Rebuilding Yerf-Dog: Rusty brake and sprocket questions

Robert.jones10

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Here are some pics of the sprocket and brake with the axle bearing. I have the following questions:

1. Can I use chemical spray rust remover from Home Depot to get the rust off the sprocket and drum and call it good? Or do i need to replace them? Seems like after using the chemical rust remover I can lightly sand the surface where it contacts the band and its good to go.
2. The axle seems to run pretty decent, should I replace the bearings anyway? I have no idea how to replace them.
3. The brake drum is 4" in diameter, so any 4" brake band will work, right? I am thinking this one
 

Kart Flipper

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You can remove the rust for cosmetic reasons to repaint. Then you can attempt to run it "as-is" (easiest/least expensive solution). However you may need the ability move the sprocket/brake freely on the shaft to align your engine, etc. It is very difficult to avoid damaging the parts when it is as rusted as yours is. Bearings will also probably be rusted to the shaft (if they spin freely, I'd leave them be).

The brake band on the one I did was a 4.2" (was yerf dog specific)
 

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Robert.jones10

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You can remove the rust for cosmetic reasons to repaint. Then you can attempt to run it "as-is" (easiest/least expensive solution). However you may need the ability move the sprocket/brake freely on the shaft to align your engine, etc. It is very difficult to avoid damaging the parts when it is as rusted as yours is. Bearings will also probably be rusted to the shaft (if they spin freely, I'd leave them be).

The brake band on the one I did was a 4.2" (was yerf dog specific)
Oh excellent. Thank you for the info on the brake band. Yeah, the axle spins freely and doesn't make any noise.
 

Kart Flipper

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Oh excellent. Thank you for the info on the brake band. Yeah, the axle spins freely and doesn't make any noise.
Not a problem. Typically when they are as rusted as yours, you end up replacing most of it. Nice thing about yerfdog is the manuals/parts lists are still available online. BMI karts carries a lot of parts for that brand.
 

Robert.jones10

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Not a problem. Typically when they are as rusted as yours, you end up replacing most of it. Nice thing about yerfdog is the manuals/parts lists are still available online. BMI karts carries a lot of parts for that brand.
So do you know of a good video or instructions on how to take the rear axle apart to get the parts off on the 3203? I have been looking for something but all I find is the original owners manual. I think I have the 3202, but I see only a couple differences between it and the 3203.
 

Kart Flipper

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Parts lists and diagrams are usually in the manual toward the middle. As far as disassembling the axle goes, it's not really anything complicated. You loosen allen nuts and go. However, when rusted they usually require a spray, heat, beat and repeat approach, hard not to damage components cause you can't hit the end of the axle or you'll mushroom the end and damage threads. On the one I did, I made a small notch in the axle hanger and bent them outward slightly to pull everything out as a unit. Had to cut the sprocket, lock collars and bearings off.
 

Robert.jones10

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Parts lists and diagrams are usually in the manual toward the middle. As far as disassembling the axle goes, it's not really anything complicated. You loosen allen nuts and go. However, when rusted they usually require a spray, heat, beat and repeat approach, hard not to damage components cause you can't hit the end of the axle or you'll mushroom the end and damage threads. On the one I did, I made a small notch in the axle hanger and bent them outward slightly to pull everything out as a unit. Had to cut the sprocket, lock collars and bearings off.
Cool, thanks, I guess just loosen the fasteners and soak in oil.
 

madprofessor

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Something we did when kids to band brakes was slip a long strip of sandcloth (think tough very coarse sandpaper roll) between the brake band and drum, coarse side against the drum. Jacked up the rear off the ground, cranked up and got axle spinning slowly, and applied brake pressure just enough to start scraping the drum. This resurfaced drums left out rusting in the rain for a long time, worked very well. New band and it's a safe brand new brake system.
For any sliding of bearings, sprockets, etc. you want to do on that axle, PLEASE sand the axle excessively BEFORE applying any sprays.
Many spray-on or brush-on rust "removers" and "dissolvers" on the market. Not going to knock any of them, just my personal choice to always lean on penetrants and lubes. "PB Blast" in its cartoonish spray can is the best penetrant I've ever found, and is available everywhere, like Home Depot. Spray and soak every half hour until happy. Don't fight the smell, you can't keep it off your skin. Note: It's NOT a lubricant! Penetrant for corroded parts only. Use actual lubes for sliding anything, just wipe off all penetrants first.
People love WD-40 for a lube. I prefer to only use it as a finish lube, because it leaves a film on the parts that repels water and prevents rust, so don't wipe it off at the end. Highest quality lubes you'll find will likely be in an auto parts store.
 
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