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Old 01-23-2010, 07:18 PM   #1
Quarry Creeper
 
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Default Need ideas for surging issue

I'm ready to pull my hair out trying to get my scaler to run properly. When I run it, it will surge then pause, surge then pause. I took a video of it at the request of the guys at RC4WD which you can see here if interested: http://s670.photobucket.com/albums/v...t=RCA_0001.flv

Here is a rundown of the build:
Aluminum ladder chassis
R2 Tranny
Killer Transfer Case
Punisher shafts
Plastic T-Rex axles
RC4WD stamped steel 1.55" beadlocks
1.55" Mud Thrashers
Tekin FXR
Novak 55T
TQ3 Tx/Rx

I contacted RC4WD about this when I first got everything together and they graciously sent me a replacement set of axles. I have installed the new axles, improved the universal shaft angles and replaced the Novak Rooster Crawler with the Tekin FXR since I shot the video. The problem has improved slightly but is still there. I contacted RC4WD again after the changes and one of their techs asked me to try several things and finally said it must have been a problem with my electronics. At this point I have tried known good electronics and nothing eliminates the problem.

Everything rolls smoothly if I remove the motor from the tranny and the shaft of the motor turns as it should (not bent). I can not find any one single component that is causing the issue and I have disconnected every component one at a time from the tranny to the axles trying to isolate the problem. I am running the 1.55" beadlocks without hexes but I did install hexes and different wheels/tires and nothing changed.

The only conclusion I can come to is that there is enough "slop" in each or several of the driveline components that collectively they are creating this problem. I don't know what else to try here. I'm not bashing RC4WD here. They have been very good to me thus far but I have over $600 worth of RC4WD parts in this rig and I am frustrated beyond words at this point.

Has anyone else encountered a similar problem? I'm hoping there is something I have not considered but I am out of ideas. Any help would be greatly appreciated.
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Old 01-23-2010, 07:19 PM   #2
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Forgot to add that I have also run this with my Futuba 3pm Tx/Rx, same result.
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Old 01-23-2010, 08:30 PM   #3
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with you trying different electronics i would lean towards mechanical. in the vid you mentioned the driveshafts were jumping? have you checked the t-case for a possible bent shaft?
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Old 01-23-2010, 08:38 PM   #4
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Yes, I've disconnected everything one piece at a time and I can't find anything off center or bent. From watching the gear on the motor shaft all the way down to the ends of the axles.

The shafts don't jump like that with the wheels off. With no wheels on there the universal shafts run smooth.

With the wheels off and no power to the truck I can push the truck back and forth an inch and a half before the tension in the drive line catches up and stops it. It did the same with the JunFac shafts I had in it as well as the Punisher shafts I'm using now. This is why I'm leaning toward the theory that it's the slop stacking and causing the trouble.
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Old 01-23-2010, 08:43 PM   #5
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here is my thought.

1. can you take your fingers and twist the shaft between the transmission and the transfer case?

if there is slop there, thats your issue. Somewhere between point A and B you have too much play. It seems to me that there is a bent shaft to get that play in the transfer case. I wonder if you took the tranfer out of play if everything disappears?

The other things to check if there isnt play in between those 2 points is both of the drive shafts between the axles. See if one or the other has play too. Remember you have those punisher shafts on there so that is a lot of rotating mass to move around. if one of them shafts are mis built or designed wrong, that also can be the issue.

Try those 4 things out in inspection and let me know. Ill check the thread again.
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Old 01-23-2010, 08:46 PM   #6
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Just read the post before I posted

what about removing the shafts and is there a lot of play in and out on the drive mounts between the inside and outside of the axle?

also when everything is disconnected does both or one of the axles bind at a certain point when turning it by hand?
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Old 01-23-2010, 08:49 PM   #7
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in your first post you mentioned you tried known good electronics. did that include changing the motor as well?
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Old 01-23-2010, 08:59 PM   #8
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Quote:
Originally Posted by team3six View Post
here is my thought.

1. can you take your fingers and twist the shaft between the transmission and the transfer case?

Yes, I'd say maybe 5* or so

if there is slop there, thats your issue. Somewhere between point A and B you have too much play. It seems to me that there is a bent shaft to get that play in the transfer case. I wonder if you took the tranfer out of play if everything disappears?

I can't take the transfer out of the equation the way the chassis is laid out unfortunately. There doesn't seem to be much play in the transfer case when I had the shafts disconnected.

The other things to check if there isnt play in between those 2 points is both of the drive shafts between the axles. See if one or the other has play too. Remember you have those punisher shafts on there so that is a lot of rotating mass to move around. if one of them shafts are mis built or designed wrong, that also can be the issue.

Everything on it has about the same amount of play except for the transmission. With the motor installed the shaft won't budge with hand pressure alone.

Try those 4 things out in inspection and let me know. Ill check the thread again.
Thanks for the help so far. I was hoping someone with more experience than I have would jump in here.
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Old 01-23-2010, 09:00 PM   #9
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Quote:
Originally Posted by 76 warlock View Post
in your first post you mentioned you tried known good electronics. did that include changing the motor as well?
Yes Sir, I dropped a Lathe 45T in it to check and there was no improvement.
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Old 01-23-2010, 09:05 PM   #10
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You know, I wish I could nip it in the bud, It seems the best way is a complete deconstruct and rebuild with process of elimination. It seems to be the only logical choice. Those axles are both lubricated too right as well as the transfer case. because if its not the axles or the gear boxes, the only other thing it could be is your electronics. You got an XBEC on there running a winch and a servo plus the usual?
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Old 01-23-2010, 09:21 PM   #11
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I just plugged the winch in this evening for the first time. I figured it'd be nice to have something working right on it, might make me feel better.

I'm running a Castle BEC but I honestly don't know if it is just providing 6v to the steering servo (Futuba) or both the steering and the winch. I currently have the winch power wired directly into the battery and I sent an email to TSC to ask if I need to do something different since I'm running a 3s Lipo.
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Old 01-23-2010, 09:24 PM   #12
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Old 01-23-2010, 09:24 PM   #13
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I'd agree with the complete tear down and rebuild but I don't know that it's going to do me any good. If I take the wheels off the problem doesn't manifest. At first I though it might be an issue with the wheels and the fact that I'm not running hexes but I tried another set of wheels with hexes and had the same problem.

If I take all the wheels off and try to put a load on the drive line (pinching the ends of the axles with my fingers) I can't feel the surging.

I'm ready to bounce my face off of a brick wall for awhile.
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Old 01-23-2010, 09:28 PM   #14
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Thank you for the diagram, that's how I've got it wired up so I guess I'm good there. It seems to be working properly thankfully.
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Old 01-24-2010, 04:00 AM   #15
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Its like something bent.. You would think in the axles how its hopping, but very weird to be both axles..
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Old 01-24-2010, 06:03 AM   #16
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I had the same problem...it's the punisher shafts, the shorter ones do not like extreme angles. The male and female have to be joined so that they are not in the same position as one another during rotation...you will have to trial and error until you find the right combo...you've got some tight angles there..
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Old 01-24-2010, 07:15 AM   #17
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You hav'nt mentioned anything about gearing, I'm unfamilier with the R2 but, can you run higher gearing? like a smaller pinnion? I had the same issue with my 55t, and I resolved it by getting the motor to spin faster with higher gearing,
The motor will spin faster, but your rig will do the same speeds you have now.
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Old 01-24-2010, 08:49 AM   #18
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Quote:
Originally Posted by the_ghetto_rig View Post
I had the same problem...it's the punisher shafts, the shorter ones do not like extreme angles. The male and female have to be joined so that they are not in the same position as one another during rotation...you will have to trial and error until you find the right combo...you've got some tight angles there..
I'll give that a shot but it was doing the same thing with the JunFac shafts I tried.
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Old 01-24-2010, 09:06 AM   #19
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I agree on the driveshaft UJ's. the 2 ends need to be 90 degrees around from each other, cant remember what the problem is but i know ive come across it before on 1/1vehicles. Somthing to do with the angles of travel and rotating speeds.
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Old 01-24-2010, 10:58 AM   #20
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I switched the U joints around so they're opposed 90* and it seems to have improved the situation. Not sure why the JunFac shafts didn't make a difference but I have improved the shaft angles since I put them in so maybe that helped out.

The problem is still there but at this point I think it's at least manageable. Its worse in reverse than forward but I think I can live with it for now.

Thank you very much for the help guys.
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