Jockey roller removal. Shimano RD-M700 Superplate
#1
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Jockey roller removal. Shimano RD-M700 Superplate
Just got a 1985 Bridgestone T-700, and it's a beauty. I was reading up on the rear derailleur. I was going to re-grease the rollers, but not sure what I'm getting into. The bolt for the jockey roller is combined with the pivot bolt for the cage. There's an internal spring in this roller/pivot bolt assembly and I'm not sure what will happen if I loosen the hex nut in the middle of the jockey roller (see pic). I've read different things about this roller in other threads, but it's not clear. Can't find any how to guidance on removing it. I'm not that shy in taking things apart to figure things out as I go, but i tend to avoid doing this when things are spring loaded. Any help would be appreciated. Also would love to know what makes this RD a fatally flawed/fragile derailleur, as I have read on this forum. Thanks.
#2
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I've never owned one of these derailleurs, but I always overhaul rear mechs when I overhaul a bike. The trick is to always unload the spring tension before disassembling the pieces that expose the spring. If you can do this in a controlled, mechanical way as opposed to stumbling into the spring unloading on you, then you're most likely fine. If you don't know how to unload the spring without randomly disassembling it, then you might run into an assembly problem later.
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I think it also probably gets lumped in with the sorta similarly concepted captive pulley Suntour Mountech- which had a very poor service record.
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Perhaps, this will help...
#5
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Thanks everybody.
I took a gamble and just removed the hex nut (part# 23 above). It was straightforward, and no spring came flying out. The only challenge was that the hex nut is not very tall, and the socket wrench can slip off the nut). I think the spring is contained in part # 14, the mysterious super plate. Will post more details later.
I took a gamble and just removed the hex nut (part# 23 above). It was straightforward, and no spring came flying out. The only challenge was that the hex nut is not very tall, and the socket wrench can slip off the nut). I think the spring is contained in part # 14, the mysterious super plate. Will post more details later.
#6
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Here's a link to instructions from Shimano. The jockey roller is referred to as the guide pulley.
Service instructions or https://si.shimano.com/pdfs/si/SI-N-65-000-00-ENG.pdf
It should also be attached to this post.
Service instructions or https://si.shimano.com/pdfs/si/SI-N-65-000-00-ENG.pdf
It should also be attached to this post.
#7
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Also here is some history of the Super Plate.
Moveable Jockey Pulley
The Huret Duopar provided the archetype for the moveable jockey pulley. In 1976, Huret invented and patented a rear derailleur with the jockey pulley mounted on a separate unsprung parallelogram. The jockey pulley on this derailleur floats freely up and down 1.5 inches, which is the difference in radius between a 14-tooth and 34-tooth sprocket. The jockey pulley is just the right distance from the sprockets in every gear, so the Duopar shifts a bit early in every gear. SunTour and Shimano responded with their own moveable jockey pulley rear derailleurs, the MounTech and the Super Plate. They had to install a spring in the second parallelogram to get around Huret's patent. Moveable jockey pulley derailleurs have extra pivots and extra parts so they're inherently less rugged than conventional rear derailleurs. Mountain bikers want strong equipment, so the MounTech and the Super Plate were dropped. The Duopar is the only survivor of the genre.
From Complete Guide to Upgrading Your Bike. By Frank J. Berto.
Moveable Jockey Pulley
The Huret Duopar provided the archetype for the moveable jockey pulley. In 1976, Huret invented and patented a rear derailleur with the jockey pulley mounted on a separate unsprung parallelogram. The jockey pulley on this derailleur floats freely up and down 1.5 inches, which is the difference in radius between a 14-tooth and 34-tooth sprocket. The jockey pulley is just the right distance from the sprockets in every gear, so the Duopar shifts a bit early in every gear. SunTour and Shimano responded with their own moveable jockey pulley rear derailleurs, the MounTech and the Super Plate. They had to install a spring in the second parallelogram to get around Huret's patent. Moveable jockey pulley derailleurs have extra pivots and extra parts so they're inherently less rugged than conventional rear derailleurs. Mountain bikers want strong equipment, so the MounTech and the Super Plate were dropped. The Duopar is the only survivor of the genre.
From Complete Guide to Upgrading Your Bike. By Frank J. Berto.
Last edited by truthseeker14; 11-26-20 at 09:46 PM.
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It's the linkage that controls the movement of the Super Plate mechanism. It's fixed to pieces #19 and #12 which I would probably call spools. #19 is fixed but #12 rotates and it attached to the cage pivot spring. Remove the cage from the derailleur body, then removing screws #15 and #16 will allow you to remove the #10 cover of the Super Plate mechanism. Attached photos show what's inside. In the last photo I tried to keep the wire under tension, using the shaft of my jeweler's screwdriver to simulate the tail of the cage pivot spring, so you can see how the wire rides in the grooves of the "spools".
#10
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All the springs seem to be in tact on the original derailleur. I checked out the b-spring and re-greased it, but that didn't help. I'm wondering whether the super plate mechanism is what's causing the body to not spring back, resulting in chain skipping. I can feel the spring action in the super plate, but perhaps it's not strong enough.
Last edited by truthseeker14; 11-24-20 at 04:35 PM.
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...I'm having trouble with the derailleur not springing back. See clip: https://youtu.be/G_SBBRMTILI
This seems to be causing the chain to skip when it's on the smallest cog and under high torque. When I put another derailleur on the bike, it's springs back in a snappy sort of way. With the other derailleur, I don't have any trouble with the chain skipping no matter how much I mash on the pedals.
All the springs seem to be in tact on the original derailleur. I checked out the b-spring and re-greased it, but that didn't help. I'm wondering whether the super plate mechanism is what's causing the body to not spring back, resulting in chain skipping. I can feel the spring action in the super plate, but perhaps it's not strong enough.
This seems to be causing the chain to skip when it's on the smallest cog and under high torque. When I put another derailleur on the bike, it's springs back in a snappy sort of way. With the other derailleur, I don't have any trouble with the chain skipping no matter how much I mash on the pedals.
All the springs seem to be in tact on the original derailleur. I checked out the b-spring and re-greased it, but that didn't help. I'm wondering whether the super plate mechanism is what's causing the body to not spring back, resulting in chain skipping. I can feel the spring action in the super plate, but perhaps it's not strong enough.
#12
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Hmm..I don't feel any binding. I had thought about drilling another hole. But before I do violence upon it, there's a couple things to point out. The body spring seems pretty strong, stronger than the spring in my RD-M550 Deore LX. Also when the chain is on the smallest cog, I can move the body back so the chain covers a bit more than 180 degrees of the cog, and it stays there. (the video above shows me moving the body back). If I then start pedaling with some torque, the chain still skips, and the body is in the same position as it was before i started pedaling. I had thought by moving the body back, the chain would not skip. Since the Super plate has influence on where the jockey roller sits (and thus has influence on how much chain is wrapped around the cog,) then maybe it plays a role in the chain skipping. I think I'm missing something, but not sure what.
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Superplate "guide pulley axle"?
It's the linkage that controls the movement of the Super Plate mechanism. It's fixed to pieces #19 and #12 which I would probably call spools. #19 is fixed but #12 rotates and it attached to the cage pivot spring. Remove the cage from the derailleur body, then removing screws #15 and #16 will allow you to remove the #10 cover of the Super Plate mechanism. Attached photos show what's inside. In the last photo I tried to keep the wire under tension, using the shaft of my jeweler's screwdriver to simulate the tail of the cage pivot spring, so you can see how the wire rides in the grooves of the "spools".
I'm about to work on one of these M700 SP that I'm trying to get working a little better. Reviving this thread to ask about the "guide pulley axle" that's referred to in the Shimano service instructions. It says "be sure not to turn the guide pulley axle, lest it should get out of order" (!) [emphasis mine]. Wondering what that means and why? I may have inadvertantly moved it when I first acquired this derailleur and did a deep cleaning without these intsructions or a parts diagram. I recall taking the guide pulley off and removing a lot of caked on grease and dirt. I never looked under the actual Super Plate cover as I was afraid to take it apart. So I'm concerned maybe this axle or the small cable linkage isn't intact. Any advice on how to check this? From the exploded view and your pictures it appears I would have to take apart and unload the cage pivot spring to get at it...don't want to open up a can of worms with that spring unloading. If you have any guidance I most appreciate it! This is for one of my Miyata tourers (I have an '85 Six ten and an '87 615, I hear you're a fan T-Mar !).
#14
Wrench Savant
I'm about to work on one of these M700 SP that I'm trying to get working a little better. Reviving this thread to ask about the "guide pulley axle" that's referred to in the Shimano service instructions. It says "be sure not to turn the guide pulley axle, lest it should get out of order" (!) [emphasis mine]. Wondering what that means and why? I may have inadvertantly moved it when I first acquired this derailleur and did a deep cleaning without these intsructions or a parts diagram. I recall taking the guide pulley off and removing a lot of caked on grease and dirt. I never looked under the actual Super Plate cover as I was afraid to take it apart. So I'm concerned maybe this axle or the small cable linkage isn't intact. Any advice on how to check this? From the exploded view and your pictures it appears I would have to take apart and unload the cage pivot spring to get at it...don't want to open up a can of worms with that spring unloading. If you have any guidance I most appreciate it! This is for one of my Miyata tourers (I have an '85 Six ten and an '87 615, I hear you're a fan T-Mar !).