Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: exvalvesetdabbler on April 16, 2025, 12:26:34 PM
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I am in the process of restoring a couple of clocks and been documenting the process as I go in the hope that someone else finds it useful. Kind of open source bike restoration. I will keep this thread updated as things progress.
The first task was to peel off the crimped rings without marking them or ending up with a screwdriver embedded in the palm of my hand. After seeing what other folk had done a large hose clip was going to be included somewhere. After a few test fits, I wasn't happy with the mechanism of the worm drive digging in to the band and marking it, and plastic sleeve inside just left some areas gripped less than others and it could easily slip off when applying pressure.
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To solve this, I machine up a collar out of some 10mm sheet plastic and made cutouts to accommodate the hose clamp mechanism and split the collar to allow it to tighten evenly over the band. It is also stepped to stop the clock being pushed through.
Also needed some way to keep the clock centered in the jig to avoid scuffing the new paintwork during re-assembly. That's the 3 screws and bushes.
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Next was the pry tool. I had to sacrifice my 'paint stirrer' screwdriver by re grinding the tip so the flat blade was angled and rounded on the back side to roll against the clock base.
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Regards
Dave
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Ring expanded and open.
I did about 4 laps to get to this point, just lifting up the crimp a little on each pass.
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Its important at this stage that the ring is sufficiently open to allow the base to lift out. You could pry it out at this point , but to avoid damage to the restored base and cover its easer at this point to get the ring open to allow the base to lift out cleanly.
The next step is to clean up the base ready for plating using electrolysis in washing soda solution. I used about 2 egg cups of soda in the container size below and a current of about 250 mA. You can use steel or aluminum as the anode (+ve) with the negative connection to the base.
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And after about 12-16 hours this is what you end up with. This was the worst one that was heavily crusted with rust and some pitting is visible. The advantage of this method is that the metal and zinc plate is untouched so they can be left sitting around for a while once they have been cleaned up.
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Regards
Dave.
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Nice work on the clock there Dave. I had a go on my 550K3 clocks but although it was just a cosmetic job I decided it was a job for a clock restorer so the internals could be checked as well.
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Weather wasn't up to much midweek so I got on with a bit of polishing indoors.
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First I took out any noticeable scratches with some part worn 400 grit wet'n' dry and then followed that up with 1200 grit and then on to 2500 grit. Then I took the polishing machine outside and gave them a final buff up. There are a few pits left where stones have hit but once fitted to the bike they'll be hard to spot. Polishing machine is nothing fancy, just the main motor from an old twin tub washing machine with the shaft threaded half inch and the mop held on with big washers and nuts.
Regards
Dave
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No stainless JIS screws in the junk box - no problem.
I mastered this method when rebuilding carbs a long time ago when stainless JIS screws were hard if not possible to come by.
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The holder consists of a piece of scrap brass that is threaded for the screw to be machined. The shoulder on the piece is the guide for the diameter. To shorten the screw, it is screwed in from the other end. The protruding piece of thread can be cut back and left chamfered and tidy. The screw in aluminum piece stops the screw backing off during machining. I find this last bit easier than running the headstock in reverse and having to keep moving the tool post.
If these were going to be visible after assembly I would radius the head a little more and give them a light polish as well.
Regards
Dave.
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To overhaul the mechanism there was a few jobs to do, I should add at this point that these gages were working ok, they had been run on my lathe using a spare tacho cable and having a listen to the main bush. Calibration was checked by comparing the lathe speed (input shaft speed) to expected readings. For Honda speedo's 2240 rpm =60 mph , for Honda tacho's its a 7:1 ratio so knowing the input shaft speed and doing the maths the calibration can be checked. It will be checked again before final assembly.
Clean up all old grease
re lube the main bush
clean up oil between the trip counter dials
re grease the cogs and worms
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If needed the clock faces can be removed and the well published two spoons trick worked well here. First cut up some 0.5 cm squares of electrical tape and put two squares on each of the painted screws holding on the face. The needle should easily pop off but take care to have the edge of the spoons right up against the shaft so that you're not bending it. Have the frame gripped in a vice and push down equally with both spoons. Watch where the needle ends up or just lay down a 3 inch square of cling film over to catch it. When removing the screws that hold the face on, use a good quality #1 phillips screwdriver and press down hard. The screws are glued from the back but should come out easily.
Remove old grease from the cogs and worm drives circled in yellow. I did this with a small brush soaked in white spirit to pick up the grease and wiping it off onto some paper towel. Turn the input shaft to gain access to all parts of the main worm drive. Wipe up any migrated oil or grease from the frame using a similar method. I find those cotton wool pads that folk use for make up removal are handy for cleaning up.
To re-lubricate the bush , I created a puddle of oil in the area marked in yellow and left it upright for a day, just spinning the shaft a few times as I happen to be passing by. Just pour out excess oil and mop up any excess with paper towel.
Fresh grease can be applied to the gears and worms, just a bit on a small flat blade scredriver wiped onto each gear should suffice. I used Apezion 101 but a white grease should do as well.
The two screws marked in blue and the plate can be removed for better access. Just make sure you put a dob of purple Loctite on them during re-assembly.
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Clean up oil between the trip counter dials in the next post.
Finding someone local to re-plate the bases is taking up too much time. Most seem to have a 4 week back log or don't want to go anywhere near vehicle restoration parts or have quite high minimum charges. Was quoted £50 + postage + VAT by one firm to do 4 bases, not sure if that's reasonable or the going rate now. Have done some myself in the past but hardly seems worth the hassle for a hand full of parts. The platers near me that I used to use for yellow zinc on carb parts ( Bag of bits, knock on the back door , cash in hand...) closed many years ago.
Regards
Dave.
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Damper oil on the bridge and sitting on the bell.
I needed to see if I could gain access to the damper pot to top this one up before I went to the trouble of cleaning off the spillage and ordering some silicone oil. It seemed reasonable to remove the top bush which also protrudes into the damper pot as the fixed element. For reassembly I made a note of the height of the bush from the face so it could go back in the same position. No idea how critical that is though. Unscrewing the 5mm brass locking nut allowed the bush to be unscrewed from the top bridge. Be careful, the needle post is flapping around within the confine of the M4 thread now.
I needed a tool to set the position of the bush and hold it there while the nut was tightened during reassembly so I got a bit distracted making one.
Damper fixed bush
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View down into the damper pot. Should be able to get some oil down there somehow!
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tool needed for reassembly.
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This is my 'practice piece' from a clock that someone drilled a hole in the side of the case and then mangled the number dials with a pointed object so no great loss if it didn't work out. I do however have a spare tacho with very little damping and damper oil all over the back of the face that will need attention.
Just waiting for the oil to arrive.
Regards
Dave.
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That's a good write up Dave, an impressive bit of work.
I once replaced a quartz battery in a wrist watch managing to have the hands fall off I was that cack handed.😁
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That's a good write up Dave, an impressive bit of work.
I once replaced a quartz battery in a wrist watch managing to have the hands fall off I was that cack handed.😁
So far I have spent an hour looking for a gage needle that went flying off across the garage behind a set of shelves and today with help from the wife spent ~40 minutes looking for a 3mm brass shim that escaped and made a run for freedom across the floor. Did some paint spraying a couple of weeks ago and left the piece dangling off the washing line too long, got too warm and the solvent flashed off before the paint flowed and then had a load of orange peel to sand back. If it's too easy everyone would be doing it. :)
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Painting the 'top bit' black.
Made a start on painting a while back, made some orange peel, and started again.
Searching for some way to hold things without wiring. Turns out that the bottom of a 1 liter fizzy water bottle is just right. Drill a hole in the bottom and screw in a stick and use that to hang it up and to rest on while the paint goes off.
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I started off with black epoxy primer topped off with Simoniz Tough black satin. The original plan was to rough them up and go straight in with the Tough Black since it claims not to need a primer. That plan was scuppered when zinc plate was found underneath the OEM finish. Zinc and Alkyd resin paints don't play nice together , hence the epoxy primer as a barrier coat.
Regards
Dave
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Cleaning up the trip meter dials.
Both old gages that I have opened up so far have had damper oil between the trip meter dials, making it tight to zero and unsightly oil stains on the dials. My first attempt was to push paper strips between the dials to soak it up. So far so good, then it reappears a few days later. So there's no other option to clean them up properly. The reason the oil ends up on the trip meter is probably due to the angle that the gages sit when on the bike and it seems to have run across the bridge straight on to the trip meter. Why it ends up on the bridge in the first place is probably incorrect storage. Fortunately the odometer is clean because I didn't want to be removing that.
The trip meter is easily removed by pulling the c clip and the two 'brass strip' circlips. Remove the drive gear and then the small circlip seen on the right hand side. All of the dials, spacers and ratchet plates will then slide off the shaft.
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Damper oil contamination.
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To clean up these components, I dropped them in a pot of white spirit, EXCEPT for the dials, these were cleaned with a stiff paint brush and a strong solution of washing up liquid.
Components ready for reassembly.
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Assembly is the reverse of disassembly. Take plenty of pictures as there are slight variations. Older variants have metal separators and a nylon bush stacked with each one. In this example the separators were plastic and had no nylon bushes in between - or someone at Nippon made these on a Monday or Friday.
Also be careful not to loose anything, I spent ages looking on the floor for a brass shim that goes between the white dial and the circlip. Running a magnet over the floor and under cupboards was no help!
Regard
Dave
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Needle tips.
Nipped in the model makers shop today looking for some luminous red/orange paint and came back with a pot of Revell SM 332 luminous red. The photo doesn't represent it well, it is more vivid orange than red and not a bad match and really jumps out at you and also matches with the color on the lid. The old paint rubbed off easily with some 1200 grit wet'n'dry. So far it looks like 1 coat will be enough.
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It's going to go a bit quiet on here for a while until I have sorted out getting the bases re-plated and finishing off painting the top bits. Damper oil is on a slow boat from China so there will be more on that task once it arrives.
I would welcome any suggestions or recommendations for getting plating done by post as there is nothing within reasonable distance to me.
Regards Dave
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I have been busy plating and painting and of course found a few other bits in the to-do box.
I searched around for a few prices to get these done commercially and the price ranged from 50-100 quid + postage and VAT for 4 bases. On top of the risk of them getting lost I was facing a minimum 4 week turnaround. The plating firm that I used to use, and was in walking distance, only does anodizing now. Next nearest was a 90 mile round trip and they had a lot of poor feedback in regard of stuff not being done after weeks or lost. I was trying to avoid setting up to do this myself just for a few instrument bases but here we are. The risk of them getting lost was too great
I have put a heavy coat on these so hopefully they will last another 50 years or so. I am tempted to blow a bit of epoxy primer over them for good measure as well.
I keep finding a few other bits as well...........
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Evidence of previous pitting remains
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PS Received my new clock faces and trip reset boots from Marcel last week and they look very good and even managed to get the correct MPH/KPH faces to match the originals
Regards Dave
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Absolutely cracking work there Dave on the gauges. Not a job I would tackle myself but if you have the time to spend looking for that small parts that decide to make a bid for freedom why not!😂
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Got around to blowing a bit of epoxy primer over the recently galvanized bases. Gave them a brief dip in dilute acid to remove any white rust, rinsed them off and dried with a hot air gun and then straight on with the primer.
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Regards
Dave.
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Not so smooth bush.
Starting to get things together for reassembly as soon as the epoxy has had time to properly cure.
I noticed that the tacho still felt a bit lumpy when spun by hand so I flushed out the bush with white spirit. Poured it in at the top and sucked it out at the bottom. The first two flushes came out quite black then brown. Did 6 flushes in total and gave it a good spin each time. Then blew out residual white spirit using an air line and then put in fresh light oil using the same flushing technique. It feels much better already.
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Regards
Dave
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Spot the difference.....
Speedo base - all 3 holes line up
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Tacho Base - mounting screw holes offset from main shaft
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I was hoping to get away with using a spare speedo base for the tacho because it was in much better condition.
Caused a bit of head scratching when the screw holes wouldn't line up >:(
Anyhow, not making much progress, thick zinc plate + paint = crimp band not going on easily.
Out with the sandpaper tomorrow
Regards Dave
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A bit more progress today. I had to scape some excess paint and sand down the plating a bit on the mating surfaces of the base. This is my first attempt and practice piece using salvaged parts from one crash damaged tacho and another with good cases and seized bush(broken glass, had standing water in at some time)
Crip ring back on the best I could. Not pretty.
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Looks better from the other side.
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Just a bit of remedial work to tidy up the scuffs on the paint and make sure water can't get in under the few wrinkles left in the crimp ring.
Lessons learned.
- clean everything and then clean again before re-assembly
- any debris inside will end up on the inside of the glass
- make sure the glass is the right way up, convex on the outside!
- too thick paint in the mating surfaces makes life difficult
- getting the ring started folding over is the hard bit
- got a big bruise on the palm of my hand now
Regards
Dave
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Question for the experts.
Why do some bases have two drain holes and some don't. The drain holes seem to let water in rather than drain it away.
Alternative versions have no drain holes and riveted light shields.
Might these be made for different climates. For the speedo's at least, the no drain hole version was a 130 mph scale version. The one with drain holes came from a UK dual mph/kph scale.
Or is one of them just an updated version.
Regards
Dave
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Different makes? One a Nippon Seiki and the other a Nippon Denso? The larger ones differ in size between the 2 manufacturers and parts are not interchangeable.
I think Peter made a machine to roll the crimp ring flat, it either rotates around the clock or the clock rotates, the wheel presses the ring flat as it passed under it.
Good job BTW.
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Different makes? One a Nippon Seiki and the other a Nippon Denso?
They are all Seiki and I have had the calipers out to be 100% sure. Internals look exactly the same. The only difference is the face plates, the fixing for the lamp shields and breather holes. Even though the UK one has 120 mph as the largest number and the other (US ?) has 130, when overlaid the actual values for a given needle deflection match up.
Things like this bug me until I can find a reasoned explanation!
The UK versions came of a S Reg F2 scrap bike I bought in the mid 80S all original but totally gnarly all round. Think I paid about 90 Quid for it from a dealer that was shutting up shop and retiring. Probably never had a wash in its life either. Cylinders were on max oversize and with a washer embedded in the crown and top ring area of a piston. Bores weren't much better. Fins on the barrels are top notch though. It was probably an ex dispatch bike and had 72K on the clock. I did recover a lot of useable aluminum bits that were free of gouges or butchery together with the yokes and a lot of bracketry, carbs/air box with all of the small bits that people usually toss when they fitted K&Ns or can't remember where they go.
Regards
Dave
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The 350/400 never got the larger type clocks, I was referring to the 500 and 550 mainly. For some reason they differ in size between Seiki and Denso, I thought that maybe there were 2 makes on the 400 and that would explain it but clearly not.
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Calibration check.
Time to check the calibration before closing up the cases.
I approached this from two directions,
1). Calculate from shaft speed Speed=60*shaft speed/2240
2). Time to clock up one mile Speed = 3600/time in seconds
Assumptions,
- lathe speed is what it says it is.
- gearing of the odometer is right.
Here's the results
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We are somewhere in the region of 2.2 to 5 mph high at 42.5 mph and 2.7 to 3.6 high at 25 mph.
I will probably strap a GPS on the bike once installed just to calibrate my brain.
Screwdriver bit in the chuck and the cable lashed to the tail stock.
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Foot note: Notice there is no difference in the colour from the main part of the face to the outer edge which would have been shielded from the sun by the inner case. These faces are from a bike that had recorded 72K but haven't seen the light of day since the mid 80S.
Regards
Dave
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Closing up the speedometer case.
First thing to do was to fit the ring back on the upper part of the case before fitting the trip reset boot. The boot from cb750faces have a mold line which needs to line up parallel with the case. I just put a bit of flowable oxime based silicone on the inside to keep it in position. Once dry I used a drill bit shank to smear some silicone grease inside the boot.
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I made a tool to get the ring starting to fold over and then used a screwdriver to press the crimp down some more each time going between each fold and folding it over further. Once at the screwdriver stage I found it easier to roll the screwdriver over the crimp while pressing down hard. Probably went around 5-6 times.
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First time around with the screwdriver, if my pension doesn't stretch out enough, maybe I could get a job crimping Cornish pasties.!
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Finished item
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Well that's about it for this project. I set the mileage on this replacement about 100 ml more than the old one on the bike was reading and once they match up I'll swap them over. The old speedo on the bike reads 9 mph high at 40 and has cut bands which is something I can work through without having to chuck it back together in a hurry to get the bike on the road.
Even though I know what the calibration of the old speedo is my brain still won't let me go through a 40 speed camera at 49 and my son who has a modern bike keeps asking why I slow right down for the cameras. I have checked it against a hand held GPS on a straight road and keeping pace with his modern bike, my brain still won't let me.
fear not , those specs of dust are on the outside after wiping off oily finger prints with a tissue and white spirit.
All the best
Dave
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Very nice job on these clocks, they are looking great and ready to put into use.
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Just when you thought it was all done,
Couldn't find the thick washers that go under the cap nuts that hold the clocks down, thought I had made some long ago but no luck, maybe they got used else where. I couldn't find anything in stainless off the shelf. 19mm od and 2.2mm thick so made some from a bit of scrap 316 stainless bar.
Drilled and hacksawed them until they were more round than square and then turned them down in the lathe using a crusty OEM washer as a guide.
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Just rubbed them over varying grades of sandpaper on a flat surface, 80 grit emery cloth, 240 grit wet'n' dry then down to 400 and 2500 grit using oil. I'll give these a polish on the buffing wheel before fitting.
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That was my Saturday evening accounted for.
Regards
Dave
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I still haven't found any M6 and M8 JIS B 1183 type 3 dome nuts in stainless has any one else come across them. The ones usually available to DIN 1587 are a bit longer and for the picky anoraks out there they won't look right.
Thanks
Dave
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Any M6 stainless domed nut should do.
I don't think there's any such thing as a JIS nut, screw yes.
I don't remember anything special about the 6mm domed nuts on the clocks myself.
I used 6 x 18mm stainless washers on my clocks IIRC. Standard thickness.
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You can find washers in stainless but they are 17mm as opposed 19mm original and they are called spacer washers so the don't quite cover the grommet. It is essential that the correct spacer tube and correct thick washer is used to prevent compressing the cushion too much. The gauges should be flexible in their mounting plates and if compressed too much it defeats the object of cushion which is to insulate the gauges from vibration.
As for the securing nuts, they are as you found difficult find and I found some in B&Q but the were zinc plated. I re-plated them in bright zinc and that did improve their appearance.
Going back on the thread being quoted £60 to re-plate a couple of bases is way over the top. I was getting them done for a fiver each, fair to say however I had prepared them so they could go straight in the tank. The drawback was the trip there and back to get them done so now I re-plate them. Those done yesterday are shown in the image.
As for band re-fitting a tool incorporating a skate board bearing in a drill press can make a quite tidy job on the underside using the support you have for the gauge. The underside isn't too much of an issue as it can't be seen.
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Any M6 stainless domed nut should do.
I don't think there's any such thing as a JIS nut, screw yes.
I don't remember anything special about the 6mm domed nuts on the clocks myself.
I used 6 x 18mm stainless washers on my clocks IIRC. Standard thickness.
There are 3 flavours of JIS dome nuts, it's the type 3 that we are interested in.
Type 1 threads do not extend internally past the nut portion
Type 2 undercut in the dome to allow the male thread to penetrate further
Type 3 is just a nut with a very thin dome friction welded on , allowing greater penetration of excess thread.
If you look at the M10 nut that hold the suspension on, it's a welded on cap.
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Left to right original JIS B-1183 OEM dome nut, copy made by custom fasteners in the 80s and DIN 1587 cap nut. note the welded on cap on the original
Regards
Dave
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Thanks for the info Kent400,
I thought about such a tool but don't have a drill press or sufficient swing over the bed of the lathe. All I had was a bearing of about 20 mm OD and that's a far as I got. I'm just not strong enough to press hard enough by hand. A flimsy half hearted setup would probably have ended up with scuffed paint. There's a video on U tube somewhere of a guy in the states doing this, made my toes curl up seeing all the rattling of the clock while he was doing it. He was spinning the clock and had the bearing on a bar attached to the drill table and levering it against the ring.
The collars, I just copied the originals in stainless.
Regarding JIS dome nuts , you can get chrome ones here https://jis-fasteners.com/products/m6-dome-nut-low-top-chrome-plated-10mm-spanner-size-322n0600. The OEM nuts were chrome. Just that most of the nuts and bolts on my bike are stainless and trying to keep it that way if I can. I'll just live with the European dome nuts for now, sure something will turn up one day. Only option at present is a 500Kg minimum order and that's a lot of clocks!
Regards
Dave
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You have seen the good, now comes the bad and ugly.
This one was refurbed in a hurry circa 1990 after having spiders inside it and loads of stone chips on the paint, up until now it has never been off the bike since then. Hoping there is no stray damper oil as well since they have always been the right way up.
Previously cleaned with scotch-brite and lacquored, despite the appearance it still has zinc plate all over and no crustiness. Most of the muck is disintegrated cushion stuck on it.
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Cut band held together with small strap and tiny nuts and screws with a bit of epoxy to stop them coming undone
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Red zone bleached and peeling off
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Small chip and dent left by large stone, same stone bounced off my face as well, hit the tank and took a bit of paint off there as well. Two for the price of one!
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Not sure what to do with this yet, I had thought about adding a miniature volt meter inside this one and this face is probably an ideal candidate as it isn't re useable as as. I do have new faces for these if I need them, though the background color is a bit off with them.
Regards
Dave.