crankcase wont split

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Scottish888
Posts: 85
Joined: Wed Feb 07, 2018 1:47 am
Location: Edinburgh, Scotland UK

Re: crankcase wont split

Postby Scottish888 » Tue Apr 09, 2019 10:31 am

Thank you to all for the good advice,
Yes, I have removed every part from both sides of the casings, with the flywheel puller that item came off fairly easily.
I expect it is stuck on the dowels as suggested.
I am picking up a nylon deadblow hammer today and will work patiently with that.
I had thought about making some expanding device for the crankcase mouth, then by opening a mm or so then tapping closed could "rock" the case free of the dowels but you folks have given me plenty to work with for the moment.
Hopefully I can split the cases this eve then get the crank out and finally see what size crankpin I need.

Regards

Scottish888
Posts: 85
Joined: Wed Feb 07, 2018 1:47 am
Location: Edinburgh, Scotland UK

Re: crankcase wont split

Postby Scottish888 » Wed Apr 10, 2019 10:14 am

Cases split and crank out :)
Took a fair bit of thumping with the new nylon dead blow hammer, had to knock it closed at the crank mouth to open the bottom of the case, put in some plastic spacers then knocked the crank case at the top to open crank case mouth and repeat. This "rocked" it off what was a corroded dowel towards the bottom of the case, it was this dowel that was the major sticking point.
Crank uses a 30mm pin

Samurai
Posts: 114
Joined: Wed Nov 28, 2012 9:53 pm
Location: Somerset, U.K.

Re: crankcase wont split

Postby Samurai » Wed Apr 10, 2019 12:23 pm

Good result mate, well done for persevering!

Scottish888
Posts: 85
Joined: Wed Feb 07, 2018 1:47 am
Location: Edinburgh, Scotland UK

Re: crankcase wont split

Postby Scottish888 » Mon Apr 15, 2019 2:40 pm

Looking for opinions on the RH crank case of my bikes engine.
It looks like it could be surface flaws from the casting process or maybe more structural?
LH case looks fine, check out the main bearing, made in Romania? is that standard?
RH case input bearing, not sure about the part under the center of the bearing, what should that look like, the clutch pushrod seal part looks way off center. Should that bearing have oil seals both sides, one side or open both?
RH main bearing has no number on either side.
included a close up of the better looking LH crank case, similar flaws there

LH crank case_edited.jpg


RH crank case_edited1.jpg


LH main_edited.jpg

double diamond
Posts: 460
Joined: Thu Apr 28, 2011 1:20 am

Re: crankcase wont split

Postby double diamond » Mon Apr 15, 2019 7:42 pm

I don’t see anything of concern with your crankcase castings. The pushrod oil seal looks off center but this is probably not a perfect on-center photograph, were it as far off as it appears, you wouldn’t be able to install the pushrod. Any signs of welding repair? That bearing typically has a metal seal on the backside, open on the inside. The output shaft bearing is also original. Note that this bearing is staked at six points. If you replace you should relieve the staking points around the outside of the bearing. Never seen a Romanian bearing, definitely want to check crankshaft endplay by the looks of that bearing.

Matt

LaceyDucati
Posts: 282
Joined: Sun Sep 19, 2010 10:30 pm
Location: Wales UK
Contact:

Re: crankcase wont split

Postby LaceyDucati » Mon Apr 15, 2019 8:58 pm

The "flaws" are casting marks and quite normal and are all most certainly nothing to worry about. inclusions can occur, but seldom are of any issue.

I've seen the the pushrod seal out of line to the bearing housing quite a few times before. Not ideal, but if it's an issue you can remachining the 14mm housing out to 15mm which normally fixes the problem. You then just use a 6/15/6 oil seal in place of the original tap washer arrangement. Unfortunately mismatches and misalignments of machining are not unusual once you start looking closely at these engines. Mostly they are not enough to cause any major issues, but occasionally they can.

Romanian bearings are not original, most originals would be RIV Italian manufacture.

Back to the cases worry when the cases look like these below! These are the sort of places that cases can fail in race use, more often in Narrowcase 350's although they tend to fail more horizontally through the drive side main bearing. These are not issues that I have ever seen in a road engine.

Img_0653.jpg




Regards Nigel
Img_0656.jpg

Scottish888
Posts: 85
Joined: Wed Feb 07, 2018 1:47 am
Location: Edinburgh, Scotland UK

Re: crankcase wont split

Postby Scottish888 » Tue Apr 16, 2019 8:32 am

Thank you folks,

Glad the cases are ok, no welding anywhere. Yes, I think I took the pic off center, I checked yesterday and the seal is more central then it looks in the pic.
The output shaft bearing feels smooth but I guess the seals could be affected when I have to put the cases in the oven to remove the other bearings. Is it good practise to re stake the output shaft bearing? I guess you can only do that so many times before the casing becomes mashed.
Is it better to use loctite instead? is heating the cases then putting in all bearings ok? How does loctite react with oven heat if used to secure bearings?
Why was only the output shaft bearing staked?
Looks like this machine has the later same size main bearings.
The bevel drive bearings run smoothly so thinking about leaving those alone.
Apologies for all the questions, used to working on Japanese machines and a bit paranoid about this Ducati

Regards

LaceyDucati
Posts: 282
Joined: Sun Sep 19, 2010 10:30 pm
Location: Wales UK
Contact:

Re: crankcase wont split

Postby LaceyDucati » Tue Apr 16, 2019 1:27 pm

Personally I would leave the staking as is before removing the bearing. Heat the cases up to 100 to 120 degrees C and tap the staked in bearing out with a drift if necessary. To replace the bearings heat the cases to about 120 degees C and drop all the bearing in. Start with the output bearing on the gearbox that was staked and if it won't start/ fall in easily, you may have to carefully scrape a little of the raised up material in the housing. If you can get the bearing back in square and easily without removing the staking all the better, as you say staking can only be done so many times. Personally I would not stake any bearings.

My test for retention is heat the cases to 100 degrees C, if any bearing are loose they will rotate in use and need loctiting. I would not use loctite on any bearings that are tight in the cases at 100 degrees C or greater. If you do use loctite with bearings that are already tight and you put the bearing into a hot casing the bearing will go tight when it cools. From my experience if you use loctite on loose bearings in cold cases they will come loose again in use with the expansion of the alloy. I am aware of this from many years of building race engine which are stripped down every few years. However if with a loose bearing you degrease the parts, wet the bearing with loctite engineering adhesive and insert the bearing in at between 100 to 110 degrees C it will stay in. I twist the bearing when I insert it before it locks to spread the loctite, but this is more just a part of my "ritual". When the casing cools you should find the bearing still free and when the casing is reheated it will remain tight. This procedure forms a thin annulus of loctite between the bearing and housing and from my experience years later you will still find the bearing retained. All this does require close temperature control/measuring, ideally with a thermocouple. If you are much cooler or hotter than the temperatures I've suggested you will either get the bearing stuck during assemble or the bearing will be tight when the cases cool. Also for your reference all the casing bearings should be C3 fit, standard fit bearings will invariably go tight after installation.

Regards Nigel

Scottish888
Posts: 85
Joined: Wed Feb 07, 2018 1:47 am
Location: Edinburgh, Scotland UK

Re: crankcase wont split

Postby Scottish888 » Tue Apr 16, 2019 2:42 pm

Thanks Nigel,

So much great information, very helpful.
I had been thinking about C3 bearings but read they run looser until warmed up so was not going to use them but having read your information I can see why C3 is used.
I suppose C3 is a recent design? Would the original bearings have greater tolerances than today's standard bearings and therefor equivalent to C3?

Regards,

Buster
Posts: 28
Joined: Fri Dec 22, 2017 12:56 am
Location: Reading, UK.

Re: crankcase wont split

Postby Buster » Tue Apr 16, 2019 3:01 pm

Rudge motorcycles specified C3 bearings to give running clearance when the cases cool and grip the outer ring.
So they have been around a long time.


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