Granite Cause of broken rear driveshaft?

[Sunnydude]

My son and I finally got out to the skate park to test out our upgraded Granite Mega with the Castle 4600kv brushless upgrade. We also replaced the leaking shocks with these: https://www.ebay.com/itm/Shock-Abso...var=572415415802&_trksid=p2057872.m2749.l2649 with 40wt oil in them. We are not running lipo just 8.4 nihd and the smile on his face as we were hitting the jumps was awesome.

After the park we swapped batteries and headed out to the field/track next to it. During this time we went to race and could hear something from his truck. Turned out one of the rear drive shafts had snapped at the wheel. What would cause this? Are there any settings we should change in the motor if the power is too much?

Thanks.

 

[Ari33]

I don't own a granite but if I was to guess, it would probably be wear and tear.

How much use has it had?
What part snapped?... A dogtooth?

You are not running lipos so brute torque is less likely to be a factor. You could probably reduce your escs punch setting which is basically a current limiter to reduce torque at lower rpms but if you are using nmh I cant see the torque being to excessive to cause that.

 

[Bri26]

Do the aftermarket shocks that you bought match the length of the stock shocks? If not, you might be over extending the suspension arms which would put a lot of extra strain on the front and rear driveshafts.

 

[jondilly1974]

Did the u-joint pop or did the composite shaft break? Your post is unclear without photos. We could help much more with some pics.

 

[bicketybam]

I don't own a granite but if I was to guess, it would probably be wear and tear.

How much use has it had?
What part snapped?... A dogtooth?

You are not running lipos so brute torque is less likely to be a factor. You could probably reduce your escs punch setting which is basically a current limiter to reduce torque at lower rpms but if you are using nmh I cant see the torque being to excessive to cause that.

What's a dogtooth??

 

[Ari33]

What's a dogtooth??

Apparantly its a film! ?

"A controlling, manipulative father (Christos Stergioglou) locks his three adult offspring in a state of perpetual childhood by keeping them prisoner within the sprawling family compound. The children are bored to tears in spite of distractions like Christina (Anna Kalaitzidou), an employee of their father's who makes regular visits to sexually service the son (Hristos Passalis). Increasingly curious about the outside world, the older daughter (Aggeliki Papoulia) hatches a plan to escape."


Ah well, at least I knew what I meant. ?

 

[Outcastblxnut]

4600 kv brushless in a mega. That's ur problem right there??‍

 

[bicketybam]

4600 kv brushless in a mega. That's ur problem right there??‍

The driveshafts are the same as the 3s BLX though. I agree the kv is too high but all I see as a problem is an overheated motor. Usually the bigger cans/lower KV motors are the ones that pop driveshafts.

 

[Outcastblxnut]

Not the motor he running nicd??‍

 

[Ari33]

Do these cars have 2 lower suspension mounting points?
If he used the inboard ones after rebuilding his shocks, the droop could exceed the dogbone lengths.

 

[Sunnydude]

We tossed the broken part but here is the piece that broke. The only yoke was missing.

Do the aftermarket shocks that you bought match the length of the stock shocks? If not, you might be over extending the suspension arms which would put a lot of extra strain on the front and rear driveshafts.

I bought the ones from ebay that people were recommending. The back ones are longer. Can get a measurement tonight.

 

[bicketybam]

We tossed the broken part but here is the piece that broke. The only yoke was missing.

I bought the ones from ebay that people were recommending. The back ones are longer. Can get a measurement tonight.

Try loosening your slipper a bit.

 

[AimlessRC]

Run the slipper at 2 turns out from fully seated.

Then, get some 710cts (50wt) in the rear and 810cts (60wt) in the front.

If you refill the diffs, go with 20k rear, 30k front.

9x out of 10 your slipper being too tight is the culprit.

 

[Sunnydude]

Thanks for all the suggestions. Will adjust slipper and dial down the punch.

Now if we could get through 2 battery packs without the esc popping loose. I am using scotch 30# tape and still coming off. Last night it popped off on my sons and the esc wires got caught in driveshaft and stripped some wire cover off.