Severely stuck fixed cup of BB
#52
Penetrating oil does nothing at all to break the cup free, but it does help some once the cup is moving.
#53
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#54
#55
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I believe that there have been tests done using penetrating oils, and that they have been shown significantly reduce (in some cases by 90%) the torque needed to break free artificially rusted bolts. My experience agrees with this: penetrating oil works on rusty bolts. If there are tests (physical tests, not theoretical models*) that prove no benefits for PO, can you share them?
*I'm an engineer that writes models based upon theory, so I like them. But data trumps theory here.
*I'm an engineer that writes models based upon theory, so I like them. But data trumps theory here.
#56
I believe that there have been tests done using penetrating oils, and that they have been shown significantly reduce (in some cases by 90%) the torque needed to break free artificially rusted bolts. My experience agrees with this: penetrating oil works on rusty bolts. If there are tests (physical tests, not theoretical models*) that prove no benefits for PO, can you share them?
*I'm an engineer that writes models based upon theory, so I like them. But data trumps theory here.
*I'm an engineer that writes models based upon theory, so I like them. But data trumps theory here.
#57
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Thats great, then please explain how oil breaks a rusted bolt free. There is no likely mechanism for that to occur. Initial torque is the same. Same with at stuck seatpost, No amount of kroil or any other penetrating oil will do anything to unstick it. - I may help some once the oxidation IS broken free.
Since you asked, though, I would suspect the reason why effective penetrating oils do reduce breaking torque has something to do with some effect on the complex physical structure of the rust/metal matrix, and/or with the effect of liquid on the surface energy of rusted steels. I agree with you that they probably don't affect the chemical structure of the rust.
The data from the first of the two videos shows some effect of a single application of POs on breaking torque. Note that other tests have used repeat application/soaking and show a larger effect.
Here's two videos that seems to use a pretty thorough approach to testing and show a modest effect of POs.
Last edited by WizardOfBoz; 02-16-20 at 02:25 PM.
#58
Yeah , ive seen that. The results dry vs PO are really close (for the most part within a few percent) and the sample size i really small. It might as well have been a fluke. Likely is. Obviously no braking free with PO is happening. The other video is with a plastic block. Hardly relevant.
#59
Soak in penetrating oil for a couple of days, I like the ATF /acetone. With a very sharp cold chisel, make a good deep notch on the outside of the cup. Then, use a very blunt chisel or equivalent and put it in the notch. Take a BFH(technical term=big f*in hammer), 2.5 or 5 pound hammer and angle the chisel so that when you hit the chisel it willl turn the cup in the direction that will loosen it. This technique is almost as good as an impact wrench, and in you case, since the cup is so FUBARD, it is probably the best becasue all you have nothing to grab onto in the middle of the cup for all the other wrench methods. This technique just uses the remaining metal of the cup.
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Il faut de l'audace, encore de l'audace, toujours de l'audace
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Il faut de l'audace, encore de l'audace, toujours de l'audace
1980 3Rensho-- 1975 Raleigh Sprite 3spd
1990s Raleigh M20 MTB--2007 Windsor Hour (track)
1988 Ducati 750 F1
#60
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That may well be, but enough people who deal with rusted fasteners on an everyday basis have experienced results and decided it does provide enough of a benefit that millions of $$ are spent each year on penetrating oils.
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Freeze-off and the sheldon bolt method with a) good quality bolt )long lever (often 2 person job) c) turning the right way
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Seems that the OP hasn't been here for at least ten days. It must have become a non-problem for him. Smiles, MH
#65
Senior Member
How about you?
Most bike mechanics aren't going to be equipped with 1/2" or larger impact wrenches and an air compressor to keep up.
And you still have to hold the rest of the bike.
My "tool set" in post 7 hasn't failed me yet in 6 "frozen" cups.
Multiple applications of Liquid Wrench dribbled in the shell from the opposite side to run down into the threads. 1st application, keep dribbling as long as it keeps running into the threads.
7 whacks & 6 cups. I was too gentle on the very 1st whack. 2nd whack I KNEW the tool would stay in place.
You still need a "tool retainer". Else you're going to have stripped tools and possibly worse problems.
At that point, a 4 lb. hammer takes less set up time. You don't have to connect it to its "power supply". You don't have to coil up & stow said "power supply".
It's akin to having your brain surgeon use a hammer & chisel to crack your skull.
Most bike mechanics aren't going to be equipped with 1/2" or larger impact wrenches and an air compressor to keep up.
And you still have to hold the rest of the bike.
My "tool set" in post 7 hasn't failed me yet in 6 "frozen" cups.
Multiple applications of Liquid Wrench dribbled in the shell from the opposite side to run down into the threads. 1st application, keep dribbling as long as it keeps running into the threads.
7 whacks & 6 cups. I was too gentle on the very 1st whack. 2nd whack I KNEW the tool would stay in place.
You still need a "tool retainer". Else you're going to have stripped tools and possibly worse problems.
At that point, a 4 lb. hammer takes less set up time. You don't have to connect it to its "power supply". You don't have to coil up & stow said "power supply".
It's akin to having your brain surgeon use a hammer & chisel to crack your skull.
...not certain you've used an impact wrench in a circumstance like this. It's not like going at a lug nut on a car wheel, and the bicycle itself tends to move around easily. So the business end of the tool either slips out or can damage the little teeth in the BB fitting (they are either aluminum or plastic.) So it might work, but you're way better off bolting the tool to the sealed unit spindle with a properly sized bolt and some fender washers, putting either an adjustable or (better) properly sized box end wrench on the tool, and hitting the wrench with a mallet or hammer. Plus you get to use a hammer.
#66
Really Old Senior Member
Lumping your two posts together. Most shops, or at least the 4 shops I worked in already had air compressors with runs to each stand. I didn't leave my impact wrench at any of them and for whatever reason no shop ever had one but there were a number of times that I brought it in to deal with a recalcitrant BB. Really doesn't take much to do the job. Course that was the good old days and I don't own an air compressor and an air impact driver. Though I'm betting any of the modern 18-20v impact wrenches with a 4ah battery will do the job just as nicely without all the messy coils or cords. And using nuts and bolts I've broken a number of fixed cups free with impact. The tools work, if someone has them already its the easy way to go.
I actually think an impact wrench is the best way to remove a stuck cartridge BB and its yet to fail me. Impacts don't really torque on things which is what causes cartridge BB tools to slip out. For installs and most removals I use a wrench on the tool with the wrench almost against the BB, this prevents the BB tool from camming out. Similarly an impact wrench never seems to can out and the bicycle doesn't move all that much sitting in a stand.
I actually think an impact wrench is the best way to remove a stuck cartridge BB and its yet to fail me. Impacts don't really torque on things which is what causes cartridge BB tools to slip out. For installs and most removals I use a wrench on the tool with the wrench almost against the BB, this prevents the BB tool from camming out. Similarly an impact wrench never seems to can out and the bicycle doesn't move all that much sitting in a stand.
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...must be quite a stand.
...must be quite a stand.
#68
Senior Member
Yes this worked for me. Just welded a bit of square tube directly to the cup and then used it as a wrench. The heat from the welding probably also helps to loosen it. But just getting a decent purchase on those damn things is half the struggle.
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Lumping your two posts together. Most shops, or at least the 4 shops I worked in already had air compressors with runs to each stand. I didn't leave my impact wrench at any of them and for whatever reason no shop ever had one but there were a number of times that I brought it in to deal with a recalcitrant BB. Really doesn't take much to do the job. Course that was the good old days and I don't own an air compressor and an air impact driver. Though I'm betting any of the modern 18-20v impact wrenches with a 4ah battery will do the job just as nicely without all the messy coils or cords. And using nuts and bolts I've broken a number of fixed cups free with impact. The tools work, if someone has them already its the easy way to go.
I actually think an impact wrench is the best way to remove a stuck cartridge BB and its yet to fail me. Impacts don't really torque on things which is what causes cartridge BB tools to slip out. For installs and most removals I use a wrench on the tool with the wrench almost against the BB, this prevents the BB tool from camming out. Similarly an impact wrench never seems to can out and the bicycle doesn't move all that much sitting in a stand.
I actually think an impact wrench is the best way to remove a stuck cartridge BB and its yet to fail me. Impacts don't really torque on things which is what causes cartridge BB tools to slip out. For installs and most removals I use a wrench on the tool with the wrench almost against the BB, this prevents the BB tool from camming out. Similarly an impact wrench never seems to can out and the bicycle doesn't move all that much sitting in a stand.
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Wow!
I have been using air wrenches since the 1970's and they are far superior to the hand methods being expressed here. But in every thing, they do a good job and far quicker than by hand. If you have ever been working in the industry as a wrench you will know your paycheck is going to be based on the speed of your repairs. The air wrenches speed up the work process. The current discussions are about air versus battery power. But they both speed up the work process. I currently use both systems, air for big jobs and battery for small jobs. But they both keep my speed of repairs up. So to keep the kerfuffule going I will add my $.02 worth.
It is interesting that today we use torque bars for our impact wrenches to keep the wrench from putting too much pressure on the parts we are bolting on. A good example is bolting a brake caliper too tight and warping it making it useless for braking. Smiles, MH
I have been using air wrenches since the 1970's and they are far superior to the hand methods being expressed here. But in every thing, they do a good job and far quicker than by hand. If you have ever been working in the industry as a wrench you will know your paycheck is going to be based on the speed of your repairs. The air wrenches speed up the work process. The current discussions are about air versus battery power. But they both speed up the work process. I currently use both systems, air for big jobs and battery for small jobs. But they both keep my speed of repairs up. So to keep the kerfuffule going I will add my $.02 worth.
It is interesting that today we use torque bars for our impact wrenches to keep the wrench from putting too much pressure on the parts we are bolting on. A good example is bolting a brake caliper too tight and warping it making it useless for braking. Smiles, MH
#72
Senior Member
I just removed one, original from a 79 bike. It would not budge even with PB blaster, until I fed it some Fall off (ATF/Acetone 50/50 mix).
It separates so you have to shake it up every time you apply.
2 days later and came off with almost no effort.
It separates so you have to shake it up every time you apply.
2 days later and came off with almost no effort.
Last edited by tammons; 02-24-20 at 06:08 AM.
#73
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