Grubee 4G 1A freewheel hub reliability

[Otto Neumann]

Greetings, motorized bicycle enthusiasts; It's been a good while!

Following my 142F straight shaft engine walking the plank, I have moved over a conical shaft engine; after some intense researching, I have finally sourced a 144F engine (for who's unfamiliar with, it's a 52cc edition of the well known Huasheng 142F, which is 49cc in displacement) off Aliexpress, and it should get delivered to me next month.

While pending the engine, I got my hands on a transmission suitable for said engine from an American Ebay shop; it's identical to a GruBee 4G 1A model, and features a freewheel hub; I've been doing some researches on the internet, and I came across some fellows which experienced said freewheel hub suddenly kicking the bucket, after either 30, or 240 miles.

I'm aware which the GruBee freewheel hub is serviceable, mine is identical to the genuine one as it features two holes for a compass wrench, I was wondering if any of you had some recommendations:

Would it be a good idea to keep the freewheel, maybe cracking it open to swap the ball bearings, and apply a decent bearing grease, or would it better to just get rid of it by either welding it solid, or swapping out the reduction pulley?

I kept my straight shaft transmission, and its non freewheel pulley is interchangeable.

 

[Sidewinder Jerry]

Post some pictures of what you have.

 

[Otto Neumann]

Post some pictures of what you have.

This is the freewheel itself; I don't have a complete picture of the transmission at hand right now, as it is completely taken apart and inside a box, I'm pending for a seeger wrench to access the reduction pulley's bearings, one of them feels faulty.

The whole transmission looks like a 4G 1A, perhaps the plastic cover also covers the bolts that keeps it attached to the engine.

 

[Sidewinder Jerry]

With freewheel failures 90% of the time its due to an overload of torque. The failure occurs with the pawls and/or the ratchet teeth. Higher quality freewheels such as White Industries can handle larger amounts of torque. Transmissions with freewheels give a much better performance than the ones with oil-lite bushings or brass bushings.

 

[Otto Neumann]

With freewheel failures 90% of the time its due to an overload of torque. The failure occurs with the pawls and/or the ratchet teeth. Higher quality freewheels such as White Industries can handle larger amounts of torque. Transmissions with freewheels give a much better performance than the ones with oil-lite bushings or brass bushings.

Oh yes, I'm well aware of it! So much so, I have the blueprints for the White Industries flanged freewheel; and I've been fiddling on a pulley designed to fit it, tragically, to be machined: The freewheel I got has a different pattern and the heavy duty one won't fit.

My 4 stroke bicycle is a cruiser model, so I geared it fairly low to exploit the torque and lower the wear on the clutch; it's fully belt driven and the ratio between the two HTD-5M pulleys is equivalent to a 10T drive sprocket paired with a 51T rear sprocket; and besides that, I go very easy on it.

With my setup, should I trust this freewheel, or just swap the reduction pulley?

 

[Sidewinder Jerry]

It's much easier to adjust your chain sprockets than it is to change out the transmission pulleys

With the 144F if you're under 200 lbs, use 26" wheels, don't have hills over a 15% grade, and keep the 5\1 reduction then you can run a 10t|32t sprockets. This'll give you a level ground speed of 33 mph.

With the 142F if you're under 200 lbs, use 26" wheels, don't have hills over a 15% grade, and keep the 5\1 reduction then you can run a 10t|36t sprockets. This'll give you a level ground speed of 29 mph.

If you're over 200 lbs then run a 36T minimum on the 144F and a 38T on the 142F. If you have steep hills to contend with 15%+ grade, then you need to build a shifter bike. Otherwise you'll be burning out clutches or having to gear very low to where your top level ground speed is under 20 mph.

 

[Otto Neumann]

It's much easier to adjust your chain sprockets than it is to change out the transmission pulleys

With the 144F if you're under 200 lbs, use 26" wheels, don't have hills over a 15% grade, and keep the 5\1 reduction then you can run a 10t|32t sprockets. This'll give you a level ground speed of 33 mph.

With the 142F if you're under 200 lbs, use 26" wheels, don't have hills over a 15% grade, and keep the 5\1 reduction then you can run a 10t|36t sprockets. This'll give you a level ground speed of 29 mph.

If you're over 200 lbs then run a 36T minimum on the 144F and a 38T on the 142F. If you have steep hills to contend with 15%+ grade, then you need to build a shifter bike. Otherwise you'll be burning out clutches or having to gear very low to where your top level ground speed is under 20 mph.

I would swap the transmission pulley only to avoid using that freewheel; or eventually, for getting to use the pulley designed for the White Industries freewheel.

With my current setup, I can finely adjust the ratio by swapping the driving sprocket, in the output shaft; I'll take a picture tomorrow

I'm under 200 Lb, and besides a few places, 15% inclined streets aren't exceptionally common around, so as for the gearing I'm pretty
much happy like so.

I guess I'll try the transmission with the freewheel sprocket around the house for a while; my 144F is pending departure from China right now.

 

[Sidewinder Jerry]

I would swap the transmission pulley only to avoid using that freewheel; or eventually, for getting to use the pulley designed for the White Industries freewheel.

With my current setup, I can finely adjust the ratio by swapping the driving sprocket, in the output shaft; I'll take a picture tomorrow

I'm under 200 Lb, and besides a few places, 15% inclined streets aren't exceptionally common around, so as for the gearing I'm pretty
much happy like so.

I guess I'll try the transmission with the freewheel sprocket around the house for a while; my 144F is pending departure from China right now.

If you're geared to high and don't have a super clutch. The clutch will burn up before the freewheel fails.

 

[Otto Neumann]

If you're geared to high and don't have a super clutch. The clutch will burn up before the freewheel fails.

View attachment 228234

I cannot source super clutches except for genuine Honda clutches, the 144F fits Gx-35/Gx-50 style clutches; staton inc used to have super duty ones but I haven't seen them selling them anymore in the past year or so.

I have adapted a 144T belt drive sprocket for 2 stroke kits on my bike by drilling 3 holes with a 3D printed jig; it's fairly large, so I can always stretch my ratio to a lower one:

I can choose to step up the drive sprocket size to a 28, 30 and 32T one, thus having the final ratio equivalent to having a 48, 45 and 44T rear sprocket; I can go even lower if I find the right HTD 5M sprocket, I don't have the math at hand tho because I didn't planned to go that low

 

[Sidewinder Jerry]

(RPM × Wheel Diameter × π)
÷ (1056 × Total Reduction)
= MPH

Those two engines max hp rpm is 6800.

If you aren't very good at figuring up Total Reduction, use this formula. Teeth pulleys and sprocket can be interchangeable

(RPM × Wheel Diameter × π × Drive Sprocket(s)T)
÷ (1056 × Driven Sprocket(s)T)
= MPH