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Starter clutch rebuild

Richard Pitman

Veteran Member
Joined
Jun 1, 2020
Total Posts
2,526
Total likes
632
Location
Worcester, England
Any hints and tips ? The factory manual is somewhat vague.

I don't have a problem getting the rotor off, big bolt and big electric rattle gun pops that off easily. I think that the challenge will come when I try to remove the three countersunk screws. Battery powered impact driver may help with those, the bigger tool would just rip the heads off.

Once that is off, I seem to recall reading that it is easy to lose the springs, perhaps place the assembly in a high sided washing up bowl to catch any stray parts ?
 
The springs don't exert all that much pressure on the caps and rollers. Usually the rollers fall out when the rotor is pulled from the crankshaft while leaving the drive sprocket behind. You might find the top broken off one or more of the caps and the springs will be collapsed to an extent. In a pinch in the distant past when easy online ordering wasn't possible, I've stretched the springs a bit and (when all the caps were in usable condition) just put it back together with functional results in some cases. I've always replaced the springs, caps and rollers but the rollers seldom show any evidence of wear in my experience. The center surface of the sprocket where the rollers grip will sometimes show some wear and/or chatter marks which can cause slippage even with brand new replacement parts. The best assembly method after replacing the parts, of course, is to put the drive sprocket into the rotor before sliding the whole assembly onto the crankshaft. Yes, the 3 screws in the outer clutch housing can be very difficult to remove at times and it's best not to use too much force (hammering on a hand-held impact driver) to remove them because of the effect the impact can have on the rotor's magnetism.
 
If you have a battery or electric impact with JIS heads that’s worked for me in the past, though I’ve ended up drilling / EZ-Outing like half of them in the past.

Getting all of the caps/springs/rollers to stay where they’re supposed to while getting everything on can be a pain, but with a little finesse it’s a relatively simple job.


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I just did my 160 starter clutch and everything Tom said above is great advice. Hopefully, you don't need to remove the 3 screws, and can simply deal with the springs, caps and rollers. You need a good compressor to blow out any metal debris because of the magnetism.
 
I just did my 160 starter clutch and everything Tom said above is great advice. Hopefully, you don't need to remove the 3 screws, and can simply deal with the springs, caps and rollers. You need a good compressor to blow out any metal debris because of the magnetism.

The main reason to actually remove the outer housing from the rotor is to be sure the housing isn't cracked (example show by the red lines in the picture below), since it has a sheet metal cover over it and a crack can't be seen from the outside.

360starterclutch2.png
 
I've never had to remove the 3 screws .... not sure why anyone would. I believe in one Honda manual it says to use silicone grease on the parts which helps to hold them in place during assembly.
I use tweezers to put the spring in place then slide the cap on with same tweezers. Use a thin tool to hold the cap and spring compressed and slide in the roller. I use a thin dental pick. I have never spent more than 5 minutes putting all the parts in place .... ie 3 spings, caps and rollers.

Check the surface the rollers contact as it may be excessively worn. Some flats will be ok.

Just saw Tom's post ... I've never had any issues with cracks or the replacement parts not working.... living the dream I guess ... lol
 
Dream--> nightmare if the sheetmetal cover or housing is wonky. I'd grab another unit and move on. The 3 screws are staked too, which is a PITA.
 
Just saw Tom's post ... I've never had any issues with cracks or the replacement parts not working.... living the dream I guess ... lol

I haven't seen many, but there have been a couple though it isn't typical. The unseen expansion in size because of a crack in the housing completely negates the new parts when the housing is cracked.
 
It all came apart very easily, those 3 screws came straight out, using my Dewalt impact driver. The problem was obvious, one of the springs had stuck in its recess, allowing the roller to drop out. Still waiting for the replacement parts to arrive, not helped by 'industrial action' by postal workers. Belay that, parts dropped through the letter box literally as I was typing this !

mLKwo6V.jpg
 
I noticed that the rotor had all those cast tabs snapped off. This was sold to me as a CB/CL 175 part. Fortunately, I still have the original rotor that came fitted to the SL175 motor, without a starter clutch of course. SL175 rotor marked '307', other part marked '306'. Interesting to see the difference in the timing marks between the rotors.

307 is the correct part for the later 175 motors, I wonder what the 306 part comes from?

YoAxuy7.jpg


o7NWVMG.jpg
 
According to oldmanhonda.com, 306 is the CB175K3.

The tabs broken off the rotor as well as the threads on the screws being worn off above the hole depth are both caused by the screws coming loose over time and the starter usage continuing despite the slippage that must have been happening. The support pin hole is also worn illustrating the movement. It's a repairable situation but if it had gone on much longer it wouldn't be.
 
According to oldmanhonda.com, 306 is the CB175K3.

The tabs broken off the rotor as well as the threads on the screws being worn off above the hole depth are both caused by the screws coming loose over time and the starter usage continuing despite the slippage that must have been happening. The support pin hole is also worn illustrating the movement. It's a repairable situation but if it had gone on much longer it wouldn't be.


Interesting that a loose housing would break the tabs. I can only wonder where those tabs went.
 
Interesting that a loose housing would break the tabs. I can only wonder where those tabs went.

I've seen a ton of that over the years, the outer housing wiggles enough to rub the threads off the middle of the 3 screws and flexes enough to crack the tabs away from the rotor as well as wobble out the locating/reinforcement pin hole too. Tabs are in the bottom end somewhere of course, hopefully just glued to the gunk and not making their way around to more dangerous areas. And all of that began with someone hearing some slippage now and then but continuing to use it anyway, probably along with some help from a poorly tuned and/or maintained engine making it even harder to start.
 
Crikey, it's worth than I thought then. I hadn't noticed those damaged threads until you mentioned it and I looked at the photographs. I did notice the wear on the locating pin and wear to its locating hole in the old rotor, much tighter in the newer one.

Luckily those broken off tabs will be in another motor, probably in a breakers yard somewhere by now.

Before reading your insight, I had already reassembled the clutch with the new parts, and done those three screws up as tight as I could get them. I used a dab of grease on the rollers to keep them from falling out when I refitted the rotor, having left the sprocket in place on the crank end. Tight starter chain making sprocket removal difficult without removing starter motor.

Of course, on testing it slipped again because the grease was stopping the rollers wedging themselves properly. A squirt of maintenance spray took care of the grease, and it now works as expected. I suppose that at some point I ought to get three new screws and that locating pin, but at the moment this is just an exercise in trying to get this motor to actually start and run.
 
And in your case Richard, you won't be using this much and you're also now aware of the potential for future issues so it will never get to the point where it was when you disassembled it.
 
I've just ordered up some high tensile countersunk screws with allen heads, also some M6 knock pins, useful to have to hand next time that cover comes off.
 
I agree with all the conversation about the clutch, but what I ended up learning is that a weakish battery will also end up causing the terrible starter clutch slipping screech. And dirty contacts in an old solenoid can do this, too, and make you crazy as well. With cleaned contacts and a well maintained battery the clutch was much better.
 
Can I just say thanks to all who have contributed to this enlightening thread. The (175) FSM has virtually no information about the starter clutch, I have learned a great deal in the last couple of days. It now makes me wonder if I should inspect the same parts in one of my other 175 engines, which sometimes makes that screeching sound described above, despite a good battery and new (pattern) solenoid.
 
When my starter clutch died, the starter would spin pretty fast (whirring noise) but no turning the engine. A screeching sound may be the starter itself, or it's planetary gears. Maybe someone else can comment on screeching noises.
 
It's been my experience that the screeching noise can be the result of 2 different situations: slippage of the clutch during cranking (if the clutch slippage is minimal and has not advanced to the "can full of nuts and bolts" sound or beyond), or a screeching noise on slowdown after a period of cranking during which the clutch worked okay. IMO the latter is often caused by the clutch parts being a bit dry of oil after sitting for quite a while, and that screeching sound often goes away once the engine gets run under normal circumstances to get oil circulated around that area again. The sound made when the planetary gears aren't aligned correctly during the starter motor assembly is usually one of a heavy whining sound during the starter motor use and often causes the starter motor to turn much slower than it should.
 
The starter gear thing you mentioned was always a go - no go thing for me. If it was wrong the starter just couldn't turn at all. There was a lot of trial and error getting everything set up properly (be sure to test with jumpers before you go to the trouble of bolting it in place!). I learned that if I ever have to deal with the brushes again it really helps to keep the starter laying flat on the bench and do whatever you can to keep the drive end together. Once you know it's cleaned and greased there's no reason to let it come apart. I guess if you want to service the commutator it's easier with it all out, but putting it back together correctly was a very big PITA.
 
I had the thing with those planetary gears, when my inner inquisitive chimp decided to take the starter apart to have a look inside. I struggled for ages to get the end cover to sit nicely, concluded that I was missing a gasket / spacer, then suddenly the gears aligned and it went back together correctly. Weird, because on casual inspection it looks simple to place the gears correctly.
 
I've just fitted some new screws and locating dowel to my starter clutch. Here's some photos showing just how badly worn the original parts were. M6 dowel had worn its locating hole way oversize. By comparison, new dowel was an interference fit in the 'new' rotor.

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1atfekL.jpg


New allen headed screws, nice and tight !

37Sa5Uq.jpg
 
That’s to be expected.

I think you’ll be very happy with how snappy the starter feels with the new clutch fits.


- 1972 CL350
- 1985 VF700F
 
Saw this old thread when searching for information about a cracked outer on a CB350 starter clutch. It didn't sound like there were a ton of instances of cracked outers and I didn't see any images. So I found this one today and thought I'd throw it out there for your viewing pleasure. The three screws were loose and the locating pin was wobbly. I'm guessing that means I should search for a used clutch/rotor assembly? Does anyone have one they'd like to unload?
IMG_3376.JPG
 
That's exactly the cracked outer housing I've been talking about, not visible before disassembly because of the soft metal cover on the outside of it. Allows the diameter to expand and makes the clutch slip even worse if not stop working altogether.
 
Regarding the soft metal cover, in my case it just fell off when I pulled the rotor assembly apart. Is it supposed to be attached in some manner or is it just held loosely when the rotor and sprocket are assembled?
 
Regarding the soft metal cover, in my case it just fell off when I pulled the rotor assembly apart. Is it supposed to be attached in some manner or is it just held loosely when the rotor and sprocket are assembled?
It is crimped all around on it's lower edge opposite from where the screws are. Normally, not meant to be removed.
 
I found a replacement starter clutch to replace the cracked one I pulled from the bike last week. Upon further inspection of the old one, I found one of the rollers was seriously mushroomed on one end, and there was serious wear on the sprocket shaft surface. Take a look:
5F6E803F-2E36-47FE-952C-2BC63BA6EC96.jpeg
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Next step is rebuild of the starter. Any advice as to where to buy a rebuild kit?
 
I'd definitely buy the full kit, probably from 4 into 1. The springs you have are old and have been compressed for 50 years, the rollers are worn out and the little caps on the springs are too. Unless you find a freshly rebuilt clutch I'd still buy the kit.
 
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