Emaxx Help!
12-17-2012, 07:00 PM
#1
Emaxx Help!
Bought a used brushed emaxx a while back! decided to upgrade everything on her. So now i basicly have a emaxx 3908 with the mamba monster in it. The rear diff is locked ? I don't think it was when i first got her. Can i unlock it ? or is that the way it is suppose to be ?
Also whats good gearing for her ? right now i have a 65t spur with 16t pinion. and shes not "crazy" fast on 4s.
Also whats good gearing for her ? right now i have a 65t spur with 16t pinion. and shes not "crazy" fast on 4s.
12-17-2012, 07:16 PM
#3
12-17-2012, 07:21 PM
#5
12-17-2012, 07:51 PM
#7
12-17-2012, 10:16 PM
#8
The diff i have is the one with the two silver screws on it. From research ive found that it is the original diff ?
12-18-2012, 09:06 AM
#9
It's shouldn't be locked, but depending on how/where you drive, you might want to leave it how it is. The 21/68 combo is great, but always watch your temps. Whenever you get a new vehicle (used) you should always spend the time to take it apart and clean everything from head to toe. I don't mind saying that I am a gigantic fan of Avid bearings/ get the better ones. They make my emaxx fly even faster. Soak them in some of that new zero weight synthetic motor oil/ or tranmission fluid. Get in the habit of doing this once a month or every 25 runs. Stainless steel screws are a nice investment as well if you are an offroader, b/c rusty screws are a pain to deal with. If you think your diff is messed up, just order a new on XXX and slap it right in. Use good diff grease, it makes the gears last much longer than some cheap stuff. Your LHS should have a good rec.
12-18-2012, 11:26 AM
#10
It's shouldn't be locked, but depending on how/where you drive, you might want to leave it how it is. The 21/68 combo is great, but always watch your temps. Whenever you get a new vehicle (used) you should always spend the time to take it apart and clean everything from head to toe. I don't mind saying that I am a gigantic fan of Avid bearings/ get the better ones. They make my emaxx fly even faster. Soak them in some of that new zero weight synthetic motor oil/ or tranmission fluid. Get in the habit of doing this once a month or every 25 runs. Stainless steel screws are a nice investment as well if you are an offroader, b/c rusty screws are a pain to deal with. If you think your diff is messed up, just order a new on XXX and slap it right in. Use good diff grease, it makes the gears last much longer than some cheap stuff. Your LHS should have a good rec.
Mainly my emaxx will be pavement, dirt roads and grass. Will leaving the diff locked do any harm ?
And i'm pretty meticulous when it comes to cleaning. I usually clean off my vehicle afterr every run and then every few runs runs tear her apart and give a real good cleaning.
12-18-2012, 12:11 PM
#11
I have the diff locked on my maxx that I drag race; you'll come to find there can/will be several advantages to a locked diff;i.e. you won't get stuck many places, you'll get off of the line faster, if you're pulling etc. and in many more cases, you wouldn't even know the difference unless someone told you what to look for. Hopping on the bay to pick up another diff just might be a good idea so you can see the difference yourself. In addition, it might not be a bad idea for you to hit up the traxxas website and download the manual/exploded views for your max so you can get a better picture of the parts you're looking at. Hope this helps.
12-18-2012, 05:13 PM
#12
If your outer diff case has only 2 screws that is the older style diff, both inside and out. These are a bit weaker than the newer style. I'd recommend going to ebay and picking up a newer style complete diff assembly, at least for the rear. The newer style diffs can also be tuned with different weight oils. Thicker oil will transmit power more evenly between the wheels (closer to locked), while thinner will transmit more power to the wheel with less traction.
As far as being locked. If you still have the plastic diff cup that means its not a spool which eliminates the diff cup. Most likely the previous owner put silly putty or something more permanent (epoxy, jb weld) inside the plastic diff cup to lock the spider gears together making it a spool. If you can't get the screws out to take the plastic cup off I'm leaning towards something more permanent like epoxy or jb weld was used.
As far as being locked. If you still have the plastic diff cup that means its not a spool which eliminates the diff cup. Most likely the previous owner put silly putty or something more permanent (epoxy, jb weld) inside the plastic diff cup to lock the spider gears together making it a spool. If you can't get the screws out to take the plastic cup off I'm leaning towards something more permanent like epoxy or jb weld was used.
12-18-2012, 05:18 PM
#13
If your outer diff case has only 2 screws that is the older style diff, both inside and out. These are a bit weaker than the newer style. I'd recommend going to ebay and picking up a newer style complete diff assembly, at least for the rear. The newer style diffs can also be tuned with different weight oils. Thicker oil will transmit power more evenly between the wheels (closer to locked), while thinner will transmit more power to the wheel with less traction.
As far as being locked. If you still have the plastic diff cup that means its not a spool which eliminates the diff cup. Most likely the previous owner put silly putty or something more permanent (epoxy, jb weld) inside the plastic diff cup to lock the spider gears together making it a spool. If you can't get the screws out to take the plastic cup off I'm leaning towards something more permanent like epoxy or jb weld was used.
As far as being locked. If you still have the plastic diff cup that means its not a spool which eliminates the diff cup. Most likely the previous owner put silly putty or something more permanent (epoxy, jb weld) inside the plastic diff cup to lock the spider gears together making it a spool. If you can't get the screws out to take the plastic cup off I'm leaning towards something more permanent like epoxy or jb weld was used.
I may order a 3908 rear diff just incase.
I've got a savage x 4.6 and the unlocked diff does leave her stuck sometimes. So i basicly know the difference in the two. I'm just looking into how I can make the best e-maxx.
12-18-2012, 09:59 PM
#14
It definitely sound like someone used epoxy or JB Weld when they assembled the diff. If you hit the out drives (where the driveshafts attach) with a hammer you might be able to get the cup off the ring gear. But you'll probably bend or damage something in the process making it totally useless.
The diff being locked isn't going to hurt anything. The worst thing a locked diff (or one with really heavy oil) does is it usually promotes under steer on higher traction surfaces. On lower traction surfaces the truck may be more likely to oversteer.
One more quick tip. I mentioned the diff you have being older and a little weaker than the newer style. An easy way to add some strength is to swap the 2 bolt outer diff cases for a set of 4 bolt diff cases or aluminum cases. The 2 bolt cases flex and don't maintain the right mesh on the ring and pinion when big power like brushless is applied to them. The gears themselves are basically the same strength between all versions. The 3903/3905/3908 Emaxx uses a sealed Revo style diff with metal inserts inside the plastic diff cup and is the strongest overall. That's the one to look for if you decide to get a whole assembly.
The diff being locked isn't going to hurt anything. The worst thing a locked diff (or one with really heavy oil) does is it usually promotes under steer on higher traction surfaces. On lower traction surfaces the truck may be more likely to oversteer.
One more quick tip. I mentioned the diff you have being older and a little weaker than the newer style. An easy way to add some strength is to swap the 2 bolt outer diff cases for a set of 4 bolt diff cases or aluminum cases. The 2 bolt cases flex and don't maintain the right mesh on the ring and pinion when big power like brushless is applied to them. The gears themselves are basically the same strength between all versions. The 3903/3905/3908 Emaxx uses a sealed Revo style diff with metal inserts inside the plastic diff cup and is the strongest overall. That's the one to look for if you decide to get a whole assembly.
01-15-2013, 09:56 AM
#15
It definitely sound like someone used epoxy or JB Weld when they assembled the diff. If you hit the out drives (where the driveshafts attach) with a hammer you might be able to get the cup off the ring gear. But you'll probably bend or damage something in the process making it totally useless.
The diff being locked isn't going to hurt anything. The worst thing a locked diff (or one with really heavy oil) does is it usually promotes under steer on higher traction surfaces. On lower traction surfaces the truck may be more likely to oversteer.
One more quick tip. I mentioned the diff you have being older and a little weaker than the newer style. An easy way to add some strength is to swap the 2 bolt outer diff cases for a set of 4 bolt diff cases or aluminum cases. The 2 bolt cases flex and don't maintain the right mesh on the ring and pinion when big power like brushless is applied to them. The gears themselves are basically the same strength between all versions. The 3903/3905/3908 Emaxx uses a sealed Revo style diff with metal inserts inside the plastic diff cup and is the strongest overall. That's the one to look for if you decide to get a whole assembly.
The diff being locked isn't going to hurt anything. The worst thing a locked diff (or one with really heavy oil) does is it usually promotes under steer on higher traction surfaces. On lower traction surfaces the truck may be more likely to oversteer.
One more quick tip. I mentioned the diff you have being older and a little weaker than the newer style. An easy way to add some strength is to swap the 2 bolt outer diff cases for a set of 4 bolt diff cases or aluminum cases. The 2 bolt cases flex and don't maintain the right mesh on the ring and pinion when big power like brushless is applied to them. The gears themselves are basically the same strength between all versions. The 3903/3905/3908 Emaxx uses a sealed Revo style diff with metal inserts inside the plastic diff cup and is the strongest overall. That's the one to look for if you decide to get a whole assembly.
