Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: McCabe-Thiele (Ted) on July 19, 2021, 03:56:12 PM
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This afternoon I bolted the crankcase halves together, I now have the primary drive shaft in place.
I then noticed that if I pull on the gear shaft shown in the picture below - where the clutch fits it moves out a bit is this normal - will the play be taken up when I assemble the clutch or is there something wrong with the gear shaft before I fitted it?
As much as I do not want to have to take the crankcase halves apart again it just feels suspicious.
.(https://live.staticflickr.com/65535/51321692956_d500e0e20a_b.jpg) (https://flic.kr/p/2mc86i7)This shaft here where the clutch fits question (https://flic.kr/p/2mc86i7) by Macabe Thiele (https://www.flickr.com/photos/187487200@N03/), on Flickr
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Not sure how it can move from side to side Ted 🤔 (if I'm remembering correctly.). The inside of the bearing is attached to the shaft, so there should be no movement there and the outside of the bearing should be clamped between the top and bottom cases. Where exactly is the movement?
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It's what you would normally call end float - grip the shaft it will pull out a little - if its out it will push back in the same amount if you get my drift. Difficult to measure I'll have a go at trying to get a figure. The bearing is solid as it's secured by the half circlips thingy. I've measured it with my caliper end part it's around 0.75mm.
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It's what you would normally call end float - grip the shaft it will pull out a little - if its out it will push back in the same amount if you get my drift. Difficult to measure I'll have a go at trying to get a figure. The bearing is solid as it's secured by the half circlips thingy. I've measured it with my caliper end part it's around 0.75mm.
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I've not as much local knowledge on the 400, but conceptually you'd not generally have a gearbox shaft "pinched" across the geabox casing to nil tolerance. Ordinarily it'll need end float and or expansion room to avoid axial loading of the bearings at maximum heat cycle.
This one looks like it's pinched by the clutch assembly to sit tight on that main bearing to give alignment to the primary drive as priority and leave the tolerance inside the box between the visible bearing and it's opposite number on the same shaft.
The clutch is also subjecting that shaft to thrust load when clutch is operated by the lever, which would make it intolerable if it moved.
The bearing you can see is equivalent to the thrust bearing on a car crankshaft and should have virtually nil play with clutch assembly tightened.
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Thanks K2-K6 I'm following your logic that there would be some clearance for the reasons you have given - I'm a little paranoid I guess. I have a partial memory that when I replaced the clutch the shaft had some end movement already. Ted
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I'd just stop pulling things by hand Ted, you'll go blind.
lol Oj good one mate tha't really made me chuckle,
tbh Oddjob I've been well stressed about fitting the crank case halves together so I'm probably seeing things that aren't there - it's been a real groundhog day but now I am where I was on the 1st June but there is no sticking conrod - that's progress in my book.
I was going to do the crankcase bolting up yesterday but like many peaking with my hay fever has gone on to irritate my Angina / breathlessness in the mornings so I just took an extra 20 mg Isosorbide mononitrate tablet today to help keep me calm!
My more rational side is saying what's the worse that can happen if there is a bit of extra end float in the dam shaft - it ain't life changing that's for sure. It probably crunched gears before I bought it - onward & upward.
As an added bonus I'm getting much better at applying a thin layer of Hondabond in the process - it made all the difference putting it on my rubber gloved finger then smearing onto the upper casing amazing what a different technique can do.
Yes still talking about Hondabond Oddjob before you comment !!
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You could always get someone else to pull the shafts by hand if not feeling up to it ;D but that's probably onto a whole new forum :o
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I am now seriously considering taking the casing apart again before I continue any further.
I can see the end small gear on the left hand side of the shaft in question through the side gap near where the oil pump fits.
I can get my finger on this gear and feel it move from side to side along the shaft when I pull & push on the shaft from the other end.
Clearly this is movement on the shaft of the gear as if there has a shim missing.
I have not dismantled this shaft.
All it will cost me is time seperating the casing & getting off the Hondabond again it just seems too much movement.
Any further opinions / observations before I have another Groundhog Day ?
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Probably a silly question but you did put the half moon bearing retainers back in. I'm sure you did, just covering the obvious.
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Probably a silly question but you did put the half moon bearing retainers back in. I'm sure you did, just covering the obvious.
Yes on both bearings also where the stud locates on the smaller bearingd were in place correctly. Before I split the casing I'm going to look at a spare casing I have that has the main gear clusters to see how it compares but more importantly if everything is in its place how can I alter the movement. It will give me a better understanding of the gearbox & how it works. I do not know if Honda make different end gear spacers on production.
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Okay I have checked the gear clusters on my 'spare' casing - there is no movement discearnable on the shaft in question as per NJ's hint.
So it's Groundhog Day again (day 3) as soon as I can summon up the enthusiasm during this current heat wave!
I knew this project woud be challenging but come on Honda not this early in the rebuild please.........!
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I have this morning grasped the nettle and started Groundhog Day 3 before the mid-day sun saps my energy.
Good news is everything was seated & in place as it should have been - 98% of the Hondabond has been removed with thinners from the two crankcase surfaces with relative ease. Only downside is some runs on my painted cases - easily fixed.
The rear countershaft / output shaft is all as it shoud be with naff all lateral movement between the end bearings.
The mainshaft however definetely has quite a lot of lateral movement between the end bearings most noticeable between the small end gear (second gear) at the needle roller end. The spacer is in place but clearly something is not right to me it's just a lot of travel. Unlike the output shaft I have not taken this unit apart.
When I find my feeler gauges I will measure it and post here again.
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Okay if I insert 40 tho" feeler gauges into the gap between the end spacer & second gear its then like I think it should be imho.
40 tho" is 1.016 mm that sounds far too much
Not sure where to start but I guess the two end bearings are places where wear is most likely. DS tell me the bearings are colour coded & difficult to find I hope the guy in parts was confused with mains bearings!
There is no obvious wear on the large mainshaft bearing inner race or contact wear where it sits against the fixed mainshaft gear. The needle roller unit at the other end looks normal the 20mm thrust washer that sits between the needle roller & second gear does not show excessive wear - you can tell which way round the washer was (is) as there is a rotary mark where it has been against the gear but the wear is very slight - certainly nowhere near enough to explain the lateral movement.
The only thing that I can see that would alter the end float as it's one shaft is the thrust washer at the small end unless the large main end bearing is made to different thickness to allow for crank case widths when they are machined?
Any advice welcome at this point.
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First thing that I have found out is that there is a slight ovalation of the slot where the locking pin sits in the roller bearing outer casing.
My thoughts are to firstly get a new pin if they are available together with the needle roler bearing plus replace the thrust washer anyway.
I have rotated the bearing to get a picture of the location hole - it does not show up the elongation that well tbh.
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If the pin hole is elongated, it may have been caused by the bearing spinning in the case as some stage in its life. Can you see any evidence of where the bearing may have spun?
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If the pin hole is elongated, it may have been caused by the bearing spinning in the case as some stage in its life. Can you see any evidence of where the bearing may have spun?
Tbh if the bearing had spun I would have expected the elongation to be radial rather than axial if those are the right adjectives. The crankcase looks odd due to shadowing but the slot for the bearing looks ok.
I have attached a photo if this helps.
(https://live.staticflickr.com/65535/51323162702_abd25218a0_b.jpg) (https://flic.kr/p/2mcfCcy)bearing location is elongated (https://flic.kr/p/2mcfCcy) by Macabe Thiele (https://www.flickr.com/photos/187487200@N03/), on Flickr
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Those definitely look like partial spin witness marks. But, I agree, the ovality would be fore to aft, not port to starboard.
Edit, but if there had been side to side play on the shaft, that would account for the slight ovality being port to starboard.
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I would have a look at mine Ted but I’m away. Make sure on the washer as it could easily have got misplaced. Hard to see that ovality giving 1 mm of float.
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Is the thrust washer behind the needle bearing Ted, there should be a 20mm washer between the bearing and the gear.
Yes, I assume you mean between second gear & the needle bearing.
The end float is more than the thickness of the thrust washer - if it was ever dished slightly it isn't now it's flat with some light rotation marks.
I've ordered a new needle bearing, thrust washer & lock pins.
The parts book shows 3 of those thrust washers are fitted somewhere in the gearbox so I've ordered all three anyway as they were cheap enough.
I can't see much point in stripping down the whole mainshaft as the endfloat is basically the gap between the fixed gear on one end of the mainshaft that fits up to the large bearing & the second gear at the needle roller end. Second gear sits next to a fixed circlip on wide splines so it can't really move anywhere except for the gap between it & the thrust washer.
As a last resort a second thrust washer might be a option ?
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Hi Ted,
I just spotted your post as I was about to post a query on the roller pins of the gearchange positive stopper. (Soon)
I have my crankcase halves assemmbled and have been measuring the 5 mainbearing borings for size.
Just been in my garage and checked this shaft for end float - mine is solid with no movement between the shaft and the inner bearing, but if I push in and pull out firmly it will move the outer bearing in the casing and shaft about 0.5mm, which appears to be the side movement in the half circlip and its groove.
Hope this helps. ;)
Regards
Dennis
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Hi Ted,
I just spotted your post as I was about to post a query on the roller pins of the gearchange positive stopper. (Soon)
I have my crankcase halves assemmbled and have been measuring the 5 mainbearing borings for size.
Just been in my garage and checked this shaft for end float - mine is solid with no movement between the shaft and the inner bearing, but if I push in and pull out firmly it will move the outer bearing in the casing and shaft about 0.5mm, which appears to be the side movement in the half circlip and its groove.
Hope this helps. ;)
Regards
Dennis
Thanks Dennis I haven't really started on the bearing with the half moon clip side of the equation. What I did notice was that when the crank case was bolted up there seemed to be an overhang of the bearing outside the casing that seemed more than I expected. It might be both bearings are not as planted as the design suggests. Perhaps constant gear changes on a revvy little 400 engineb takes its toll on the bearing fittings. Very useful info thanks. Ted
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Hi Ted,
This is the overhang on my bearing FWIW. ;D
Dennis
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That bearing is fitting far too proud for some reason, it should be flush 🤔 well, more flush than it appears to be in the photo.
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Hi Ted,
This is the overhang on my bearing FWIW. ;D
Dennis
Hi Dennis, My overhang is about the same or marginally more. Not sure if new half moon clips would change anything. My bearings were installed dry maybe a smear of Hondabond would help stop further lateral movement. I have a spare gear cluster set that came with a casing from a member. I'm planning to try them for comparison. If they're a tighter fit I will use them. There is no ovalation on the needle bearing locator hole.
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"It might be both bearings are not as planted as the design suggests. Perhaps constant gear changes on a revvy little 400 engineb takes its toll on the bearing fittings. Very useful info thanks. Ted"
Typically of bikes in general and certainly in these engines, there's essentially no real thrust load of any significance with all the gear teeth straight cut.
Clutch operation is the largest (which should be opposed by the clutch assembly clamping it's shaft on that principle bearing) but the rest of tolerancing is to facilitate accurate movement and controlling engagement of the dogs and their relationship to the shift drum along with it's forks. Insignificant load that would cause wear though in that direction.
Even the crankshaft has no effective thrust bearings as it's not subjected to that force.
In a car with helical cut gearbox and clutch pushing directly onto crankshaft end, then they need to be mitigated, but on these it's just positional accuracy without much force that could cause components to wear.
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"It might be both bearings are not as planted as the design suggests. Perhaps constant gear changes on a revvy little 400 engineb takes its toll on the bearing fittings. Very useful info thanks. Ted"
Typically of bikes in general and certainly in these engines, there's essentially no real thrust load of any significance with all the gear teeth straight cut.
Clutch operation is the largest (which should be opposed by the clutch assembly clamping it's shaft on that principle bearing) but the rest of tolerancing is to facilitate accurate movement and controlling engagement of the dogs and their relationship to the shift drum along with it's forks. Insignificant load that would cause wear though in that direction.
Even the crankshaft has no effective thrust bearings as it's not subjected to that force.
In a car with helical cut gearbox and clutch pushing directly onto crankshaft end, then they need to be mitigated, but on these it's just positional accuracy without much force that could cause components to wear.
Well made point about the gears being straight cut not helical I hadn't given that factor any thought.
One of the reasons I love this site so much is the knowledge of its contibuters being greater than the sum of the whole - its not just "corroborative detail intended to give engineering verisimilitude to an otherwise basic & unconvincing narrative" to misquote Poo-Bah of G&S fame.
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Are the half rings proper half rings? We have had numerous engines through here where someone has been in them in the past and they have used half of a piston ring as a substitute.
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Are the half rings proper half rings? We have had numerous engines through here where someone has been in them in the past and they have used half of a piston ring as a substitute.
Good question NJ- they look okay I've ordered a new pair for belt & braces - Ted
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I've just done some work on the two gearshafts - fitted two new end needle roller bearings plus the locating studs and half circlip washer that retain the big ball bearings.
Also replaced the thrust washers (3). Tbh it has not really made much difference to the end float on either shaft.
Most worthwhile part of splitting the case down again is replacing the primary drive shaft bearings.
I have a spare set of gears in a spare crankcase set that seemed pretty tight until I cleaned them up with some petrol etc and they are pretty much the same as regards end float / side movement so I'm putting it down to the nature of the bike at present.
BiL is going to take a look as he is an experienced rebuilder of Japanese & Italian bikes though not of Hondas oddly enough he likes his Yamahas.
Currently in PAUSE MODE on assembling the crankcase so will do some more frame work.
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I could put an extra standard thrust washer on each of the shafts on the same end as the existing ones - it would certainly make it much more rigid - might be Mr Honda designed the movement to be there - could end up with a hot gearbox that would stick in gear?
I have re-read all my manuals & they do not give any figures for end float or indeed mention it- it's at times like this I wish I knew what the gear shifts were like when it was ridden by a PO 12 years ago. The only mention about the gear clusters is to ensure the end bearings are properly located by the pin or half circle clips.
I'm currently doing bit's of frame building as I try to work it all out in my head & process any advice from folk here.