Trouble with my trikes brakes

Joined
Dec 8, 2016
Messages
5
Location
Port St. Lucie Florida
I have an old Sun Floridian Trike and a rusted OCC Chopper so I used the rear of the Trike and joined it to the Chopper. I ordered a Coaster brake conversion but now the bike doesn't stop. I assume because the Sun sprocket is a Free Wheel, the Trike only had a front brake. I was thinking of getting a Fixed sprocket which I think will do the trick but the Trike axle is solid and not sure how to remove it so I can get the sprocket off. Anyone have an idea on how to remove a Sun axle which is probably over 20 years old? I wasn't sure if the sprocket change is the answer or if the Free Wheel can be modified to a Fixed sprocket without removing the axle.
 
Joined
Feb 20, 2013
Messages
682
Location
Axedale, Victoria, Australia
Website
axerail.coffeecup.com
In Australia, a coaster brake is one where you apply backwards pedalling to apply the brake. It is usually a single sprocket drive and there is an arm on the left side fixed to the chainstay. The harder you apply the backwards pressure, the more it stops the wheel. Is that what you have?
 
Joined
Dec 8, 2016
Messages
5
Location
Port St. Lucie Florida
Yes, without weight on the bike the drive wheel does stop but once riding the trike when you pedal backwards to apply the brake it does not stop no matter how much pressure is applied. The brake arm is attached to the chain stay, this causes me to think it's the rear sprocket.
 
Joined
Feb 20, 2013
Messages
682
Location
Axedale, Victoria, Australia
Website
axerail.coffeecup.com
With the wheel off the ground, it should not be possible to turn pedals backwards more than a part turn. What happens when you try?

Sitting on it should be the same result.

If it doesn't work the same under load, it could mean it needs attention or replacement. I've never pulled one apart except to modify it for front tadpole use so didn't worry about it going back together. There's not much in them so it should be easy enough. I do have one somewhere if you need to find out.
 
Joined
Dec 8, 2016
Messages
5
Location
Port St. Lucie Florida
I had the rear section off the ground, moved the pedals forward, gained speed and the applied the brake. The drive wheel stopped, when I sit on it and move forward and then applied the brake by pedaling in a backwards motion, the bike does not stop. My thought is the sprocket as the loaner was from a Sun trike that did not have rear brakes. The sprocket appears to be a free wheel as it spins backwards like as a geared cassette.
 
Joined
Feb 20, 2013
Messages
682
Location
Axedale, Victoria, Australia
Website
axerail.coffeecup.com
The sprocket appears to be a free wheel as it spins backwards like as a geared cassette.
I'm puzzled that the pedals "spin backwards" but only when the trike is rolling with you on it. In other words, the wheel stops when there is no real forward rolling force on it. That would indicate that it is defective or might need a clean or lubrication. If it's a free wheel you could possiblt hear it clicking.

Have you held the brake on the wheel and checked to see how easy/hard it is to rotate the wheel with the brake applied?
 
Joined
Dec 8, 2016
Messages
5
Location
Port St. Lucie Florida
The pedals don't spin backwards because the brake from the coaster brake conversion kit activates. The sprocket on the axle continues its forward motion even though the chain from the axle to the coaster brake locks as its to brake. From my experience with coaster brakes and cruiser, bmx bikes, is that when the coaster brake is applied, the rear wheel slows or locks depending on the amount of pressure applied when moving the pedals to a rear position.
On the trike, no matter how much pressure is applied to the coaster brake by pushing the pedals backwards, the rear axle and sprocket continue spinning forward. I'm not sure if the coaster brake conversion kit is defective or if the sprocket on the axle is a free wheel? When you spin the sprocket backwards it does make the traditional clicking sounds that a cassette makes. I see on some coaster brake conversion kits they come with a simple axle sprocket that doesn't have bearings and simply moves forward and backwards as the axle moves.
It has me puzzled, Sun bicycle has a 24T fixed sprocket for the axle which I was going to try but not sure how to even get the axle out as it appears to have been pressed in. As being part of the AZ community, I would hate to scrap the Sun rear assembly and then purchase a new trike conversation kit that comes with the coaster brake and rear axle, its expensive. I may need an easy fix but I just haven't been able to sort it out yet.
 
Joined
Oct 19, 2012
Messages
799
Location
Wakefield, UK
If the rear sprocket was fixed you'd never be able to press the pedals backwards as they'd continue to rotate forwards. There may be some freewheel mechanism within the brake to allow a fixed sprocket elsewhere but there must be some freewheel somewhere.
Some pictures of the mechanism may help someone point to the defect.
 
Joined
Dec 8, 2016
Messages
5
Location
Port St. Lucie Florida
On the coaster conversion kit there's a fixed sprocket that a chain goes to the sprocket on the trike axle which is not fixed. The other sprocket on the coaster brake conversion is a free wheel and it drives the chain drive. The coaster brake is on the side of the conversion kit that has the fixed sprocket. When you apply the coaster brake the drive sprocket locks up depending on the amount of pressure given, the fixed sprocket on the other end of the conversion kit also locks as its attached where the coaster brake arm attaches to the chain stay. The sprocket on the axle continues to spin forward even the coaster brake was applied. This leads me to believe that either not enough pressure is being able to attain a stopping motion or the axle sprocket is wrong for the application. When the bike is raised at the rear and you pedal forward and then apply the brake the drive wheel stops, when you sit on the bike which is applying weight and then do the same thing, the bike does not stop.
 
Joined
Feb 20, 2013
Messages
682
Location
Axedale, Victoria, Australia
Website
axerail.coffeecup.com
That's weird. So, you have a conversion. That changes the ball game. A picture at least would be good. I'm puzzled as to how you can have two sprockets, presumably chain driven as there would be no need for one at least to be there, doing two different things.

It seems like it might be a DIY modification rather than a commercial conversion. Anyway, conversion means it is no longer what it was and maybe what it was, was a braked wheel mechanism.
 
Top