Increasing Spring Tension - Rear Derailleur

[J Schwartz]

Greetings

I have a couple of older long cage Deore LX, 9-speed Rapid Rise rear derailleurs in great shape on 2 bikes.

RD-M580 SGS

Given the longer chainstays and hence longer chain on my Appa, I'm thinking it may be advisable to try to increase the spring tension on one of them.

I take the bike off-road a lot and there's a lot of slap.  I could change up components but I want to try this first.

It's my understanding the spring tension can be increased by placing the spring end into a different hole in the derailleur cage.

However, from my limited internet research on this, it appears that this particular derailleur may only provide 1 hole and therefore no adjustability.

There's not a lot of info on the Shimano site for this mech.

So, I'm coming to the group before taking the derailleur apart.

Does anyone know if that particular derailleur allows spring tension to be increased?

Thank you

J Schwartz

[Matthew P]

Hey J.
I'm interested in this. It sounds like a DIY derailleur clutch.
I Google searched that and got some promising hits.
If you dive into this, please share.
Thanks
Trying to stay on task in San Diego,
-Matthew

[Matthew P]

Hi Ken,
I'm curious. Why do you leave the clutch de-activated? Are there downsides to using the clutch?
Thanks
-Matthew

On Monday, April 5, 2021 at 4:36:27 PM UTC-7 KenP wrote:

I changed my derailler to one of the newer Shimano shadow; it has a clutch switch, but I leave said switch off and it still provides more wrap and tension than my older derrailler.   It's not rapid rise thouigh.  I'm running 30 34 52 in front and 11-28 in back. 9 speed.

KenP

[Jim M.]

I would suggest replacing the spring with from an XT or XTR. You can get a new spring for $5 or so.

When I had too much slap and occasional thrown chain from an LX (which worked fine otherwise), I switched to an XT  derailer and the problems disappeared. I assume it's mostly the chain tension that helps.

jim m

walnut creek, ca

[J Schwartz]

Jim

That's a great suggestion ...I didn't even know that was a possibility 

I'll look into the stronger springs 

Jason

[aeroperf]

Just so we know what we're talking about, here is the exploded view.

https://si.shimano.com/pdfs/ev/EV-RD-M580-2367.pdf

There is a spring that runs the body (2), and a spring that tensions the cage (9).

As a Mechanical Engineer, if I had two of these, I'd take one apart just on general principle.  :-)

[J Schwartz]

So according to the drawing , if there's a 2nd hole for greater tension , it will be in the Outer Cage Assembly (part 10) ...which would allow the cage tension spring (part 9) to be wound up more.

random photo from Park Tool website:

I've heard, but not confirmed, that this derailleur doesn't have that 2nd hole.

I studied electrical engineering rather than mechanical, so naturally I don't really feel like taking the derailleur apart to find out.

Regarding Jim's suggestion on replacing the spring with one from a more off-road specific derailleur ...

I assume that Part 9 is the same spring to replace?

Should I look for an XT or XTR spring from that particular era , 9 speed, etc?

Thanks

[Martin Alvarez]

I've got an old Atlantis w crazy chain slap.  I can't look at a stick on the road without the chain slapping around.  The gears are always slipping on the rear as well.  Drives me nuts.

On Tuesday, April 6, 2021 at 7:16:26 PM UTC-5 KenP wrote:

With the clutch on, shifting the chain is tight moving onto the big front chainring of 52 while the rear is in certain positions, plus, to remove the wheel the clutch needs to be turned off anyhow, so I just left it off.  Next ride I'll test it again. The largest practical rear is 28 on my setup.  I tried 30 but the chain  when long enough to go big-big is too loose small-small.   It took a long time to figure out to  grind away some of the front derailleur cage and bend it down some to shift the front reliably. It's an IRD one specifically designed for the size chainrings installed.   I like your idea of tightening the spring on the  rear  derailleur now that there is the old Shimano one to experiment with.  Thanks for asking.

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[Egon Conway]

Wow, interesting mod. I've added a longer B-Screw to derailers to get a little more spring tension, not the most elegant solution, but no need to take the derailer body apart. I'm interested to hear how it goes if you do take it apart. Good luck.

On Monday, April 5, 2021 at 5:05:15 AM UTC-7 J Schwartz wrote: