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Probably a dumb question… but

Probably a dumb question… but

Old 06-04-2016, 08:35 AM
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Default Probably a dumb question… but

My savage flux XL was working fine yesterday when the pinion gear came loose. I replaced it today and now I'm having nothing but problems.

By biggest and most concerning issue is the truck runs strong in reverse but just runs up RPMs and barely move going forward. My first thought is the diffs are shot but there was no sign of that yesterday and it seems like reverse would be screwed up too.

I have an Alza racing centre diff in the truck. Could an empty center diff cause this issue? What would make the truck not go forward but perfect in reverse?

😢😢😢😢
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Old 06-04-2016, 09:02 AM
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I would try recalibrating the ESC with your tx/RX. Also when messing with the pinion gear did you have to unplug the motor wires? If so I would try switching two around.

Last edited by CptKlink; 06-04-2016 at 09:14 AM.
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Old 06-04-2016, 09:20 AM
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I see what your saying but it's not reversed. The motor is free spinning full speed forward. But in reverse the gears catch and everything runs fine. If I creep the truck it will move but if I apply anymore throttle the center diffs along with the dice shafts free spin, but only going forward.
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Old 06-04-2016, 10:28 AM
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Make sure all the set screws are tight on your outdrives. It's also possible there's binding somewhere. I find it hard to believe you didn't change anything other than the pinion gear. Maybe the mesh is weird and the teeth are pointy?
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Old 06-04-2016, 11:09 AM
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So I couldn't sleep with the truck like that (I work nights) so I started a tear down and things only got more confusing. In kind of a good way though. I was expecting to pull the diffs and find missing teeth but they looked fine.

I powered the truck back on half assembled with the tires and under power everything was spinning fine until the out drives on the diff. So I opened up the diff and expected to find spider gear teeth missing but no. They looked perfect also. For some reason it seems as if they just aren't engaging. Maybe I left the screws holding the gear on the diff too loose??

When I tested it half assembled the tires would move but when I hit the break everything would stop moving except them. They would keep free spinning in the same direction for a second or two.
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Old 06-04-2016, 11:23 AM
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Have you check the little drive pins in the diff output cups?
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Old 06-04-2016, 05:16 PM
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I just pulled the diff all the way apart and put it back together. I'm still running grease in them. Could a lack of grease cause this?

After that all I have left to think is an electronic problem. I'll try resetting the esc. That's kind of my last hope.
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Old 06-04-2016, 07:00 PM
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My Associated truggy does the same thing when the spider gears in the rear diff are worn. The teeth on all the gears look fine but the spider gears all have the edge worn off of each tooth. They just slip past each other which essentially leaves it front wheel drive. When you go in reverse the weight of the truck shifts to the front wheels and it goes fine. I think you're rear diff spider gears are worn.
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Old 06-04-2016, 08:06 PM
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Ya i would start feeling the teeth of all the gears with your fingers. If they feel sharp at all the means there worn and in need of replacing.
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Old 06-04-2016, 09:11 PM
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Originally Posted by Micah78
My Associated truggy does the same thing when the spider gears in the rear diff are worn. The teeth on all the gears look fine but the spider gears all have the edge worn off of each tooth. They just slip past each other which essentially leaves it front wheel drive. When you go in reverse the weight of the truck shifts to the front wheels and it goes fine. I think you're rear diff spider gears are worn.
Thanks for that insight. Might be my issue.
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Old 06-04-2016, 10:32 PM
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I tried to order new spider gears a minute ago. Amain had them listed in stock, put 2 in the cart but theres only one set in stock. Talk about aggravated.

Tower doesn't have any and I can't find them anywhere else on the internet. I almost got frustrated enough to order a whole different set of diffs but calmed down before I blew some money that I didn't need to spend. The spider gears are only 8 bucks.

I can't wait until HPI get's there stuff together so they can restock all their parts. I guess I have a shelf ornament until then.
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Old 06-05-2016, 01:23 AM
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Have you tried dollar hobbyz?
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Old 06-05-2016, 04:49 AM
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Might be able to shim the gears to ensure engagement, assuming they aren't worn a lot. Gear diffs need to be re shimmed occasionally for best performance and life. Leave just a little free play.
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Old 06-05-2016, 01:44 PM
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If you could find these ( http://hpiracing.world/en/part/hbc8101-1 ) They would be your best option.

http://www.thobbies.net/product/2287...Set-Lightning/

http://www.ndheli.ca/hbc8101-1-hard-...tning/dp/16203
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Old 06-05-2016, 05:32 PM
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You guys are the best. Found some hardened steel gears on eBay. Just ordered them. Hopefully I'll be back up and running by later this week.
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