BuggZy99

My Feedback: (2)

im starting to think i may have a problem, there busting at the rate of about 1 per gallon.
i put new drive cups and new dogbones and it happened again today after about a 2 1/2 hours actual playtime.
anyone else with this problem ?? or can anyone give me an idea at what to look at.

thanks
Eric

chowderhead72

My Feedback: (4)

Are you jumping on pavement or other very high grip surface? Any major cartwheel accidents? Is it always the same dog bone?(ie right or left) I have shreded two axle cups one dogbone type and one ball type on two different vehicles both of which were the result of huge cartwheel wrecks (14+ revolutions before I lost count)

BuggZy99

My Feedback: (2)

nope, its not really during jumping or cartwheels, i only run it in sand but i just noticed my medium compounds are on the rear, maybe they bight to much and make the shafts absorb un wanted stress. As for the dogbones, its left and right, not one more then the other.

chowderhead72

My Feedback: (4)

Can you tell which end is breaking? axle or diff? Are you using your droop screws or are they backed out for maximum travel? If you are not aware the droop screws are the grub screws in your upper a-arms that limit downward travel.

BuggZy99

My Feedback: (2)

droop screws are about in 1/2 way.... i did think that also, making for easier bottoming out.
might release them a little more, im also using the rear sway bar but i dought its that.
as for breaking, they always snapp in the diff drive cup, the ball litterally breaks right off.

..............................

maybe wen you jump you hold the throtle wen you land...

BuggZy99

My Feedback: (2)

nope, not that either, the last one busted on the streight, theres little bumps but not enought to life the truck completely airborn.

BuggZy99

My Feedback: (2)

heres a pic of my truck from the rear, is it sitting to low ??

hellya

you should try some ball drives.... it has a 3 point contact to displace the torque more evenly

bigger the better

Honestly only snapped one drive cup and that was when I hit the edge of the garden where it meets the grass and there is a 5-6" lip and it bit real hard.
I have the set screws set down about 1/4".
The sway bar I have never use and seem to roll less and handle better.
If running in sand you may be running in an uneven surface and the bar will only lift the opposite tire putting stress where it does not need to be - Ditch the bar and try that.

cyclops1970

My Feedback: (5)

Would you think if you changed from grease in the diff too maybe 100000 might slip and not give straight torque too the dog bone ?
just a thought !!

fgbasher

My Feedback: (10)

make sure the dogbone has a few mms of play inside thedrive cups. You may have them too tight and causing them to snap under the pressure.

D0G

My Feedback: (1)

Do the ball cups get rid of the little bit of play that the dogbones have inside the drive cups? And by the play I mean...ummm, the rotational play..!? if that makes sense..lol not the play between the 2 Drivecups needed for suspension travel.

radio_controlled_mad

theres no play in ball cups (apart from to allow movement of the a-arms) - the bones have 3 bearings on each end that fit in the grooves inside the drive cups,the bearings when worn down can be repalced with new bearings - you dont have to replace the full dog bone

carpy100

the less droop you got the better it is for the dog bones(and the handling).
ball drives are stronger but not bullet proof.maybe it is the sand making something bind?
if you run ball drives everything is sealed within the rubber boots and packed with grease(although these need changing regularly)

mud slinger

Sound's to me like you could be running too much droop on the rear of the car causing the shafts to rub on the drive cups when at maximum droop.

Put your car on a stand with the wheels and wishbones un supported, then push the drive shaft hard into the wheel drive cup and spin the wheel, if it feels lumpy reduce the droop until it runs smoothly.

If your running ball drives on any surface you must grease them regularly with a good quality high load grease and NEVER run them without the protective boots. If one splits replace it as soon as you spot it, clean and re grease the drive and all should be well.

Ball drives will out last the standard dog bone drive by a long way and be much more reliable if correctly set up and maitained.

ammdrew

you have the rear lower arms pulled too far in, when you compress the suspension the dogbone binds and it can no longer move left and right so the cup breaks ( stress has to go somewhere), I have seen the diff case also break from the same pressure. This often happens when the lower arm gets pulled out, then you re thread it together but give it a few more turns to make sure it will not pull out again.

you should have 4-5 threads showing on each side( rough guide line) most important with the suspension completely compressed you should be able to slide the dogbones left and right, 3 mm of play would be excellent at that point.


droop screws control weight transfer only, they will have little if any effect on drive train life.

mud slinger

Droop screws set the maximum ride height or the car,

They can have a very big effect on the life of the drive train if not set correctly.

As far as the droop screws controling weight transfer, can you give us some more info as to how this works as i'm puzzled on that point !!!!

radio_controlled_mad

if you raise the back end up off the car - its the drop screws/diff mounts that are taking the weight of the wheels/rear a-arms

ammdrew

When you brake the vehicle transfers weight forward to the front wheels, you control how much unloaded weight transfers with the droop screws, when too much transfers you build momentum and unweighted the rear tires causing the vehicle to loose rear traction and turn around.

Front, when you hit the gas the car is allowed to lift the front end, the tighter the droop screws the sooner you come to full front weight, the less weight you transfer to the rear tires, the less traction you have at the rear.

This is a fine tune adjustment, one of the largest handling changes you can make when you get to new tracks, to tight limits suspensions, too loose allows death wobbles, and uncontrolled spins.


Drive train will remain inline no matter were the droop screws are, as the vehicle sits on the shock springs, idea is level or near level dogbones at ride ht, allowing the vehicle to unload and angle the dogbones when jumping or driving is not going to effect drivetrain life, with droop screws removed the arms do not fall far enough to create a bind at the dogbone and will not hurt the vehicle, they will however go far enough if you remove the shock also, but then it is really hard to drive.

carpy100

this is also the reasoning for running a heavier wt oil up front, something people just cant get there heads around! it makes a hell of a lot of difference.
i personally run with my rear lower arms almost horizontal in the static rest position.1000wt heavier oil up front.

mud slinger

Your basic theory it correct in the way weight transfers in the car but its the shocks and spring and suspension setup that controls weight transfer not the droop screws. The droop screws set the maximum downward travel of the wishbone, this should be set (on an off road car) so that you have the maximum downward travel allowable by the shocks and drive shafts, if the droop screws are'nt set at all you could end up breaking a shock or drive in a crash as there is nothing stoping the wishbones travel past the limit of the stroke of the shock or drive. Droop screws wound in too far will limit the suspension travel causing the car to bottom out sooner and give a poor ride on bumpy ground.

If you need more rear traction then put some anti squat on the rear wishbones, its a job any idiot can do on an FG. Anti squat will stop the rear of the car squatting under acceleration (hence its name) but the weight shift is now transfered to the rear wheels causing them to dig into the track surface harder giving more traction.

BuggZy99

My Feedback: (2)

ok, heres my update ,
the rear rose joints where so worn out that they popped off the eyeball on the chassis, fixed that and problem solved.

hndaman1

My Feedback: (6)

where did you get your rose joints from? if you don't mind me asking?[8D] the ones on my hammer are getting pretty sloppy, and need too be replaced, and you cannot buy those seperate from duratrax without buying a whole another part you don't need..

BuggZy99

My Feedback: (2)

i bought these parts from advancehobbies in ontario, canada.
Ball and socket joint for M8, adjustable (# 6029/5)