SunLite Springer forks

[blwnmny]

I'm thinking about getting a set of the Monarck springer forks for a build, the Felt Abraham linkage forks I can not find. Has anybody used the Sunlite 1 1/8 Monarck style forks? What is your opinion on quality? Although I might not have a choice at this point.

 

[Kruez]

I purchased a third option from Smoopy. @Smoopy. It's a good fork. There is a thread here somewhere with a full comparison.

Sent from my SAMSUNG-SM-N915A using Tapatalk

 

[blwnmny]

I think I found the thread, it answered my questions.

 

[Kruez]

It's a good thread!

Sent from my SAMSUNG-SM-N915A using Tapatalk

 

[A.S.BOLTNUT]

I think I found the thread, it answered my questions.

Got a link home slice ?

 

[blwnmny]

No link, but here's the thread.

 

[ZygoteLittle]

Thread link:
http://www.ratrodbikes.com/forum/index.php?threads/monark-mega-sunlite-deluxe-kai-cheng-fork.74436/

Sunlite springer on my 2006 Schwinn Manta-Ray 3-speed w/front drum brake

 

[KD5ZXG]

I need to make a bracket for fender stays to move with front fork. Right now its just a mockup held together by tiewraps. It rattles...

Also been experimenting with short stacks of Belleville cone washers as countersprings on top.

So far, all cones I've tried are too stiff. Except the sealing type with neoprene. But those lack spring temper. Its just rubber bonded to junk metal, for some other purpose entirely. May be similar in shape to a Belleville, not really made to be a spring...

I have not achieved float. Maybe that's geometric impossibility, but does return with less hammer. Some of that could be rubbing, not springing. 3/8 cones with neoprene are tight. I have four stacked on top, and one on each end of the main springs. For now, not using the original urethane bushings, not saying that was the right call.

Hit a curb at full 2nd gear while looking at something else. Didn't kill me, so I guess it worked. Until that happened, I wasn't even sure it could deflect. Even with some counterspring, Sunlites are very stiff.

 

[KD5ZXG]

For fender stays:

I think this shape might clear most of the obstructions?
Just have to bend a flat bar at angle and drill two holes.
Red and blue would be two sides of the same bend.



Theoretically, as the right piece of scrap hasn't jumped
out and volunteered just yet...

 

[KD5ZXG]

So, anyways: About them Bellevilles...

My first batch ordered from Fastenall were impossibly too strong.
Over 1500lb apiece. Our fork wants parallel pairs, so double that.
High carbon too I'd imagine. Not something for outdoors unless
you want to clean and oil it constantly.

Second batch from the Homely Despot were neoprene backed
sealing washers. No spring but what the rubber provides. Half
have already caved and inverted. So cones now spoon instead
of clamshell.

Still work, sort of. But not so much by counterspring as friction.
Only room to stack about four per each side (two clams each).
Not five failed clams as collapsed here, taking it way too far...

This one I want to try next. Maybe closer to the right spring?
https://www.grainger.com/product/GRAINGER-APPROVED-Disc-Spring-1NEE6

Still, minimum 95 pounds each to begin deflection. Maybe 127.
Pairs of those plus my 190lb weight vs. the original Sunlights.
Would that be even close to neutral buoyancy, or still too stiff?
Add weight of bike when finished with TSDZ2 motor and batt...

Carbon fiber becoming a thing in some racing suspensions.
Great illustration, but not everything you see below applies.
No interlocking flange on steel washers I've been looking at.
Ups vs downs might want to be slightly different size. Then
again: 10mm vs. 3/8 in 302 stainless, maybe that's possible...

https://www.compositesworld.com/art...spring-big-performance-small-package#carousel
Last pic of article shows a bike w. Carbon Belleville rear suspension.

My other thought was to abuse a few turns of the original springs
by popping them above the stop, then twist to adjust. Don't know
how to fix in place so it wouldn't wear metal-on-metal at the pinch,
or unscrew itself out of adjustment. Works on back of some seats,
but those are stamped to properly hold the midpoint of springs.

If I ever get ambitious enough to spend the change, suppose the
original springs could be replaced by a stack of cone washers too.
Originals coils are stiff, not adjustable, not yet proven a problem.
Maybe no need to fix. For sanity check, I'll try the counterspring
experiment first. Could just be making things worse...

 

[RustyGold]

It seems to me that what you need is a damper of some kind. Even if you found the perfect spring pressure you are looking for...you wouldn't float as much as you would pogo.

For springs, in general...if the sunlites are too stiff (I assume they make them stiff to avoid pogo-ing)...you can look into (beehive) valve springs. You can get them in just about any spring pressure...they may tend to be on the shorter side, so you may have to cobble a way to stack them.

You could also experiment with rear mountain bike shocks...but, you'll loose the classic look.

Jason

 

[RustyGold]

I haven't used these on anything yet, but they have an air/oil shock that can be dialed in by varying air pressure and oil amount. Both work in compression and rebound.

...and they have a neo-classic look as well .

Jason

 

[KD5ZXG]

Well, neoprene sealing washers definitely compress against posts with considerable
friction. Just one on either side of the stop feels significant. Don't pretend how long
that friction fit might last in a floating situation. Mine don't float, so I can't say yet.
Would prefer steel over neoprene for most of the spring though.

OTOH, Steel cone springs can spoon in pairs or triplets for cone-to-cone friction
damping that doesn't require rubbing the post. How much damping I don't know,
but mfgs harp as-if it were pretty significant. Spooning will multiply spring force,
which could easily become too much. Still shopping for thinner Bellevilles that
might open some tuning options, depending how they are stacked...

Spooning example about 9 minutes into this video.


Video doesn't say a thing about damping. Had to read elsewhere. Does go on
about centering misalignments. Edge resting on edge complicates. Flanges we
saw on the composite example seem made to address. Mix of two cone sizes
might help. Edges cupped by adjacent faces, rather than fight to align edges.

How much the air/oil damper costs?

 

[RustyGold]

How much the air/oil damper costs?

As much as you are willing to pay . One of the cheaper ways would be to get a couple of those motorcycle steering stabilizers on eBay (Chinese, of course). You could run two, one on each side, parallel to the springs. You'd just have to make sure you've got enough stroke and make some brackets. I think they run $20-30 each.

Jason

 

[RustyGold]

The other direction would be to modify a rear air/oil mtb spring to replace the current springs. Cheapy new ones can be had under $100. But, like I mentioned above...they lack at anything but an industrial appearance. You could make covers for them?

 

[KD5ZXG]

In regards to my earlier drawing of Post #9. Might
have found appropriate material to anchor the stays.

Old slot cover probably works better, thicker material.
But this flimsy prototype seems close to right shape.
Maybe a little longer than it eventually ought to be...



Big hole goes inside fork, then ribbon bends around
front, to anchor stays above the front linkage pivot.
Angled such that it doesn't block wrench access.