1972 Norton Commando Combat Rebuild (6) - root cause of the blown engine
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- Опубликовано: 13 окт 2024
- Music: CRASH by Ikson
@iksonofficia
/ ikson
Thank you Dave for the additional footage in this video.
Hello guys, thanks for coming back. In this video, we will be confirming the primary route cause of the catastrophic failure of Dave's Norton commando engine.
This will be the last video for a little while. Dave has various parts from the donor bike out for machine work. But as soon as the parts come back and he's ready to resume the reassembly process, we'll pick the series up again.
Here’s a link to the Playlist for this project:
• Feature | 1972 Norton ...
Here's a link to the AccessNorton forum thread on Dave's rebuild:
www.accessnort...
Here's a link to Dave's RUclips channel:
/ @swooshdave
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Christ almighty mate I think I'd have had a nervous breakdown if I'd dropped a bullock like that !!
I'm a recent convert to Norton Commandos having had Triumph's and BSA's for years, that's why I've only just seen your channel/videos, and began to lap up all the information I can on the model , so through your pain you have imparted an extremely valuable tip and boy has it made an imprint on my mind. So if its any consolation, although I imagine you're well 'over it' by now 3 years on , Thank-you.
Kind regards Damian, Hinckley, Leicestershire, UK.
Thank you Damian for your note. Glad you enjoy the videos and best of luck with your Commando! They are fantastic bikes. Best wishes, Mike
I once forgot to tighten up and secure the nut that holds the drive pinion on to the oil pump on a Fastback. At 70 mph it blew a hole in the crankcase as the big end shot out downwards. I'm here now almost 50 years later because just before it happened I had the thought "What would I do if the engine seized?" Answer - grab the clutch. BobUK.
Yikes! That's a very similar story to Dave's Bob. He managed to grab the clutch at 70MPH and pull over and saw a great big pool of oil under his bike! Best wishes, Mike
Mike, thanks for filming this now instead of 3 years ago, thereby sparing us from all of the screaming and crying.
Ha ha, thanks Jim. Yes, it would not have been pretty, but certainly amusing 😉
Isn't that the way it is in life, something so small ends up causing so much trouble. Very interesting video. I enjoy watching you fellows.
You're correct to diagnose the problem to the oil pump oil seal. But the reason why the oil seal came off is the washer on the shaft. The Norton spares parts drawings does not include a washer. The oil seal has to adhere to the shaft and the oil pump. Norton recommends using a sealant on the oil seal to keep it in place.
Good you had beer after, you both needed it I think. 🍻
Thanks Mike and Dave for sharing 👍
Thank you David. It was a really enjoyable project to follow. Best wishes, Mike
Nice that Shep is an organ donor. But how gut-wrenching to learn of the cause of the horror.
I know! It's very upsetting that it caused so much damage, but luckily Dave was aok and I think he will enjoy the rebuild process. It will be great to see it back on the road again. He has some very interesting plans for the bike that we will share. Best wishes, Mike
This was a very interesting look at what appears to be an all too common issue. I've been through similar problems with various harley's and other "dry sump engines" some small seal can easily cause oil problems. I look at such issues after better than fifty years wrenching, and question how the guys building the engine at the factory, could just let such a seal "float" unconstrained. I've long enjoyed the Brit practice of piston oil pumps, over the common gear oil pump so common here in the states. A great pump, with not so great a system keeping the oil inside. Thanks for showcasing this, Mike.
Thanks John for your great comment. I enjoyed reading it. Best wishes, Mike
A couple of dollars, phew all the damage.
Thanks for sharing Dave & Mike, an interesting insight as to the consequences of 'missing' parts.
atvb t ..
I know Terry! It's difficult to see all that damage caused by a little rubber seal, isn't it! Best wishes, Mike
Dang! I'm about to take my timing cover off to replace that same seal for good measure! Also will be pulling pump off to check if there's any free play etc. This makes me appreciate the $120 I spent a few months back getting an oil pressure gauge!
Great idea! Hope all is well, Best wishes, Mike
Your Manx fly is back to front
@@petergray5491 ???
@@petergray5491 Oops, thanks Peter! Nice catch. I will let Dave know that he has it the wrong way around (assuming that he wants the correct side facing out). The toes are facing the wrong way. Cheers, Mike
Great videos that oil pump seal is a certain bad thing if not looked at with installing a lot of people have forgotten this little seal
Very instructive thanks
Hey Dave. I had the exact same thing happen to me. Very disheartening and an expensive mistake. I vowed to have assurance. Any time I reinstall the timing cover now, I fit a oil gauge to a spare and reworked banjo fitting at the left rocker rocker shaft. If I have stable pressure, I know the rubber didnt leak. so critical. refit a normal banjo and off racing. $80 oil gauge and spare banjo good assurance
Thanks. Nice Triumph. Nice? ... beautiful.
Thank you very much John! That's my pride & joy up there ;)
Long story but had my engine rebuilt north of Hamilton, Ont. for $1700 (CDN) Was told by the mechanic that he had to take the engine apart again as something he repaired caused the pushrod to strike the inside of the head. He shaved down the diameter of the rod so that it would not bind. Somewhere in the process, part of the spring element of the oil scraper ring was broken off rendering the oil ring ineffective. It was burning oil so badly, I couldn't see. Also, oil was pouring out from the front at the base gasket. Ended up putting a new set of Hastings rings in MYSELF and repairing the base gasket as well. Inside the combustion chamber was small bits of aluminum shavings that were stuck to the valve seat causing it to backfire. Won't be going back there anytime soon. Brings true that old saying, "if it ain't broke don't try to fix it."
Ouch! Yes, this has been rough for Dave. Hopefully he will see it back on the road again soon. He's having machine work done now and then will begin the rebuild process. Best wishes, Mike
stan -- you should name the shyster that did the screw-up
Great video!
Thank you very much! It was a really enjoyable time. best wishes, Mike
What are the names of parts suppliers. I understand there are some parts NOT available new but you are getting several new or at least NOS parts.
Yes, there are some great Norton dealers here in the USA and in the UK. A few names include: OldBritts, Fair Spares, CNW (Colorado Norton Works), Andover Norton, RGM and Norvil. You can get NOS parts off ebay but most of the parts we buy from dealers are faithful reproductions, some using the original specifications.
@@TheMightyGarage - that is good to know. Don't a Google search just shows so much. Then one never knows who is trust worthy either.
I have been window shopping for another bike. Have not ridden for 5 or 6 years. A friend just traded for some Norton's - all basket cases in sure. There suppose to be enough parts to build 3 bikes. Although I have not heard a price tag yet.
@@vwmountainman9701 Good luck! I hope it goes well. It sounds very interesting. Yes, you should be able to buy everything that you need from one of the Norton dealers. You may have also seen it but there is a fantastic online forum called AccessNorton.com where you will find answers to every question that you can imagine! Best wishes, Mike
Feked in the UK (great reliable DHL delivery to US) and Baxter Cycle in the US have been great too, good prices and variety of parts options.
straight 50 oil cant force its way thro big ends on cold start blows rubber seal out ?
I was bimbling along the dual carriageway on a v hot day and my engine blew up. Until now I thought perhaps it was v low on oil and overheated but on looking at the conical washer there is a slight split in it. Could this have caused low oil pressure? I found 2 x10 thou shims behind it. I have a photo of the washer if anyone can help me with the diagnosis.
Hi John, yes absolutely that could have caused the seizure. This is just what happened to Dave's.
hi mick where is the assembly video of your norton?
Hi Rahul, if you mean all the videos for Dave’s Norton, which will also include videos of him reassembling his motor, here is the link.
ruclips.net/p/PLgDzKiI-i6nbw_53Ou_FzB65IfDxYQooY
But if you mean my own “Shep“ Norton Atlas project, unfortunately I haven’t started rebuilding it yet! But here is a link to the playlist for the Shep project, which I hope to resume again in the future.
ruclips.net/p/PLgDzKiI-i6nYTzxrLolDHnSxPiWRXeiOd
Best wishes
Mike
@@TheMightyGarage Apologies, but that link takes me to the "cover page" for the seven disassembly videos - of which this is number 6 - for the broken engine. Am I doing something wrong or is there another series for the rebuild?
@@brucebear1 Hi Bruce, no problem. Sorry, the link was to Dave's videos but I have edited the comment above to include a link to the my own Shep project, but it doesn't have any rebuild videos yet as I haven't begun to restore it. Hopefully one day! ruclips.net/p/PLgDzKiI-i6nYTzxrLolDHnSxPiWRXeiOd
Can you tell me where I can get my Norton case Machining out to update the oil system
Hi Josh, I will ask Dave. He knows of a couple of places. Cheers, Mike
@@TheMightyGarage thank you very much I have just recently locked the bottom end up and would really like to do some updating
Josh, first this machining is only needed on the Combat (or any 72 750) and secondly I wouldn’t necessarily recommend all of the work I had done. I had the advantage that one of our club members is a retired machinist. If I hadn’t had that resource I would have done an alternative mod that just needs drilling and not machining. Old Britts use to offer the machining service but they don’t any longer. I need to dig that info up on the alternative mods from the Access Norton forum. Stay tuned. It might take me a bit.
Here's a good post that shows you don't need to remove the baffle. The idea is to relocated the oil pickup from the front of the engine (like every other Norton engine) to the back. Lord knows why Norton messed with the Combat so much. There's a reason it was a one year only disaster. Some people drill one new hole, others drill several small ones. Plus you need to block the forward hole. www.accessnorton.com/NortonCommando/crankcase-mods-and-build-update.27847/post-421743
That's really bad luck.
Ouch, I know! How a little seal like that can cause so much damage indirectly! Best wishes, Mike
Is that poor design ? Surely Norton development would have foreseen this circumstance.
Poor design? No, that WASHER hanging on the pump seal spigot is a non-standard part and probably several times thicker than it needed to be (if it needed to be there at all) so no surprise the seal simply dropped off!
IF a SHIM (part 067784) is required to set the correct amount of seal compression, then, in my opinion, the pump spigot (066191, 'Mk3 cover oil pump feed bush') should be removed and the shim inserted between the pump body and the spigot flange.
Sigh! A sad end to that motor.
Hi Scott,
Oh, it’s amazing what Dave and some talented friends will be able to do with the motor. He has all intentions of repairing the crank cases.
Mi Ty Oh good. I misunderstood and thought it was beyond repair.
Scott Cary Anything can be fixed. We’ll see if I change my mind. I want to keep the serial number but the more I think about it and how non-stock that bike is I’m not so sure.
I had a rod go on a Norton (the one before the one I have now, it was a 1970, ran low on oil at the end of the 5-hour production race at VIR, Virginia). My partner heard something wrong at the end of the fabled back straight and pulled the clutch. There was less apparent damage - the broken case pieces were still there, hanging by cracks; besides the big broken area, there was a small crack just under the cam journal area (more about that later), also the cylinder skirt was cracked much like yours. Since the pieces were all there, it was possible to just peen the broken bits down and heli-arc. There didn't seem to be any issues with the strength of the case - I raced it and rode it as daily transportation (or as Mike would say "traans - pahwt" for another year before I sold it. We checked the alignment of the main bearing bores and they looked good.
The one odd problem that we weren't sure we could fix was that the rod had hit the com journal from the inside of the cases, just behind the points near the tach drive. The cam bush was cracked and when we pulled it, it was obvious that the bore for the bush was distorted. It took gentle skimming of the bore back into something like the right shape and then line-boring after the new bushes were in. In truth, we didn't have to do much to get the bore in shape and the line-bore process didn't take much metal off the inside of the bush, so it all seemed to go well -- it's just that the process took longer, and had us more uncertain of success, than the other repairs to the case. Like the main case repair, it was no problem for the next year I rode the bike.
Good luck and good riding in the future. Best wishes, Bb
brucebear1 Thanks for the story Bruce. I’m fortunate to have enough spares available I don’t have to save the broken cases unless I want to retain the serial number. Luckily the frame number is on the title and that’s good enough here.
I watch this guy install pistons and rings he didn’t seem to have a clue took the rings out of box and put them strait on pistons and fitted barrels no checking for ring gap when fitting pistons commented on how tight they were Dosnt surprise me that he left out seal may be ask the purpose of the seal !!!? See what is response is
hey robert just because you didnt see it on the video Dosnt mean that Dave didn't check it off camera and he Dos actually have more than a clue thank you for your comment