Evo Center Diff
 

OK, I've been running my Evo for several months now. I have taken first in the A Main the last two weekends against the nitro's. I have been planning my center diff conversion for awhile now but haven't been able to complete it yet. I should have it completed soon.

Here are a few pic's so far.
http://home.earthlink.net/~j1138/evo/d0.jpg
http://home.earthlink.net/~j1138/evo/d4.jpg

I have installed the Hardcore Titanium skid plate along with an ofna center diff and spur. I have fabricated the new battery trays which will mount on either side of the truck. I am working on finishing the motor mount.

Thanks goes to Mike for all the help with my recent brushless questions. I think the BK36xx and the Lehner 1940/14 are going to be the HV combo I will go with.

That looks great , you and me had the same idea. But for my first evo i went with a tranny. What size spur is that?.

Nice, man! I like the idea of that skid, must add some rigidity. Should make up for the loss of strenght you get by the holes for the spur.

I like it very much, Starscream. Can't wait to see the finished truck! Nice work

This BL combo sounds good, too. You will get a heck of a truck!

This skid, are there some extra parts to keep the hinge pins in place?

The skid plate gets installed right over the stock skids so there is no change to the hinge pins. I don't have the skid plates installed in the pics.

I did have to fabricate a thin piece of alum to mount the center diff mounts.

I am using the ofna dominator 65t mod1 spur and a 10t mod1 pinion from Mike.

Ya, I had to take off quite a bit of material to get that spur in there but the Titanium skid should make up for the loss of material and rigidity.

If you have to you can always reinforce the sides.

Very, very nice!

Any up dates yet ?.

Yep,

Here's some pics:
http://home.earthlink.net/~j1138/evo/cd0.jpg
http://home.earthlink.net/~j1138/evo/cd1.jpg
http://home.earthlink.net/~j1138/evo/cd2.jpg
http://home.earthlink.net/~j1138/evo/cd3.jpg
http://home.earthlink.net/~j1138/evo/cd4.jpg
http://home.earthlink.net/~j1138/evo/cd5.jpg

It seems that my truck was having multiple diff issues. The f/r and center diff are going bad. I got the center diff used so I'm going to look into getting an aluminum center diff. I switched out the center diff with a center slipper for now until I get ahold of aluminum replacements. I would really like to have a slipper attached to the center diff. Since I would have to custom make the slipper mount, I'll have to wait and see how things go.

I made accomodations to allow the role hoop to remain installed. I like the role hoop for protection purposes and it makes a nice place to mount my esc. The batteries are now mounted on each side of the vehicle and the motor and controller in line down the center for better weight distribution. The batteries are mounted on top of the chassis because I plan on using Lipo's as soon as the funds are available. I want the Lipos on top of the chassis for better protection.

This truck currently weighs in around 11 pounds on 14 GP3700's.
I haven't raced it yet so I'll have to keep you posted on the race results. :)

I still have my original setup to fall back on in case this version has major issues :cool:

Looks great, as for your center diff issue ofna makes a all aluminum center torq senseing diff. And you can change the gear. It costs a $100.00 bucks at tower hobbies. This might be what your looking for. How does your revolt handle With the center diff ?. I just orderd the gmaxx tranny, 9L, & l can heat sink for my evo from mike.

I haven't got the truck on the track yet but the test runs at the house have been impressive. The truck is very responsive and easy to drive. I have the gearing as low as currently possible which is 18.5 to 1 so I reduced the cell count to keep the motor temps down.

I am eager to take on some nitros with this truck.

Whats the ofna part number for the diff you mentioned?

Thanks

Starscream, Excellent work, very nice. Are those shafts connecting the diffs custom? If not, What are they for origionaly? where did you get them?

Thanks crazyjr,
I got the center diff fixed and re-installed last night. The truck drives really nice with it. I am using an Unlimited Engineering 105mm drive shaft in the rear and an ofna lx comp driveshaft in the front with UE yokes. I can't wait to get this truck back on the track and take on some nitro's :D

Looks really nice, I'm jealous. I've been pondering the same idea, except making a kind of custom truck, then I realized its already been done by Bomb-Proof and Cold Fusion lol. Guess i'll have to stick with smoking all with the xxx-t.

That is until somebody converts a jato

I've got a feeling the Jato will be done soon...

I decided, no more compromises. I am using the center diff along with the revo two speed and a slipper clutch. Here are some pics of the work up:
http://home.earthlink.net/~j1138/evo/cds0.jpg
http://home.earthlink.net/~j1138/evo/cds1.jpg
http://home.earthlink.net/~j1138/evo/cds2.jpg

I'll post more pics when this is complete.

GREAT work !!!!!!

Is that a tmaxx tranny?

Thanks,
By the way, I raced this truck, with the center diff, the week before last and found that the truck was very slow compared to the other nitros. The gear ratio was 18.5:1 so I'm not sure why I couldn't get much top speed down the straight. Althought the truck was very easy to control, I was really lacking in the speed department. I still took third place in the A-Main but most of that could be attributed to the other guys breaking down. :rolleyes:

Anywho, I removed the center diff, re-installed the two speed tranny and regained my monster power and speed and took first last week. Therefore, I am merging the two together :)

Its still a Revo tranny (just a few mods here and there).
I removed the 28t output gears and the output shaft. I added another 43t gear which you can see in the pic. I removed the bottom of the tranny so that the 43t gear can mesh with the center spur and had to remove some material on top of the tranny case so the 43t gear can spin freely. I used some lexan to encase the two speed module and keep it clear of dirt and debris. The tranny now mounts backwards which requires the f/r diffs to be filpped. I did this so I could mount the batteries on the left side of the truck giving me a lower CG and more evenly distributed weight.

I should have the aluminum diff mounts completed tomorrow night and should get my new spur gear for the diff in a few days.
Just in time to race on Saturday :D

Cheers

Starscream my hats off to you. You have the most radical REVO out there. When the tranny is done can you show us how you did the diff conversion, i for one am very interested even if i stick to nitro this could give me the advantage i need to run with the truggies

Star your work looks awsome. Could'nt you just play around with the spur on the diff, or the pinion to make your truck faster ?.

Respect!

Sweet truck!

Thanks Dafni,
Its still a work in progress but I'm getting there. I took the truck to the track yesterday but we didn't have enough trucks to race. The truck handles well with the center diff and transmission. The added hardware increased the weight of the truck ~12 oz. I still need to dial in the shocks for the extra weight though.

Here are some pics of the almost finished truck. I say almost because I have no brakes yet :eek:

http://home.earthlink.net/~j1138/evo/evo-diff0.jpg
http://home.earthlink.net/~j1138/evo/evo-diff1.jpg
http://home.earthlink.net/~j1138/evo/evo-diff2.jpg
http://home.earthlink.net/~j1138/evo/evo-diff3.jpg


As always, I'm looking at my options for a better solution. I may use the center diff from the ofna pirate10. It's the same size as the revo f/r diff so I will loose some weight and lower the tranny height a bit.

OK,
Here's the next generation of the evo center diff.
This time I incorporated a mugen 1/8th diff into the Revo transmission itself.
Here's some pics of the final product:
http://home.earthlink.net/~j1138/evo/rcd1.jpg
http://home.earthlink.net/~j1138/evo/rcd2.jpg
http://home.earthlink.net/~j1138/evo/rcd3.jpg
http://home.earthlink.net/~j1138/evo/rcd4.jpg

I had a hard time getting a good photo of the diff because the lighting wasn't very good but you should be able to get the jist of what was done.

I think I may have lucked out and even have the right size dogbones to finish the job :)

I will only have front brakes for now but I plan on mounting this tranny backwards on the gorilla revo chassis, when it becomes available, so at that point I'll have rear brakes.

I'll break in this diff this weekend and report how it goes...

Cheers

Awesome! Thanks for sharing!

:Love:

I raced my Revo with the latest center diff solution and put it to the test. It worked well during practice and through the first heat. For the second heat, I geared the truck up a touch, for more top speed, and the center diff plate failed :eek:
Well, back to the drawing board. I need to make this plate bulletproof for this BL powerplant so I'm going to use a thicker diff plate and figure out how to ensure the screws for the gear do not come loose. Other than a little melted plastic on the tranny case it worked well. This can be corrected with proper spacers.
I'll report back when this is fixed
:)

Thanks for the update, Starscream. Too bad it failed, but testin' an' improvin' is what it's all about.
This idea is sweet. If it works in the end, it's fabulastic.

How do you feel about the accessibility ( ? strange word, if it exists at all) I'm a bit worried about having to take the tranny apart for oil changes. But on the other hand, when you found a good vweight for the center, you hardly touch it anymore.

I try to magic a Revo diff to an EMaxx output gear, and I'm thinking about using a modified ringgear as "plate", or just a 1mm steel disc.
The output shafts still give me trouble.

thank you
DAF

daniel, you did got my email about that idea i had right??

Shure, I sent you a reply, remember?! We'll have to talk about this.

But it doesen't hurt to tinker, if I have the stuff lying around anyway.

Ah!

though i really don't understand what your plan is.. :)

Removing the tranny isn't too bad but I can see how it would be a pain if I have to take it apart often. I'm hoping that once the diff is bulletproof, my tranny maintenance will be minimized. :W:

Currently, I am using 10,000 weight but might try something a little higher next time (for more rear traction).

Since I only have front brakes, I may put this on hold until the gorilla maxx revo kit comes out. I plan on mounting the tranny on backwards so I will have rear brakes. I'd rather not break during a race just to test out my diff :eek:

Dafni, keep us updated on your diff solution. Are you using the gorilla single speed conversion?

No Gorilla tranny on this experiment. I need the extra room. Plus, for heavy motors on stock motorplate, I prefer the stock tranny. (8 instead of 4 mounting screws)

Sure I'll keep you updated, but chances are this "experiment" will never leave the workbench.

Hey starscream. On the mugen center diff. Do you have some specs on that. Will it fit in a emaxx tranny? I want to run a center diff with out all the open parts. On a monster truck the extra gear reduction will help to. Where Would I find one of these diffs as well. I may get one to try. thanks. I like your work. All I have to say is YOU THE MAN!!!!

Hey star !!!

How is your diff & tranny combo working out ?. My Evo is apart right now the chassis is getting extended.

Thanks coolhandcountry,
I am still working on upgrading my center diff. It is comming along quite well and I plan to have it finished in a week or so. I most likely won't impliment the diff until I get the gorilla revo conversion though. (hopefully mike will get these soon :) )
I got the mugen diff from ebay. You can get a f/r diff or a center diff (either will work). A diff from an xray will work as well but I couldn't find one for the right price. The mugen diff uses 5mm shafts and the xray uses 6mm shafts. the 5mm shafts work fine for me.

I'm not really familiar with the emaxx tranny so I took a peak at the traxxas exploded views. It looks like the e-tranny has a 31t and a 36t output gear. The diameter of the mugen diff is the same diameter as the revo 28t output gear so the diff should easily fit in the e-maxx tranny. However, unless you get real creative, you'll probably want to convert the tranny to a single speed.

I am going to be using the center diff plate of the ofna pirate 10. I will need to trim the plate diameter down a bit but it seems that this plate is exactly what I needed to finish the job.

I'll post more pics when this is complete.

Hey Starscream. On the center diff. Did you seal the diff with a piece of metal and then mount the stock revo gear on?If not, how did you get a plastic gear for a mugen diff that small. If i'm right, that is how i converted my revo tranny to foreward only

crazyjr,
Thats exactly how I did it. The first plate I used was too thin for the job. I believe the screws backed out and ended up tearing out of the mount points. The new plate is twice as thick with twice as many mounting screws and better threading. A little lock tight and I should be good :cool:
The gear used was a stock output gear that I cut and shaved down to fit. I got a better gear this time and am confident that it will hold up much better.

That's how i converted my revo to foreward only, so far it has held up well. Except i mounted the output gear to the shift cog, not a diff.

Hey Starscream. How did you get a white revo output gear? I just looked at my revo tranny and all the gears except the output gear were white, they were black. Are you using the same tooth from a different source.

Believe it or not, its the Primary Forward gear
Traxxas Part#5396
I had to do a bit of cutting, grinding, and drilling to get it like that.

I am using a gear from sdp-si.com this time around. This new gear has more surface area and is easier to work with.