Assembling a Tiger Cub Flywheel // Paul Brodie's Shop 

Paul, I enjoy watching you work. I grew up with a machine and balancing shop in my basement. My father even balanced the transmission on the lunar rover. Spent most of my life balancing and blueprinting engines.😊

Thats definitely a hands on class Id attend right there. That particular skillset is one of the ones that separates engine builders from engine assemblers.

I've done several crankshafts like that and it's is very time consuming and aggravating, you made it look easy 👍. The idea of using a wedge is a great idea, thanks.

Right on time, guys.

It was about 1964 when I changed my first crankpin on a Cub no handbook just a big Sweeney and Blocksidge had/fly press and a try square. A Blue and White Cub with alloy guards and an energy transfer system no battery, a nightmare to ride in the dark. A pig to start but loved it.

Really well done guys. Can’t wait to see the new seat when it’s done. I really like the shape you’re going for.

Brillant work!. You have the patience of a rock awaiting its trip to the sea

Great episode, in the Tiger Cub story. really well explained thank you.

I made a fixture when I did the BSA crank, still had a little bit of truing to do. I have a lead mallet which was originally for tightening the nut on sports car wire wheels. That tool illustrated in the Haynes manual is the Triumph special tool for assembly and disassembly of the flywheel. Best wishes, Dean at Retromeccanica, UK.

You sir are an excellent teacher. You patiently explain the what and the why that only comes with experience.👍🏍

Good afternoon! Very satisfied with the process. Have a nice weekend!

I've never seen how this was done. Thanks for the insight.

Oh, nice,... .001" is super. When I first saw a crank like this being assembled and trued, it was so educational, on a Matchless G2CS 250 I owned, a persistent crankpin breaker..!! The old timer who rebuilt it had a truing stand and final adjustments to alignment were done with holding the flywheels in his hand and he smacked the one needing to move with a lead hammer and then rechecked. Method stayed with me throughout my career as a mechanic myself.

I just worked on my BSA B40 today… to make it ready for the nicer weather. I’ve put on a new rear tire, replaced the broken kickstart return spring and made up new brake- and clutch cables. Damn it felt good to be back in the shed and as the cherry on top Mr. Brodie uploaded a new Tiger Cub video. Thanks Paul and Mitch :) keep up the great work!

I had a cub more than sixty years ago. I rebuilt it into what would now be called a cafe racer. It had a plain journal big end bearing which was changed the a roller. The flywheel assembly was rebalanced, can't remember the ratio. The inlet valve was increased in size so was the inlet port which was polished. The cast iron inlet guide was shorted and an Amal carb put on it. The camshaft was replaced with a high lift longer duration sports cam and a 10 to 1 piston fitted. That bike used to fly. The 250 cc 2 stroke Arial Arrow couldn't catch it. I won't say what speed it did down a slight incline because you won't believe it, but I was expecting the con rod to let go any minute, it didn't. Not the most fuel efficient though.. love your videos, brings back lots of memories..

Thanks Paul, You made that look easy, obviously you have setup flywheels a few times before! Many people have had to knock them back and forth to get them right. You are truly an old school fitter/engineer. You could go beyond what is needed and have it dynamically balanced? No, only joking!

this reminds me of work I've done on harley flywheels (the school i went to had these old jigs we put them into and to adjust we hit them with a lead hammer)

Nice press. Also, I like your idea of aligning the flywheels before the pin is all the way in. Good idea. 😎

Thanks Paul & Mitch! I noticed that you answered my question already - Alan asked about the aluminum plug. "Great show!" BTW, really like the seat form. Final product should look great and be pretty comfortable!

Should have called it 'Precision Beating a Tiger Cub crank' Pretty amazing you can still get a NOS crank-pin and rod assembly! I use a log splitting wedge as well as a spacer wedge, that way you can have crank in vice with some pressure and use wedge to open the' tight side' Japanese cranks almost always have a parallel crank pin so need a little more care to maintain clearance and not crush bearing cage "Yoda's BFF 1 day ago I've done several crankshafts like that and it's is very time consuming and aggravating, you made it look easy 👍. The idea of using a wedge is a great idea, thanks." If you went to MMI Orlando in early 2000's, Ed Sherbet or I would have taught you to do cranks that way, precision beating with a lead hammer. Polaris cranks are probably most difficult as they need around 15 tons or more to take apart and put together, Yamaha normally around 6 tons, Honda can be very variable, 1.5 to 7 tons, Suzuki 4~6 ton

Thanks for the knowledge might not ever pay someone to do this again got a south bend lathe and a press

Stellar content. Thank you again so much Paul and Mitch for sharing these journeys. Cheers !

Always enjoy watching you Paul.

I'm not looking forward to this process on our '56 Tiger Cub restoration. Working on a very early cub, round head, small flywheel that has been run with low/no oil. Lots of problems. Good news is the whole engine seems very low miles. I wasn't aware they used needle/cylinder bearings on the big end of the rod. Thanks for these excellent videos. Especially thankful for the mistakes. Students really should see the grace and forgiveness one can give when mistakes are made. Good for you, good for them.

I replaced so many crank bearings on two-strokes in the seventies and eighties, maybe have done a single one since!

Another fan of the Swiss army knife is Allen Millyard but he uses mostly the scissors.

I’ve always wondered how motorcycle cranks were assembled.now I know. Another awesome video,Paul!

Lead hammer is the preference for assembly and truing. Myself, I have a lathe to check for true. It takes time to do it right and you do it well. And I do realize you are from Canada but it's pronounced aermacchi. You don't pronounce the Mackie. It's Italian made not made in Finland. And I have watched many of your videos on frame building. I do own 1 Harley 1 Norton Commando s 1 BSA and 1 67 Ducati Diane 250cc. As far as my credentials. I spent three years taking every course at MMI Phoenix not to mention being in the motorcycle business for over 10 years as a certified technician. But many years before that working on my own motorcycles and making mistakes. I did it wrong first and had to go to school to find out how to do it right. So anyway keep up the good work the videos are very informative and instructional. And I will promise not to nitpick on anyting as long as you stop saying aira Maki

That is going to be a good looking seat. I really like the shape of the pan You made. Sporty... 😎👍

Thanks, I learned a lot from this video

Luckily a 9 Pound Hammer was a little too heavy... The seat plug is looking good. This is going to be a very pretty and well sorted bike. All perfectly explained and executed. And perfectly filmed. Thankyou, sirs. (There would have been a guy or two in Coventry back in the day doing this day in, day out, year round. They probably got it down to 5 minutes. 'Bollocks to it' sounds quite nice in a Cov accent)... Keep yourselves well.

My grandsons and I enjoy your videos a lot. You are a great illustrator/teacher. I'm in the process of rebuilding a Vincent crank now. How do you keep such a clean shop, I'm jealous.

Hi Paul and Mitch from the UK 🇬🇧

I'm sure, though correct me if I'm wrong, there was a factory bullitin about the use of a hammer to assemble the crank, it wasn't a ball pein though it was a sledgehammer. Haynes of course says a meat tenderiser will do the job.

Another perfectly executed video by the builder and the videographer. Will you show the balancing process Mr. Brodie? I sure would appreciate seeing how you go about it. I just sent off my sons 07 KX250 crank out for a complete work over.

Paul's famous quote "that's a good fit" I would expect nothing less from his capable hands.

Perfect

Thanks Paul, Thanks Mitch

Pumped to see some balancing!

Interesting!

Perfection, mate. I've come to expect nothing less!!!!

Great job great videos!!!!! You definitely made it ez to understand. Have a nice weekend

nice job, you are an artist :)

Great episode, the truing process was very informative and entertaining. It is unfortunate the paint melted on the frame. Too late now, but in the future a couple spray layers of PVA would have protected the paint from the resin, and you can remove the PVA with water.

Love this precise content! Thank you for sharing... Will we ever get to see the surface grinder in action? Best from Sacramento

No workshop would be complete without a Swiss army knife 👌

Awesome work Paul and Mitch! I always learn something from your videos. Than you!

Damn Paul is one of those guys who's just like....Ok I can figure this out....and he does.

As usual, another great video from you guys..... I wish I could do an apprenticeship w/ you and learn how to do stuff like this. 😁

Just thinking of Kentucky windage from the balance holes in the crank halves as they grab oil and sling it.

Another great video. I'm so happy I found out your channel 😁✌️. Grande Paolo continua così! 🙏🏼🤩

it went well coz you had an old bloke working on a old bike thats a good fit

Thanks Paul & Mitch! I assume the plug in the end is for the oil system?

never had to straighten one but I've checked them for straightness a couple of times. seeing you do the whole procedure takes the mystique out of it and makes it do-able. some of the stuff in those reasonably priced manuals is laughable but I think they are aimed at the guy working in his driveway on the weekend.

I’ve never rebuilt a crank.... yet! I wonder how much fiddling a twin would take?

Be sure to remove the slotted galley plug on the right side fly wheel and clean out the sludge trap.

I got a bit lost when you got to the big pinch in the vise. And if you started with ten thousanths run out on one side how did that get fixed? Just pushing things around did it? What was the last piece for too? Plug an oil gallery? I am doing 1917 and 1920 Harley flys now as we speak. Precise stuff!!! Thanks, Thailand Paul

Brilliant video, I’m going to do my crank next week! Hopefully it will go as smoothly as yours 🤞

Surely that’s an Alpha big-end assy? Cubs as standard had a bushed big-end as far as I know. So is the aluminium plug part of the oil-supply mods needed with an Alpha conversion? Thanks for another very interesting video Paul and Mitch. It took me back to days of stripping and reassembling my BSA C15 on my Mum’s dining table (really!) along with my mate Pete and his Lambretta engine. My poor mother!! Les in UK

Thanks for the interesting video. How is crank balancing done? I've been using bead-balanced tire inner tubes last few years on my two motorcycles ('74 Norton Commando and modern Triumph Bonneville) with great results (no more lead weights stuck to rims and paying the shop for balancing). Was wondering if something similar to bead balancing has ever been used on engine crankshafts? Perhaps some sort of steel tube attached to the flywheel, small ball bearings free to circulate within to achieve perfect balance at all rpms?

very intresting

The volatiles from polyester resin will pass through cling film (saran wrap) also sodon't waste yout time trying it !

Had you thought about putting a TIG tack weld in to lock it in place? I know they do it on high HP applications.

Hi Paul Wednesday 2nd March U.K. came and went and no Vid ?. Hope we are not asking too much ,two vids every 7 days . Look forward to Piston been fitted and maybe you can show us all how to make billet buttons or Teflon ones on the lathe. stay safe .

I just can't get over how you basically need a hammer to build a motorcycle engine, I build car type engines, and a hammer is the last needed, I still can't believe the cranks survive what they do! But I have a scooter engine I'd like to build, I want to make it a two cylinder, starting from a 39mm bore/ 49cc engine, use a big bore kit. With 52.4mm bore, with 41 mm stroke, x2 approximately 88cc per cylinder, or with the striker crank. Around 96cc, with larger valves, ported head, 'Heads' well they would be welded together! I'm thinking maybe the cylinders could be kept separate, but either way, I'd like to tap the oil passage, to run it through a cooler before going into the heads, would machining the cooling fins down, and closing them in, to convert to water cooled, be too much? I wonder if a high volume oil pump could be made using two pumps, and a bit of machining, surely I could get 12 HP from near 200cc, I'd want extra oil volume. Because there is more area to pump oil into, I thought about using the cam as an oil passage, to oil the lobes, with the 81cc engine I have now, with cam, large valves ported, exhaust and larger carb, it started with 3hp+/-, surely it's making 5 maybe 6 HP now, but double cylinders doubles firing events per. RPM! So wouldn't that make more power? Sorry to ramble, but I didn't even mention what I was going to ask to begin with! 😆 Haha, but the cranks, balancing, does the piston weight effect Ballance that much? In car engines, we always put light pistons on heavy rods, and vice versa.. always had the machine shop handle the balancing , but I'm hoping I can get rid of the vibration, even if I don't build the 2cylinder, I'd like to balance it so I'd feel better about revving it to 10k maybe 11k, I can hit 9500 easy, not 10k starts to worry me, originally 8500 is it, peak power anyway, but I have seen 10350rpm, I heard ppl turning 11k- great video..

That was brilliant ! (Even if I didn’t understand exactly the goal of squeezing the flywheel in the vice 😞…)

Hello...👍👍😃😃

When I was spending all my spare time at the motorcycle shop in the late “50”s didn’t the first Cubs have a plane bearing on the rod big end ? Good videos

I wonder what the part number is for the roller big end, my parts book only shows a bushing on my 65 square head.

Love the vids thank you. Do you cover optimum room size or ratios anywhere please? I will be building an extension so I have the option to change size now easy. I would be looking to seat 6 people. Cheers

👍👌

Are the main journal shafts pressed on too?

Are you ever gonna build a bike frame again, motor or pedal?

😎✌️

Probably better than when it left the factory…

10:11, 18:47 I need to brush up on my compilation editing...

Assemble the "ENGINE".

After you got the fly wheel aligned, it looked like while you were spinning it the gap between both plates was inconsistent. Was this in fact true or was it due to inconsistencies in the milling of the plates themselfs causing it to only look that way?

How about the sludge trap, did you clean it out?

Did you clean out the sludge trap in the timing side flywheel?? Bound to be full of engine debris??

Paul, is that rubber wheel you had on the die grinder a Cratex abrasive? Looking for similar, looks like 2 1/2" dia.

How much pressure did it take to press the pin back in?

Was the pin to block the oil gallery up? Also hitting the end ov the crank is going to throw the crank out again?

My mate Gromit, who used to work as a motorbike mechanic, always refers to Haynes as "The Book of Lies" ! ; ) Been using your CarboArD technique on a cargo Ebike prototype recently Paul...what's your distance consultancy day rate for a poorly paid UK bicycle mechanic?!

Brand new 55 years old, hahaha

P

Crankshaft not flywheel

First again!