pudding - the forks work smoothly, the bike rides great now and it now feels much steadier in the corners.

...just a thought.

 

[Ipa62]

Interesting, I hadn't considered stuffing the extra length down into the shock tube, somehow it would seem difficult to force down 2 extra inches (50mm) of spring length and then screw on the cap, but will give it a try.
Another part of this puzzle is the fork oil. The manual calls for 223cc's of 30 weight, which seems like a fairly large volume and a heavy oil. I have read all kinds of numbers on this subject. What did you use?
And then of course there is the rear, have you changed shocks and what did you use?

 

[MaxPete]

I clamped the fork in a vise with aluminium jaw protectors by holding onto the brak caliper mounting bosses - and it really wasn't hard to get the fork cap back on. Just be careful to not cross thread it.

I found that it was easiest to hold the cap in place with one hand and turn the fork tube with the other hand - until the cap was in 2-3 complete turns. Then I mounted the whole fork leg into the triple clamp and tightened the LOWER pinch bolts - ONLY - and tightened the fork cap the rest of the way.

As for oil (which goes in AFTER the spring is inserted but BEFORE the fork cap), I used 6 oz of 20W Lucas fork oil but my bike is a '76 and each year is different.

 

[TwoManyXS1Bs]

Do a forum search on "laden sag".
Don't cut the springs until after you've done the laden sag thing.
Might find this helpful:

http://www.xs650.com/threads/xs1b-front-upgrade-winter-project.43795/

 

[MaxPete]

"laden sag" ...sounds like a Norwegian salad dressing.

 

[Ipa62]

All good info, thanks. It's now salad time.

 

[MaxPete]

Sorry - missed your question about the rear shocks.

I simply bought the moderately priced stock sized shocks from MikesXS Canadian affiliate XS650Direct. They cost about $99 and work just fine.

Pete

 

[Ipa62]

BTW, this is pretty good reading on suspension setup.

 

[mrtwowheel]

Looks to me like your new spring is meant to be used without the spacer. Starting with the hardware that you have, I would ditch the spacer, install the spring, then the washer or a thick washer that fits close to the tube I.D., then cut the spacer or cut a PVC spacer to a length that barely allows you to screw in the cap, in other words, all of the spacer that can be used and still put the cap on while forcing the spring down.

Scott

 

[5twins]

I think the longer spring is going to end up sticking out above the top of the fork tube. But this is common on many forks. You just have to compress the spring and top cap some to get the cap started. My tool of choice for this is a 3/8" drive T handle. You can push down and turn at the same time .....

Everybody who works on bikes should have one of these. It turns your whole socket set into T handles.

 

[mrtwowheel]

I think the longer spring is going to end up sticking out above the top of the fork tube. But this is common on many forks. You just have to compress the spring and top cap some to get the cap started. My tool of choice for this is a 3/8" drive T handle. You can push down and turn at the same time .....

Everybody who works on bikes should have one of these. It turns your whole socket set into T handles.

Yep, it should take some force to put that cap on, take it easy on those threads. Take a break, gather your strength, and start again if you have to.

Scott

 

[MaxPete]

YUP - I agree with Mr. TW and 5Ts thoughts above and that is essentially what I did, except for the shortened spacer.

I didn't add anything above the spring - and the bike feels good to me so I think I will leave it that way. If you are a bigger guy or want a really firm ride - then add some sort of spacer. You just need to be certain that it will not shred or flake off and contaminate the fork oil.

As for getting that fork cap back on - 5Ts Tee-handled tool should work well or the method I used which was to hold down the cap with one hand and turn the fork tube with the other hand until the cap was in 2-3 full turns. It was stiff but doable without too much effort and it ensured that I had a good enough feel to confirm that the cap was NOT cross-threaded in the top of the fork tube.

This is very important because the threads are quite fine and the cap is fairly soft aluminium - so getting it cross-threaded would almost certainly damage the cap and/or the fork tube.

Cheers,

Pete