RCCrawler Forums

RC Rock Hugger · 02-07-2007, 07:09 PM

Has anyone played with link angles to cure some of the torque twist we get on the TXT's? The truck seems to work pretty well but I think it could work better. I think a big problem with the torque twist is caused by the lower links being mounted above the axle centerline, and the link geometry in general. I know mounting the links up high is a quick and easy way to get lots of ground clearance but there might be drawbacks to it also. I think it could work better with a better designed suspension geometry. I am building another TXT and am going to play with some different setup's.
People mask it with different shock configurations but I think changing the forces that cause he twist would have better results.

Has anyone ran he #'s in the four link calculator? This computor doesn't have excel.

Flame away

bustedcrawler · 02-07-2007, 07:40 PM

I can run the numbers, but I can also tell you having run my txt bone stock with the links below the axle centerline that you will still have torque twist. Almost every vehicle has torque twist to some degree, laws of physics require it. Some like the TXT are just worse off. The motor sits up high giving it a nice moment arm to act on. Also it is not just the center line that the links mount on, but how the links intersect each other and the ground plane.

RD400 · 02-07-2007, 08:20 PM

I have found that with a low ratio axle like TXT's are, a 2:1 link seperation horizontally (more at the axle, less at the chassis), with equal length links top and bottom, with double triangulation is about the best set-up I have ever found.

That being said, weight placement makes a MUCH bigger difference. Getting the weight as low as possible is the only way to stop the metronome known as the TXT from rocking. Look at how bad a 1:1 truck would be with 2 to 1 ratio axles. Most trucks run 5 to 1 or greater axles...

RC Rock Hugger · 02-12-2007, 07:15 PM

Well I got my truck running today. The torque twist is minimal compared to my sons. There is a couple things I did different than the way my sons truck it set up. The biggest diference is the way the shocks are mounted, his are still on the cantilevers, mine are axle to frame. His has alot more flex but lots more TT. I will play with the angles of my shock some to see what difference it makes. I also mounted my lower links in front of the rear axle but about in the middle, his are still above the axle. Next we will remount the shocks on his to see what kind of difference, then we'll play with the link angles some.

RXcrawler · 02-12-2007, 11:36 PM

Get as much weight as possible off the chassis. And get that weight as low as possible. And like RD400 said link seperation. I had my lower links mounted at the ends of the axle next to the ears for the steering knuckles instead of the stock mounting location. Also helps to get the shocks as far out to the ends of the axle too.

ROK_TOY · 02-13-2007, 09:16 PM

Is there a program that will help to set up the links properly?

I've done alot of modifying recently....and as far as the links go, I made them all the same length. (upper and lower) Could this be a problem?

-rok.

RC Rock Hugger · 02-14-2007, 02:35 PM

Quote:

Originally Posted by ROK_TOY

Is there a program that will help to set up the links properly?

I've done alot of modifying recently....and as far as the links go, I made them all the same length. (upper and lower) Could this be a problem?

-rok.

There is a guy on Pirate4x4.com named triaged that came up with a 4 link calculator. I have no run any #'s through it but it is a great program from what I hear.

RD400 · 02-16-2007, 04:30 PM

Quote:

Originally Posted by RC Rock Hugger

There is a guy on Pirate4x4.com named triaged that came up with a 4 link calculator. I have no run any #'s through it but it is a great program from what I hear.

For 1:1, that program is good. For R/C, it doesn't translate. The physics of power to weight is totally different which calls for a different setup.

minor_threat · 07-27-2009, 01:48 AM

just bumping an old thread for input. I designed a new chassis, used traxxas shocks drooped and no toque twist. switched to rc4wd 100mm and have issues getting the droop to work and switched to sprung and now the chassis sways. of course i didn't put any oil in, as when i did, the shocks didn't compress at all, and went back to stock axial sprung to see, and no twisting at all. goes to show that it's not numbers every time. oil, shock response (sloppy or firm) and placement have something to do with it.

Tanis · 07-27-2009, 01:29 PM

Quote:

Originally Posted by minor_threat

oil, shock response (sloppy or firm) and placement have something to do with it.

absolutely

02-07-2007, 07:09 PM	#1
RC Rock Hugger Pebble Pounder Join Date: Apr 2006 Location: Jackson Posts: 105	Torque twist, link geometry Has anyone played with link angles to cure some of the torque twist we get on the TXT's? The truck seems to work pretty well but I think it could work better. I think a big problem with the torque twist is caused by the lower links being mounted above the axle centerline, and the link geometry in general. I know mounting the links up high is a quick and easy way to get lots of ground clearance but there might be drawbacks to it also. I think it could work better with a better designed suspension geometry. I am building another TXT and am going to play with some different setup's. People mask it with different shock configurations but I think changing the forces that cause he twist would have better results. Has anyone ran he #'s in the four link calculator? This computor doesn't have excel. Flame away Last edited by RC Rock Hugger; 02-08-2007 at 07:03 PM.

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02-07-2007, 07:40 PM	#2
bustedcrawler RCC Addict Join Date: Apr 2004 Location: 5280 Posts: 999	I can run the numbers, but I can also tell you having run my txt bone stock with the links below the axle centerline that you will still have torque twist. Almost every vehicle has torque twist to some degree, laws of physics require it. Some like the TXT are just worse off. The motor sits up high giving it a nice moment arm to act on. Also it is not just the center line that the links mount on, but how the links intersect each other and the ground plane.

02-07-2007, 08:20 PM	#3
RD400 Rock Crawler Join Date: May 2005 Location: omaha Posts: 858	I have found that with a low ratio axle like TXT's are, a 2:1 link seperation horizontally (more at the axle, less at the chassis), with equal length links top and bottom, with double triangulation is about the best set-up I have ever found. That being said, weight placement makes a MUCH bigger difference. Getting the weight as low as possible is the only way to stop the metronome known as the TXT from rocking. Look at how bad a 1:1 truck would be with 2 to 1 ratio axles. Most trucks run 5 to 1 or greater axles...

02-12-2007, 07:15 PM	#4
RC Rock Hugger Pebble Pounder Join Date: Apr 2006 Location: Jackson Posts: 105	Well I got my truck running today. The torque twist is minimal compared to my sons. There is a couple things I did different than the way my sons truck it set up. The biggest diference is the way the shocks are mounted, his are still on the cantilevers, mine are axle to frame. His has alot more flex but lots more TT. I will play with the angles of my shock some to see what difference it makes. I also mounted my lower links in front of the rear axle but about in the middle, his are still above the axle. Next we will remount the shocks on his to see what kind of difference, then we'll play with the link angles some.

02-12-2007, 11:36 PM	#5
RXcrawler Moderator Join Date: Apr 2004 Location: In my head Posts: 2,744	Get as much weight as possible off the chassis. And get that weight as low as possible. And like RD400 said link seperation. I had my lower links mounted at the ends of the axle next to the ears for the steering knuckles instead of the stock mounting location. Also helps to get the shocks as far out to the ends of the axle too.

02-13-2007, 09:16 PM	#6
ROK_TOY Newbie Join Date: Dec 2004 Location: California Posts: 32	Is there a program that will help to set up the links properly? I've done alot of modifying recently....and as far as the links go, I made them all the same length. (upper and lower) Could this be a problem? -rok.

07-27-2009, 01:48 AM	#9
minor_threat Rock Crawler Join Date: Jan 2009 Location: east bay Posts: 544	just bumping an old thread for input. I designed a new chassis, used traxxas shocks drooped and no toque twist. switched to rc4wd 100mm and have issues getting the droop to work and switched to sprung and now the chassis sways. of course i didn't put any oil in, as when i did, the shocks didn't compress at all, and went back to stock axial sprung to see, and no twisting at all. goes to show that it's not numbers every time. oil, shock response (sloppy or firm) and placement have something to do with it.

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