Mad Monkey diff

[lordnikon]

It was pointed out to me that my diff was way to tight, no counter rotation when spinning the wheels by hand and very notchy.

I'm rebuilding it with new balls, plates, thrust bearings etc and it now feels super smooth and rotates as expected. Broken it in but sounds like a hoover when running.

Do these cars just have noisy diffs ?? It has the Kevlar 52T and kevlar idlers too if this makes any difference ??

[lordnikon]

Should add it has some rc lazy ceramic diff balls in it, but a standard kit thrust bearing

[racingdwarf]

sonds like it maybe slipping a little, run it a little tighter, if you are running on a high grip surface with the slipper tight, you may need to run the diff tighter, and back the slipper of a little.

[bazdonsop]

there is a video series on you tube done by racer53 on this subject and i found it extreamly usefull as i have burnt out my diff and destroyed the idlers after two months of light use,
I have gone for ceramic answer diff bearings and ceramic bearings on iders, kevlar diff 52t, acetal idlers and team acc diff grease.
after £40 on a diff and the monkey kit only £65:confused: well you know where i am going with this but its worth it not having to keep doing it.
my diff too is a little noisey but feels really smooth
Hope this helps

p.s when setting up the slipper like shown in the video, make sure the slipper isnt too tight, lets just say i took it on the chin:o

[lordnikon]

Its on a high grip astro with the slipper backed off, think i will try tightening it alittle and see how it goes. Could just be its noisey, drowns out the fan :thumbsup:

[gordy]

I've been using the stock diff and had no issues at all. I think the key is to use a really good grease on the thrust race not ball diff grease it just doesn't work on the thrust race mines quiet

[lordnikon]

Well after 3 hours of testing last night its still noisey lol

If i tighten the diff anymore it will lock up and stock counter rotating, the slipper is backed off and its still making a racket. Wondering if i have maybe put the thrust race in wrong or something, really cant be bothered pulling it all apart again........ rapidly losing my patience with it too - DEX210 here i come

[VintageRacer]

Is it noisy all of the time or just at launch? My sons makes a squeal as he starts which I assume is the slipper, but it is quiet once it's going.

I don't think I've done anything special. The diff is tightened until I just can't turn one wheel whilst holding the other and the spur.

He is running a tame motor (17.5) which might be helping.

[lordnikon]

Its pretty noisey all the time, makes the launching squeel and then does go quieter. I've got a turned down 5.5T on mine, so its equivilant to running a 7.5T i would have thought.

[Tom3012]

A squarking diff on launch usually means its too loose... Did you replace the diff spring when you rebuilt it? If the springs old and tired tbis really wont help you set the diff... Something to try! ;)

[lordnikon]

Yep new spring, screw & nut, thrust bearing, diff plates, diff balls, all cleaned and degreased before being rebuilt with new stuff. Kevlar gear was fine so this stayed

[Robbiejuk]

Yep new spring, screw & nut, thrust bearing, diff plates, diff balls, all cleaned and degreased before being rebuilt with new stuff. Kevlar gear was fine so this stayed

How about making us a video of the noise? Might help us ascertain what it is and what it isn't.

I haven't used the kevlar diff gear yet, but I do have the nylon idlers, I personally think thats all you need to replace in the gearbox as I have never had a problem with the diff gear itself.

If your car is making a chriping noise on take off it is definatley a slipping diff. Did you compress the diff spring with a pair of pliers a few times before you put it in?

[lordnikon]

I just grabbed the diff gear when ordering the nylon idlers, wanted to build something as strong as possible.

I stripped it all last night again, replaced the thrust bearing and packed with plenty of grease, touch wood it now seems ok. Not sure what i did originally but maybe damaged the thrust bearing when bedding in ?? :confused:

[Robbiejuk]

I reckon it was the spring, it has probably bedded itself in now and so when you put it back together again you were able to tighten the diff properly rather than it feeling tight but it was not actually tight enough.

Good to see you have sorted it :thumbsup:

[Black Sheep]

I've just finished putting my mad monkey together, I've taken it apart and done different things with the dif, tightening it as much as I can each time.

at the moment I'm certain the dif is slipping so I cleared the grease out of it (used a thin lithium grease) and put a thin smear of the grease provided in the kit.

when I try and roll the car along it's stiff and doesn't roll easily, the pinion on the motor isn't turned (brand new motor)

I don't think I can back the clutch off much more before the nut will come off.

at the moment, when the car is off the ground the left rear wheel spins under light power, but not the right,

sorry it's not much to go on, I'm used to things like Tamiya TL01's, ball diffs and slipper clutches are new to me!


is it better to have a thin amount of grease or a good amount of stiff grease?

[SamRCRacing]

If the diff is tight then losen it off about 1/4 of a turn, and there is a little washer that if you leave out it puts allot of resistance and spur wont turn. It's green and very small, I had the same probem yesturday.

HTH

[Black Sheep]

I remember putting the little green washer in, I'll try slackening the diff off a little,
will that not allow the diff to slip still?

[SamRCRacing]

losen the slipper to counteract it, that should do it.

[Black Sheep]

The slipper is as loose as I dare go, the bolt is flush with the end of the nut poking through.


going to strip the diff again tomorrow and leave it snug but not tight and see how that goes.

at least I'm getting good practice for doing running repairs.

[nmpsilva]

I had the same problem.
My gears were always striping and if i losen the slipper anymore the nut would fall.
I solve the problem with the dremel.
I sanded a little bit of the spring on each side and it gave me the control off the slipper.
Now the slipper slippes and the nut wont come off.

Cheers

[SamRCRacing]

Good idea, might try that myself, I usually run a loose diff and a medium tighness slipper.

[Robbiejuk]

You should be able to spin the gearbox freely by hand when constructed without the pinion attached. If it is tight then it could be a number if things. Badly meshed gears, missing spacer on the layshaft, or the diff is way to tight.

Take it apart and check that everything is seated properly. Take apart the diff and clean it rebuild it. Put some black grease on the thrust race. Compress the diff spring with a pair if pliers a couple if times and take your time to put it back together. Tighten it a bit at a time and checking it by inserting a Allen wrench in each outdrive. Holding them together and trying to turn the pulley. Once it has become very difficult to move the pulley by hand give it a quarter turn more just to be on the safe side. Your diff should feel very smooth and when you turn one outdrive the ithe should turn in the opposite direction.

When you come to putting the gearbox back together make sure you have all the parts in the right place. When you put the long bolts in to hold the gearbox case together and also hold the motorplate in place only do them finger tight, this can stop it binding and also helps to nit strip the threads in the motorplate.

[Black Sheep]

Thanks for the advice, I'll give it a go later.

I checked the hubs and found one was tighter than the other, sorted that out and now with wheels in the air both spin at the same rate, which is one thing sorted.

at the moment it moves, but doesn't take off, visibly not using all it's available power, so something slipping somewhere - will try your method for re-building the diff and checking the gear box.

how much grease (if any) should be in the diff?
and if so, where should, and shouldn't it be?

[Robbiejuk]

This is a good little guide for rebuilding your diff

http://mrmagoo-rc.blogspot.com/2011/01/building-ball-diff.html?m=1

This is pretty much the way I do mine.

[Black Sheep]

Diff build and working, think it might be slipping slightly from time to time,

just got to get the clutch set up now, although running it a little loose while motor and gear box wear in might be a good idea?

[racingdwarf]

Do you still have the original diff washers and balls fitted?, also are you using the original bronze bushes in the centre of the diff & outdrive or replaced with bearings?

I found that if I fitted 2xbearings in the centre of the diff they were very slightly to wide,meaning the diff wouldn't tighten fully, now use 1x bearing and 1x bush in the centre of the diff,works fine, I am also using the kevlar diff,1xmetal idler and 1x nylon idler and AE spur. I'm not sure on the diff balls, I never fitted the kit ones, put some others in that I had in a parts box.I also started to use AE diff plates, direct fit, I have had no probs with these, but others have so take care! if you use them

Been running for around 3xmeeting with a 6.5 and all is well so far:thumbsup:.

[Black Sheep]

I've built it following kit instructions with the kit parts, no upgrades and no intentional modifications :)

[racingdwarf]

Ahh, may be worth changing the diff balls,and upgrading they are not the best and could well have flat spotted by now,thus causing the diff to slip and also sound rough as old boots. I have read that most people have done this