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Old 09-19-2008, 11:47 AM   #1
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Default 8ight locked diff question

I was wondering if it would be possible to lock the center diff and run only rwd with say 500k (or something that would work) diff fluid in the rear? I was thinking about trying this on the L8ight model when it comes out. Anyideas on how to do this with out totally FUBARing my car?
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Old 09-19-2008, 12:52 PM   #2
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You could just put some diff lock lube in the diff to lock it. Here's the link for ya http://www.tiltedrc.com/product_info...434271ef090e51
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Old 09-19-2008, 12:55 PM   #3
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To my knowledge outside of jbwelding your center diff there currently isnt a way to completely lock it. I have tried 2 different methods.

1)Racers edge diff lock putty. That pretty much locked the diff completely but after one day of running it loosened up. Took diff apart and OMG what a mess! It took me alot of scrubbing to get all of the stringy gunk out of the diff case and gears. I definately DONT recommend using that stuff!

2)Ofna diff lock lube. Does not lock the diff completely(can diff it out when manually turning it). I dont know if that would do the trick for you or not. I will tell you the stuff is very messy to work with but will probably be easier to clean up than the racers edge stuff.

If you really wanna lock your center diff contact Chad at dynotech racing. I know he is working on producing a locked diff but dont know where he is at in the process. Below is his website addy. Hope this helps.

http://dynotech-racing.com/
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Old 09-21-2008, 09:15 PM   #4
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you could try some goop/shoo goo (contact adhesive) and if you wanted to take it out you could soak it in some acetone for a few days and that would disolve it.
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Old 09-22-2008, 10:45 AM   #5
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i was just thinking of machining a aluminum piece that would replace the gear set inside of the diff any thoughts on doing this or any ideas?
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Old 09-22-2008, 11:22 AM   #6
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Isn't it ironic that a mechanically simpler thing (a locked diff) is harder to achieve than a more complex one (a workin diff)?
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Old 09-22-2008, 11:33 AM   #7
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Quote:
Originally Posted by Camberlink View Post
i was just thinking of machining a aluminum piece that would replace the gear set inside of the diff any thoughts on doing this or any ideas?


thats basically how the Pro's do it....but why do u need a locked center in the first place ?
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Old 09-22-2008, 02:41 PM   #8
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The guys around me running their 8's setup for the oval are just using heavy diff fluid. 300k or 500k. Some use silly putty mashed in there. Others use the diff locker fluid from Ofna.
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Old 09-22-2008, 04:35 PM   #9
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Quote:
Originally Posted by Integra View Post
but why do u need a locked center in the first place ?
Because he said he wants to run it RWD.



I have a center spool for my MP-6 that I bought years ago from Fironi but it was expensive ($45). I thought this was the best setup for 4wd parking lot bashing with slicks. I took it back out when I found an off road track because you have to have a center diff for off road. If you had a lathe you could just make one really easy.

If you really wanted to you could find someone really talented with welding and weld the small gears together like they do in real cars when they are too cheap to buy a spool for drag racing. If you could manage to do that the only cost would be another set of the small spyder gears if you ever wanted it to function again. Not really sure how good of a weld you could get on something that small that wouldn't destroy the gears. I have obviously never welded! I can't think of anything else that would keep them from moving.
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Old 09-22-2008, 04:39 PM   #10
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Because he said he wants to run it RWD.

whoops....didn't even see that.
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Old 09-22-2008, 04:40 PM   #11
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Here's pics of the other idea mentioned above about dropping something in the case to lock it. If you are handy you may be able to make one for an 8ight?
http://www3.towerhobbies.com/cgi-bin...cker&search=Go
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Old 09-23-2008, 12:27 PM   #12
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I thought about welding the gears that would be no problem ( I am a certified aerospace welder and i have a Tool and Die degree) but I figured that machining a locker (like one ones in the tower hobbies link that bjr48 posted)would be easier and i wouldn't have to worry about the shock load on the welded gears. I was just wondering if there was anything I would have to worry about.

thanks
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Old 09-23-2008, 12:40 PM   #13
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Quote:
Originally Posted by Camberlink View Post
I thought about welding the gears that would be no problem ( I am a certified aerospace welder and i have a Tool and Die degree) but I figured that machining a locker (like one ones in the tower hobbies link that bjr48 posted)would be easier and i wouldn't have to worry about the shock load on the welded gears. I was just wondering if there was anything I would have to worry about.

thanks
Wow! Wish I knew all that. I am a "hobby machinist" and a controls engineer. They all laugh at me when I run out to the shop here at work and want to use the Bridgeport. They say "what in the heck are you trying to do now?" "Why don't you just buy a NEW rc car?"
Go to google and type "welding diff"
On full size cars the concern is added stress possibly breaking the diff with big tires that grip like crazy in corners and if the welds ever break that you will probably tear up everything in there.
Maybe just look around a little in relation to full size cars but I don't know what the big fear would be on an RC? Let us know what you do and good luck! I guess if I had your talent I would try to mimic the lockers I showed you if you can so it's removeable and wouldn't come loose and destroy everything. And not really worry about stressing an RC diff.
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Old 09-23-2008, 02:29 PM   #14
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I was thinking later that the spool might be easier to machine and figure out dimensions! Here is a shot of mine in my home made snowmobile. It's being used just as an idler gear so notice there are no drive cups. They just insert in the end and are held in by set screws. The ends of the spool have shoulders for the bearings to push onto then the bearings just fit in the regular diff mounts in place of your gear diff...

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Old 09-23-2008, 03:02 PM   #15
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I make a center locker for the losi. I also make some other goodies for the losi that are oval specific.

The last thing you want to do is make the car a RWD, it will be undrivable and only do donuts.
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