3 HP Briggs/Cranbrook Build

[tnjeff]

Tell me about moving, just finding stuff even when I labeled boxes with fair description of contents is a $^&^.

Yeah, when had a basement, everything was in the basement, somewhere. Now I'm just trying to find the best places to put stuff that makes sense. Wood tools here, mechanicing stuff there, yard tools somewhere else. Seems to be alot of crossover.

Looking at the crankcase wall of the engine does the engine crankshaft rotate counter clockwise?

Well, I'm not sure, but I think it rotates clockwise. I think when you pull the starter rope it spins it clockwise. So that would make the clutch side left hand?

 

[msrfan]

The threaded hole in the left side of the crankshaft is right hand thread, The nut that holds the flywheel on is also right hand thread.

 

[MEASURE TWICE]

Anyway without worrying about bolts loosening due to not having self tightening due to the shaft spinning, I just want to know if this pans out as true.

If both side of the crankshaft are Right Hand Thread, then one side has to be not self tightening due to the rotation. Logic I think has it that both cannot be self tightening in this case.

 

[msrfan]

The flywheel nut would be prone to loosening except it is a tapered and keyed shaft that does not allow it to spin.

 

[tnjeff]

It's right hand thread. Now that it's off the clutch will move outward about an eighth of an inch. Do I need to use a puller to get it off of the shaft? There's a circlip on the end of the clutch but it doesn't seem to have anything to do with holding the clutch on the shaft. Thanks.

 

[msrfan]

Soak the clutch shafts in penetrating oil for a while, then remove the snap ring and the clutch bell can be taken off. It looks like a conventional unit, so after you get the bell off, there's probably another snap ring you can remove and reveal just the inner hub. It appears you should be able to remove the rest of the clutch with light prying against the motor with a couple of screwdrivers. If that doesn't work, you can try a puller and/or heat a little with a propane torch. The main thing to keep from damaging the clutch, don't get too heavy handed with it. Easy on the pullers and pry bars, not too much heat and no hammers. If you use a puller, put the bolt back in the shaft part way to prevent damaging the threads. As soon as it starts to move off the crank shaft, remove the bolt and the rest should be easy. Then clean everything, polish the shafts if there's rust or corrosion, lube the bushing and reassemble. A coat of paint on the bell would also help.

 

[tnjeff]

Thanks msrfan. I just need to get a new pair of snap ring pliers. I'm not too sure how much work the Briggs will need to get running. Been sitting for quite a few years. I was measuring the motor mount holes yesterday and some oil leaked out. Looked pretty clean and fresh. I was in harbor freight yesterday and checked out the 79cc Predator and got wobbly for a moment, but I want to try it with the Briggs. I think I'll learn more.
Jeff

 

[tnjeff]

By the way, here's some inspirational thought on "The Big Project".

 

[MEASURE TWICE]

Some of the older clutches are made in a way the there are two sections that work with the keyway. If both are not aligned together when installed, then it grabs and is hard to remove. There is this dimple in side that must align with the keyway. I would hold the inside of the clutch bore on one end and rotate the other half to be aligned. The newer clutches don't have that and then if it is stuck it is like was said above. I use some emory cloth to take take rust of both clutch bore and the crankshaft on very old stuff.

 

[tnjeff]

Well, after I removed the inner snap ring, the blocks and the backing plate just fell out. It did have the dimple. Came off easily with the puller.

All the parts:

And the shaft:

Thanks for your help guys. Next step is the angle iron motor mounts. The only tricky thing about that is since the mounts will be bolted to the frame, the holes in the frame will have to be drilled exactly perpendicular to the frame tube. I do have a drill press but it's in a very small storage room and I'm not sure
I could make it work for this anyway. Thinking about bolting the bottom bracket to my little work mate bench and then making a guide for the hand drill.

 

[KCvale]

Next step is the angle iron motor mounts.
The only tricky thing about that is since the mounts will be bolted to the frame, the holes in the frame will have to be drilled exactly perpendicular to the frame tube.

Just to be clear...
You intend to put a huge engine in the worst Wallmart <$100 bicycle everyone knows to avoid?

And then drill it's frame?
Why?

 

[tnjeff]

Hi KC.

Just to be clear...
You intend to put a huge engine in the worst Wallmart <$100 bicycle everyone knows to avoid?

And then drill it's frame?
Why?

Well, regarding the cranbrook frame, it happens to be what I have, and I'm not sure that everyone knows to avoid it. I have read both favorable and unfavorable comments on this and other forums. Anyway, it's what I have. Be assured that I am constantly on the lookout for other, better frames that can be had reasonably.

As far as drilling the frame, I don't weld at this time and for this particular project, I'm trying to do as much as I can without it. I understand the reservations about drilling the frame, and I am not 100% there yet. I could (probably) make a plate and pay someone to weld it to the frame. Or I may not.

So for the Big Why, I have two main goals here. One, to learn to build a functional drive train by myself, or at least using all of the good advice on this forum. Two, to collect and experiment with different parts (brakes, hubs, etc) to be used on the next build (the one with the good frame and solidly welded pieces). Once
I find stuff that works, it will be transferred to the next build. Oh, and I have to learn how to get the engine to run too.

This bike, in addition to being a "test bed" will, if it runs at all, be used for leisurely trips from one end of the drag strip to the other. It will not be street ridden, no land speed record attempts or anything of that sort, so I'm hoping that as long as I keep it within that narrow envelope, any problems that I have won't be catastrophic.

I've admired your builds and your philosophy since I found this forum a year or so ago and I hope to learn alot from you.

Thanks,
Jeff

 

[xseler]

Well played, sir!


I built a Cranny almost 5 years ago (before I found this forum & discovered how 'uninformed' I was) that has a drilled frame. I've ridden this bike hard --- both street and fire trails --- with zero issues. Maybe I'm just lucky. Look'n forward to the next 2000 miles on this frame.

Full disclosure, about the only part remaining of the original Cranbrook is the frame. Keep calm & ride on!

 

[MEASURE TWICE]

I have used the clamps that are used on the seat posts to tighten the seat, for places else where on same size tube on the frame to attach parts to.

Since the clamps use a bolt and nut, I just added threaded rod and extend the rod to attach an additional structure. I call it the skeleton frame where I will be adding fire proof fabric that is to look like the skin of a California Sheeps Head Fish, this for parades.

I bought these parts online. They are steel and can be stretched open enough to clear the tube and be bent back where then I put the threaded rod and nuts and split lock washers on. They would weaken after many bendings so that I would be aware of.

There are various size tubes on the frame I have an some I have not found a way other than CNC Milled Parts that they sell for motorbikes and whatever. They however are not cost effective for someone who picks the trash as I did for my frame, its a JC Penny Foremost from maybe 60's to 70's Era.

Also do not forget that steel cable and turnbuckle for holding the engine from the top of the cylinder, from one of the cylinder head bolts or what you can find. I just would keep it to just that one, the engine platform should be bolted as that is necessary for rigidity.

I got a Mig Welder so I would weld the platform, but for my bike to be modular and go back from one use to the other OHV Legal off road, trail riding, I thought of these clamps.

Look and search the web and the forum to see what could be used to do without welding and the use of clamps that don't require a large cost or your owning and operating a mill and lathe.

 

[KCvale]

Well, regarding the cranbrook frame, it happens to be what I have, and I'm not sure that everyone knows to avoid it.

It's not so much the frame itself, I mean it's steel, very thin steel but steel non the less.
The thing is most everything attached to it is junk, especially the back coaster brake.

I built a Cranny almost 5 years ago (before I found this forum & discovered how 'uninformed' I was) that has a drilled frame. I've ridden this bike hard --- both street and fire trails --- with zero issues. Maybe I'm just lucky.

Your rear hub has not self destructed yet?
Lucky indeed.

 

[xseler]

It's not so much the frame itself, I mean it's steel, very thin steel but steel non the less.
The thing is most everything attached to it is junk, especially the back coaster brake.


Your rear hub has not self destructed yet?
Lucky indeed.

The rear hub grenaded over 2 or 3 years ago. It probably helped that I rarely used the coaster brake. I've got Weinman wheels with Shimano CB E110 internals now. The frame is the only thing left of the original bike.

 

[KCvale]

The frame is the only thing left of the original bike.

My point exactly.
Spending another ~$100 on the bike to start with really pays off in the long run, actually, for the Cranbrook, usually the short run.

 

[xseler]

I imagine that this hobby is very similar to most hobbies.......many people have the best intentions of following through with their projects, but most don't. A Cranbrook gets them in the door fairly inexpensively and isn't a financial disaster when they lose interest or can't complete the build. I would bet that 1/2 of the engine kits see less than 50 miles in their entire life. Maybe 20% are never even started. There's not a 'long run' for most of these builds.

If I had known that I'd still be enjoying this 5 years down the road, I may have looked for something more substantial at the start. However, probably like most folks, I just used what I already had.

This has been the most enjoyable and least expensive hobby that I've ever had!

 

[tnjeff]

I have used the clamps that are used on the seat posts to tighten the seat, for places else where on same size tube on the frame to attach parts to.

Another good idea. I had thought about making the angle iron mounts run laterally instead
of longintudinally (one front and one rear, instead of left and right) and using a u clamp bolted to the angle iron. Doesn't seem like that would be rigid enough. Be cheap to find out though.

It's not so much the frame itself, I mean it's steel, very thin steel but steel non the less.
The thing is most everything attached to it is junk, especially the back coaster brake.

Agree. I hope to build my own wheels and to be able to spend the bucks for front and rear discs, or front drum and rear disc. Overkill?

This has been the most enjoyable and least expensive hobby that I've ever had!

Yeah, I need something to tinker with and a problem to solve. Can't say I'm good at it, but I do enjoy it! Probably won't get much done this weekend with family obligations and all.

 

[curtisfox]

There is also motorcycle clamp, that work good for clamping a lot of stuff even motors, all different sizes............Curt