truggy diffs into Revo, what fluid weight?
 

Hey guys I just bought some non-assembled HB D8T diffs, two fr/rr and a center diff. I am curious on what oil viscosity I should use? I have some 100k traxxas weight oil here, but I think that is only good for the center I'm sure?

Does anyone have a oil weight converter to translate ratings from one brand to another?

Also, does anyone have a manual to assemble these differentials? How many shims should I use, etc.

This will be used in my Revo for racing, which btw, can outrun 90% of the truggies at the track with a single speed conversion.

Thanks for the help

How were you planning to fit these in a revo- do you have some of Mikes Hybrid diff cases?

How many shims depends on how tight or loose they feel once dry-assembled- usually you do it by feel since every diff has tiny variances.

Diff fluid weights tend t be the same or very similar from brand to brand- for 1/8 scale diffs something around 5k front & 3k rear, or 7k front & 3 or 5k rear is fairly typical ( I use 5k/3k for my UE diffs in my Gmaxx ).

^ what Neil said.

Shim until tight and then back off a fraction of a hair. You don't want them tight but you want as little play as possible. Do the shim dance!:yes:

Any good shim job will have you assembling and disassembling each diff several times. Trial and error are the only way to a good shim job. Set aside some time and plan accordingly. It's worth it in the long run.

Well no it's not, I have 100k traxxas diff fluid, and I am not sure how it compares to the typical 1 - 10k rating of the brand you are mentioning. I know that there are a few different ones.



I just noticed that the diffs I bought do NOT come with pinion gears. I just looked it up on AMAIN, I found this gear, which all I need for this is Mike's Revo shaft adapter, right?


http://www.amainhobbies.com/product_...al-Pinion-Gear

100k is 100k, doesn't matter which brand it is really in that sense- if you need 3k or 5k, then buy 3k or 5k of whichever brand takes your fancy. 100k of traxxas oil doesn't equal 10k of brand X oil- the ratings are consistent in that sense across brands ( allowing for different formulas ) as far as I'm aware...



Yep, that's the one you want- don't forget to add some shims though ( something like 8x10x0.2mm will do the trick usually ).

If you buy that pinion, you shouldn't need a converter since it appears to already have a 6mm shaft which is what the stock Traxxas sliders use. If it were an 8mm shaft the whole way, you would need Mike's adapter.

Basically you go till tight, and then back off one shim. Again, a tight constant mesh causes unwanted heat. You want just half a hair of play.

The more in depth answer is that if you are using "X" size shims, and if 4 is too tight, 3 may be too loose. You may need to use 3 "X" shims and one "Y" for a perfect mesh. 3 ".2mm" shims and 1 ".1mm" shim, for example.

When assembled, if you turn the diff input, the outputs should almost instantly turn as well. Then turn the input in the opposite direction. If turning the input in the opposite direction immediately turns the outputs in the opposite direction, it is too tight. There should be just a hair of play when changing directions, like 5 minutes on an analog clock. Just a tick. Not tight, but not loose.

Get a bunch of different sized shims. In this hobby they are nice to have around. You could spend a whole weekend on diff shimming if you want to get real anal about it. It will definitely help, but in the long run, everything breaks.

Diff shimming is the same as setting a spur/pinion gear mesh. Don't bury it in the teeth, but also don't leave it sloppy.

Yeah but the pinion does not have a straight through hole, so the cross pin/set screw on the shaft will not work. That's why I think the RC monster Revo adapter is needed.

Suicideniel, are you sure? I will look it up tomorrow some more, but I was sure that their are more than one. :neutral:

Paralyzed, thanks for the info on the shimming method. I will have to put these things together when I get the V1 cases.


For the center diff, I was thinking of either using a plastic center diff mounts and use some aluminum angle to mount to the chassis. OR use Mike's UNIVERSAL center diff/motor mount somehow. I could prob situate the center diff to at least ONE truggy CVD, and then use Mike's Revo shaft adapter, preferably for the front. I shall see.

Nope, the Rc-M revo adapter has an 8mm bore for 8mm pinion shafts.

What you would do if you want to use a revo shaft is simply get a set screw to use instead of the pin, or dremel the pin portion off.

But, if you are fabbing in a center diff dog bones and cups are the way to go. There are so many shafts available, you should be able to find a combination that works.

for instance I used an lst center cvd and a hyper 8.5 front shaft to put a center diff in the last e-maxx I built.

I needed around a 100mm shaft, so I got into the r/c section of ebay and just searched 100mm. If nothing matched then I search 99mm, then 101mm. (you usually have a few mm's to play with)

I always end up finding a shaft that will work. If you absolutely can't find a shaft Rc-Monster Mike can make custom length shafts.