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cliffw0970

Brat 'Grinding My Gears'

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I was hoping someone could shed some light on this problem.

IMG-4912.thumb.jpg.03898fb607008cbd66727491026c452b.jpg

On my second set of diff gears. They just seem to strip within five minutes. Not had this issue with ANY of my other cars.

I knew these (second set) were going to go within 60 seconds, so I deliberately just helped them along to make sure the problem was blatantly obvious when I opened up the gear box.

Anyone any ideas?

Thanks,

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Alu side plate flexing is the usual problem , not as fast as this potentially . Not making a judgement here but are all required components fitted into the gearbox ? . All components fitted in correct order and the right way round ? .

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6 minutes ago, KEV THE REV said:

Alu side plate flexing is the usual problem , not as fast as this potentially . Not making a judgement here but are all required components fitted into the gearbox ? . All components fitted in correct order and the right way round ? .

+1 must check the fit and assembly... sometimes you have to assemble, disassemble, and reassemble those gearboxes at least a few times, playing around with spacers (bending things if necessary) until the gearbox is solid and smooth. And pay close attention to which direction the manual says to install things. It might not seem like it makes a difference, but it does.

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6 minutes ago, KEV THE REV said:

Alu side plate flexing is the usual problem , not as fast as this potentially . Not making a judgement here but are all required components fitted into the gearbox ? . All components fitted in correct order and the right way round ? .

Yeah, correct, present and pretty tight in there. Its really bizarre. The gearbox is horrible to assemble, not a fan third time round!

 

 

 

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1 minute ago, El Gecko said:

+1 must check the fit and assembly... sometimes you have to assemble, disassemble, and reassemble those gearboxes at least a few times, playing around with spacers (bending things if necessary) until the gearbox is solid and smooth. And pay close attention to which direction the manual says to install things. It might not seem like it makes a difference, but it does.

I have the replacement parts so will go again tomorrow. Maybe I AM missing something.

Something is certainly not right for it to happen twice in a row.

I searched for a video last time but couldn't find anything!

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10 minutes ago, Toolmaker72 said:

Just the one side that has worn?  Looks like a building error tbh

Not sure how I would miss it twice!

Re-building tomorrow, will give it a little more respect this time round!

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Is it the occasional popping/clicking noise?  Then the diff gears are slipping.  You might want to try sticky anti-wear grease on the diff.  It cannot solve the problem by itself, but it could help.  

I would also make sure the 3 bevel gears face the correct side.  While I don't think it should make a big difference, I still follow the picture on the manual.  The peg side faces up, the diff spur next, and then 3 bevel gears.  All on that side of the aluminum plate.  While you are at it, see if the pinion on the motor has the worm gear seated squarely on the cut side of the motor shaft.  

IBiqP5g.jpg

Before drive cups are installed, try to move the diff gears from left and right with a screw driver or a pencil to see if there is any slop.  Who knows, bearing supplier might have shipped thinner bearings.  If there is slop, you can use shims to reduce it.  Brat isn't really known for diff slip, because it's got much smaller tires. Compared to Blackfoot or Monster Beetle, the diff has to spin faster. That means less torque from the tires to mess it up.  A lot of times when I'm messing with something new, I take off and rebuild it, and the problem is solved. Half the times I don't even know why.  

 

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1 hour ago, Juggular said:

Is it the occasional popping/clicking noise?  Then the diff gears are slipping.  You might want to try sticky anti-wear grease on the diff.  It cannot solve the problem by itself, but it could help.  

I would also make sure the 3 bevel gears face the correct side.  While I don't think it should make a big difference, I still follow the picture on the manual.  The peg side faces up, the diff spur next, and then 3 bevel gears.  All on that side of the aluminum plate.  While you are at it, see if the pinion on the motor has the worm gear seated squarely on the cut side of the motor shaft.  

IBiqP5g.jpg

Before drive cups are installed, try to move the diff gears from left and right with a screw driver or a pencil to see if there is any slop.  Who knows, bearing supplier might have shipped thinner bearings.  If there is slop, you can use shims to reduce it.  Brat isn't really known for diff slip, because it's got much smaller tires. Compared to Blackfoot or Monster Beetle, the diff has to spin faster. That means less torque from the tires to mess it up.  A lot of times when I'm messing with something new, I take off and rebuild it, and the problem is solved. Half the times I don't even know why.  

 

Thanks for that. Plenty to look for tomorrow when I try again!

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