TREK 760 advice needed
08-04-18, 01:26 PM
#1
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TREK 760 advice needed
I'm interested in this TREK 760 frameset. As you can see by the picture, a shifter screw has been broken off in the braze on. Removable? Methods? I'm assuming I couldn't use any heat. Potential for success? Fair price for the frameset? Thanks in advance.
08-04-18, 01:31 PM
#2
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I suspect it could be corroded and seized at the threads. Maybe you can drill a pilot hole part ways into it's center, soak it in penetrating oil then use a screw extrator.....but I suspect it will not be easy....
Good luck!
Good luck!
Last edited by Chombi1; 08-04-18 at 09:02 PM.
08-04-18, 01:39 PM
#3
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Try soaking for a while. All else fails, drill and retap. Frame better be REALLY cheap before I go through that hassle. I like Treks, but only so much BS to put up with to save one.
08-04-18, 02:26 PM
#5
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Without seeing any other pics, knowing it has the shifter boss issue, $100 tops, preferably less. How much risk can you tolerate?
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08-04-18, 02:44 PM
#6
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My tolerance does not reach to $100; which is what the seller wants. I'd be much more comfortable with $50. But I would want to be fair. I anticipate that extraction will not be easy and I might need to recruit a machinist. The seller has only posted one picture of the full frame set and it is difficult to tell what condition the paint is in. It's obvious the chain has marred the right chain stay. I asked for the picture of the shifter boss and you can see that is pretty rusty. The frame is about 100 miles away but I'll probably take a look to get a better idea. I guess it wouldn't hurt to first ask if there is any room for negotiation.
08-04-18, 02:47 PM
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$100 seems really steep agree with $50, have you looked in the frame - how is the internal rust? (also would see what a good bike shop could do before drilling).
08-04-18, 03:00 PM
#8
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If you offered me $50 for a DECENT '84/85 Trek 760 frameset, even with the screw issue, I'd send you packing.
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08-04-18, 03:38 PM
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Could you get a pair of vice grips on what’s left of the screw shaft?
If there’s enough material to grab the procedure I’d use is:
apply penetrating oil, silicroil, PB blast, whatever flavor you like.
Hit it with either a low set heat gun, or even a hai dryer on high. Then some canned air keyboard spray upside down, so you’re cooling it with the liquid propellant.
The idea is to expand and contract the materials to creat minute space for the oil to penatrate. Time and heat change are your friends.
After a few cycles of the heating and cooling, let it sit for a few days and periodically hit the area with the oil.
After a day at or two, grasp the broken screw head with the vice gripes and hopefully it with back right out.
the other option is file the screw flush to the braze, and using a punch, dent the center of the screw. Then drill out using a “left handed bit” so if the screw does let go during the drilling, it will back out.
Might come right out, might be a huge nightmare.
EDIT: know what? I’d bring that picture to you LBS and get a rough estimate too.
If there’s enough material to grab the procedure I’d use is:
apply penetrating oil, silicroil, PB blast, whatever flavor you like.
Hit it with either a low set heat gun, or even a hai dryer on high. Then some canned air keyboard spray upside down, so you’re cooling it with the liquid propellant.
The idea is to expand and contract the materials to creat minute space for the oil to penatrate. Time and heat change are your friends.
After a few cycles of the heating and cooling, let it sit for a few days and periodically hit the area with the oil.
After a day at or two, grasp the broken screw head with the vice gripes and hopefully it with back right out.
the other option is file the screw flush to the braze, and using a punch, dent the center of the screw. Then drill out using a “left handed bit” so if the screw does let go during the drilling, it will back out.
Might come right out, might be a huge nightmare.
EDIT: know what? I’d bring that picture to you LBS and get a rough estimate too.
08-04-18, 08:34 PM
#10
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If all else fails, electric discharge erosion:
https://electroarc.com/difference-mdm-edm/
Check with a machine shop for local availability.
https://electroarc.com/difference-mdm-edm/
Check with a machine shop for local availability.
08-05-18, 06:09 AM
#11
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As the saying goes: When you snooze you lose. The frame is gone. Sold to someone else last night. Temptation gone. Thanks to all who responded.
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