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Old 01-20-2009, 07:52 PM   #16
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yea marshal that was funny
Thanks. Why are you calling me marshal?
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Old 01-20-2009, 08:17 PM   #17
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Thanks. Why are you calling me marshal?
Definately wouldn't be the sig, that's for sure.
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Old 01-20-2009, 09:36 PM   #18
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i dont do anything random when i build my diffs, just follow the instructions and all goes well..

the bit about holding the outdrives in place and seeing if the pulley will still turn i do, i make sure its tight until i cant turn the pulley by hand then on the front diff i give it another 1/2 turn and the rear another 1/4 turn.. from here i just adjust in the car

one thing i recommend though, is using ceramic diff balls..
the lifespan of the diff plates almost quadruples with ceramic balls installed instead of the steel ones

last time i built diffs i used a modified version of the ones that came in my car... used bigger diff plates and more diff balls (and ceramics).. this diff has never come loose, its always felt smooth and i've run that same diff in modified touring for about 3mths!
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Old 01-20-2009, 11:35 PM   #19
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Building diffs are pretty easy once you get the hang of it, but it does take time to do it right. Things you need;
400-600 grit sand paper, red label associated silicone (stealth lube works too, black label, but the red stuff works better), black grease and new diff rings, thrust ball bearings and thrust ball rings.
First step; sand the diff rings in a figure 8, make sure you keep em flat while doing this. Once the shiny surface is gone and you can see all the scratches, you're good.
Step 2; assemble the thrust bearing, only thing to say about this is use plenty of black grease.
Step 3; if the spring is new, compress it with pliers.
Step 4; assemble the diff, use just enough silicone to fill the holes with, then push the diff balls in them and put a small, small drop of silicone on top of every ball.
Step 5; tighten the thrust bolt until the diffs come together, then work in the silicone, continue tightening and working in the silicone. Tighten as tight as you can without putting anything in the out drive to hold it.
Step 6; breaking in the diff, do this on a car stand, NOT on the track. Simply apply 1/4 to 1/3 throttle while car is on the stand and hold one of the tires for about 10 seconds, then start rotating that tire in reverse for about 10 seconds. Continue with all tires a few times, then tighten the thrust bolt and repeat.
Step 7; setting the diff tightness. This depends on your motor application, the hotter the motor, the tighter the diff (although when in doubt, tighter is better, you can adjust it later to be a little looser). But this is a good start;

Quote:
Originally Posted by Govert
Install it in your car and check diff slippage by blocking the spur and one rear wheel. For instance: Block the left rear tire with your left hand. At the same time, block your spur gear with the same hand. Now gently try to turn your right rear wheel with your right hand. If you can actually feel it will turn, stop and tighten your diff a little bit untill your diff won't be able to slip.
The only things I will say here, is that only with hot motors does the tire need not slip at all, and while doing this make sure your slipper is all but locked.

Step 8; setting the slipper, this is of course a preference unique to most racers, but one thing should be noted above all else: the slipper should slip before the diffs ever think about barking. Using the same method as above, loosen the slipper until you are sure it is slipping and the diff isn't. Set slipper to your preference after that, but no tighter, if slipper is too loose then you need to tighten the diffs before tightening up the slipper.

This is the info that was given to me by a Losi driver at a regional event last year, since I started using this method my diffs have been noticeably smoother and last longer. I use this method for both on (no slipper though) and off road cars, and rebuild my diffs every 2 months. And that is only because I am obsessed with working on my cars. One thing to note, when building diffs this way, they will feel a little scratchy, this is the diff balls actually rolling across the diff rings that hand sand paper applied to them, the purpose of the sand papered rings is to get better grip on the diff balls to make them not slip as easily allowing for a slightly looser diff, also this is why the red label associated silicone is better than the stealth lube.
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Old 01-21-2009, 12:46 AM   #20
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Since when did I need sand paper? The instructions shows how to assemble it but I was just wondering if there is anything more I should watch out for.
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Old 01-21-2009, 01:18 AM   #21
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Since when did I need sand paper? The instructions shows how to assemble it but I was just wondering if there is anything more I should watch out for.

Sandpaper is needed to roughen up the surface of the diff rings. In this way the diff balls will grip better. This allows you to even loosen up your diff more than the situation where you don't sand your diff rings. So your diff is loosened up and at the same time will slip less soon.

I pretty much build it the same as trilerian does. The only thing I use is Schumacher diff grease instead of Associated.
Very important thing to do is compressing the spring. I do it one or two times, most of the time two times in opposite directions, to avoid a crooked spring caused by the angle of the pliers (not noticable with your eyes).
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Old 01-21-2009, 03:30 AM   #22
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Sandpaper is needed to roughen up the surface of the diff rings. In this way the diff balls will grip better.
And wear out much quicker too due to increased abrasion!

Personally I have always felt the diff plates should be left polished, let the pressure do the gripping, then you won't wear diffs out every race meeting. Never had a problem with diff action - and I have always used steel balls too! Be sure to degrease the parts before installation, they tend to be packaged with an oil coating to prevent corrosion.

Also key is the thrust bearing - really pack it with the black grease. I just used the Mugen Super Grease on my last diff and it seems very impressive, very thick indeed.

In my opinion the diff halves cause far more rough diffs than the balls and plates do. If the halves are a soft plastic they can distort (or be moulded badly in the first place) and cause many high spots. Yokomo SD-501 is a major offender. Machined alloy and steel halves are always much smoother.

Oh, and diff stickers are brilliant! I haven't touched my diffs for god-knows-how-long since fitting stickers to keep the dirt out.
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Old 01-21-2009, 07:03 AM   #23
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Well I built the diffs following the instructions and some of the advice on here. Just another question, if the diffs aren't smooth what do I do?
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Old 01-21-2009, 07:16 AM   #24
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Originally Posted by rcdude8 View Post
Since when did I need sand paper? The instructions shows how to assemble it but I was just wondering if there is anything more I should watch out for.
Most kit manuals show the assembly process, but don't go in to all the little extra things some folks do to get a better build. Sanding the diff rings is one of those little extras. Some people swear by it, some don't believe in it. For me the jury is still out on that one.


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Originally Posted by rcdude8 View Post
Well I built the diffs following the instructions and some of the advice on here. Just another question, if the diffs aren't smooth what do I do?
Depends on what you mean by not smooth... most touring car diffs even when built properly won't feel butter smooth in your hands, only when they're in the car with the wheels on will they feel right.
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Old 01-21-2009, 07:27 AM   #25
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Ok thanks for that Trips. You help has been very.......umm....helpful .

Anyways lets hope it works out because its going to be a pain if I have to pull it apart.
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Old 01-21-2009, 07:51 AM   #26
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Is there anything wrought with using to much grease if it doesn't sling out all over my car ?
Will my diff's not brake in right with lots of grease or is it something else ?
Thanks
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Old 01-21-2009, 08:40 AM   #27
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Is there anything wrought with using to much grease if it doesn't sling out all over my car ?
Will my diff's not brake in right with lots of grease or is it something else ?
Thanks
With the thrust, you can't have too much grease.

With the diff balls, I have found with some cars that the tolerances are very tight around the rings and diff gears - basically there is very little room for the silicone grease, and if you over-pack it you don't get enough pressure on the balls. So a light smear is all you need there.
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Old 01-21-2009, 09:03 AM   #28
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I don't think too much grease is a problem for the diff, but the extra grease can attract dirt and make a diff feel gritty before its time.

A little dot of grease on each diff ball is all it takes, any more is not going to help. For the thrust bearing, use plenty, just don't go crazy and have grease all over the place.
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Old 01-21-2009, 09:41 AM   #29
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I don't think too much grease is a problem for the diff, but the extra grease can attract dirt and make a diff feel gritty before its time.

A little dot of grease on each diff ball is all it takes, any more is not going to help. For the thrust bearing, use plenty, just don't go crazy and have grease all over the place.
+1 on that Trip that is the way i was told and i was also told that if you put to much lube in there the balls will slide until they flat spot so i stick to the little dab a do ya deal and seam to be ok
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Old 01-21-2009, 10:07 AM   #30
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Originally Posted by Govert View Post
Sandpaper is needed to roughen up the surface of the diff rings. In this way the diff balls will grip better. This allows you to even loosen up your diff more than the situation where you don't sand your diff rings. So your diff is loosened up and at the same time will slip less soon.
Guys that sand diff rings are do so to make them flat. Diff rings are rarely if ever flat to start with, they're full of high and lows. I start with a 400 grit paper and gradually work to 1000 grit. The finished product is a nice FLAT smooth set of diff rings. The surface shouldn't be rough. A well built diff feels smooth, it should never feel notchy.
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