Condor bevel drive 350 rebuild

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Gas Mark 5
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Condor bevel drive 350 rebuild

Post by Gas Mark 5 »

Hello everyone,

I'm new here, not strictly a Ducati owner, but I have a 1976 Condor A350 which at least has a Ducati engine, and as I am currently rebuilding the engine I thought I better sign up here.

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For those who don't know, they were built for the Swiss military, with imported Ducati engines. The engine in questioning is a bevel drive 350cc single (spring valve, no desmodromics). I am not entirely sure what changes Condor made to the engines other than re-badging them. An external oil filter has been fitted, I have been told the compression ratio is lower, but the piston, cylinder and head all look normal Ducati to me, so I don't know how this was achieved. As it was all in working order when I got it, I just did routine maintenance on it and rode it all over the place.

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Anyway, coming back home one day the engine cut out a couple of times. I sounded just like it was running out of fuel, so I switched to the reserve and carried on to see if I could make it home. A few hundred metres later the engine completely seized and threw me off. I was fine, only going slowly around a muddy country lane, and the bike only has a couple of scratches and a bent footpeg, but the seized engine is of rather more concern. It had plenty of oil in it, and had had an oil change a couple of hundred miles before, with no signs of anything breaking up. As rebuilding a Ducati engine looks like quite a project, I decided to bring it back up to university with me, where I could work on it whenever I get fed up of writing lab reports.

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What a student's bedroom should look like :P

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The top half came off without an issue, worryingly in a way, as a new piston / cylinder isn't the end of the world, but a new con-rod comes to over £600 :? .
Whilst trying to undo the nut retaining the output sprocket, the big end suddenly gave up its grip and the piston poked its head out of the crankcase.

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Better that it is no longer seized solid, but the big end is still very grumbly, I am sure it must be the cause of the seizure, although I won't know why it gave up until the cases are split. There is a coating of metal shards all over the insides of the engine, presumably the remains of the big end. The metal shards are also what I assume caused the scoring of the piston;

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Anyway, I carried on disassembling it, the flywheel / rotor put up a fight, but with the correct puller it eventually let go.

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The stator was the next stubborn part, even with an impact driver one of the retaining screws still refused to come out. In the end I had to grind the head off the screw. Once the stator was off there was no pressure on the remaining thread of the screw so I could just undo it by hand, with no damage to the stator or crankcase. I don't think the swarf from the grinding really matters with all the flakes of ex big end decorating the engine innards, anyway it is all coming apart. :(

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I am just about ready to split the cases now, however the manual I have states that the starter spindle (visible in the bottom right of that image) should be removed, and the starter gear behind it also before the cases are split. I can't find anything retaining the starter spindle. It has about 0.5mm of slack, but I can't pull it any further out, and it doesn't look like there should be any sort of interference fit there so I don't want to start walloping it. Does anyone more familliar with these engines know how to remove this part, or should I try splitting the cases and pull it out from the other side?

Hope this is of some interest to people, let me know if I am going to heavy on the pictures - I find it easier than trying to describe things, but I don't know if it slows the page down for others...

Any advice would be appreciated, I'm more used to mobylette engines (dead simple) or 2CV engines (fix everything with an 11m spanner and a hammer), so the Ducati is a bit different...

Thanks,

George
Jon Pegler
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Re: Condor bevel drive 350 rebuild

Post by Jon Pegler »

The kickstarter shaft on widecase Ducati engines remains in the crankcases when they are split.
In fact, you could have left the return spring in place.
This shaft is the first item fitted to the cases when assembling the motor and should have very little end float.
When the cases are apart, check that all the shims are intact.
If one of the 0.5mm or 1mm shims have broken, the starter gear can touch the main gear cluster when running, causing a nasty noise/gear damage.
If you are using an early Ducati factory manual or the Clymer manual it might state that the kickstarter shaft should be withdrawn before splitting the crankcases.
This is correct for a narrowcase Ducati motor but does not help with the later widecases.

Jon
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Craig in France
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Re: Condor bevel drive 350 rebuild

Post by Craig in France »

Hi George,
Gas Mark 5 wrote:. .. not strictly a Ducati owner
Oh, I think you are!
Gas Mark 5 wrote: I am not entirely sure what changes Condor made to the engines other than re-badging them. An external oil filter has been fitted, I have been told the compression ratio is lower, but the piston, cylinder and head all look normal Ducati to me, so I don't know how this was achieved.
The oil filter was an original Condor modification, and the exhaust and silencer should also be Condor items - the bike should be quieter than a 350 Mark 3. Apparently, the compression ratio is 8.2:1 as against the Mark 3's 9.5:1, and I think this may have been achieved by changing the cam (but don't quote me ...).
Gas Mark 5 wrote: ... but a new con-rod comes to over £600 :? .
?. Barry Jones at Classic Ducati has complete kits at £360, for example. Go http://www.classicducati.com/index.php? ... ductId=486. There's even a Mark 3 rod on its own on eBay at the mo', current price £10 (# 271388047292).
Gas Mark 5 wrote: Any advice would be appreciated ..
There's a Haynes manual that covers the wide-cases. It may be helpful (in a Hayne's kind of way ...)

Have fun!

Craig
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Craig in France
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Re: Condor bevel drive 350 rebuild

Post by Craig in France »

There's a copy of the Condor handbook on eBay, btw. Go:

http://www.ebay.co.uk/itm/DUCATI-Single ... 4d185d14b4
Gas Mark 5
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Re: Condor bevel drive 350 rebuild

Post by Gas Mark 5 »

Thanks Jon - that saved me a lot of confusion! Wish I hadn't taken off that return spring now, looks like it will be fun to refit. There is a significant amount of play in that shaft though, I'll probably have to take it apart and make sure all the correct shims are in place anyway. I left my micrometer at home, but as soon as a new one arrives I'll measure and label all of the shims before I forget where they came from.

Now that you mention it Craig, I seem to recall something about a different cam profile, it hadn't occurred to me that changing the valve timing would alter the true compression ratio, that makes much more sense. Thanks for the con-rod info too - I was just pleased to find that Lacey ducati was an english supplier with many positive reviews, but if I have to shell out for a new con-rod it's good to know that there are cheaper alternatives.

I wasn't sure whether to bother getting a Haynes manual or not, I always feel I ought to, but then I had a think about the 2CV Haynes manual, and all it is useful for is torque wrench settings, and even then half of them are wrong. :roll:

Anyway, with all that information I bit the bullet and pulled the cases apart.

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Went surprisingly smoothly, although I think putting it back together will be the challenging part. :P I've just tied all the shims to their respective places for now, and photographed every stage of the disassembly so I can remember how it fits back together.

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That magnet has been earning its keep! I'm going to be spending quite some time making sure every trace of swarf is removed...

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All the innards - fortunately the seizure seems to have happened so quickly that the bearing material hasn't had a chance to cause any more damage, all the gears look fine, and there are no flakes of metal around the valves so presumably it didn't have time to make it around the oil circuit.

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The source of all my woes... Getting on for 1mm of slack up and down. Hopefully most of that is from disintegrated rollers rather than missing rod material. Now I just need to find someone with a great big press to split the crank. I had a chat with my physics lab technician today, and I think I might pop over to Dover on Saturday and see if the bike place there can press it apart. Then as Dave pointed out, if it's all ruined I can join him for a pint at the adjacent beer festival and drown my sorrows :-D .

I'll let you know how it goes when I manage to get the crank apart, thank you for all your help. Whilst I have the engine in bits, are there any modifications I can do to improve the oil flow to the big end? I've always kicked it over a few times before starting it, and let it warm up before riding anywhere. I gather from what I've read that oil flow to the big end can be a problem with these engines, but I don't want to go starving other parts of the oil circuitl. A new (higher output) oil pump is on the list of new parts for the rebuild...

Thanks again for all your help,

George

P.S. That manual looks brilliant, thanks Craig! I'll definitely have a bid if it stays at that price. I have a Condor manual, which I am in the process of translating, but the one I have I think is more for the use of the soldiers, that looks like a proper workshop manual.
Gas Mark 5
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Re: Condor bevel drive 350 rebuild

Post by Gas Mark 5 »

P.P.S. Are the dimensions of the con-rod the same for both 250 and 350cc mark III engines?
Jon Pegler
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Re: Condor bevel drive 350 rebuild

Post by Jon Pegler »

Hi George,

The con rods on the widecase 250 and 350 motors are the same. 135mm long, centre to centre.
These rods are longer than the narrowcase ones, so be aware of what you're buying.
Usually, the rods come as an assembly with the crank pin, thrust washers and big end bearing complete.
The crank pins do come in different sizes throughout the widecase models, starting with 27mm pins, going up to 30 and 32mm pins.
You have to get the correct crank pin to fit the flywheels.
I would guess that the Condors have either a 30 or 32mm pin.
You'll scare yourself when you see the price of a replacement rod kit. And that's before it's fitted.

Jon
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Robin172
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Re: Condor bevel drive 350 rebuild

Post by Robin172 »

You'll probably know this but make sure you clean the sludge trap out. You'll be amazed at the amount of junk that's ends up in there.
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Craig in France
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Re: Condor bevel drive 350 rebuild

Post by Craig in France »

Gas Mark 5 wrote: Thanks for the con-rod info<snip>
Nigel Lacey’s ‘Arrow’ con-rods are the Dog’s, but possibly reflect Nigel’s interest in racing :-D :Uwin: . So OTT for a Condor … But by all means e-mail/phone him - he may have something cheaper to offer. Nigel is one of the most helpful guys you could meet. Same goes for Barry, btw.
Gas Mark 5 wrote: I wasn't sure whether to bother getting a Haynes manual
The main use for a Haynes, IMO, are the photos - just in case you need one as a reference.
Gas Mark 5 wrote: Getting on for 1mm of slack up and down. Hopefully most of that is from disintegrated rollers rather than missing rod material.
As Jon suggests :) , unless the pin and washers are entirely undamaged, it's normal to replace the set (rod, pin, bearing, washers). You don't want a repeat performance.
Gas Mark 5 wrote: …I think I might pop over to Dover on Saturday and see if the bike place there can press it apart.
If not, there are several people in Kent who should be able to help. Chris Bushell, for example. Pm me for his e-mail, if need be.
P.s. And remember: you need someone who can press it back together correctly, too! :shock:
Gas Mark 5 wrote: Whilst I have the engine in bits, are there any modifications I can do to improve the oil flow to the big end?
(See what others say, and by all means check with Nigel and Barry). But the main cause of big end failure is the quality and frequency of oil changes. You're most likely simply the victim of previous owner abuse ... :wah"

That said, the most common mod is/was to install additional drain lines from the head on race bikes. But not needed on a road bike.
Gas Mark 5
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Re: Condor bevel drive 350 rebuild

Post by Gas Mark 5 »

Thanks again for all your help Craig, I've just spoken to Chris and I'll pop over next week to split the crankshaft. I suspect after that it will be a matter of going without food or heating for a few weeks before I can afford to do anything else on this engine, but I'll keep you all updated. :P

As far as I am aware, the previous owner of this bike was the Swiss military, which surprises me a little as I imagine they would have been fairly good regarding regular oil changes and so on. Then again, the bike is nearly 40 years old, and had been sat in a warehouse since 2001, so I suppose this isn't completely unexpected.
Robin172 wrote:You'll probably know this but make sure you clean the sludge trap out. You'll be amazed at the amount of junk that's ends up in there.
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Duly amazed... Can't have been functioning as much of a sludge trap, that stuff was packed solidly, I still haven't gotten all of it out. :(
Is that plug always such a pig to unscrew by the way? I've been undoing it in quarter turn increments every couple of hours for the last few days :roll:

Anyway, I'll let you all know what's happening by the end of next week, thanks so much everyone -?-

-George
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Craig in France
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Re: Condor bevel drive 350 rebuild

Post by Craig in France »

Gas Mark 5 wrote:Thanks again for all your help Craig, I've just spoken to Chris ..
No worries and good news. Say 'Hi' to Chris for me ...
Gas Mark 5 wrote:Duly amazed... Can't have been functioning as much of a sludge trap, that stuff was packed solidly ...
That's as it should be. A centrifugal sludge trap is an old-fashioned but effective way of getting the worse contamination out of engine oil. Problem is, once the trap is full, it don't work no more :roll: .

It may shock you to know that cleaning out the sludge trap is scheduled in the owner's handbook as a 'once every 10,000 km' service operation :shock: _?_ . Of course, no-one does ...
Gas Mark 5 wrote:Is that plug always such a pig to unscrew by the way?
Pretty much :) . Obviously it need to go back in similarly, e.g. Loctite and peened. But Chris will advise.
Gas Mark 5
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Re: Condor bevel drive 350 rebuild

Post by Gas Mark 5 »

Just a minor update, as progress has been slow due to studying physics full time, and a life in general getting in the way. Anyway I popped over to Dave's house a few weeks ago to cook some engine parts in his oven, as I have been banned from doing that in my house ( :roll: ). Most of the bearings came out without too much of a fight, although it wouldn't have been possible without a slide hammer type bearing puller. The RHS main crankshaft bearing scared me by coming out like this;

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However with a second pair of hands, and a really big lever, the outer relinquished its grip as well

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A very shiny new box of bits arrived from Australia for me the other day, and the crankshaft has been split, so now begins the rebuilding process. :)

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I'm also experimenting with a DIY soda blaster for cleaning up the cases, so I'll post the results of that here. I just had some baked bean cans and brake pipe tubing lying around, and thought it would be fun to try. :roll:

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Anyway, thanks again everyone for all your help. As soon as I have a crankshaft again, there will be plenty more updates, and probably questions too.

George
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Robin172
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Re: Condor bevel drive 350 rebuild

Post by Robin172 »

Re. the sludge trap screw. Nigel Lacey sells ones with a hex. head (Allen bolt type) which makes these easier to put in and get out. If you decide to put one in remember to have it in place before balancing the crank. I know someone who didn't do this and had to strip his engine again when this was pointed out to them.
Gas Mark 5
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Re: Condor bevel drive 350 rebuild

Post by Gas Mark 5 »

Thanks for the tip, I'll definitely be getting one of those. The original one was seriously hard to remove, I much prefer socket heads.

I was under the impression that if a crank was rebuilt with parts the same weight / dimensions as the original, it only needed aligning accurately, the weight distribution would be the same as when it was first balanced? I haven't pressed it together yet though, I still need to look into all of that side of things. Thanks for the tip - I remember how frustrating it was when I rebuilt an entire mobylette engine, put it back in the frame and then found I had fitted the crank seals back to front. And tearing that engine down again was a bit less of an undertaking than this, hopefully it won't have to come apart too many times due to my stupidity :roll: .
Gas Mark 5
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Re: Condor bevel drive 350 rebuild

Post by Gas Mark 5 »

Well, I definitely think the original big end is past its best...

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And this is only about half of the bearing cage / rollers, the rest was fairly evenly distributed around the inside of my engine.

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So, the crank still needs pressing back together with the new rod. The small end needs reaming to suit the gudgeon pin, and the cylinder needs boring to suit the oversize piston. While I usually try to do everything myself, I don't have a lathe or hydraulic press etc. so Chris and Paul are going to do these bits. Then I'll just be left with the jigsaw puzzle to piece together again. :)

In the mean time, I need to fit new bearings all over, and I can clean up the head a bit, give the valves a go with some lapping compound. Fingers crossed I'll be on the road again in time for the summer. ;)
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