donnytate

all of a sudden i only have front wheel drive on my savage. What do i need to fix?

twomanytoys

Either you broke a rear drive shaft, dog bone or diff blew up. Those are the most common with the savage. Put the car upside down. Roll one rear wheel and see if the other turns. Roll the spur gear and see if all teh wheels turn. Check drive shafts.

donnytate

any suggestions if its the differential/?

twomanytoys

Replace it.

PrjctStrtFrce

My Feedback: (10)

You don't need to fix anything, you just need to get one of [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXDLG8&P=Z]these[/link] or [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXDLG9&P=Z]these. [/link] Once you do find out which one fell out, make sure to put a good amount of lock tite on it so that it doesn't come out again.

twomanytoys

Thats ONLY IF that is the problem. That would be the easiest adn cheapest if it were but I doubt it.

PrjctStrtFrce

My Feedback: (10)

Think about it, he would have to blow BOTH rear dogbones for it to be ONLY FWD and if the diff blew, then it would still rotate or spin pathetically. I highly doubt that he snapped a center dogbone. The cups would be first to go before the dogbones IMO.

To the OP-do a visual inspection of the screws and the obvious before you take your diff apart.

twomanytoys

If you broke 1 rear dog bone the rear will not spin. Its an open differential. It needs both sides to be connected to work. If it were a locked diff in the rear then you would have one rear tire spinning. If the diff were blown the fronts will spin under power and the rear would free wheel. If the rear drive shaft were broke it would act the same way as if teh diff were blown. I have 2 savages powered by LRP engines and have blown many rear diffs, snapped many rear drive shafts and and dog bones.

twomanytoys

PrjctStrtFrce Do a little test so you can learn how an open diff works. Take one dog bone out from one rear and one front. I bet it wont move! Both sides need to be intact.

46u

My Feedback: (3)

I agree first thing is to check the set screws in the drive cups like PrjctStrtFrce said. Then go from there.

BudBud

I am not betting on that one, they turn the wheel with the least resistance. The thicker the differential fluid is, the better chance of driving a little it has. The screws and pinion would be my first guesses. Glen

46u

My Feedback: (3)

Hold the rear wheels from turning and turn the front wheels and see where the moving of the drive train stops. If it is the rear diff you will hear some bad noises when you put pressure turning the front wheels.

BudBud

If it is in the differential, another quick check is to hold the front end up and roll the truck backwards in an arc across the floor on the back tires. If it turns free with no grabbing spots or clicks, it is probably not the differential. If it grab and stops, clicks, jerks, you have probably broken a gear inside. That is assuming the bones are intact, which you can see from the outside.

twomanytoys

I will bet my whole rc arsenal on this. I am an ASE certified mechanic and the diffs in these are just like in cars. If an axle breaks it will not move. Take a dog bone out and you will see. The fluid controls the traction from one side to another. If you have very very thick oil which acts almost like a locked diff then yes you will get SOME power to one wheel. In stock form the oil is not thick enough to send enough power to the non broken axle to make it move. I hope all it is is just a shaft screw but if its not it will be one of what I have mentioned.

BudBud

Hey man, I am on your side! They will not normally move without an axle or dogbone. I would not bet a lot on it though, it would be my luck that a chunk of debris from a broken gear would be wedged in the bevel gears and I would be out. In my wheelie truck, I run Mobil 1 wheel bearing grease to keep the differential from unloading on one tire. I think it would drive without a dogbone. Glen

twomanytoys

Ok my bad!

-SomeGuy-

Like I say in all these types of threads: Take whatever is missing/broken from the front to replace it in the rear while you wait for your parts, if you need to order/pick up that is. Rear WD is better than nothing.

PrjctStrtFrce

My Feedback: (10)

Don't need to be ASE certified to know how an open diff works I understand your point though and I did mention that it would spin pathetically. I was also thinking of MY set-up, and not thinking of the stock set-up, which would act more like an open diff than my 50k oil set-up.

From my STOCK experience, I have only had the set screws come out a few times and have yet to snap any dogbones or blow any differentials with the exception of a stripped pinion gear and a bevel gear. From the sounds of it, it seems as if the OP has a stock truck as well.

All this and the OP hasn't even chimed in yet! [>:] It's only 9:30pm in his/her time zone.