jacksbike

Hi all,
I have acquired an older 1970's Raleigh Gran Sport in fair condition. I have managed to free the stem , so far, from the frame and am working on the stuck seat post. What I am currently involved in is removal of the 2 stuck, frozen, Stronglight alloy cotterless crank dust caps. I obviously have to remove them in order to access the bb to overhaul it. So far, I have rounded out the 5 mm hex head dust cap holes, and have sprayed on PB Blaster. So far, still frozen. Any ideas how to remove the dust caps without massive destruction ? I hate to get to the point of enlargening the dust cap center hole and trying to poung out the screwed in dust caps with a punch and hammer. Suggestions from anyone ? Thanks.

due ruote 

Until I got to the part about rounding out the hex head, I was going to congratulate you on having dust caps. Did you tap on them when you sprayed the PB Blaster? I'd do that a few times, spray some more, and let it sit for a day. Can you dremel a slot in the cap and try a screwdriver? That's all I can come up with. Good luck. btw, you do know you need a Stronglight crank puller for the next step, right?

rhm

+1 on Dremel a slot for a screw diver; alternately you can drill two holes for a pin spanner... either way I'm afraid your precious dustcap is toast, but you will eventually get it out.

Chombi

You might have to destroy the caps if they are well stuck on the crank.
Most manufacturers treat those caps as throw-away items as many would plastic tire valve caps and they do not invest too much into designing and producing them in high enough quality that the treads will resist binding or corroding (the metal ones) on to the crank. If you end up getting replacements, I would screw the caps on and off on both sides a few times tp clean up the threads on them and once they come on and off smoothly and can screw in completely to the bottom of the crank bolt well, put a bit of grease on the threads to avoid seizure in the future. Also, periodically take the caps off for cleaning and re-greasing and you will not have any problems with them later.
Actually, the slotted type dust caps despite the description, they actually catch dust and fibers and lint, from cycling socks and pants legs that repeatedly rub against the caps when pedalling, and once you add moisture into the collected material it starts the whole corrosion and seizure process on metal cap and crank threads. .........that's why I leave them off my cranks.

Chombi

randyjawa 

I believe that you are dealing with aluminum oxide seizure. I have been told that soaking the frozen parts, in ammonia, will attack the oxides causing the problem. At least, I think it was ammonia. Has anyone else heard of this method for dealing with alloy seizures?

Don't just give it a try. For all I know, the ammonia might eat aluminum too.

Chombi

Freezing the cap might also work to break the oxide seizure, the small mass of the cap will make it shrink much faster than the crank if you concetrate the spray of the freezing media on it, them manipulate the cap before the crank contracts too. It could be "Freeze-Off" time!

Chombi

jacksbike

Gee, folks, thanks for all the great suggestions ! I have tried PB blaster on the dust caps, with no go. I fully realize that the dust caps are toast, and that is all well and fine. In the past, I usually would try, as suggested, elongating the opening hole and trying a very large blade screwdriver. Yes, I do believe I surely have aluminum oxide seizure, etc. The idea of drilling 2 holes and utilizing a pin spanner sounds good. Freezing -good idea, but what substance do I use to do it ? I do understand that by freezing the outer cap, it might shrink so I can then unscrew it. What wonderful magic freeze goop could I use ? Thanks a million to everyone for the suggestions. I bet that after the dust caps come off, I will be dealing with frozen bb cups too !

cinco

I had the same problem a while back and after complete failure with nondestructive methods I had to get nasty. My last resort was to drill small opposing holes in the face of the cap, heat it up with a small torch, and turn it out with a pin spanner after having broken it free with a punch and hammer. Not much fun and a bit scary, but it worked.

RobbieTunes

1-Check to see if you have 2 small allen wrenches. Not too small that they'd break, but not too big that a hole would be too big.
2-Drill two small holes just big enough for the 2 small allen wrenches. Insert the long end of each wrench into the hole.
3-Cross the allen wrenches a ways out from the holes. Now you have a rigged wrench, of sorts.
4-Hold both wrenches in pretty much the same plane and turn them to simulate a pronged remover.

Sometimes works in a jiffy. Works on the self-extracting rings (no drilling, smaller wrenches).

Chombi

"Freeze-Off" made by CRC, available in auto parts stores. You should be able to look it up in the internet.
I removed a really badly seized stem and BB cups from a frame with Freeze off last year. Cups wouldn't budge before that with PB blaster and lots of force with a big wrench. Freeze-Off made them move in like 30-40 seconds after blasting the cups with it. I don't guarantee that it will work for all situations, but sometimes you have to give anything you can find a try and that's how it worked for me.
I think it will really help if you analyze the situation and find out what areas/parts you need to freeze to "break" it off. In my case, I concentrated the spray on the cups and avoided the BB shell as much as possible so the cups shrank away form the BB shell.
Beware though as the product is highly flammable, so you have to stay clear of sparks, confined palces and pilot lights when you are using it.

Good Luck!

Chombi

RobbieTunes

Thanks for the tip. I may try that. I wonder if I can get my CO2 cartridge to spray on it somehow.....

funkflex

I removed a stuck set by tapping in the edges of the broken off dust cap. My set was slotted and when I tried to turn the cap with a screw driver, the soft metal just tore apart. I then used a flat center punch to lightly tap the cap edges away from the inner crank wall. After only a few taps the cap came loose. My caps were toast already and yours seem to be in the same boat. Take your time and they will come free.

MetinUz

I would like to point out that this is not the correct application for Freeze-off. We are dealing with steel cap inside aluminum crank. Aluminum has a higher coefficient of thermal expansion, so simple application of heat will do the trick. Freeze-off works well when an aluminum part is stuck inside steel, such as stem or seatpost in a steel frame. I recommend the allen wrench trick after using a hair dryer to heat the area.

Chombi

Didn't know that it was a steel cap. There are lots of aluminum caps out there too. I have aluminum caps for my Stronglight and Mavic cranks right now that I bought separate from the cranks, so they are not that unusual. I still think it can work with a seized steel cap though if you are careful and try to just freeze the cap being careful not to hit the crank too much with the stream from the nozzle. Once the oxidation cracks/breaks the cap should come off easy.

Chombi

James1964 

This thread is old, but I thought I'd share my successful method to remove dust caps from a Stronglight 93 crankset.

The crankset is on a 1971 Gitane Tour de France and, based on everything else on the bike, had never been serviced. Both caps were frozen and the hexagonal wrench holes started to strip as I tried to remove the caps with a 5mm hex wrench. To loosen and remove the caps, I sprayed PB Blaster to the cap threads and then heated the caps with a small butane torch that we use in the kitchen for caramelizing the sugar on top of creme brûlées. (I ran the blue flame from the torch directly on the dust cap threads.) After doing this 4 times to each cap, I then tried to unscrew them. Fortunately, both unscrewed without any additional damage to the hexagonal holes and both the dust caps and crank arms showed no discoloration from heating.

francophile 

Zombie thread!

Helps to spray a shot of PB blaster in each hole pre-emptively, thus avoiding the removal pressure needed to round out the hole. After a squirt, I put the crank arm at 12 o'clock position for a few minutes, then rotate to 6 o'clock will be enough to distribute it evenly. I've been doing this for years now and have yet to round a single cap out.

But if nothing else, you can drill holes on either side of the cap, then use a pin spanner to pop off. Or there's take a Dremel and cut a flat to remove with a coin if no proper tool is available. I've seen both on hordes of Stronglight and Nervar cranks over my lifetime..

Still haven't had to use heat yet. Basically just what @rhm posted, which is pictured here. PS - congrats on getting yours out and welcome to BF!

dddd

After adding a penetrant from both ends of the threading, and waiting a few minutes or longer, I take a hammer and wooden dowel, impacting around the cap's periphery until it screws out with a normal amount of force.

This has literally always worked for me.

Rounded hexes can be dealt with by taking a 7/32" (5.5mm) Allen key and first sawing off the long leg. Then carefully taper one end over a span of a few millimeters using a file or grinding wheel, so that it can be hammered tight into the hole so as to really engage the (now-tapered) opening. This can supply a quite good amount of torque, and without totally messing up the cap's appearance.

scarlson 

Can also hammer a Torx bit into the cap's wallowed-out hex. Torx will have a little more bite.

And I guess I'd use heat. Not a lot of heat! Just enough to get it to the boiling point of water, or so. You won't damage anything this way. Just play a small torch over it until water dropped on it boils off, but not aggressively sizzles.

Try also: citric acid. You can get it at grocery stores for canning. Lay the bike on its side and drip it round the ring where the threads are. This should limit the exposure to a small portion of the crank.

If you have to destroy the cap, you can drill small holes near the edge and use a punch to try and hammer it round in circles. It may come loose from the shock and rotation. Best to use lots of lubrication when doing this.

Hudson308 

This is a timely resurrection, as I'm currently trying to coax one of the caps from the TA Specialties crank on a '71 Sports Tourer. Before reading this thread, I've tried soaking with PB Blaster, heating the area of the crank itself around the edge of the cap, slicing a "cross" in the cap for a large phillips driver bit, etc. So far I can get it to budge about 30 degrees of rotation, then nothing. I've been soaking and heating and trying to work it back and forth to break things loose, but it's not turning any easier. I've finally given up for now. My guess is that a small section of the crank threads have stripped, and will only move a bit before wedging tight.

nlerner

I’ve been battling this dust cap on a steel Nervar crank for at least a couple of years now:




The alloy cap in the steel crank spelled trouble. You can see that I’ve managed to chisel out most of the top, but the threaded part is still there and taking up too much space to get that crank bolt off. It’s really just an occasional project as I don’t have a matching NDS arm. But I do think these cotter-less steel cranks are kind of cool.

scarlson 

You can probably fill the recess with sodium hydroxide (lye or caustic soda). Mix a spoonful with a cup of water, wear gloves! And carefully pour it in there. It'll preferentially dissolve the alloy cap over the steel everything-else.