How to determine replacement XT/XTR derailleur?

[rjc92879]

I have an early 90's Merlin MTB frame with 90's era Shimano xt and xtr on it. I now use the bike primarily as a pavement hill climber (I live in a hilly residential area) with maybe 20% off road. Recently, the front derailleur stopped returning when released by the shifter. The derailleur shifts to a larger chain ring perfectly. When shifting to a smaller chain ring, the shifter appears to release the cable correctly, but the derailleur is not returning, despite obvious slack in the cable. I have to kick it over with my heel. Lubricating the various pivot points did nothing. I assume the return spring broke or wore out. Based on the age, I assume I should replace it rather than try to repair it.

The shifters and the rear derailleur are XTR. The front derailleur is XT. The front has three chain rings, the rear cluster has 8 gears.
I looked up on eBay and see numerous used XT and XTR front derailleurs. I assume I can also buy a new one.

Questions:
Am I going to have to buy a used derailleur to match my existing components, or can I buy a new one?
How do I determine which model derailleur(s) would work as a replacement?
Is XTR noticeably better than XT?
Is a used XTR derailleur in good shape as good (or better) than a new XT derailleur?

I have attached a photo. If you need one from a different angle, please let me know.

Thanks in advance

[Painkiller]

looks as if you are sporting a Fd-m737 8speed. The problem with a new xTr/XT is the name is the same but The drivetrains have changed alot. A new one will more than likely be for a 2x10 setup with a big ring capacity of say 40 tooth. What is your seat tube Dia. ? how many teeth on your big ring? First did you disconnect your cable to check if the spring was bad by hand? It could be that the cable and housing is the culprit. Do this first, after disconnecting the cable check the movement of the derailleur and check the housing by sliding out of the stops to check for binding. replace back into stops and pull on cable by hand to double check for binding. If you are lucky to have binding, replace cable/housing and you are good to go.
If after this test and the spring is broken, and you just want to get the bike rolling again most any 7/8 speed triple top swing bottom pull will work that do not cost as much. such as STX, STXRC, DeoreLX. these will do 42/44/46/ tooth big rings for the most part ,plus other exceptions with other gearing changes. Do the the test, measure your tube diameter or look on the inside of your clamp and let me know what it is and I may have something for you, new or used.

[elmore leonard]

I'm a near novice but front deraileurs can be tricky. I would take it off, soak it clean and lubricate it. Pull the cable out of the housing and lubricate it if it is good. Otherwise replace it. Then go through the set up process for installing it. Good video on this site. I subscribed for a month and learned a lot. I have had bikes were the previous owner had run the cable improperly to the deraileur. So check the cable routing to the tie down bolt as well.

[rjc92879]

Thanks for the reply, painkiller.
I had the front derailleur shift cable break on me last September. That might have been the first indication that the derailleur was starting to bind in some way. I replaced all of the cables and housings on the bike, so I am confident that is not the problem.
The big chain ring has 46 teeth.
One thing missing from my tool kit is any kind of micrometer/caliper. Using the best ruler I have, it appears the interior diameter of the seat tube is 27mm or 1 1/16th inches (or are you asking about outside tube diameter?). I can call Merlin tomorrow morning to verify.
I have been slowly refurbishing the bike while I ride it (new wheels, cables, housings, etc.) The bike is set up perfectly for its current use, so as things continue to break or wear out, I will try to stay with the same specs.
Given that the rest of the bike is XTR, I would probably like to find the correct used XTR derailleur or an XT at a minimum.

[rjc92879]

Painkiller,
Thanks for the m737 designation
I found a couple of 737 XT front derailleurs on eBay for $15 to $20 shipped.
Are there any other XT models that would work?
Could you tell me what the compatible XTR model would be? That would be my first preference.

http://www.ebay.com/itm/251771567684?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
http://www.ebay.com/itm/221647190071?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

[Painkiller]

yes ,the clamp size would be the outside of seat tube preferably close to where it mounts. it will say on the inside of the clamp if you remove it and look. on the back side of the cage it will give the model #. look for something such as FD-M737 or FD-M738.Howm any speed is your rear? 8 or 9? Realize that Nos and used exact replacements will be abit pricey but will keep the bike true if that is what came on it original. Also it is easier to help someone if we know where about you are located.
Return with the info and I will see if I can help further

---

(01-01-2015, 07:22 PM)rjc92879 Wrote:  Painkiller,
Thanks for the m737 designation
I found a couple of 737 XT front derailleurs on eBay for $15 to $20 shipped.
Are there any other XT models that would work?
Could you tell me what the compatible XTR model would be? That would be my first preference.

http://www.ebay.com/itm/251771567684?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
http://www.ebay.com/itm/221647190071?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

your top link is wrong pull. your bottom link is correct pull but we need your correct clamp size.
are 8 or 9 speed? first gen XTR was 8 speed FD-m900

[Painkiller]

I would not be so picky if you ever need a rear cluster for an 8 speed XTR. used clusters are not a good idea and new ones are costly, usually $200 and up. but I would be more than happy to sell you one or two.

[rjc92879]

Painkiller,
You are being very generous with your time.
I will pull the front derailleur off in the morning and try to determine the clamp size.
The rear cluster is 8 speed.

[Painkiller]

(01-01-2015, 07:59 PM)rjc92879 Wrote:  Painkiller,
You are being very generous with your time.
I will pull the front derailleur off in the morning and try to determine the clamp size.
The rear cluster is 8 speed.

no problem, most alloy frames will be 34.9 or 31.8
look for FD-m950 for XTR also should work. pay attention to the way your arm looks where the cable pulls from. your picture (or lack of) tells me your cable runs under your bottom bracket then up to the derailleur or along the top tube down the seat tube around a pulley and up to the derailleur. let me know

[rjc92879]

Painkiller,
Your eye is good. The front derailleur is a FD-M737. The seat tube/clamp diameter is 31.8
The shift cable runs under the bottom bracket up to the derailleur.
The rest of the components are first generation XTR. RD-M900 rear derailleur. FC-M900 crankset. Same generation brake/shift assembly.
Repeating other information, so you don't have to look for it:
Rear cluster is 8spd.
Large chain ring is 46 teeth.
As I start looking more closely at the components, I see that I am also going to need new chain rings and a rear cluster pretty soon. $200 for a NOS cluster is pricey, but I can start budgeting if that is the way to go.

[Painkiller]

That bike is fairly high end, you never said what it was, Gt? An XTR crankset oooouch
You will be lucky to find one, Nos for under $600. These are major league vintage parts that you seek. Gently used XTR crank would be cheaper if you come across one.
Is your rear cluster XTR also? Pound the pavement, you never know what you may find. Here is a pic of what the back of an XTR cassette looks like, Plus a picture of how much one may have cost back in the day. I wish my gold portfolio was doing as well! I Hope your shifters are good, those will ease the pain of $200 for the cluster when you find out how much they may want for those. Lets see some pictures of the rest of the bike sometime. Welcome to my world, not sounding so great is it? puts tangible meaning to "you want to play ya gotta pay". Unless you are lucky and that is chump change, then you are good to go!

[rjc92879]

Painkiller,
If you look back to the first sentence of my first post, you will see that I clearly stated what I had
"Fairly high end"? I believe in its day, it was top of the line. Because you asked, I took a picture of the bike for you, the first one I have taken in 20 years. The lighting isn't the best, but you get the idea.
In the early 90's, I bought an aluminum/ceramic Stumpjumper with full XTR (I thought it was full XTR, apparently the front derailleur was XT) off of a bike rep, who was switching companies and therefore had to switch his ride, for $850. That was a whole lot of money to me.
I rode that until mid 96, when I picked up a 92 Merlin MTB frame and new Mag21 RockShox for $600.
I switched the components over, sold off the Stumpjumper frame and shock, and have been riding the Merlin ever since.
I had about $1,300 into a bike that would have cost over $3,500 new, in the 90's.
I had way more money in the 90's than I do now, and even then, I was trying to buy things at 20-30% of retail.
Yes it is an XTR cluster. I have a receipt for one I bought in 1996 for $69.99. I will give you that much for the one you are holding right now. That's twice what you paid for it
I don't believe I need an XTR crankset. I already have one. I just need chain rings. And that cluster you are holding.
Seriously, right now I just need to fix my bike so I can ride it without having to kick the front derailleur over with my heel to drop down chain rings. This is my only working bike and I need to ride it, I was riding it Saturday, kicking on the derailleur. I will ride it again today.
I will probably try to pick up a used XT derailleur to get the bike functioning.
Beyond that, I don't have to have vintage XTR, I just need to be able to ride the bike.
I also don't need a cluster or chain rings right now, but I will eventually.
If you want to send me a phone number, I will call you and maybe we can do some business.

[Painkiller]

Nice looking frame. That is exactly what I recommend, get the bike functional and go from there. Now that you have a better idea of the cost of things high end and retro. You should have all the info you need to make wise choices. Same problem with trying to save a shock like that also so keep that in mind along the way. Looks like an 1" 1/8 steer tube from the pic, if it is that will be a plus should it need replaced. That is about it. I do not normally sell grade A vintage parts. I need them for what I do and to hard to come by. It is kinda dog eat dog on that stuff.

[rjc92879]

Painkiller,
Thanks for sharing your expertise.
You were very generous with your time.
I really appreciate the advice.
Take care.