Topic: PROBLEM SOLVED!!!!! How to remove the charging rotor (CB350 Twin)

[Raul CB750K1]

I'm trying to remove the charging rotor of my CB350 twin but have been unable until now. If I'm not wrong, the crankshaft has a threaded hole only for the retaining screw. Once you remove the retaining screw the rotor should just slip out. As it gets really stuck, the orifice is threaded. That way, using the Honda tool (a big bolt), screwing it in will exert force outwards when the tool finds the crankshaft.

Instead of that tool I'm using a three-clamp extractor tool. The point doesn't fit inside the threaded crankshaft hole, but just in case I've inserted a slightly smaller bolt there, so the pressure is exerted on the crankshaft end and not on the threads. But for the life of me the rotor will not come out. Using my "common sense torque wrench", I know it has been enough so I don't want to twist it more. My question is. It is time to use the "heat wrench"? It is the only solution I've come to no, unless you tell me I shouldn't use the three-clamp extractor.


Raul

[bryanj]

Raul DONT use a three legged puller it usually wrecks the outside of the rotor Try thr rear wheel axle some times they are the same thread as the thread in the rotor and it will push the rotor off the taper shaft

[oldbiker]

Hi Raul, I made a simple slide hammer to remove the rotor on my bike. It fetched the rotor off with two good slides. The sliding lump weighed about 1 to 1 1/2 lbs.

[Raul CB750K1]

Bryan, that's a great piece of advice!!! I have already removed the rear wheel, so I'll check it out. I have a concern about it though. How hard is the rotor internal thread? Will the axle ruin the threads if the rotor is too tight? I once stripped a bycicle cranckshaft because of that, and have become very wary of that.


John, what's a "slide hammer"? Is one of those wedge-shaped forks that you use with a hammer to remove steering junctions and the like?


Raul

[Jonesy]

Raul, The fork-like thing you describe is referred to as a "pickle fork" by many mechanics. It it wedged between two parts (usually a steering ball joint and steering knuckle on a car). A slide hammer (also called an impulse hammer) is a long threaded rod (usually about 1.5-2ft long) with different threaded tips that screw into the part you're trying to remove. On the threaded rod is a sliding heavy spool-shaped weight. After the tool is threaded into the rotor, you forcibly slide the weight away from the rotor until it strikes the end of the rod. This imparts a brief but very strong pulling force on the rotor.

[Raul CB750K1]

I see... something like an impact driver. No way to find those here. I'm having trouble to find a simple valve spring compressor... Auto parts shops here are specialized in high-tech tools like car detergents, air fresheners or carpets. I wish I live in the US, where you could find specialized tools in the Sears tools department while my wife do the shopping in JC Pennys...

I think I will try Bryan's tip. Will post pictures.


Raul

BTW, with the three-prong extractor I have, I noticed that it was so small that it was damaging the rotor side. Thus I bought a bigger one. It doesn't touch the rotor side, but still it's too tight.

[Bodi]

The rotor threads are plenty hard, usually you strip the threads on the axle. So don't reef on an axle, especially if the poited axle end only allows a few threads to engage. Try to find a hard metric bolt to fit; it isn't any oddball thread, just a fine thread metric size. Import car dealers should have a selection.

[Raul CB750K1]

So you don't generally use the "heat wrench"? That should loosen up things a lot.

[Bodi]

Heating a permanent magnet rotor (I'm pretty sure the 350 uses that) is a bad idea. At some unknown temperature (depending on the magnet type, pure iron is about 1400F but alloys are often much lower) all magnetic material loses its residual ("permanent") magnetism. Then you would still have a fine flywheel but not an alternator any more.
Also, magnetism is erased by hard shocks. Not completely, but the residual magnetism is reduced. So whacking the rotor with a hammer or dropping it is not recommended.

[dusterdude]

daggone bodi,you`re full of good news today. 

[Raul CB750K1]

EUREKA!!!!!! Rotor removed. To see how please continue reading....


Bodi, thanks for the advice. Actually, my concern was founded on the fact that the rotor is made by different pieces of metal with different polarities, so I thought that maybe the heat would make it crack at the seams.


Anyway, I have to publicly express my gratitude to everybody, specially Bryan. He's an asset to this forum. I tried the wheel axle trick and it worked like a charm!!! The only problem was to get a hold of the engine so it didn't turn along with the rotor, but one I got it attached to the table it was pretty simple.

I have attached some pictures. First one is the three-leg extractor attached -note to Raul: next time ask the forum before spending 20 euros in a tool you probably won't use anymore-

Second one is the wheel axle attached. Third one, the rotor removed. The axle simply unscrew by hand.


The fourth one is a proof of the horrors I'm discovering with every dissassembly I do on this engine. The starter clutch screws were loose, so they have worn out part of the rotor and part of the clutch, though I think they all -even the screws- are usable. What's the way to install them, loctite or a whack on the head? One of the plunger's springs is broken. By the way, I noticed that the starter chain seemed to be loose. Is it suppoused to be that way or do I have to replace it? There is no tensioner anywhere.


Raul

[dusterdude]

raul,a whack on your head or the screw head?

[Raul CB750K1]

The whack in my head is what my wife gave me when I returned home and touched everything with my greasy fingers!!!!

I mean using a chisel to give a whack on the screw head and the plate where it attaches to. Seems like if sometime before somebody did it, I don't know wether in the factory or the same guy that rebuilt the engine and put two tubes of gasket sealer did it as he ran out of loctite....


Raul

[Terry in Australia]

Well done Raul, obviously your 350 rotor wasn't anywhere near as stuck as my f*cking F2 rotor, even the factory tool that Mike Rieck sent me wouldn't budge it, and I ended up destroying the thread in the rotor, and on the tool!

In hindsight, my rotor was probably rusted onto the taper, when I bought the bike (on Ebay) and brought it home, I dumped the oil straight away, and it was a milky cream color, which of course means that there was a fair percentage of water in the oil, and had been for some time.............

Finally I hired a big puller like the one in your pic, and heated the knackered rotor/crank taper while slowly tightening the puller, and "BANG"! It came off and fell between my splayed legs, almost crushing my 3 gonads under it's super-heated weight! Luckily I had a spare rotor and rotor bolt, so my alternator functions perfectly, but what a bastard of a job! Incidentally, the 3 leg puller did no damage to the old rotor, the only damage was caused by the "official" Honda Tool! Cheers, Terry.

[Jonesy]

I think Raul had an advantage over you in this case... (what was that saying about the "power of 3"..)

[Raul CB750K1]

Yep, we both are "men of three". I had three legs pulling the rotor, but Terry had three balls to crank the wrench!!!! That would explain the scratches on my ball when you returned it!!!

I haven't opened the bottom end yet, but I'm expecting the worst. Learn from me: don't trust that a running engine means an engine in good shape.

When I dumped the oil I wal a lot of metal shavings. I started to preparte to replace plain bearings or even camshaft or crankshaft. After removing the head, I started to understand what was the cause: the cam chain tension was not adjusted for a while. Thus it has been hitting the cylinder tunnel walls, shaving off them. Not to the point to render it useless, but a clear indication of poor maintenance. I also found a small piece of metal that seems like a small tooth. Doesn't seem to be a tooth from a gear, and the rest of smaller chainwheels are complete, so I don't know what will I find. I assume that, as long as the bottom end is almost covered in oil, nothing so serious should have happened there.


Raul

[Bodi]

For the sprag clutch, you should try and get a new spring (and cap if it's worn) and check the diameter of the rollers and replace if worn. 3 springs and caps would be a pretty excellent investment if they look worn.
The screws need to be quite tight. Clean the 2 faces and the screws and the countersunk holes. Use an impact driver, but keep the impacts to a minimum (that magnet thing again). Then use a centre punch or chisel to stake the screw heads in place as you suggested. It came staked from Honda, either someone removed the housing for some reason or it shook loose. If one spring or roller jams the off centre force really likes to loosen or even crack the housing.
The chain is normally what seems to be quite loose; it only does anything when trying an electric start, if it doesn't skip then don't worry about it.

[Raul CB750K1]

Bodi, thanks for the advice.

BTW, are you still in Nashville?

Raul