Author Topic: Has anyone done their own crank?  (Read 1899 times)

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Offline Greggers

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Has anyone done their own crank?
« on: December 02, 2017, 11:19:50 PM »


'Cos I'm thinking with a decent press and a few other bits it wouldn't be so hard ...  would it?

G

Offline Foy(notFox)

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Re: Has anyone done their own crank?
« Reply #1 on: December 03, 2017, 04:07:42 AM »
I've also thought about it. I have a press and in the original Yamaha manuals you can see the box-type assemblies they used for supports and the things they used to push the webs apart.

If you had a lot of time on your hands am sure you could fabricate copies.

Afaik the sticking-point may be the tonnage you need to push the pins out but perhaps you could use heat to help things along if your press wasn't big enough to do it cold

« Last Edit: December 03, 2017, 12:43:06 PM by Foy(notFox) »
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Offline Greggers

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Re: Has anyone done their own crank?
« Reply #2 on: December 03, 2017, 09:09:38 AM »


https://www.ebay.co.uk/itm/Heavy-Duty-Hydraulic-Workshop-Garage-Shop-Standing-Press-20t-20-ton-UK-CE-certif/281634075178?epid=1260932373&hash=item4192b2f22a:g:W~oAAOSwDmBY5feZ


Is what I was thinking about...  20T should be ok ?   Foy . -  could you point me in the right direction for a look at those manuals - are they online anywhere?

Offline KGR33N

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Re: Has anyone done their own crank?
« Reply #3 on: December 03, 2017, 12:02:17 PM »
I've also thought about it. I have a press and in the original Yamaha manuals you can see the box-type assemblies they used for supports and the things they used to push the webs apart.

If you had a lot of time on your hands am sure you could fabricate copies.

Afaik the sticking-point may be the tonnage you need to push the pins out but perhaps you could use heat to hel things along if your press wasn't big enough to do it cold


Hi Graham (Foy)
It would be great to be able to see these manuals on the Aircooled RD technical section if possible.

The photos from the manual and a brief description would be a great idea for Well Ard. Im sure Del and most of us on here would appreciate this.

Regards KGR33N
Yamaha RD 250 C (1976)
Yamaha RD 250 C (1976)
Kawasaki GPZ 1100 (1983)
Yamaha XJ 600 N Diversion (1995)
Ducati Hypermotard SP (2013)

Offline Foy(notFox)

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Re: Has anyone done their own crank?
« Reply #4 on: December 03, 2017, 12:56:18 PM »
Is what I was thinking about...  20T should be ok ?   Foy . -  could you point me in the right direction for a look at those manuals - are they online anywhere?

Hi Greggers. I've not actually checked if they're online as I'm thinking back to reading the manuals long before the internet came out. I've still got various manuals and the older ones show the press tools whereas the newer (coffin tank) ones don't. The Yamaha Special Tool and Electro-Tester Instruction Manual has line-drawing of them and some poor quality B/W pics of them in use. I'll try to post some up.

Someone was selling the manual on Ebay recently for about £5
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Offline Foy(notFox)

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Re: Has anyone done their own crank?
« Reply #5 on: December 03, 2017, 01:00:54 PM »
Here is a link to the manual in case anyone is interested. It didn't sell (for £4.99 + £3.30 P&P) but am sure if you contact the seller he'd be happy to re-list as a Buy It Now


https://www.ebay.co.uk/itm/Yamaha-Special-tool-and-electro-tester-manual-tools-and-testers-price-list-1971/172964408216?hash=item28457b6b98:g:EGcAAOSwOgdYp46L

There are also several for sale in USA but they have a plain cover and have a specific year on them. I believe the one I have is 1972 
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Offline Foy(notFox)

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Re: Has anyone done their own crank?
« Reply #6 on: December 03, 2017, 01:03:57 PM »

Hi Graham (Foy)
It would be great to be able to see these manuals on the Aircooled RD technical section if possible.

The photos from the manual and a brief description would be a great idea for Well Ard. Im sure Del and most of us on here would appreciate this.

Regards KGR33N

Hi KGR33N. I'll see what I can do. It's quite hard to take good pictures of the pages without the flash bouncing ff them and I don't want to split the book to scan the pages but I did photograph the Electro-Tester pages for a member on here and have them on my Photobucket page. Could do something similar for the press tools
« Last Edit: December 03, 2017, 05:42:21 PM by Foy(notFox) »
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Offline Phil Featherstone

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Re: Has anyone done their own crank?
« Reply #7 on: December 03, 2017, 02:05:26 PM »
There are some tooling pictures and description in the tech section.
PFP Phil
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Offline Foy(notFox)

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Re: Has anyone done their own crank?
« Reply #8 on: December 03, 2017, 04:20:46 PM »
Ok. Here goes. It's no PDF so probably not fit for the Tech section proper plus the tooling covers all the engine sizes (up to 350cc) so would really need to post it in both the sub-250cc and the 250cc and above one.


1970s Yamaha crankshaft assembly/dis-assembly jig with variable 'crank width gauges (stops)' to suit range of engines


1970s Yamaha crankshaft separating tool - in 4 different diameters for range of crank sizes. one pair has threaded holes in body. other doesn't




key to model suitability for different size tools. assume for coffin-tank RDs we'd refer to AS1/2 for the RD125; CS1/2 for RD200; YDS3/5 etc for RD250; R5 for RD340/400




step 1 would be to push the two sides of the crank apart. so tighten the squared blocks round each crank



then tighten the threaded pins to push against the non-threaded blocks



et voila. you have two parts that you can now strip further


So that parts looks pretty simple. In as much as you wouldn't need a huge amount of force to push the halves apart. Making the blocks however wouldn't be that easy. If you made them from steel and wanted it to be of similar sturdiness it would take a hell of a lot of hacksawing to cut the blocks out then you'd need to make accurate holes in the centre and include a lip to catch the inside of the crank webs. So if you don't know a lathe-owner with hours to spend helping you you're kinda stuck. The other option would be to make the tool from several thinner metal plates then weld them together. Bit like donner-kebab production. Than you'd need to put a fairly big drill and tap through one set to accept the threaded rods. And you'd also need to drill right through two opposite lengths of the 'blocks' to make bores for the clamping-bolts/nuts. Enough to sidetrack the average guy for a week or three and the tool would probably look a lot rougher than you envisaged - but for single-use would be fine. 

Next stage is to press the pin out the crank-halves. The Yamaha manual doesn't give you any details on the tool but from what I can see its purpose is to comfortably support the crank assy while you put enormous pressure on the pin. And then there is a rectangular box to put on top when you press it a ll back together. The base of the tool has holes for pins to accept different size adapters and also a sliding-stop to slam up to your work to keep it all secure.

If you are only going to be working on one size crank you would obviously be able to dispense with the extra slots and holes for other sizes but you're still going to have to do a lot of planning to make sure your bits do the job that Yamaha designed this tool for. And you can't pick the engineers' brains to say things like 'how tall should the sliding bit be?' or 'How thick would the base need to be to take the pressure of the press?'. So once you've spent a week or so finalising your measurements you can start cutting your metal plates.

I did this to make up an adapter for pushing my Mondeo driveshafts out the hubs and pressing wheel-bearings in/out. Much simpler operations perhaps but similar principle. Without spacial cutting equipment it takes a long time but there's no reason you can't do it. You can saw 3mm or 4mm plate and then double it up. Or even triple it up.



so what's happening here? well the side walls of the tool must need to be tall enough to keep the nose of the crankshaft off anything hard. But the drawing shows a hole in the bottom of the jig base and it looks like the two metal strips plates are supporting the web here so why can't the crank sit much lower during this operation? there also needs to be a cut-out in one wall to allow the conrod to sit freely. whatever the case it appears that all the parts can be separated with this operation

There are then several steps to re-assemble the parts...



so you start with the bare jig and both walls then select 'crank width gauge'. this picture shows one half of a pair. the one with relief for conrod


   
at the back is the other half with same dimension. the width here isn't as we look at it horizontally. it refers to the width of the crank in some way so it's actually the height of these stops that is relevant



you then put the other half of the crank on and set the tool in place



then tighten the nut which was previously 'loose tight'  ;)



then press together using the box. note it suggests 5-8 tons pressure



and also advises to keep the force above the pin



then once you've assembled both sides you press them together. looks like the whole assy is supported on the strip plates and a wedge is put in one side of the upper assy to stop it going squint



So that's it in theory but I don't know if I could realistically set aside time to make the tools and once it's assembled you still need to align it to fine tolerances. With a brass mallet afaik. But if Allen Millyard can build Kawasaki Quintiples and Honda SS50+50s who's to say someone can't knock this up in their shed....
       
« Last Edit: December 03, 2017, 04:23:41 PM by Foy(notFox) »
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Offline 5port

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Re: Has anyone done their own crank?
« Reply #9 on: December 03, 2017, 04:38:11 PM »
Well, with the right tools and a press, you can push/press cranks apart and refit.  However, the cost of having it done by a good crank rebuilder is relatively small and, with experience, they are likely to be able to do it well.   ;)
BTW, Heat is not a good idea for most cranks, yes they get warm in use but, most cranks have heat treated components and it is not a good idea to use direct heat on them, unless specified in a manual.  Cheers

5port
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Offline Phil Featherstone

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Re: Has anyone done their own crank?
« Reply #10 on: December 03, 2017, 09:51:34 PM »
Hi guys being someone who builds cranks for a living may I give a small piece of advice. If you decide to go to the trouble of making these jigs and plates and plan to do more than one crank then you will want to get some parts heat treated, also you would be wise to practice on a crank that is spare rather than your best one. You will need at least one good dial guage. Accuracy on assembly is crucial for a nice smooth running engine . As 5port has said having it done by a professional is not that expensive. I know I only charge 25 for a single cylinder and 50 for a twin and most others are probably about the same for labour.
Best of luck if you decide to go ahead.
PFP Phil
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Offline Greggers

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Re: Has anyone done their own crank?
« Reply #11 on: December 03, 2017, 10:09:43 PM »


wow - what a reply from Mr.Foy - thanks for taking the time to put that together, it's a fascinating insight into how it's done (for them's that have mechanically inquisitive minds like what i do...).

What surprised me a bit was that an 8T press would be enough to crack it, I was really expecting 15+

Anyway, if I had time I'd probably have a go, but I haven't so it's off to the crank builder for me ...

Thanks again Mr. F..




Offline betty foRD

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Re: Has anyone done their own crank?
« Reply #12 on: December 03, 2017, 10:10:30 PM »
+1 for just letting someone else do it.
Everything is possible, nothing is easy and u less you plan to do it over and over then why bother.
Of course it may be all about the challenge, I can understand that. For me , I’d rather spend the time out on a bike. Spend too much time doing other stuff already!
Rev 'em till they rattle

Offline ixe13

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Re: Has anyone done their own crank?
« Reply #13 on: December 04, 2017, 01:02:59 AM »
Easy , just follow these instructions , it's a 3.30 min. job.


https://www.youtube.com/watch?time_continue=1&v=r8lCGTltAm4
« Last Edit: December 04, 2017, 01:11:24 AM by ixe13 »

Offline 5port

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Re: Has anyone done their own crank?
« Reply #14 on: December 04, 2017, 09:45:33 AM »
Yes, impressive skills by the backroom crank guy.  Notice he uses top quality parts, but no measuring tools and eye alignment.  I was surprised he seems to start the b/e pin with the large hammer, guess the pin is hard enough not to burr at the face.  Also guess the Honda quality is good enough to just hammer the pin flush and get the b/e float in tolerance.  Bear in mind, it is a simple single.  However, it would be interesting to do some QA on his product.   :)

5port
« Last Edit: December 04, 2017, 12:21:49 PM by 5port »
5port