Classic & Vintage - Mountech RD: fixed, still needs work, or replace it?
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12-04-10, 04:17 PM
I've been having problems with the SunTour Mountech RD on my '84 Univega Gran Turismo: rough shifting, and not being able to get to the smallest rear sprocket from the one next to it - but I could from several gears away. I finally had time to investigate, and discovered that the derailleur seemed bent. I got it straightened, such that the jockey wheels are pretty much in the same plane now, and it works much better, but still not as well as I remember it from several months ago. (I readjusted high and low screws too.) When I look at the derailleur arm, it still seems to be hanging wrong: 1) the jockey wheels are not vertical, the lower one is closer to the wheel, and 2) it seems slightly pigeon-toed, as if the the front of the jockey wheels are closer to the center line of the bike than the back of the wheels.
Here is a picture which hopefully shows what I mean:
Based on how I can wiggle things around, there seems to be a lot of sideways slop at the top jockey wheel joint: I can lightly pull the bottom wheel outwards and everything gets much more vertical, but it doesn't stay in that position. I can't tighten that joint any further.
So, is this derailleur, dead, dying, or just in need of a more skilled mechanic? Or does it look fine and I'm just a big whiner?
If I replace it, are there any suggestions? The Mountech has a chain capacity of 38 (though I think I calculated 40 on the bike itself). I would prefer something C&V, all metal, and not blackened, but would consider other stuff to. For example, I looked at the Shimano XT reverse low-normal RD, but it's pretty modern looking and more expensive than I'm hoping for. The SunTour Cyclone Mark II GT only has a 34 tooth capacity, apparently. I'm using Rivendell's Silver shifters as bar-ends.
12-04-10, 04:44 PM
http://www.users.globalnet.co.uk/~hadland/page35.htm - a history of why Suntour failed, and how Mountech RD's helped.
I'm guessing many would say replace it? The design itself seems to be flawed.
12-04-10, 04:46 PM
I had the same bike with the same RD a while back, and it failed at that fat upper pulley. I don't think you have anything to lose by trying to straighten the cage as I agree it's at an angle, but ultimately you might be best off at replacing it. Lots of good options: Deore LX or XT of that era, in particular.
12-04-10, 04:57 PM
There's one nice thing for a touring bike that the Cyclone lacks: a barrell adjuster. If you went with the Cyclone, you might consider incorporating one somewhere in your setup. I have one and love it, but that's a detail I constantly wish it had.
12-04-10, 06:42 PM
Way back in 82 or 83 I used a Mountech on my Woodrup (it was a fairly new model at the time, and the price was right) it was pretty much awful from the get go...
Relaced it with a Huret Duopar. IMO save yourself the headach and replace it.
That's a good picture!
It looks to me that your derailleur hanger is bent.
12-04-10, 08:45 PM
Are you sure your hanger isn't bent?
But if you're sure it's not that, and if a Cyclone isn't what you need, then a Suntour VGT or VXGT should work, and they have a barrel adjuster. I bought a NOS VXGT last year for (I think) $25.
If the Mountech contributed to Suntour's demise, the V-series is probably what gave them their success in the first place. They work great, and last forever.
12-04-10, 09:22 PM
+2, that hangar is bent.
I have a second generation Mountech on my Fuji Touring Series, works great and doesn't have that goofy jockey wheel that failed all the time. It's like any other RD. You might try searching one of those out.
12-04-10, 11:42 PM
Thanks Guys. How exactly can I tell if the hanger is bent? If it is, then that compounds the problem, but isn't the only problem. This bike shifted nice and smooth until mid to late summer, and then started having problems. The bike fell against a tree once, but that was on the left side of the top tube, not the right side by the derailleur, and there have been no other strong bumps. Not only that, the cage was pretty easy to bend - certainly easier than the hanger, which is part of the drop out, so I would expected that to bend first (if it had been bumped). And don't forget the slop in that one joint that is the apparently famous for failing. I forgot to say that I have a Sachs Huret New Success on a different bike, which I could possibly cannibalize.
12-04-10, 11:47 PM
The Mountech is a dog compared to most other Suntour derailleurs... a VX GT will put a big smile on most people's faces as it is a wonderful derailleur.
12-05-10, 12:24 AM
I would suggest that the second generation Mountech is a vast improvement. It shifts perfectly on my TSIII...this is the first gen:
Note the open cage and the funky upper jockey wheel that covers the pivot. Here's a second generation:
Note the full cage and, although hard to see, the normal upper jockey wheel.
This version didn't suffer from the issues of the first gen...that funky jockey wheel getting impacted with dirt and the cage bending. But, as the disrealigears guy say, by the time the second version came out the name had already been tarnished.
I've found my second gen to be more than acceptable:
12-05-10, 07:33 AM
There are a lot of DIY derailleur-hanger alignment tool instructions on the interweb. Here's one from Dave Moulton:
12-05-10, 02:29 PM
I have a Mountech derail on a 85 Schwinn Le Tour Luxe and it still works fine. I looked at your cage position there on the Fuji and it looks right to me when compared to mine. Supposedly they had problems with dirt getting into the spring inside the third pully. If you can clean out the third pully with solvent then relube it should return to normal. But only do that as a last resort after all other attempts have failed.
History also said that Superbe Tech derailleurs were junk too, but I've one with over 150,000 miles on it and has never given me the least bit of trouble. Maybe when it gets to 200,000 miles something might happen to it then I'll scream: "god this crap was made cheap!"
12-05-10, 05:28 PM
Result: the hanger *was* bent. I used Dave Moulton's method as Neal suggested, and sure enough, the bottom of the hanger was bent toward the centerline. I got it straightened up, put the derailleur back on, and tested the shifting on the bike stand (it's raining outside). Shifting is much smoother, and so is trimming. Also, both jockey wheels are now right in line directly beneath whichever sprocket the chain is in. Still, it couldn't hurt to start developing a stock of replacement parts, so I'' keep an eye out for some of the derailleurs you guys suggested.
The Golden Boy
12-05-10, 07:27 PM
There was someone here that posted something to the effect of putting a Mountech RD on a bike with a Helicomatic hub would somehow cause the inverse to implode upon itself.
I have an 84 Stumpjumper that would have come with a Mountech RD, it's been replaced with a Shimano XT M-735 RD, paired with the original SunTour AG Tech FD. The rear wheel and RD had been replaced by the original owner.
12-05-10, 07:40 PM
You know, I see the Park Tool for this pop up on our CL once in a while. I ought to try to snag one...checking the hangar should be part of any rebuild/refurb shouldn't it?
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