What is ticking!
 

I have been having a persistant problem with my Cen Matrix Tr. Under moderate to hard acceleration and the hardest braking something in my drivetrain clicks! I have replaced everything in the rear driveline.. Entire new diff, retightened every screw and it still clicks. Checked the center diff and its fine but it still ticks! Thought it was a stripped wheels hexes and tried other wheels still ticks.


any ideas?

Checked all the driveline pins and bearings?

Its your biological clock........

it's your front diff. shes on the way out. the ticking under hard braking is a dead giveaway.

so why does it click under acceleration!? i replaced the front 2 weeks ago- everything is new. Under low braking there is no clicking.

went through and checked bearings and everything spins free




Did i mention it reduces power to the wheels drastically under throttle

The rear end experiences greater load than the front under acceleration, and the front end is loaded up more under braking. Have you checked the bevel gears in the front diff? Maybe it needs better shimming?

I had a strange clicking on my buggy one time. It was one of the suspension mount screws, it was too long. Under light loads it was silent, but heavy loads would make the diff outdrive move (deflect) enough to contact the end of the screw sticking up.

I spend an hour just now trying to figure this thing out. re assembled the truck as is with my spare diff. Truck acted as if re entire rear driveline was disconnected from the driveline But it was quiet. Then i took the rear apart thinking that the shimmoing on the ring/pinion was too tight- removed two shims and the clicking returned. Then i quit while I was ahead and came inside.

This leads me to beleive that the case on my spare diff is slightly longer then that of the original. so it requires the pinion to be closer to the case. but when moved closer to the case it binds on the outside of the diff housing evident by the wear marks. but any less shim behind the pinion results in a loose mesh and the diff clicking.... I think.

SO. What I plan to do is order all the parts that went bad for the original diff and reinstall it into the truck... That should resolve the problem... I hope.

Well i fixed the rear diff.. shimmed and set.. checked the front diff... the internal gears had some wear so I replaced those.

AND THE DAMNED THING STILL TICKS!

I am out of options.

Please tell me whats wrong!

Here are my possible problems and solutions
- Stripped wheel hexes, tried different wheels
-Rear diff gear mesh, re shimmed, replaced unit, shimmed again
-front diff, replaced unit-twice checked mesh. still nothing
-Center diff failure- found that crospins were worn, replaced them still ticking.

whats next?

<embed width="448" height="361" type="application/x-shockwave-flash" wmode="transparent" src="http://s152.photobucket.com/flash/player.swf?file=http://vid152.photobucket.com/albums/s195/asdf1010/PICT0003-5.flv"></embed>

check the outdrives where the pins from your driveshafts ride. a grove will cause binding and a tick like sound sometimes under load. its happened to every r/c ive raced. either that or i am crazy. recently this happened to my rc8, didnt notice it until it spread one of the rear diff outdives and snapped it in half..... first lap

DId your Rc8 occasionally lose drive to the front or rear?

Still sounds like a slipping diff. Are the bearings good on the diff pinions? Worn bearings can allow enough deflection for the gears to get past each other. Any cracks in diff housings? Worn housings can do the same.

Housing is new. gotta check the bearings. I really hope it is something that simple.

not sure of your trucks designs, but could it be the diff housing is flexing like the maxx?

my maxx makes the SAME noise unless im running 60% punch on low start...and im pretty convinced its the case flexing

Whenever I replace a diff, I generally just replace the whole thing (go buy a brand new diff off ebay).

This way, it solves any diff issues there may be. Because a bearing issue can even be the cause for the gears going, or a case flex issue from an old fatigued case, etc. So I just replace the whole thing to be safe.

you got some deep pockets:yes:

Not really, no. I've had to replace a total of 3 diffs in all my years in RC.

First one was the front diff in my E-Maxx. That time I actually did buy a ring and pinion...

Then the rear diff in my Revo 2.5R went. Ebayed a new one for like 15 bucks (cheaper than a ring and pinion).

Then the rear diff went in my G2R and I replaced them with Mike's Conversion.

My cases are aluminum and are fine. Ring and pinon are hardened steel which makes me beleive they are fine. We will see- I have to sort this out by sunday

Also, how much play is in your CVD's (center) do they slide back and forth. If they do, consider putting something that prevents them from doing that. They run much quieter.

they dont slide back and fourth at all. my pinion is shimmed corrrectly

Run it for 1 hour doing that and then look for the metal filings... should tell you where the noise is coming from...

I don't mean something solid.

In my G2R I put a couple o-rings on one side and a small spring on the other. They can still move any which way, but this helps keep them centered, which means quieter CVD's that are less likely to pop out. Haven't had a problem yet.

pull your front driveshaft and run it. if your worried about it unloading to the front just wire a shaft(allen wrench, anything) through the front cup to hold it stationary. do a couple high grip passes and see if the tickings gone. don't run much its hard on the center diff, but fine for a couple passes. that'll get you 50% diagnosed......:tongue:

Thats a good idea.

Like you said- might be a bit much for my CD tho

My Muggy did the same thing, it was the front diff. The gears looked perfect when I pulled it out but I replaced the ring and pinion then shimmed it and haven't had an issue since. Also double check all your drive cups to make sure the screws aren't coming loose. Locking it into RWD will help with find the problem but it will be very hard on the CD so make it quick and don't push it too hard!

Are you running a plastic spur? Even if your not to me it really sounds like maybe the motor mount is flexing and the mesh is spreading? What does your spur and pinion look like? Seems like something is flexing, check everything for hairline cracks. :neutral:

Spur and pinon are fine. ended up running 2 packs of 6s through to find the problem... ended up rounding all the teeth off my rear diff ring gear.. and shattering a pinion. Both of which were hardened.


As of now i have donor gears in from a CRT they are quiet and work well.

Sounds like it was a bit tight... Or your rear bulkhead has the pinion at a funny angle.

To me, it kinda sounds like a set screw is loose on the pinion, or on the rear center drives. There's gotta be some evidence of what is causing that somewhere; you don't get that kind of noise with no visual clues.

I think it was the pinon- the teeth on it were rounded. which leads me to beleive that it just wore out...

If I have clicking in a 3 diff car (and it doesn't click while all wheels are in the air) I hold the front wheels on the ground with the rears in the air and give it some throttle for a few seconds (if it's cogging don't keep pushing it). That will put load on the center diff and the front diff (the amount of load will depend on your center diff oil)
If there is clicking then it will be the center or the front.
Then do the opposite with the rears on the ground and the fronts in the air.
If it is clicking then it is the center or the rear.

If it clicked both times it's most likely center diff related. When it's the center diff spider gears it will often be jerky as well, because when they slip (and click) it swap between diff action, to locked diff, to no power fairly quickly.
If it only clicked when the rears are on the ground then it's likely to be in the rear.
If it only clicked when the fronts were on the ground then it's likely to be in the front.
If it didn't click at all, but still clicks while driving then your center diff probably doesn't have thick enough oil to cause enough load to find the click.

Did you rebuild the diff with new bearings? If the teeth in the diff were worn off, they would push past each other and wear out the bearings. When you put new gears in with those old bearings, they will slip past each other much easier.

i checked All bearings when I reinstalled. they seemed fine.. truggy gears are working well, lots more punch then the stockers (3.45 ratio)

"They seemed fine"... famous last words... now go replace those bearings!

I worked it out! Your lipos - lol

that there is funny:lol:

tick. tick. BOOM!

thanks chris you smartass :lol: