Go Back  Bike Forums > Bike Forums > Classic & Vintage
Reload this Page >

Suntour MounTech partial teardown and exploded view

Notices
Classic & Vintage This forum is to discuss the many aspects of classic and vintage bicycles, including musclebikes, lightweights, middleweights, hi-wheelers, bone-shakers, safety bikes and much more.

Suntour MounTech partial teardown and exploded view

Old 09-30-12, 07:38 PM
  #1  
BluesDaddy
I got 99 projects
Thread Starter
 
BluesDaddy's Avatar
 
Join Date: Nov 2008
Location: Hills of Central NH
Posts: 1,603
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 42 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Suntour MounTech partial teardown and exploded view

Working on my '84 Le Tour Luxe (gratuitous beauty shot)



The MounTech rear derailleur was coated in 30 years of greasy grime so I decided to disassemble the bottom end to clean and lube it.



I looked at the Disraeli Gears page about this derailleur where they describe it as being overly complicated and prone to failure. Fortunately this example is in good shape, but the wheels weren't rolling smoothly.

Time to take it apart.



I took photos so I could get the pieces back together correctly. I've winged before and had bad results, so this time I wasn't taking any chances.

BluesDaddy is offline  
Old 09-30-12, 07:39 PM
  #2  
BluesDaddy
I got 99 projects
Thread Starter
 
BluesDaddy's Avatar
 
Join Date: Nov 2008
Location: Hills of Central NH
Posts: 1,603
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 42 Post(s)
Likes: 0
Liked 1 Time in 1 Post
I took out the pins that hold the two sprung pivots and let the pivots swing to the slack position, then started taking apart the complicated 3rd pivot/jockey wheel.








Last edited by BluesDaddy; 09-30-12 at 07:54 PM.
BluesDaddy is offline  
Old 09-30-12, 07:40 PM
  #3  
BluesDaddy
I got 99 projects
Thread Starter
 
BluesDaddy's Avatar
 
Join Date: Nov 2008
Location: Hills of Central NH
Posts: 1,603
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 42 Post(s)
Likes: 0
Liked 1 Time in 1 Post
The jockey wheel runs on a large, thin steel bushing. The pivot spring end distorted the bushing when the spring was at rest, making the pulley stick, but when the spring is up to tension, the problem goes away.







All clean "exploded view" of the bottom end. I did not feel brave enough (nor did I have the need) to take apart the parallelogram.



Last edited by BluesDaddy; 09-30-12 at 07:59 PM.
BluesDaddy is offline  
Old 09-30-12, 07:49 PM
  #4  
mobilemail
Senior Member
 
mobilemail's Avatar
 
Join Date: Apr 2005
Location: Gateway to the West
Posts: 785

Bikes: You mean this week?

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 24 Post(s)
Likes: 0
Liked 8 Times in 4 Posts
If you blow it up, I have a couple more in my parts drawer in the came condition - working well, but the top pulley is kinda rough.
mobilemail is offline  
Old 09-30-12, 08:06 PM
  #5  
BluesDaddy
I got 99 projects
Thread Starter
 
BluesDaddy's Avatar
 
Join Date: Nov 2008
Location: Hills of Central NH
Posts: 1,603
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 42 Post(s)
Likes: 0
Liked 1 Time in 1 Post
There is a piece left over! How does this happen?? The ring is a dust seal or maybe a spacer, but the edge is chewed up so I thought it might do harm than good so I left it out.

But that little bit... what the heck is that?



It looks like a broken-off tab or maybe a key. It fell out of my cleaning rag. I'm baffled.

Here's the front derailleur, BTW:



Looking forward to getting these back on the Schwinn and trying 'em out!

Last edited by BluesDaddy; 09-30-12 at 08:09 PM.
BluesDaddy is offline  
Old 09-30-12, 08:19 PM
  #6  
poke em
Senior Member
 
Join Date: Oct 2010
Location: Coeur d Alene
Posts: 245
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Likes: 0
Liked 1 Time in 1 Post
That piece goes in the split of the top jockey wheel spindle, after you install the spring. I think it is supposed to keep the spring seated. My blue line derailleur had one in it, so I reinstalled it.

Edit,

Not the jockey wheel spindle, but the spindle where the cage pivots in relation to the body of the derailleur. You can see in the first picture that the slot is full of metal, that is the top of the tab.
poke em is offline  
Old 09-30-12, 08:30 PM
  #7  
mobilemail
Senior Member
 
mobilemail's Avatar
 
Join Date: Apr 2005
Location: Gateway to the West
Posts: 785

Bikes: You mean this week?

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 24 Post(s)
Likes: 0
Liked 8 Times in 4 Posts
I really like the Mountech front derailleurs. In my experience, they work better for closely spaced chainrings (aka half-step plus granny setups) than modern derailleurs do.
mobilemail is offline  
Old 09-30-12, 08:42 PM
  #8  
BluesDaddy
I got 99 projects
Thread Starter
 
BluesDaddy's Avatar
 
Join Date: Nov 2008
Location: Hills of Central NH
Posts: 1,603
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 42 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Thanks, poke em.
BluesDaddy is offline  
Old 09-30-12, 11:41 PM
  #9  
Captain Blight
Senior Member
 
Captain Blight's Avatar
 
Join Date: Oct 2009
Location: Minneapolis
Posts: 2,473

Bikes: -1973 Motobecane Mirage -197? Velosolex L'Etoile -'71 Raleigh Super Course

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Mobilemail, we are of one mind on this. I went through a lot of front mechs finding out what worked and what didn't; and the Mountech just works, and works well. That it's easy on the eyes is a bonus. First-gen Shimano 105 is great for 40-52 jumps, which I also have; but for 1/2 step with bailout ("Eject! Ejeeect!"), nothing beats Mountech. I've got 7 in my Stategic Reserves.
Captain Blight is offline  
Old 09-30-12, 11:50 PM
  #10  
Captain Blight
Senior Member
 
Captain Blight's Avatar
 
Join Date: Oct 2009
Location: Minneapolis
Posts: 2,473

Bikes: -1973 Motobecane Mirage -197? Velosolex L'Etoile -'71 Raleigh Super Course

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
BluesDaddy, thanks for this. I've been reluctant to maintain my Mountech mech, solely based on the D.G. info. I can see, now, thanks to your documentation, that it's within grasp of a mere mortal such as myself.
Captain Blight is offline  
Old 10-01-12, 10:54 AM
  #11  
Chris Chicago
Senior Member
 
Chris Chicago's Avatar
 
Join Date: May 2009
Location: near north side
Posts: 1,333
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 81 Post(s)
Liked 24 Times in 16 Posts
how does it run now? i noticed mine had a rough jockey wheel a couple years ago but never got it running smooth. did your effort do the trick?

also, I cant figure out where poke em is saying that part goes in the first pic. any clues?

thanks
Chris Chicago is offline  
Old 10-01-12, 01:55 PM
  #12  
acoffin 
Senior Member
 
acoffin's Avatar
 
Join Date: Jul 2011
Location: St Louis
Posts: 608

Bikes: 72 Lygie (SS conv), 87 Ironman Expert, 94 Allez Sport, 16 Black Mountain Cycles Monstercross

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 25 Post(s)
Liked 14 Times in 4 Posts
Originally Posted by Chris Chicago View Post
how does it run now? i noticed mine had a rough jockey wheel a couple years ago but never got it running smooth. did your effort do the trick?

also, I cant figure out where poke em is saying that part goes in the first pic. any clues?

thanks
I'm pretty sure the tab goes in the slot in the end of the top return pivot bolt. I hope those words make sense.

Anthony
acoffin is offline  
Old 10-01-12, 03:32 PM
  #13  
smallpox champ
Senior Member
 
smallpox champ's Avatar
 
Join Date: Apr 2009
Posts: 157

Bikes: '84 specialized expedition, '87 specialized sirrus, '84 specialized stumpjumper sport

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 32 Post(s)
Liked 56 Times in 13 Posts
There are two tabs for both of the lower pivot bolts, they not only seat the spring but also prevent the slotted bolts from pinching. The flared end should be seated against the spring.

Servicing the derailleur does help the jockey, but it will become rough again. It is a chronic problem and the Achilles Heel of the Mountech.
smallpox champ is offline  
Old 10-01-12, 08:21 PM
  #14  
BluesDaddy
I got 99 projects
Thread Starter
 
BluesDaddy's Avatar
 
Join Date: Nov 2008
Location: Hills of Central NH
Posts: 1,603
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 42 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Captain Blight, I think the key is to remove the stop pins so you can de-tension the two sprung pivots, then you can work on them without having springs go flying. The pin for the upper pivot is obvious; it rests against the body of the derailleur near the mounting bolt. In post #1, the 3rd photo, you can see daylight through the hole where it goes. The other pin looks like a screw into the back of the third pivot. See post #2, 3rd photo.

I'm not done with the overhaul of the bike yet so I can't say how well it'll work. I'll report back when I've tried it out. This is going on a fair-weather road bike; I hope it will go for a while before it gets contaminated again.
BluesDaddy is offline  
Old 07-08-14, 07:08 PM
  #15  
Chris Chicago
Senior Member
 
Chris Chicago's Avatar
 
Join Date: May 2009
Location: near north side
Posts: 1,333
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 81 Post(s)
Liked 24 Times in 16 Posts
So how did it function after the breakdown?

i ask bc mine just gave out as far as I can tell. I threw a used shimano Altus on the bike in its place and the gears have never shifted better, so I'm not going to try to fix the mountech most likely
Chris Chicago is offline  
Old 07-09-14, 07:56 AM
  #16  
The Golden Boy 
Extraordinary Magnitude
 
The Golden Boy's Avatar
 
Join Date: Aug 2009
Location: Waukesha WI
Posts: 13,017

Bikes: 1978 Trek TX700; 1978/79 Trek 736; 1984 Specialized Stumpjumper Sport; 1984 Schwinn Voyageur SP; 1985 Trek 620; 1985 Trek 720; 1986 Trek 400 Elance; 1987 Schwinn High Sierra; 1990 Miyata 1000LT

Mentioned: 79 Post(s)
Tagged: 0 Thread(s)
Quoted: 2360 Post(s)
Liked 1,002 Times in 592 Posts
Originally Posted by Chris Chicago View Post
So how did it function after the breakdown?

i ask bc mine just gave out as far as I can tell. I threw a used shimano Altus on the bike in its place and the gears have never shifted better, so I'm not going to try to fix the mountech most likely
Did you see the https://www.bikeforums.net/classic-vi...und-today.html Thread?
@fender1 posted this:



Originally Posted by fender1 View Post
Figured I would start a thread for the odd things we come across. Be it on the road, found on bikes or whatever. I'll start. Below is a homebrew solution to fix an old Suntour Mountech derailleur. This came to me on a mid-80's mountain bike I picked up recently. Pretty cool repair.

[IMG][/IMG]
__________________
*Recipient of the 2006 Time Magazine "Person Of The Year" Award*

Commence to jigglin’ huh?!?!

"But hey, always love to hear from opinionated amateurs." -says some guy to Mr. Marshall.
The Golden Boy is offline  
Old 07-09-14, 08:07 AM
  #17  
The Golden Boy 
Extraordinary Magnitude
 
The Golden Boy's Avatar
 
Join Date: Aug 2009
Location: Waukesha WI
Posts: 13,017

Bikes: 1978 Trek TX700; 1978/79 Trek 736; 1984 Specialized Stumpjumper Sport; 1984 Schwinn Voyageur SP; 1985 Trek 620; 1985 Trek 720; 1986 Trek 400 Elance; 1987 Schwinn High Sierra; 1990 Miyata 1000LT

Mentioned: 79 Post(s)
Tagged: 0 Thread(s)
Quoted: 2360 Post(s)
Liked 1,002 Times in 592 Posts
Originally Posted by mobilemail View Post
I really like the Mountech front derailleurs. In my experience, they work better for closely spaced chainrings (aka half-step plus granny setups) than modern derailleurs do.
Originally Posted by Captain Blight View Post
Mobilemail, we are of one mind on this. I went through a lot of front mechs finding out what worked and what didn't; and the Mountech just works, and works well. That it's easy on the eyes is a bonus. First-gen Shimano 105 is great for 40-52 jumps, which I also have; but for 1/2 step with bailout ("Eject! Ejeeect!"), nothing beats Mountech. I've got 7 in my Stategic Reserves.


I do realize this is an old thread- but this bears repeating- that Mountech FD is the cat's pyjamaz.

Not only is the Mountech highly functional, not only is it a nice looking unit that's easy to adjust, it's also even lighter than the Suntour XC Pro derailleurs.

The big thing wrong with this is that it says "Mountech" on it. And people go away screaming like it's a death fork or Helicomatic.
__________________
*Recipient of the 2006 Time Magazine "Person Of The Year" Award*

Commence to jigglin’ huh?!?!

"But hey, always love to hear from opinionated amateurs." -says some guy to Mr. Marshall.
The Golden Boy is offline  
Old 07-09-14, 08:25 AM
  #18  
Chris Chicago
Senior Member
 
Chris Chicago's Avatar
 
Join Date: May 2009
Location: near north side
Posts: 1,333
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 81 Post(s)
Liked 24 Times in 16 Posts
that quarter mod is pretty cool. not sure if it would be worth the effort though. mine never ran great and the spring for the pivot to the right of the quarter (in picture) gave out so the cage just flops back and forth like a pendulum. I got really frustrated trying to get it to work while the mosquito were having me for dinner and my kids were asking their usual 15 questions per minute. which is why the cheapo c10 that replaced it is now my favorite bike part.

bless you c10
Attached Images
File Type: jpg
1392793089.jpg (49.3 KB, 178 views)
Chris Chicago is offline  
Old 07-12-14, 10:13 AM
  #19  
mrmw
Senior Member
 
Join Date: Dec 2005
Location: Atlanta
Posts: 603

Bikes: 1982 Schwinn Super Sport S/P, 1984 Miyata 610, 1985 Panasonic LX 1000, Centurion Pro Tour 15 1983

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Likes: 0
Liked 5 Times in 2 Posts
Originally Posted by mobilemail View Post
I really like the Mountech front derailleurs. In my experience, they work better for closely spaced chainrings (aka half-step plus granny setups) than modern derailleurs do.
I like them too for 28/38/48 rings.
mrmw is offline  
Old 07-12-14, 04:26 PM
  #20  
The Golden Boy 
Extraordinary Magnitude
 
The Golden Boy's Avatar
 
Join Date: Aug 2009
Location: Waukesha WI
Posts: 13,017

Bikes: 1978 Trek TX700; 1978/79 Trek 736; 1984 Specialized Stumpjumper Sport; 1984 Schwinn Voyageur SP; 1985 Trek 620; 1985 Trek 720; 1986 Trek 400 Elance; 1987 Schwinn High Sierra; 1990 Miyata 1000LT

Mentioned: 79 Post(s)
Tagged: 0 Thread(s)
Quoted: 2360 Post(s)
Liked 1,002 Times in 592 Posts
Originally Posted by mrmw View Post
I like them too for 28/38/48 rings.
Just looking at your "my bikes" thing- do you/didn't you have a Centurion Pro Tour?
__________________
*Recipient of the 2006 Time Magazine "Person Of The Year" Award*

Commence to jigglin’ huh?!?!

"But hey, always love to hear from opinionated amateurs." -says some guy to Mr. Marshall.
The Golden Boy is offline  
Old 07-12-14, 04:41 PM
  #21  
dddd
Ride, Wrench, Swap, Race
 
dddd's Avatar
 
Join Date: Jan 2010
Location: Northern California
Posts: 8,395

Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.

Mentioned: 118 Post(s)
Tagged: 0 Thread(s)
Quoted: 1220 Post(s)
Liked 716 Times in 505 Posts
Back in the day, I fully rebuilt the Mountech rear derailer that came on my 1984 Stupjumper Sport.
I concluded that the larger the diameter of a pulley bushing, the higher will be the rotating friction.
That derailer did go on to survive until I sold the bike some 12 years later, but I never repeated the rebuild and just occasionally shot some motorcycle chain lube at the critical big pulley over the following years.

All "normal" Suntour derailers, except for the later high-zoot models, had (and have) larger-diameter pulley bushings than most other derailers. I think that this dimension was copied from Simplex. It increases contact area while also imparting frictional forces at a greater radius, thus increasing resistance torque and power.
The high-zoot models had excellent ball-bearing pulleys that could be bought as an accessory to upgrade any derailer with 5mm or 6mm pulley bolts. Great product!

As for the C10 Altus, I found this style of part-plastic Shimano derailer to work well enough for racing, though in the end I lost a CX race after leading well into the final lap when mine ejected the pulley cage pivot shaft and cage towards the spokes. Ouch!
Might have been the rebuild of the "A" pivot that I performed, since the internal circlip may have had a "directional" installation that I perhaps didn't notice.
These circlips have a sharp side and a rounded-edge side iir.
So, even though there is a stealthily-hidden access plug that allows one to pull out the circlip and remove the cage pivot assembly, I dis-recommend doing this ever.

Here's a picture of the bike that I raced on (I took off the rack of course), the front derailer is in fact a Mountech, and works nicely while easily staying clear of the crankarm even when riding in the big ring.
The rear derailer had not yet exploded when this photo was taken some years ago.

dddd is offline  
Old 07-13-14, 04:33 AM
  #22  
mrmw
Senior Member
 
Join Date: Dec 2005
Location: Atlanta
Posts: 603

Bikes: 1982 Schwinn Super Sport S/P, 1984 Miyata 610, 1985 Panasonic LX 1000, Centurion Pro Tour 15 1983

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Likes: 0
Liked 5 Times in 2 Posts
Originally Posted by The Golden Boy View Post
Just looking at your "my bikes" thing- do you/didn't you have a Centurion Pro Tour?
I would have responded sooner but I got caught up in one of the timeless wonders of the interwebs which I had to watch in its entirety: https://archive.org/details/WhatsOperaDoc

Yes, guilty. The '83 Centurion Pro Tour 15 is my daily ride right now (full photographs below in its inaugural post), having elbowed its way ahead of the newly revived '82 Schwinn Super Sport S/P which I rode all spring into early June.

https://www.bikeforums.net/classic-vi...r-15-hawk.html

Last edited by mrmw; 07-13-14 at 04:46 AM.
mrmw is offline  
Old 07-13-14, 08:54 AM
  #23  
mobilemail
Senior Member
 
mobilemail's Avatar
 
Join Date: Apr 2005
Location: Gateway to the West
Posts: 785

Bikes: You mean this week?

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 24 Post(s)
Likes: 0
Liked 8 Times in 4 Posts
Hey, if anybody wants to trade me their mountech front for the mountech rear in my junk box, I'll gladly set you up! I will even include the vintage grime!
As for replacements, I will confess that just about every modern derailleur that I have used shifts with more ease and precision than the mountech did. You don't find as many that had the incredible capacity though. The Shimano Acera has become my go-to budget replacement for the older derailleurs. Cheap, reasonably attractive, shifts well, decent capacity. I do, however, try to keep it out of my spokes. :-)
mobilemail is offline  
Old 07-13-14, 09:38 AM
  #24  
Pars 
Senior Member
 
Pars's Avatar
 
Join Date: Jan 2008
Location: Aurora, IL
Posts: 2,465

Bikes: '73 Raleigh RRA, 1986 Trek 500 commuter

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 50 Post(s)
Liked 15 Times in 10 Posts
Originally Posted by BluesDaddy View Post
There is a piece left over! How does this happen?? The ring is a dust seal or maybe a spacer, but the edge is chewed up so I thought it might do harm than good so I left it out.

But that little bit... what the heck is that?



It looks like a broken-off tab or maybe a key. It fell out of my cleaning rag. I'm baffled.
Both of my Cyclone MKII use these, and one is missing the tab thing. These never show up in the exploded parts diagrams online, must have been a design change on the Cyclone at some point. At any rate, I could use one of these tabs if anyone has one laying around.

I made one from some scrap metal, but it doesn't tighten up as well as the real deal.
Pars is offline  
Old 07-15-14, 09:29 AM
  #25  
Chris Chicago
Senior Member
 
Chris Chicago's Avatar
 
Join Date: May 2009
Location: near north side
Posts: 1,333
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 81 Post(s)
Liked 24 Times in 16 Posts
pars, I will be willing to sell you on of those tabs for $10.

oh, I just noticed you are relatively local so that should save on shipping. pm me your address and I will drop an envelope in the mail
Chris Chicago is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.