Any Center Diffs for the E_REVO????
 

Anyone know who makes or if traxxas is gunna make a center diff for the E-Revo???

traxxas has a part number for one,but not yet released as far as I know

I am working on one right now, and it will be a real center diff, not the 2 spider gear crap that traxxas sells... Just need to get my proto drawings to the machine shop...

well, lincpimp, if you have one in the works...then i guess I can forget about trying to figure out how to make one myself...using a diffcup & the 33t gear....do you have any mock up pics?

Linc you could make yourself a small fortune if your design works!

i would like to try a real diff,what kind of time are you thinking linc?

I would like to incorporate the FLM Tranny case. Extend the lower ends for the diff to fit and bore out the bearing holes to fit the larger bearings. I think Mike and Jamie could figure this out to fit a 1/8 center diff for the hot bodies. It would be a bolt right up I think. Same concept as the slipperential only utilizing the the tranny more so and encased. I think this would also need custom drive shafts to fit, they would have to be a bit shorter. The good thing about this way would be no figuring where to put a motor mount I would think. Too bad I suck as CAD, otherwise I would get one figured out.

Not at the moment, but I plan to use the stock lower gear, and have it machined slightly. I will most likely use a kyosho/ofna diff cup and internals, as they are readily available and cheap. I need to give the machinist a ring gear to duplicate the internal portion of it and then modifiy the external area to accomodate the modded gear and space everything correctly. I would have to get custom output shafts made, or modify the existing output shaft to fit.

Not really looking to make much money, but I have quite a few designs that would sell well.

I would like to get to the machinist this week, as I need to get a KB shaft turned down to 5mm for Paralyzed... After that I could figure out the rest in a few evening and a couple of trips to the machinist.

Sounds interesting...

Linc, you idea sounds like the one i had, but the machinist i know, says he can modify gears, but as for making them, he won't.... my idea was to use a thunder tigre cup & internals, and mod the lower gear to mate up to the cup as well, and mod the shafts to work, but since your farther in, than i am, and have access to a machinist....i'll let you fly with it...and wait for the product.....and also sign me up for one as well....keep us informed....

I can do that. I dropped the parts off at the machinist today and should have something back in a few days. He is going to machine me something rough and I will measure and mock up with those pars and then get back to him with final measurements. Sounds like the easiest way at the moment.

sounds good linc, cant wait to see the rough one....

Well, I have a update for everyone....I got my modded ring gear back today, and I have one shaft allready made, I just need to get one more measurement for the last shaft, however I can post a few pics tonight, showing the ring gear that was modded along with a drawing of the specs for the ring gear and the shaft lengths ect....plus I will give a list of products needed to do this as well....
PICS to follow

Sounds good, I will be interested to see the pics.

here you go, I still need to work on the shafts, but it fits inside real good, just need to use 1 shim in front of gear and that is all, also at the back of the cup into the tranny, I used a 8X12 bearing, so here are the pics....

http://img.photobucket.com/albums/v4...Picture001.jpg
http://img.photobucket.com/albums/v4...Picture003.jpg
http://img.photobucket.com/albums/v4...Picture002.jpg

As you can tell the shafts need to be finished, however....the shaft at the back of the cup is 16/32 in length, & it needs to be 13/32 from the back of the tranny, and the front needs to be 13/32 as well, instead of 8/32...so at this time Im ordering a new lower shaft, and redo the shafts & get the correct lengths for everyone...to go by......so it's real close, and very cost effective as well..

What length screws are you using to attach the gear to the modded ring gear? I am not too familiar with the thunder tigre cup. I am guessing that the screws will have to be an exact length so as to not protrude into the interior of the diff and catch on the output gear...

I also thought you were going to use an ofna spider diff, did that not work?

Im not sure of the screw length, as for i put them in, and cut them to length, then sanded then flush on the inside, as for the cup i used a Onfa hyper 7 diff cup assembly, and the modded ring gear is after the teeth have been removed, i think its gonna work, just got to redo the shafts is all....it's very strong and wasn't to hard to do....once i get all the dimensions for the shafts, I'll add them to the sketch and post them here as well...

That clears up a few questions. Can you assemble the input shaft and the center diff assy into the back section of the trans case and snap a pic from the side? Something like this:

http://i206.photobucket.com/albums/b...p/DSCF2517.jpg

Just want to see how well the gears line up. If your modded ring gear is below the level of the input gear, the idler will not contact it. I had issues with the savage cup and my adapter in that respect. I could reduce the thickness of the adapter and try again.

yup sure can, give me a few minutes....

here you go...
http://img.photobucket.com/albums/v4...s/dscf1479.jpg

linc, one suggestion you could use to lower the diff cup, is replace the 6X12 bearing on the cup side with a 8X12 bearing, then the end of the diff cup will fit nicely into the bearing, & you will gain a few MM doing this....

Looks promising... I just got an erevo center diff in the mail (thanks jayjay283!!!), and may have to see if my machinist can mess with the gears.

Are you still using the oring gasket with the modded ring gear? I have a feeling that will help, as the diff gasket I am using causes some issues with overall length.

I would still like to have a custom made part that would be completely bearing supported, as yours is still rifing on the output shaft on one end...

Still the small 8x12 bearings required to have it supported are problematic...

No real way to get around the bearing issue, a bandaid fix at best.

I would almost like to try your setup, and remove the bearing carrier area of the diff cup. That way the original bearings could be used, and I could see the wear on the output shafts from the diff load directly on them.

May have to try that out, I have a spare ofna cup and ring gear. Back to them machinist!!!

Any idea if traxxas will sell the gear seperately?

I did that, actually opened up the hole in the trans case so that the extra length of the bearing carrier on the diff cup can sit thru the 8x12 bearing and go outside the case a bit, you can see it in this pic:

http://i206.photobucket.com/albums/b...p/DSCF2523.jpg

yup, very true, im now waiting for a new lower shaft, so i can turn it down and cut it to the new lengths that are needed, so maybe mid next week for me.....fortunate for me, my machinist does it on his lunch break, so no cost for me at that part, and I have access to a lathe and I can turn down the center of the shaft to the correct size needed and take measurements from there.... both designs look good.....keep up the work

I am in the process of buying a small lathe for doing stuff like this... I may try drilling and taping the gear I have... Might work. I also had the lower shaft turned down to be 6mm od along the length. I still have to cut it and drill the pin hole too. Fun stuff.

what the bolt circle diameter for the diff cup? and i see you got your traxxas gear still waiting for mine so can i get measurement for that too? waiting for parts sucks i got nothing to measure right now. what are the angles for the traxxas gear?

here is the drawing for the bolt pattern to drill & tap the 3mm holes in the ofna ring gear, after i finish my shafts, I'll get those dimensions and add them to the drawing as well....FYI, scroll down a bit, pic is at the bottom......sorry dang scanner placed it there...lol
http://img.photobucket.com/albums/v4...oltpattern.jpg

I have the shaft lengths, if anyone is interested.....just let me know, so tonight I will hopefully be able to test it, but I think it will not have any issues at all......
http://img.photobucket.com/albums/v4...s/DSCF1510.jpg

Well, everyone I was able to get a complete set of batts ran thru it last night, hopefully i can ge ta few more runs in today...if it stops raining that is, after i get a few more in, I'll pull it out and check it for leaks and wear ect....but so far it's working good and no wheelies, which is nice.....Im running 30k in the center....

How much are you planning to sell them for? When are they going to be available? You can pm me the price.

to be honest with you george, im not sure if I will be selling them, BUT, i did shoot Mike a email, with all the info about it, including the specs for him to make them, & hopefully he will get back to me.....it actally didn't cost me to much, the hard part is getting the ring gear modded by my machinist at work, and I can do the shafts....but this was done on our lunch breaks....that's why i sent the info to Mike, but if someone was to start a thread and we can see how much interest is in them, maybe Mike would be more apt...to produce them for you guys.....

Sorry if this sound like a dumb question, but what is the difference between this center diff and the traxxas one?

the traxxas one only uses 2 spyder gears, then you have the output gears, which isn't a real strong design IMO, the one I made has 4 spyder gears and then the 2 output gears, which is a stronger desing, and so far to date it has been working flawlessly

So its like the diffs in my lst2! Yeah I see how that is alot more durable. Are you going to be selling this new diff?

Im very limited on resources to be able to build it, part of it is, I have a machinist at work that does the ring gear mod, on his spare time..lunch ect, and I then turn down the stock shaft & cut & mill it to length myself, I can provide all the info ect for someone to make it or have it made for them, it is a quite simple design, I have sent the info to Mike, but have yet to hear anything from him.....

Thanks sjcrss, I made my CD following your info and coaching.

http://i177.photobucket.com/albums/w.../hyper_cd1.jpg

http://i177.photobucket.com/albums/w.../hyper_cd2.jpg

That looks great, good job, and im glad to be of help, now there is 2 in existence now...mine & yours....I hope you enjoy it...

Would this also work in the 3.3 trans case?

The way it is done right now I would say no, it will not fit in the 3.3 Revo Tranny. I have a second Hyper 7 center diff waiting for me to try and fit it in a 3.3. I haven't had the chance to look into it yet. It might fit with a little more grinding of the Hyper 7 spur gear but there's not much left that can be taken off of it. There is less room in the 3.3 tranny case than the one for the ERevo as the output gear of the 3.3 CD is much smaller.

That looks pretty good there.
Nice job mistercrash. Almost looks facotry.