Hot bodies 1/8 diffs

[cmac]

So I see the Ofna Spider six diff's on Amain hobbies web site. Can someone give me a link to the 13t pinion gear please?

[WEB]

Look at the ofna Hyper 7 parts and they should be one on page number 2 it does not say it is 13 teeth but it is you can look up part number to see if it is 13 teeth:)
WEB

[MiRatlhed]

Here is the link to the UE Instruction manual for the 6 Spyder diffs. This has the Ofna part numbers listed on the parts list.

http://www.unlimitedengineering.com/...ctions-WEB.pdf

[cmac]

Originally Posted by MiRatlhed

Here is the link to the UE Instruction manual for the 6 Spyder diffs. This has the Ofna part numbers listed on the parts list.

http://www.unlimitedengineering.com/...ctions-WEB.pdf

Thanks for so much for the link.

[cmac]

OK. I got the Hitec 7955 servos, and got them installed. The steering is much better, but still under hard acceleration it pulls hard to the left. It is a good amount of torque steer. I noticed when I pulled my UE diff cases apart it says nitro on one side and electric on the other. I assume that you place the ring gear on the electric/nitro side depending on what drives your truck. Could the side that the ring gear is on contribute to the torque steer? If I switch the ring gears to the other side wouldn't it just pull to the opposite side? I have 300,000 wt diff oil in the Slipper 7,000 wt. in the front diff, and 5,000 wt. in the rear diff. Should I go even heavier in the center diff?

[cmac]

I took the truck out to a very large parking lot this morning and it definitely pulls to the side. I have to correct with counter steer and if I don't time it perfectly when I let off the throttle it becomes very hard to control. Does anyone have any experience with one of these? http://www.google.com/url?sa=t&rct=j...UXf5YN_qhpgzzg
I wonder if this would help keep the truck straight under hard acceleration?
http://www.google.com/url?sa=t&rct=j...-PQqJVvV1f0vtw

[suicideneil]

I think a regular Gyro would be cheaper and do the same thing...

http://traxxas.com/forums/showthread...ng-to-the-left

http://traxxas.com/forums/showthread...-1-gyro-config

[cmac]

Originally Posted by suicideneil

I think a regular Gyro would be cheaper and do the same thing...

http://traxxas.com/forums/showthread...ng-to-the-left

http://traxxas.com/forums/showthread...-1-gyro-config

Thank for the reply Neil,
too late though I already orded the D-box. Do you have any thoughts on the torque steer issue? I never had this problem with the original truck.

[JERRY2KONE]

Torque steer is a pretty common problem for 1:1 vehicles, especially in dragsters with huge power plants installed. Sorry I am not too familiar with your setup, but if you have an overkill of power in it than you will have to suffer some of this, and find ways to compensate for it. Using a GYRO can help greatly, which is what this "D" box looks like it is. Only with a fancy name added for extra hype. The main problem would seem to be in one of your diff's meaning that you may have to play with the lubricants in your diffs in order to offset the torque twisting your rig to one side or the other. If you have 4 wheel drive try disconnecting the front driveshaft and let it freewheel and see what kind of effect it has on this issue. It might even be that the front and rear diffs are not equal and they could be fighting each other. You have an issue that there could be an easy fix for, but first you have to determine exactly whats causing the problem. Process of elimination seems to be your best friend at this point.

[cmac]

Thanks Jerry,
great advice, I will give that a try.

[RC-Monster Mike]

If you get a hard pull it is could be a couple things. A nice tight servo saver would be the first place to look, along with the attached servo horn and linkages. Excessive play in the linkages could also contribute to this effect. Likewise, the linkages should be properly adjusted - left and right side should be attached in the same positions on either side and be the same length, for example. A common thing to do with Maxx trucks used to be putting the steering linkage on the top of the steering knuckle/pivot block rather than the bottom, which results in massive bump-steer. Diff setup can also contribute - if you have too heavy a diff oil or a locked diff, this will not allow the left and right side to spin at different rpms, which is progressively more important under power or at high speed, as no two RC tires are likely to be EXACTLY the same diameter and therefore must spin at slightly different rpms to drive straight. Usually the "pull" is caused by a loose or improperly adjusted linkage or steering component, though. :)

[cmac]

Thanks Mike,
I may have to play around with the steering linkage, and or the diff oil. I appreciate you taking the time to shed some knowledge on the subject. I did get to drive the truck with the HPI D-Box installed, and it is a whole lot better. the truck does not get out of control when I let off on the throttle like it did. I still have counter steer a little under 3/4 throttle, but overall it's way more controllable. Thanks to everyone who chimed in on this subject,
Mike.

[RC-Monster Mike]

The D-Box is only masking the problem, Mike - while it makes a huge difference, you really should find and eliminate the root cause - then reinstall the D-box. With such a sweet truck, it is well worth the trouble to make it perfect, too. :)

[cmac]

Mike, you are right. I am going to find out the cause of the problem. I too am a perfectionist, and I love to tinker around on these cars and trucks. I realize that the D-Box is just a band-aid and to me it is not a real solution. I think that I will start with the diff's. I have 7k in the front, 5k in the rear, and 300k in the slipper. I should mention that I have 4 wave springs on the slipper, and it is locked for now. I need to let it slip some. I just wanted it to throw the front wheels up in the air at will, but I think that it is contributing to the problem. Do you think I should try a lighter diff oil in the center. 100k ??????
Mike.

[RC-Monster Mike]

Even 50K in the center will allow wheelies at will, Mike - I can wheelie my truggy with 10K from a standing start on grass. 50k will allow some give while feeling largely like a locked diff. 300K is totally defeating the center diff - I don't think this is the root cause of the problem, though. The servo saver would be a primary candidate, along with linkages and bearings. A plastic rod end could be cracked but not broken, for instance - you wouldn't see the problem, but it would pull away/flex under stress when in use. A stuck bearing could also create the pull - there should be signs of this if it is the case(scars on the shaft it rides on, for instance). If you are using 1/8 diffs with diff outdrives, it could be as simple as a loose set screw on one of the drive cups(would send power to only one wheel and eventually diff out to the wheel not receiving power). The truck should accelerate nice and straight without the D-box.