Tinybaum

Hey guys,

I did a search on the board for the dif cup mod and didn't see anything that i needed. I know a 10mm compression fitting works, problem is here in the states I went to the hardware store and all the have is 3/8 which is something like 9.5mm[][]

So my question is to the CEN owners in the states, what did you use to mod these cups? I looked into ordering some online but shipping was like $15 yikes!!

Anyone run into this, have a solution. I've broken 2 in the 2 times I have gotten to run my truck, and i dont think that i was all that tough on my truck

Thanks in advance

Tiny

alvinl

What I did was sand the inside of the fitting until it would slide over the diff cup. It works great. It will seem as if you are taking off a lot of material, but don't worry. Dremel or sand it a little then try it until you can foce it onto the diff cup. If you don't have a dremel, wrap a piece of sand paper around a long philips bit and put that into your drill and use that to sand the fittings. It works.

BootMachine

Put the diff cup in the freezer for a few hours and then heat up the compression ring ROASTING hot. See if you can slide the two together!

I have read in some of the diff cup mod posts that some of you guys are using pieces of fuel tubing to "tighten things up"..where are you guys putting this fuel tubing? Just a piece in the diff cup before the axle goes in?

dustin7837

My Feedback: (1)

I couldnt find compression fittings either. On my mt2 i used copper tubing and sanded it out a bit to fit it, but after like a year and a half they seem to have stretched and i broke two diff cups. I just got a ff buggy and so today i did the diff cup mod and i got a 4" piece of 1/4 inside diameter steel pipe. I took a drill bit that is the same size as the diff cup and drilled the pipe out. Then i just held it with vice grips and put the pipe on my bench grinder to make it a bit thinner. Then i took off my shock towers and ground the bottoms down a bit where the mod would hit. It only cost me 1.89 CDN$ for the pipe, but i ruined like 5 dremel bits and a pipe cutter on it. I dont think these steel bands will stretch any time soon

Tinybaum

Alvinl, thanks for the advice, i will try that.

I have a dremel so I will try that. Did it weaken the fitting any? How did they hold up. Anything has to hold up better then the factory ones. I am gonna stop and get the fittings in the morning, and try it out before i take the truck out tomorrow.

Hopefully i can run the truck without any problems!! I haven't even had the body on yet still working on my carb adjustments some. Got all figured out but the high speed, and I think that is cause i'm not letting enough fuel into the carb for high speeds.

Any of you happen to see the OS .18 that went on ebay for like 60 bucks?? If I had trusted the guy broke the engine in right i would have snagged that.

Also saw an MT2 and a buggy it looked like both together plus tools and some parts for 160. All the truck needed was Dif Cups.

Thought i'd share that.

Thanks Again

Tiny

alvinl

You will lose a little metal off the fittings, but mine have held up great. i have not broken a diff cup with the mod but I have broken other parts (mostly my own fault). I have had a problem with the CA glue breaking loose and the fitting slipping around, but so far no breakages.

dustin7837

My Feedback: (1)

I had a problem with that ^ as well at first. So i switched the glue for a bit of JBweld (2 part metel adhesive apoxy) and i dont think i could get the rings off if i wanted to lol.

Tinybaum

Well i got the dif cups DONE, I planned on testing it today, but didnt make it out cause of weather. I will take it out tomorrow, and post on how the ol' truck held up.

Also got my bearings in that I ordered, so must play was taken out of the wheels with that, and just by testing the steering seems to be tighter.

Thanks for the suggestions

Tiny

poor judgement

the optional alloy steering link will take away what slop is left in the steering, well 99% of it... pricey tho, as with most cen parts, im afraid

dustin7837

My Feedback: (1)

does that aluminum link actually help??????
I looked at it but for 18 USD or whatever it is i didn't buy one because i didnt think it would help anything except looks.

poor judgement

i spotted one cheap on ebay and grabbed it... its made a lot of difference, yea. i didnt expect that much, but with that, bearings in the steering upright bits, and the extra wheel hub bearings, there is very, very little play at all - especially with a more powerful, metal geared servo behind it all and the servo saver tightened up a fair bit...

but i hear u - the price is a bit steep, even tho it is a nice little item. keep ur eyes open, one might come up cheapish again - they retail around £19 over here...!

Tinybaum

Is that something that we might be able to get DrHonda to make?

Tiny

poor judgement

maybe - find a pic of the steering link and get a few sizes n send him a pm mate.

mulletman

did Dr.h quit posting?, if i had cash i would love to get a linkage

alvinl

I swapped out the steering link on both my MT2 and ATX. If Dr. Honda is interested and needs one for sizing, I can send him one of my old ones. It should be a very easy part for him to make.

Tinybaum

Alvinl, thanks for offering that up!!

Ill message him tonight and see if it is something that he is interested in making.

Tiny

RogersRacing

Hi Tiny,
I am a MT2 newb also and as u can tell, these dudes are a wealth of info and innovation and we r lucky to have all this info at our fingertips. I also went thru a few cups and am still sorting out the right sized fitting. I have the JT racing chassis hop-up and to put the dremel to the strut towers makes me nervous. I have found that by fitting a 6mm section of fuel line in the diff cup it takes all the slack out of the drive and I havn't broken a cup since. I work in audio world so i got some really strong heat shrink and shrunk a 10mm length around each cup. I'm not suggesting for a moment it works as good as the brass fitting but it is hanging in there.
I'm hunting some thin wall s/steel tube to try the mod without having to butcher the strut tower.They are still nice and straightjavascript:void(AddText('[8/|]')). it's getting real hot here so I am about to start a new thread about fuel storage.
Later,

CR

Tinybaum

If you get 10mm pipe, or 3/8 and sand it you should be ok, the compression fitting has a curve in it that does the rubbing, i just ordered more cups, and im gonna try some other things out. I will post what i find if it works, if not ill hide the ideas in shame. I have the compression fittings on them right now. I just need a place that has 10mm around here, the 3/8 was find but even with a dremel i found it a pain to grind it.

I tell you these people are great i have learned a ton in the week or so i have been on here. . . .truely is a wealth of knowledge here


Tiny

RogersRacing

Yeah Thanks Tiny, but when you finally get all the planets to line up and you go out for a blast and come home with every-one and everything in one piece and your nostrils burning from the nitro........its SOOOOOOOOOO worth it!!!

Cheers
CR

Tinybaum

Im getting there, i have a good feeling about the next time i take it out

Tiny

alvinl

My 3/8 fittings do not rub the shock towers, even with the new ARO towers. After gluing the fitting around the diff cup, grind a bit off the outside of the fitting if it is rubbing. You can put the diff cup into your drill so the end with the fitting is sticking out, spin it and touch the outside with sandpaper. If you need to take a lot off, use a file instead of sandpaper. It works pretty good. Someone else here gave me that trick, wish I remembered who so I could give them credit.

azzman

These were my exact words:
"Stick the cup in a drill so you can spin it, then hold some sandpaper against it, do this till it fits, if its taking to long then use a file, but dont go too far!!"

And heres a pic:

alvinl

THAT'S IT! Thank's Azzman. Sorry I could not remember where I got that tidbit of info.

dustin7837

My Feedback: (1)

Where do you get those fittings and what are they meant for? They look like brass which would be stronger than my old copper ones but less work than my steel pipe attempt.
Thanks

digout

Ideally a 10mm SS thin tubing would be great for the diff mod. Since 10mm tubing is not available around here, I ended up using a 7/16" SS tubing from Tower Hobbies and honed (drilled) it out to the 10mm I.D. Maybe if CEN's promises turns out to be true on the new NX outdrive being stronger, we won't need the diff mod anymore.