RCCrawler Forums

JaredVW · 07-11-2010, 10:51 PM

ok guys so heres the issue i'm running into. i have an ax10 with the axial clockable C's and VP high steer knuckles. i have axial CVD's for the axles. it seems as though if i steer the rig while digging, the wheels seem to fight each other. the outer wheel seems to want to pull itself to full lock and then back off. it does that rapidly over and over. i thought that my EPA was set to sharp. by the time i got it to stop, the wheels were almost stright! any ideas, something i missed? any info would help.

BTW, i didn't have any issues like this before the cvd's.

KC_JoNeS · 07-12-2010, 12:40 AM

Quote:

Originally Posted by JaredVW

ok guys so heres the issue i'm running into. i have an ax10 with the axial clockable C's and VP high steer knuckles. i have axial CVD's for the axles. it seems as though if i steer the rig while digging, the wheels seem to fight each other. the outer wheel seems to want to pull itself to full lock and then back off. it does that rapidly over and over. i thought that my EPA was set to sharp. by the time i got it to stop, the wheels were almost stright! any ideas, something i missed? any info would help.

BTW, i didn't have any issues like this before the cvd's.

It sounds to me like you have your caster wrong. Do you have your clockable Cs on backwards?

Can you use photobucket or something to host a photo, and post up a photo of your front end?

Casey

92LILREDYJ · 07-12-2010, 07:50 AM

Need a little more info on the rig please. Like your front link setup? 4linked? What are the links made out of?

oldhippie · 07-12-2010, 08:04 AM

Quote:

Originally Posted by JaredVW

BTW, i didn't have any issues like this before the cvd's.

You answered your own question.

The cvds are binding.

JaredVW · 07-12-2010, 10:19 AM

this is my caster. looks correct to me.

here is a top and front view of the front axle.

gunnar · 07-12-2010, 10:37 AM

Do you have in-out slop at the wheels? Might be some slight mis-alingnment between the cvd pins and the kingpin screws, they need to line up to make the cvd turn smoothly.

With Ackermann knuckles, one wheel will turn further than the other, so they will fight each other to a degree, but it shouldn't be a big problem.

AlphaQup · 07-12-2010, 10:47 AM

I had the same problem. I think it is due to the fact that the CCDs can't be offset by 90 degrees. Seem to me that one shaft should go into the locker at a different angle than the other. And you will find that the cvd pins break veery rapidly if you have the inner wheel hopping badly when digging. Try to run more toe angle if possible. I think it might help to have the outer wheel pointed inward more while turning. Or just put the dog bones back in. Solved my problems. Seems to turn better with worn out dog bones than axial Cvds.

AlphaQup · 07-12-2010, 10:53 AM

Quote:

Originally Posted by gunnar

Do you have in-out slop at the wheels? Might be some slight mis-alingnment between the cvd pins and the kingpin screws, they need to line up to make the cvd turn smoothly.

With Ackermann knuckles, one wheel will turn further than the other, so they will fight each other to a degree, but it shouldn't be a big problem.

And one last thing. Order some of gunnars music wire cvd pins. I can say that they last about 5x longer than stock pins.

TSK · 07-12-2010, 01:05 PM

Quote:

Originally Posted by AlphaQup

I think it might help to have the outer wheel pointed inward more while turning.

Proper ackerman angles would have the inner wheel turning at a sharper angle than the outer wheel.

Also, if it's not the cvd's not being properly aligned in the knuckle/kingpin area like Gunnar suggested, I see the problem being electronics related. Specifically lack of power to the servo. When digging, the motor draws alot more amps due to the increased load for trying to drag the rear end around. this increased amp draw, plus the amp draw of the servo trying to hold the front wheels at full loc, whilst the front wheels fight each other, is causing the servo to cut out intermittently. That's why when you try to adjust your EPA's to fix the problem, your wheels are almost straight. Try a BEC.

JaredVW · 07-12-2010, 10:49 PM

it's not the electronics. i have a 55turn and a rooster. a JR 8711 for the steering. and a CC BEC.

TSK · 07-12-2010, 11:32 PM

Then it's the cvd's not being aligned. What locker are you using?

JaredVW · 07-13-2010, 08:57 AM

well, i put some dog bones back in it and set thw EPA's as high as i could till they started to bind, and then back it off a hair. i drove the truck around and the issue is gone. i'm not sure why, but it works now.

I have the heavy duty axial locker with OD ring and pinion.

TSK · 07-13-2010, 12:02 PM

About how much steering angle were you getting out tf the cvd's at full lock?

oldhippie · 07-13-2010, 12:32 PM

Are ya sure ya have axial knuckles and not berg knuckles? Vanquish makes both and it will throw the cvds out.

JaredVW · 07-14-2010, 09:12 AM

Quote:

Originally Posted by TheSCorpionKing

About how much steering angle were you getting out tf the cvd's at full lock?

with it in my hand and no load on it, i could go untill the cvd started to bind. any further and the tire would have been buried into the shock. it's only under the dig load that it wobbles like that.

oh and i'm sure they are axial VP knuckles because they don't bind while running it on a stand.

gunnar · 07-14-2010, 09:39 AM

It might be the difference in turning radius due to your Ackermann knuckles. Try this: remove your rodend from the right side of the tie rod, add three 3mm flat washers between the rodend and tie rod tube, (creating toe-out), and test while digging again. You will have toe-out when the wheels are centered, but the wheels will be become more parallel as you turn. See if that helps or hurts.

JaredVW · 07-14-2010, 10:44 PM

ok. i wondered about that from reading other builds. i will let you know what happens. thanks for the tips so far

KC_JoNeS · 07-15-2010, 12:29 AM

Yeah, the ackermann on this makes a bit of sense. The inside wheel will turn sharper to create a tighter turning radius.

Do the CVDs have a worse turning angle than dogbones with outers? Somehow I find this a bit hard to swallow.

gunnar · 07-15-2010, 12:38 AM

Most CVD's turn around 43-45 degrees. Stock dogbones are around 31-33, modded dogbones around 37-38.

KC_JoNeS · 07-15-2010, 01:05 AM

Quote:

Originally Posted by gunnar

Most CVD's turn around 43-45 degrees. Stock dogbones are around 31-33, modded dogbones around 37-38.

If this is the case, how would slightly different angles be at fault for a bind? CV = constant velocity, meaning what goes in comes out equally...not out of phase at angles. If this holds true for these CVDs, then this hypothesis has holes in it.

There MUST be something else at play. Perhaps the CVD itself has an issue. Could also be how the CVD is held in. Mine are on order, so I am sure I will have a much clearer understanding of this.

Casey

07-11-2010, 10:51 PM	#1
JaredVW Pebble Pounder Join Date: Dec 2007 Location: Arvada Posts: 103	steering binding issue ok guys so heres the issue i'm running into. i have an ax10 with the axial clockable C's and VP high steer knuckles. i have axial CVD's for the axles. it seems as though if i steer the rig while digging, the wheels seem to fight each other. the outer wheel seems to want to pull itself to full lock and then back off. it does that rapidly over and over. i thought that my EPA was set to sharp. by the time i got it to stop, the wheels were almost stright! any ideas, something i missed? any info would help. BTW, i didn't have any issues like this before the cvd's.

07-13-2010, 08:57 AM	#12
JaredVW Pebble Pounder Join Date: Dec 2007 Location: Arvada Posts: 103	well, i put some dog bones back in it and set thw EPA's as high as i could till they started to bind, and then back it off a hair. i drove the truck around and the issue is gone. i'm not sure why, but it works now. I have the heavy duty axial locker with OD ring and pinion. Last edited by JaredVW; 07-13-2010 at 08:59 AM.

07-12-2010, 07:50 AM	#3
92LILREDYJ Rock Crawler Join Date: Dec 2009 Location: Beaumont, Tx Posts: 507	Need a little more info on the rig please. Like your front link setup? 4linked? What are the links made out of?

07-12-2010, 10:19 AM	#5
JaredVW Pebble Pounder Join Date: Dec 2007 Location: Arvada Posts: 103	this is my caster. looks correct to me. here is a top and front view of the front axle.

07-12-2010, 10:37 AM	#6
gunnar Ex Nor-CalRCRC slave Join Date: Dec 2008 Location: San Mateo, CA. Posts: 2,242	Do you have in-out slop at the wheels? Might be some slight mis-alingnment between the cvd pins and the kingpin screws, they need to line up to make the cvd turn smoothly. With Ackermann knuckles, one wheel will turn further than the other, so they will fight each other to a degree, but it shouldn't be a big problem.

07-12-2010, 10:47 AM	#7
AlphaQup Quarry Creeper Join Date: Sep 2009 Location: Concord Posts: 215	I had the same problem. I think it is due to the fact that the CCDs can't be offset by 90 degrees. Seem to me that one shaft should go into the locker at a different angle than the other. And you will find that the cvd pins break veery rapidly if you have the inner wheel hopping badly when digging. Try to run more toe angle if possible. I think it might help to have the outer wheel pointed inward more while turning. Or just put the dog bones back in. Solved my problems. Seems to turn better with worn out dog bones than axial Cvds.

07-12-2010, 10:49 PM	#10
JaredVW Pebble Pounder Join Date: Dec 2007 Location: Arvada Posts: 103	it's not the electronics. i have a 55turn and a rooster. a JR 8711 for the steering. and a CC BEC.

07-12-2010, 11:32 PM	#11
TSK Shelf queen Join Date: Aug 2008 Location: Internet Posts: 5,857	Then it's the cvd's not being aligned. What locker are you using?

07-13-2010, 12:02 PM	#13
TSK Shelf queen Join Date: Aug 2008 Location: Internet Posts: 5,857	About how much steering angle were you getting out tf the cvd's at full lock?

07-13-2010, 12:32 PM	#14
oldhippie I wanna be Dave Join Date: Feb 2009 Location: 20 miles southeeast of downtown Sacramento Posts: 2,373	Are ya sure ya have axial knuckles and not berg knuckles? Vanquish makes both and it will throw the cvds out.

07-14-2010, 09:39 AM	#16
gunnar Ex Nor-CalRCRC slave Join Date: Dec 2008 Location: San Mateo, CA. Posts: 2,242	It might be the difference in turning radius due to your Ackermann knuckles. Try this: remove your rodend from the right side of the tie rod, add three 3mm flat washers between the rodend and tie rod tube, (creating toe-out), and test while digging again. You will have toe-out when the wheels are centered, but the wheels will be become more parallel as you turn. See if that helps or hurts.

07-14-2010, 10:44 PM	#17
JaredVW Pebble Pounder Join Date: Dec 2007 Location: Arvada Posts: 103	ok. i wondered about that from reading other builds. i will let you know what happens. thanks for the tips so far

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07-15-2010, 12:29 AM	#18
KC_JoNeS Tossin' Salad Join Date: Jun 2010 Location: Petaluma Posts: 1,826	Yeah, the ackermann on this makes a bit of sense. The inside wheel will turn sharper to create a tighter turning radius. Do the CVDs have a worse turning angle than dogbones with outers? Somehow I find this a bit hard to swallow.

07-15-2010, 12:38 AM	#19
gunnar Ex Nor-CalRCRC slave Join Date: Dec 2008 Location: San Mateo, CA. Posts: 2,242	Most CVD's turn around 43-45 degrees. Stock dogbones are around 31-33, modded dogbones around 37-38.

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