smontanaro 

I need a chain tension bolt for a first gen SunTour Cyclone GT derailleur. This guy (I'm pretty sure it's the same between Cyclone and Cyclone GT):

I figured I'd see if I could figure out what other derailleurs might share that bolt with the early Cyclone units. Unfortunately, the only parts diagrams/parts lists I could find were in this SunTour Small Parts document on Disraeli Gears. It dates from 1983 or thereabouts, so the Cyclone series it shows is the Mk II. Though not identical, I think perhaps the bolt from the Vx shown in that document might work as a substitute. If I'm going to sacrifice a functioning derailleur to get a small part, I'd rather sacrifice one that's somewhat less desirable. Anybody got a Vx and an early Cyclone who can compare the two versions of this bolt? Any earlier Cyclone exploded parts diagrams I've not discovered out there? How about a mangled early Cyclone they'd be willing to part with?

T-Mar

That bolt is actually two pieces, The outer piece is just a cap that screws into the slotted spindle that retains the spring. They appear to be the same parts as used in the V, VT and Vx but the stated part numbers are different. The bolts on other SunTour derailleurs of the era are definitely different.

steelbikeguy

hey Skip, I've pulled a VGT Luxe apart sorta recently, when I was trying to see if that lower pivot spring was compatible with the 1st gen Cyclone. For those who care... it's not.

I did take a few pics of the VGT Luxe when I had it apart.....




I'm not sure how well you can see it, but that "bolt" in the lower left corner has a really thick "head". The Cyclone bolt head is much thinner. Not really a good match.
If it helps, I've got both the VGT Luxe and a Cyclone GT in front of me, and both of these "bolts" measure 19mm OD (measured w/o removing them, though).

I've had some issues with Cyclone GT's myself and have had to pick up spares to cannibalize for lower pivot springs. I might have one of these bolts that I could spare.

Steve in Peoria
(about to try putting a GT's long cage onto the body of a short cage Cyclone)

clubman 

I'd been looking for a Cyclone 3 pulley spring and eventually found a match with a short cage Sprint 6 speed model. I had pulled apart 3 others first.
It didn't seem worth the effort afterwards.

smontanaro 

Thanks for posting that diagram, T-Mar. That's exactly what I failed to find in my searching. Of course, I didn't have access to your library.

Yes, I only need #19 in the diagram you posted, the chain tension screw (p/n 28110511 - was called a chain tension bolt in the Vx diagram I found on Disraeli Gears). I don't need the castellated bolt (#21, chain tension axle).

Comparing your diagram with the Vx on the Disraeli Gears site, it seems clear the assemblies are different, not just that outer bolt/screw. The part numbers are also different. If, as steelbikeguy suggests, they can be swapped, it seems pretty clear the V/Vx part will likely stick out.

DiegoFrogs

Keep in mind that on the GT version, the pivot for the cage and the axle for the guide pulley are all the same part- any swap between the long and short cages needs to also include that shaft.

smontanaro 

I'm sorry, I don't understand what you're saying. Can you repeat it, referring to the parts diagram (and part names/numbers) from T-Mar's post?

steelbikeguy

for anyone curious about the difference between the short cage Cyclone (1st gen) and the GT version, I just swapped a GT pulley cage and shaft onto a short cage Cyclone. Seems to work fine, although... SunTour seems to be using their practice of using shims to compensate for imprecise parts.

Here's the derailleur that will be getting the GT cage & shaft....




a shot of the back, showing how the lower pivot shaft threads into the pulley cage...



this shot shows the pulley cage unthreaded from the shaft. To the left of the cage, you can see a stamped steel "washer" that fits between the cage and the derailleur body. It seems to function as a wear surface, in order to not wear out the pulley cage. Although... it rides against the alloy derailleur body, so...?
I am used to the screw at the other end of the shaft coming loose first, but in this case the pulley cage came loose first. This meant that the spring was still retained between the screw and the shaft. I taped up the jaws of a vice-grips pliers to grab the end of the shaft and broke the screw loose.



a shot of the derailleur body, the spring, shaft, a shim that fit between the screw and the shaft, and the screw.



a closer look at these parts



here are the pulley cage and shaft from a Cyclone GT donor. This didn't have a shim under the screw. Instead, there was a shim between the pulley cage washer and the derailleur body. In this case there seems to be some rust between the washer and the shim. I scraped this off and greased it before installing in the new derailleur body.



here we see the GT cage installed on the new body. The short cage and shaft is shown in the upper left, and the donor derailleur is in the upper right.



The only real wild card in the process is the matter of shims. I suspect that SunTour kept fairly decent tolerances on the derailleur body, but the stamped steel washer and the crudely machined shaft are probably where the dimensions can vary a bit. SunTour used shims to adjust the freewheel bearings in the Perfect/Pro-Compe and some Winners, and it appears they continued this practice in the Cyclone lower pivot. If anyone does start swapping pulley cages like I've done, try to keep the shims, washer, pulley cage, and shaft all together as a set.

oh... as background, maybe I should mention that like a lot of folks who are getting older, I like the GT version because it can handle wider gearing. Unfortunately, ebay seems to have a large supply of the short cage Cyclones. Since I have been fixing broken springs, the short cages aren't an issue.
Also... I seem to have parallelogram springs that get weaker and can't push the chain over to the small cogs. Swapping derailleur bodies seems like the only fix.

Steve in Peoria

ofajen

Did the original part happen to come off during a ride? That happened to me many years ago.

I rehabilitated mine a few years ago with off the shelf parts from the local hardware store. Looks odd but works perfectly.

Pointless at the moment, since both my bikes are running SS, but if I decided to put a few gears on one of them, I’d probably run the Cyclone. If you ever get so desperate as to go this route, I can check to see what odd collection of parts were needed to pull this off.

Otto

smontanaro 

Yes, unfortunately it did.

ofajen

If you decide to go the low end route and use a metric bolt and some carefully chosen washers, let me know and I’ll figure what ended up working for mine.

aitti

4funbikes

did you find what you were looking for here? I’ve got it if not. Cover postage and it’s yours.

smontanaro 

Thanks, yes I'm all set.