# Custom build of a crankshaft trueing stand



## malmac (Apr 3, 2020)

DAY ONE
We have a couple of 1960 vintage BMW motorcycles. I want a crankshaft trueing stand so that eventually I can press the old cranks apart and rebuild them. In the short term this stand when completed will permit me to check cranksahfts sources from elsewhere and confirm their alignment.

Day one was get the base machined off. I was quite happy with the result.

Mal


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## tq60 (Apr 3, 2020)

We did not use a press to straighten cranks.

In books there would be photos of that but not how we did it in the engine shop.

Hammer and chisel.

Turn in centers to locate high spot and the trick is to determine where the "bend " is, journal or main...

You place it low spot DOWN then place chisel in top corner and tap with hammer and roll chisel around the top of the arc.

Rakes a bit of practice and convincing brain that hammering down on something causes it to rise is difficult for brain to understand.

You are relieving stresses in crank and it moves.

Less chance of breaking things...

Sent from my SAMSUNG-SM-G930A using Tapatalk


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## DavidR8 (Apr 3, 2020)

I presume this is the process you're doing @malmac








						Overhaul of a 2-cylinder crankshaft - Salis Parts
					

The photos are a compilation of the work done on different crankshafts: R67/2, R60/2 and R69S.




					www.bmwclassicmotorcycles.com


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## mattthemuppet2 (Apr 3, 2020)

wow, that is not a trivial undertaking!


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## DavidR8 (Apr 3, 2020)

mattthemuppet2 said:


> wow, that is not a trivial undertaking!


I recall reading an article about rebuilding Carillo crankshafts with roller bearing rods. It basically said there's no way you're getting it apart without a whole lot of cursing.


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## malmac (Apr 3, 2020)

DavidR8 said:


> I presume this is the process you're doing @malmac
> 
> 
> 
> ...



David we have an R69s so that link is exactly what I plan to do, eventually. We have a 30 ton hydraulic press and as I gradually manufacture the jigs and press tools required I guess it will all come to pass. Timeline is open ended.

Thanks for posting the link I had not seen that before.

Mal


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## malmac (Apr 3, 2020)

tq60 said:


> We did not use a press to straighten cranks.
> 
> In books there would be photos of that but not how we did it in the engine shop.
> 
> ...



The R60/R69s cranks are actually pieced together cranks with roller bearing big ends.

However I have no doubt working with fine tolerances and runtouts is generally a character building experience.

I hope I can muscle up to the challenge.

Mal


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## malmac (Apr 4, 2020)

Some advice on setting up the next machining task would be appreciated.

I am going to cut 60 degree dovetails on the feet of my stand legs.
This will allow me a certain amount of adjustability.,
My problem is that the two feet need to be as close as dam it to being exactly the same width.
If they are not the same width then they will either be sloppy in the dovetail slides or one will be tight and the other sloppy.

I thought I might spot them together using my TIG with 4 small tacks.
That way I can do one end and then reposition them in the 3 way vice to machine the other ends without them getting out of position.
Then machine them up as one piece before taking the tacks off with a small bevel.

But maybe there are much better options that you know of that would achieve the goals in a better way.

Thanks in advance.


Mal


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## Liljoebrshooter (Apr 4, 2020)

Scrape them to fit.   Just like a dovetail on a machine.

Joe


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## francist (Apr 4, 2020)

Or slot them part way in from the ends so you could tap in or thread in small wedges to fine tune the fit?

-frank


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## malmac (Apr 4, 2020)

Liljoebrshooter said:


> Scrape them to fit.   Just like a dovetail on a machine.
> 
> Joe



Thank you for your suggestion.
It makes me realise I have two stages in the process.
Firstly to try and make them as near as possible to identical.
Secondly fitting them up so that they actually work.

Your suggestion will certianly come in handy as the second step needs to be sorted.

Mal


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## malmac (Apr 4, 2020)

francist said:


> Or slot them part way in from the ends so you could tap in or thread in small wedges to fine tune the fit?
> 
> -frank



Hi Frank.

I have attached a diagram of what I think you are suggesting. Is this what you mean or am I barking up the wrong tree?

Mal


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## francist (Apr 4, 2020)

No not quite but I could also see something like that working. What I was getting at was more like below, a slot through the foot at each end that would allow some sort of wedging action to take place and slightly spread the ends of the foot. A tap-in wedge, or in the case of my scribble here a conical wedge with threads that could be wound in or out depending.

This would not be anywhere near as nice a contact area as something like scraping, but I also wasn’t sure how much movement or sliding would really need to occur once you had a position established. It’s also possible I have completely misinterpreted your graphic of the setup, it would not be the first time!

-frank


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## extropic (Apr 4, 2020)

As I understand it, the function of the dovetail ways is to keep the V-blocks aligned while allowing the distance between V-blocks to be changed.
I'm thinking there is an easier way. Instead of using dovetails, think "box-ways". The bases of the V-blocks could straddle a rectangular base or they could guide in a slot in the base. Either of the box-way options only need one flat vertical plane and one flat horizontal plane (not equally spaced angled planes) on each part. Clamp the linear motion with lock screws behind a gib, bearing opposite the vertical guide plane.

I hope that's clear enough. If it makes no sense, let me know and I can generate a rough sketch.

Depending on the precision you're trying to achieve, I'm hoping you have access to heat treating and surface grinding.


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## malmac (Apr 4, 2020)

francist said:


> No not quite but I could also see something like that working. What I was getting at was more like below, a slot through the foot at each end that would allow some sort of wedging action to take place and slightly spread the ends of the foot. A tap-in wedge, or in the case of my scribble here a conical wedge with threads that could be wound in or out depending.
> 
> This would not be anywhere near as nice a contact area as something like scraping, but I also wasn’t sure how much movement or sliding would really need to occur once you had a position established. It’s also possible I have completely misinterpreted your graphic of the setup, it would not be the first time!
> 
> -frank



Frank, thank you for the wonderful sketch. It really does work better than 1,000 words.
In my case I dont believe that would work because my blocks are 24mm by 48mm and 124mm long.
However if the slot was set closer to one side then maybe it could be an option.

The thing I like about these deliberations is they really get the grey matter churning along.
Like, how much accuracy do we need.

The parts are not going to be moving rapidly or frequently. So wear and tear is going to be low.
The real issue is here is keeping the two legs in alignment.

Mal


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## malmac (Apr 4, 2020)

extropic said:


> As I understand it, the function of the dovetail ways is to keep the V-blocks aligned while allowing the distance between V-blocks to be changed.
> I'm thinking there is an easier way. Instead of using dovetails, think "box-ways". The bases of the V-blocks could straddle a rectangular base or they could guide in a slot in the base. Either of the box-way options only need one flat vertical plane and one flat horizontal plane (not equally spaced angled planes) on each part. Clamp the linear motion with lock screws behind a gib, bearing opposite the vertical guide plane.
> 
> I hope that's clear enough. If it makes no sense, let me know and I can generate a rough sketch.
> ...



Your suggestions re the box-way option needs to be considered.
Given the ffet will be moved and then locked down with a bolt, I thought the 60 degree angle with one side guide adjustable, would allow me to fine tune the precision based on the amount of drag I wanted when repositioning the feet.
The main problem being then the machining of the two feet to be as near as possible to being the same dimensions.


Thanks for your suggestion.


Mal


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## malmac (Apr 5, 2020)

Well here is the daily update, as I got a bit done today.

I tack welded the two feet together at a point that will get machined off when the feet get their 60 degree cuts. I then drilled two 4mm holes through from the side that don't get the 60 degree cuts.
Then I tack welded the end of two four mill rods that I used to keep the two feet aligned even 
	

		
			
		

		
	




	

		
			
		

		
	
when the end tacks get machined off.

I then managed to cut the first dovetail. If you look in the pic you can see the tack weld on the end of one of the 4mm rods.
So far so good.

Mal


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## malmac (Apr 17, 2020)

Well here is an update on progress with the trueing stand.

The legs are not attached at this stage but it is starting to take shape.

Mal


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## malmac (Apr 22, 2020)

I plan to have a handwheel on the right hand side / or maybe the left which will wind the legs together or apart.
Here are the taps I made to cut the brass nuts for inclusion in the feet of the stand.
Next step is to machine up the 12mm trazoidal threaded rod which the nut will engage with.

It is the first time I have used tool steel and attempted the harden and temper process..... well I can say I have a long way to go to get that process to a more controlled level.

Mal


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## malmac (Apr 22, 2020)

accidently p[osted the above comment twice. Couldnt work out how to totally delete the post.


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## malmac (Apr 24, 2020)

I am sure you all know that small job that jumps into the middle of a larger project and you see that there will be an element of cross over. Well this was a small project to make a new cross slide brass nut for a friends old lathe. It just so happens that I am going to use the same trapazoidal thread on our trueing stand...... so now I have the custom taps made and have made a new nut for his cross slide.

Now its time to get back to the main project.

Mal


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## francist (Apr 24, 2020)

I’m curious, how do you find the performance of the taps? They look great from here, but I’m just wondering if you’re pleased with how they’re cutting for you.

-frank


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## malmac (Apr 24, 2020)

Frank, it is the first time I have made taps for an acme/trapazoial thread profile. Some things have worked and some things only just work.
The 1 degree taper for these threads is the way to go in my opinion.
The taps are working on the brass but not fantastically, as in the cutting process is very slow, but the thread is fine when the cut is finished.
How could this be improved I ask myself?
Well I plan to reharden the taps to a higher hardness as when I tempered them, I think that too much hardness was lost. I think this is the biggest problem I have at present. The taps have a zero rake, neither positive or negative, so they would probably not be much good in their current form for cutting other than brass. I hope this answers your question.

Mal


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## francist (Apr 24, 2020)

It does, thanks. Like I said, they look great from here and kudos to you for endeavouring to make your own 

-frank


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## malmac (Apr 26, 2020)

Before I continued on with the trueing stand I heated the taps up to red hot and held them there for about 3 minutes. Then quenched them in water. Then I heated my shop oven up to 450F with the two taps on the shelf. After 30 minutes I took them out and let them air cool. I then just touched up the cutting faces on the diamond D bit grinder stone.
The taps cut like they had been bought in a shop. Admittedly I was only cutting a thread through 22mm of brass but that is what I set out to do and it worked perfectly.
The centre holes in the brass nuts are for oiling the interface between nut and shaft.
Next step is to machine up the threaded shaft with LH thread one end and RH thread the other. It will have a centre bearing and two end bearings. Well bushes anyway.
Once I get the shaft all operational I can finish off the legs which involves some careful TIG welding.

Mal


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## Laytonnz (Apr 27, 2020)

Project looks great! Wish I had that talent, this is my rough and ready trueing stand.. needed it asap to rebuild a 2 smoke crank it done the job but no where near as flash as that thing!

I just cut a wedge out of some acetyl and that was how I adjusted the crank webs.
	

	
	
		
		

		
			





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## malmac (Apr 27, 2020)

Laytonnz said:


> Project looks great! Wish I had that talent, this is my rough and ready trueing stand.. needed it asap to rebuild a 2 smoke crank it done the job but no where near as flash as that thing!
> 
> I just cut a wedge out of some acetyl and that was how I adjusted the crank webs.
> 
> ...


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## Laytonnz (Apr 27, 2020)

Nice, to be honest.. this was a first for me aswell. My race bike big end bearing was about shot and in need of replacing so I thought it cant be that hard? Well... it took me ages to get the crank trued up, it took a while for me to realise where to give it a wack.

I enjoy making tools also but lacking a milling machine makes things more challenging sometimes.

I will follow your progress with great interest, keep up the good work!

One thing I will mention is that my DTI was picking up on the ball bearings rotating, next time I would make some discs with bushings, but the V's you have will work perfectly well.

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## malmac (Apr 28, 2020)

Got the threaded rod machined up today.

Mal


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## DavidR8 (Apr 28, 2020)

Looking forward to seeing the assembled unit. Nice work!


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## malmac (Apr 28, 2020)

Laytonnz said:


> Nice, to be honest.. this was a first for me aswell. My race bike big end bearing was about shot and in need of replacing so I thought it cant be that hard? Well... it took me ages to get the crank trued up, it took a while for me to realise where to give it a wack.
> 
> I enjoy making tools also but lacking a milling machine makes things more challenging sometimes.
> 
> ...



I have not actually pushed my crank apart yet. And that means I haven't pushed it together. Did you build special tools to hold the crank while you pressed out the crank pin. I can see you have a single where as my engine is a twin, so a few more variables. In theory I appreciate the long winded process of pressing the crank back together....... did you check the runout in stages as you pressed your crank together?

In regards to bearings on the stand, I am planning to mount a set of bearings (which are removable) but only for use to do a static balance of my flywheel/clutch assembly. My bike has a dry clutch like a car so the combined mass of flywheel and clutch pressure plates etc is considerable. I thought I could get a smoother engine by making sure that assembly is as balanced as I can make it.

Mal


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## DavidR8 (Apr 28, 2020)

malmac said:


> I have not actually pushed my crank apart yet. And that means I haven't pushed it together. Did you build special tools to hold the crank while you pressed out the crank pin. I can see you have a single where as my engine is a twin, so a few more variables. In theory I appreciate the long winded process of pressing the crank back together....... did you check the runout in stages as you pressed your crank together?
> 
> In regards to bearings on the stand, I am planning to mount a set of bearings (which are removable) but only for use to do a static balance of my flywheel/clutch assembly. My bike has a dry clutch like a car so the combined mass of flywheel and clutch pressure plates etc is considerable. I thought I could get a smoother engine by making sure that assembly is as balanced as I can make it.
> 
> Mal


I have ridden a few modern Beemers (GS1200s and RT1200s) and what strikes me a curious is how they seem to shake at idle but are beautifully smooth at speed. I don't quite understand how the shake at idle doesn't increase at speed.
Sorry for the tangent


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## malmac (Apr 28, 2020)

DavidR8 said:


> I have ridden a few modern Beemers (GS1200s and RT1200s) and what strikes me a curious is how they seem to shake at idle but are beautifully smooth at speed. I don't quite understand how the shake at idle doesn't increase at speed.
> Sorry for the tangent



David

We also own a R1200GS and while it has twice the engine capacity of our old bikes it is way smoother in terms of engine vibration. You do raise a good point and I am no engineer so can't give you a reason. The new bikes do have a balance shaft in them which is part of the answer but not really what you are talking about. Even the old bikes without a balance shaft have a rocking motion at idle which smooths out once the revs build a little.

Mal


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## DavidR8 (Apr 28, 2020)

The first time I rode a Beemer I near dropped it when I blipped the throttle! The rocking is real!


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## malmac (Apr 28, 2020)

DavidR8 said:


> The first time I rode a Beemer I near dropped it when I blipped the throttle! The rocking is real!



There are two issues here. One issue is the balance between horizontally opposing cylinders, which I think gives us the rocking motion. The second issue is gyroscopic precession which is caused by the crankshaft running in line with the axis of the bike rather than across the bike like most Japanese four cylinder bikes. I think the action that caused you to nearly drop the bike may have been caused by the second issue. 

Mal


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## malmac (Apr 30, 2020)

I did do a short video of the feet being moved my the cordless drill but alas the file was too big to upload.
Suffice it to say the device is working as planned.
The second photo shows the thrust bush which is needed to make the whole show work.

Just need a turn wheel and to get the legs finished and it will be test time with the crankshaft.

Mal


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## malmac (May 3, 2020)

Well folks, thanks for watching but that is phase one completed.
There are a few additions I will make.
1. a set of roller bearing as an alternative to the green plastic tips. The bearings will be used to do a static balance on my flywheel and clutch assembly.
2. I maight put a little handle on the handwheel to make fast adjustment easier to achieve.
3. Some sturdy adjustable mounts for the dial gauges. I have magnetic stands but sometimes I find them not 100% to my taste.

I am very happy with how smoothly it can be adjusted and given it probably weighs in at 8kgs, there is plenty of stability.

Mal


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## Tozguy (May 3, 2020)

Super work Mal, makes me want to turn the handwheel.


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## malmac (May 3, 2020)

Tozguy said:


> Super work Mal, makes me want to turn the handwheel.



I am just a self taught person and this is probably the most indepth single project I have undertaken.
So quite satisfying to see ideas turn into 3 dimensions and for it all to work pretty good.

Thanks for taking the time to comment.


Mal


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## malmac (May 14, 2020)

Starting to work on stage two of the stand. This is the frame to hold the dial gauges. Shaft will be able to be mounted at several heights to suit the task at hand.

Also had the new timing gears turn up, so had a slight detour to machine up some custom shafts so I could check the backlash on the gears prior to final assembly. Just in case they were wrong size and had to be exchanged.

Mal


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## malmac (May 28, 2020)

I find it quite frustrating when I find a thread I am interested in and the thread comes to an abrupt ending part way through the project.
	

		
			
		

		
	



So in an attempt to avoid that for my fellow machinists.
Here is the trueing stand with the latest additions.
These really sturdy and totally adjustable arms will allow me to put my dial gauges where ever I want them.

Still a few things to go but getting close to being ready for checking runouts.

Mal


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## francist (May 28, 2020)

I’m guilty of that as well, although with me I really have to watch that I don’t lose interest myself before i finish something!

Nice progress on the stand — I like how all of the parts seem well thought through and of robust design.

-frank


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## DavidR8 (May 28, 2020)

Great work! Well thought out, I'd definitely like to see it in action.


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## malmac (May 28, 2020)

DavidR8 said:


> Great work! Well thought out, I'd definitely like to see it in action.



I did a short video of activating the dovetails and tried to post it, but it was rejected as a too large file.

If you use Facebook, you can search my small facebook page "Wasted Gears" and scroll down to view that video.

However you are right, I should do a short video on setting up and running a runout check on a crankshaft.

Cheers


Mal


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## malmac (May 28, 2020)

francist said:


> I’m guilty of that as well, although with me I really have to watch that I don’t lose interest myself before i finish something!
> 
> Nice progress on the stand — I like how all of the parts seem well thought through and of robust design.
> 
> -frank



Frank

I suspect some projects don't get finished, however many probably run into time delays and then the motivation to post the updates just gets lost.

I searched a lot on the internet looking for a good design and really didn't find anything that seemed achievable with what materials I had laying around. So what you see has been built totally from scrap I had on hand.

Mal


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## Superburban (May 28, 2020)

Awesome design and execution.


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## malmac (Aug 21, 2020)

Well got the third shaft finished today, so now I am ready to use the contraption.
Because this will the first time I have had a go at adjusting a pieced together crank, I have homework to do get get my ducks in a row in terms of process.
Its one thing to wack the crank and get a feel for how hard to hit but really I need to make sure I know where to hit and measure.
I have set up the stand so that each time I give it a wack I can measure both runout and crankpin offset without having to move gauges around which is time consuming.

Mal


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## NortonDommi (Aug 21, 2020)

That is an awesome piece of kit you have built.  Have you ever watched any of Allen Millyard's videos?  https://www.youtube.com/user/millyardviper


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## malmac (Aug 21, 2020)

NortonDommi said:


> That is an awesome piece of kit you have built.  Have you ever watched any of Allen Millyard's videos?  https://www.youtube.com/user/millyardviper



I was not aware of him, but on your recomendation I will certainly check him out. Youtube is an endless supply of amazing material. Thank you for your compliment and the link.

Cheers

Mal

I did not recognize his name so went and checked out the first test ride. Then I realised I did watch one of his videos some time back of how he built the 6 cylinder crankcase out of two four cylinder jobs. Very clever man.


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## malmac (Sep 19, 2020)

before I start flogging the crap out of my crankshaft I would like to clearly conceptualise, where to hit to get a given change in the crank alignment. I am not a really smart person so I thought to help me get my mind around how the crankshaft alignment works I would build a play crank out of wood and steel. I didnt get it finished but here is the beginning. The three members that will be connected together. I am not sure how much precision plays a part in the process but I figured this is a non destructive exercise and should help my understanding of the alignment issues I am up against.

Mal


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## FOMOGO (Sep 19, 2020)

I've done a few Harley crank assemblies over the years, but far enough apart in time that I pretty much have to relearn the process each time. You've
 done a really nice job on your rig. Mike


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## Mike_Mac (Sep 19, 2020)

This link to my restoration of my 1914 Humberette engine may help you. I must say I found it very difficult too, trying to get my head around the problem. You will need to search flywheel or crank to find the correct pages. Good luck. Mike









						REPORTS ON A 1914 HUMBERETTE RESTORATION
					

Rebuild Report No. 1 on a 1914 Humberette 3rd August 2018 Hi, I am an old vehicle enthusiast from Norfolk, England ('old' in both senses of the word!). I have recently joined the AACA forum and thought I would record the restoration of my new project for any interested parties to follow. Last yea...




					forums.aaca.org


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## malmac (Sep 19, 2020)

FOMOGO said:


> I've done a few Harley crank assemblies over the years, but far enough apart in time that I pretty much have to relearn the process each time. You've
> done a really nice job on your rig. Mike



I am awe struck by the people who actually put together Kawasaki Z900 roller cranks. I have just two cylinders, imagine four cylinders.
But I assure myself it is not impossible, just takes time and lots of attention to detail.
Well lets hope I'm right for once.


Mal


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## malmac (Sep 19, 2020)

Mike_Mac said:


> This link to my restoration of my 1914 Humberette engine may help you. I must say I found it very difficult too, trying to get my head around the problem. You will need to search flywheel or crank to find the correct pages. Good luck. Mike
> 
> 
> 
> ...



Ahhh Mike

You make my project look like child's play. You are quite encouraging.
I have started reading through your posts, straightening doors, chopping up trees etc.
Thank you ever so much for sharing the post I never would have found it otherwise.

Regards


Mal


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## malmac (Oct 2, 2020)

well the project has moved to the next phase.
Understanding how the crank articulates before I start bashing the hell out of a nearly perfect crank, that just needs a tweak.

Here is my crank model. Still needs conrods.

Mal


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