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Workshop => Suspension and Chassis => Topic started by: Allison#51 on October 09, 2015, 01:38:00 PM
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Why is the Bumpsteer so bad on my roll design +3's with 400ex spindles? I can get the toe equal at extended and compressed lengths by spacing the tie rod ends down some but it toes way out in the middle of the travel no matter what.
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I never checked the toe on mine through the stroke, only at dry weight. Are you using a roll steering stem? I have called roll several times on different issues, never had any luck getting info. The girl who answers the phone is nice, but can never answer my questions. Always tells me Doug will get back to me...maybe in my afterlife.
I would check mine, but unfortunately it is several states away. Are you running any camber? Pretty sure these are supposed to be ran at 0' of camber
Best regards
- Jason
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I never checked the toe on mine through the stroke, only at dry weight. Are you using a roll steering stem? I have called roll several times on different issues, never had any luck getting info. The girl who answers the phone is nice, but can never answer my questions. Always tells me Doug will get back to me...maybe in my afterlife.
I would check mine, but unfortunately it is several states away. Are you running any camber? Pretty sure these are supposed to be ran at 0' of camber
Best regards
- Jason
I'm just running the stock stem. I'm curious if the roll or other brand stems are different. And I am running like 3/16" camber so I'm sure that is playing into it. That's the first I've heard that they're supposed to be 0' camber, I'm glad you said that! Thanks man.
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I can't offer measurements as I'm not with my R's but I did set them up per Roll Design instructions. I run +3 Roll arms with 400ex spindles and a Roll stem and have not noticed much bump steer in the dunes.
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I am curious how you got negative camber? I am running a Lobo and I can adjust to 0' but no farther. The only way would be to remove the jam nut on the top heim. I have been looking for a heim with a longer threaded section so I can put a jam nut on the back side.
Anyways I brought this up before and I believe it was Sidcon that told me the roll front ends are designed to run at 0'.
Best regards
- Jason
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If anything I thought my heims were out pretty far to get the negative camber that I have. I feel like they won't have a lot of threads left if I set it at 0' but I could be wrong. I'll work on it tomorrow and snap some pictures. I thought most companies recommended setting it up with negative camber though. When I set that should it just be at ride height?
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Are you 100% its roll not jrd, or similiar? Are you cycling it with no shock, or is it within the actual range of travel?
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I actually went and worked on it tonight. I set it at ride height and found that I had more negative camber then I thought. I don't have a good angle finder so I used a square and measured to the top of the tire and it was about 1/2" so I reset the camber to 0 at ride height. I double checked with a two foot level first checking the rear tires for plumb then going to the fronts. Then I reset the toe to straight up. Went back and checked camber again. Most setup instructions will say to thread your heims in all the way then back each side out an equal amount of turns but my right side has to be out like 2 or 2 1/2 turns farther than the left to get the camber correct.. Kinda weird but everything looks good on both sides. Then I went back to checking Bumpsteer. Shocks are off. I have three washers spacing the tie rods down. I raised it up to the extended length of the shock and set the toe to straight up. Dropped it down to halfway through the travel and again it toed out but not as bad. This time it was 9/16" out before it was moving 13/16". Dropped it down to the compressed length of the shock and the toe measurement returned to straight up.
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(http://i603.photobucket.com/albums/tt116/Allison55/Mobile%20Uploads/B234588F-1BF8-487C-AA63-C7C714355608.jpg) (http://s603.photobucket.com/user/Allison55/media/Mobile%20Uploads/B234588F-1BF8-487C-AA63-C7C714355608.jpg.html)
This is where the heim has to be to achieve 0' camber at 7 1/2" frame height. It's threaded out pretty far. There is a little over 3/4" of threads in the arm
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You might have a mixed set of arms. Bottoms are too long or tops are too short. Measure and post them to check against what others have. Mine are threaded all the way in and I have 0'. You are fine with that much thread, there is not that much radial loading being applied on to the threads on the top ball joint.
Also have you measured center to center on your tie rod ball joints? Pretty close on right and left?
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I noticed you are not running roll tierods and oem rod ends. That is most likely the first issue. I have found on mine washers make it worse. I would compare you misalignment height to an oem and start there as a base. I have a narrow frame but my bump steer is almost none. It just barely toes in at full bump.
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What offset are your wheels? Are you running spacers? The closer you can get the centerline of your tires over those heims the less bumpsteer you'll have. Basically, the farther your tires get from the steering pivot point(the heims), the more the tires act like levers when you're trying to steer.
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You might have a mixed set of arms. Bottoms are too long or tops are too short. Measure and post them to check against what others have. Mine are threaded all the way in and I have 0'. You are fine with that much thread, there is not that much radial loading being applied on to the threads on the top ball joint.
Also have you measured center to center on your tie rod ball joints? Pretty close on right and left?
(http://i603.photobucket.com/albums/tt116/Allison55/Mobile%20Uploads/C543A3B6-A2E6-4D6A-833B-0C90F0E32A71.jpg) (http://s603.photobucket.com/user/Allison55/media/Mobile%20Uploads/C543A3B6-A2E6-4D6A-833B-0C90F0E32A71.jpg.html)
Upper is roughly 12" from center of the front bolt to the end
(http://i603.photobucket.com/albums/tt116/Allison55/Mobile%20Uploads/B00BD528-CA44-4CAC-BE92-7B452DE7F221.jpg) (http://s603.photobucket.com/user/Allison55/media/Mobile%20Uploads/B00BD528-CA44-4CAC-BE92-7B452DE7F221.jpg.html)
Lower is roughly 16" from center of the bolt too the edge of the spherical bearing cup. And the tie rods are pretty close to equal lengths.
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I noticed you are not running roll tierods and oem rod ends. That is most likely the first issue. I have found on mine washers make it worse. I would compare you misalignment height to an oem and start there as a base. I have a narrow frame but my bump steer is almost none. It just barely toes in at full bump.
I have quite a bit of adjustment with the spacers on these I can go either taller or shorter than stock. I'm pretty close to the stock ends height right now but I am gonna play around with it a bit more.
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What offset are your wheels? Are you running spacers? The closer you can get the centerline of your tires over those heims the less bumpsteer you'll have. Basically, the farther your tires get from the steering pivot point(the heims), the more the tires act like levers when you're trying to steer.
They are 4:1s no spacers.
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You have the inners mounted under the flag?
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400 ex spindles rod end goes under, on stem flag it goes on top.
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400 ex spindles rod end goes under, on stem flag it goes on top.
Yeah they're on there right. I don't think they would fit the wrong way.
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If someone could measure their +3's uppers the way I did so I can compare that would be sweet!
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(http://i603.photobucket.com/albums/tt116/Allison55/Mobile%20Uploads/C543A3B6-A2E6-4D6A-833B-0C90F0E32A71.jpg) (http://s603.photobucket.com/user/Allison55/media/Mobile%20Uploads/C543A3B6-A2E6-4D6A-833B-0C90F0E32A71.jpg.html)
Upper is roughly 12" from center of the front bolt to the end
(http://i603.photobucket.com/albums/tt116/Allison55/Mobile%20Uploads/B00BD528-CA44-4CAC-BE92-7B452DE7F221.jpg) (http://s603.photobucket.com/user/Allison55/media/Mobile%20Uploads/B00BD528-CA44-4CAC-BE92-7B452DE7F221.jpg.html)
Lower is roughly 16" from center of the bolt too the edge of the spherical bearing cup. And the tie rods are pretty close to equal lengths.
In the above pic are the heims set for 0deg camber? If so then there's plenty of meat to bring it in to a negative camber. Are you trying to bring the top of the tire in or out?
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If someone could measure their +3's uppers the way I did so I can compare that would be sweet!
I'll measure mine when I get home after work. I have similar issues with Roll front end setup
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In the above pic are the heims set for 0deg camber? If so then there's plenty of meat to bring it in to a negative camber. Are you trying to bring the top of the tire in or out?
Yes with the heims set there it's at 0' camber at 7 1/2" ride height. I had negative camber in it before. By backing it out to 0' I was able to improve the Bumpsteer slightly.
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I'll measure mine when I get home after work. I have similar issues with Roll front end setup
Awesome thanks! I'm trying to get this figured out before my race this weekend. I know it'll be better then what it was before. I about got thrown off in the whoops last race. Something still seems off though.
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I guess it's just a trade off between bump steer and handling. Just a suggestion, get a stabilizer and pull in your camper to -3 to -6. You shod habe acceptable bump steer and really good handling
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I got roughly the same measurements on a set of +3 Roll Lobo II arms
(http://i603.photobucket.com/albums/tt116/Allison55/Mobile%20Uploads/C543A3B6-A2E6-4D6A-833B-0C90F0E32A71.jpg) (http://s603.photobucket.com/user/Allison55/media/Mobile%20Uploads/C543A3B6-A2E6-4D6A-833B-0C90F0E32A71.jpg.html)
Upper is roughly 12" from center of the front bolt to the end
(http://i603.photobucket.com/albums/tt116/Allison55/Mobile%20Uploads/B00BD528-CA44-4CAC-BE92-7B452DE7F221.jpg) (http://s603.photobucket.com/user/Allison55/media/Mobile%20Uploads/B00BD528-CA44-4CAC-BE92-7B452DE7F221.jpg.html)
Lower is roughly 16" from center of the bolt too the edge of the spherical bearing cup. And the tie rods are pretty close to equal lengths.
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Okay thanks! That's reassuring. Still confused why other sets are different. I tightened everything back up tonight on it and I'm still not real happy with it but it should be better. It gets really weird when I try to string align it! like the axle is shifted way to the right. Part of it is that lonestar didn't machine the splines far enough on the right side of the axle. I had to cut a shorter spacer to make the cotter pin hole line up. Drives me crazy.
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If your using a string from rear to front and it seems off it may be your Frame. Stand it up on the grab bar and use a 6' level to see if the center of the swingarm at the axle housing is in line with the center of frame at the pegs and the steering stem. If your running mx you should be setting your camber .5-1.5 degrees, I've never heard of setting it at 0 but I've not heard everything.
Thanks!
Steve
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If your using a string from rear to front and it seems off it may be your Frame. Stand it up on the grab bar and use a 6' level to see if the center of the swingarm at the axle housing is in line with the center of frame at the pegs and the steering stem. If your running mx you should be setting your camber .5-1.5 degrees, I've never heard of setting it at 0 but I've not heard everything.
Thanks!
Steve
Yeah that's a good idea I'll do that. I was kinda thinking about pulling the rear tires off too and running a straight edge off the rear hub to the front and measuring in to the frame on each side. I will probably put some camber back in it for next MX season but I'm currently setting up for ice racing and it's gonna be different on each side.