wheelman Posted March 30, 2011 Share Posted March 30, 2011 I was looking at the ball joint attachment to the control arm the other day and thought about putting a shim/spacer between the joint and arm as a fix for bump steer. Has anybody tried this or does anyone have an opinion on whether its a good idea? My reasoning is it would be simpler than moving the inner pivot and could probably be accomplished using some washers assuming the adjustment required is small enough. Making a spacer from 6061-T6 aluminum would be very simple. Down sides would be longer bolts holding the ball joint to the control arm and possible loss of some anti-dive as the spacer would be between the control arm and TC rod. I can't see how this would be affected much as a large spacer would be a bad idea. Anyway, what do you guys think? Wheelman Quote Link to comment Share on other sites More sharing options...
timzcarman Posted March 30, 2011 Share Posted March 30, 2011 http://www.zccjdm.com/catalog.php/azcarbum/dt93255/pd1789104/CAMBER__BUMP_STEER_SPACER_ZCAR_ Something like these? Quote Link to comment Share on other sites More sharing options...
tyler031734 Posted March 30, 2011 Share Posted March 30, 2011 http://www.zccjdm.com/catalog.php/azcarbum/dt93255/pd1789104/CAMBER__BUMP_STEER_SPACER_ZCAR_ Something like these? That price really hurts. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 30, 2011 Share Posted March 30, 2011 Read the bumpsteer FAQ post, it should help. Although it is called a bumpsteer spacer, what that spacer does is change what part of the bumpsteer curve the car is in. It's better described as a roll center corrector. That particular one also adds negative camber, but you can get bumpsteer spacers from MSA and elsewhere that don't affect camber. If you want to use a spacer, what you need to do is get a bumpsteer spacer kit for the tie rod, and then either ream the steer knuckle to fit the kit with a tapered pin, or drill the steer knuckle to accept a 5/8" bolt. All of this is in the FAQ post. Quote Link to comment Share on other sites More sharing options...
wheelman Posted March 30, 2011 Author Share Posted March 30, 2011 I know what bump steer/roll center adjusters are, in fact I have them on my car now, what I was curious abourt is putting a spacer between the ball joint and the control arm. I installed power steering, in the process the rack ended up a little higher than it had been so I either need to move the inner pivot up or the outer end down (in relation to the tie rod end). That is if I even want to mess with it, the bump steer is not bad (haven't actually measured it, driving impressions), it's just there and will bother me until I can do something about it. It is the "safe" direction though, toe out on compression, so thats at least one positive to the whole thing. I was thinking it may be a simpler job to place a spacer between the ball joint and the control arm than mess with the steering arm and tie rods. I'll have to ponder it some more, it may have other "bad" side effects than a change in anti-dive as I suggested in my first post. Wheelman Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 30, 2011 Share Posted March 30, 2011 (edited) I know what bump steer/roll center adjusters are, in fact I have them on my car now, what I was curious abourt is putting a spacer between the ball joint and the control arm. I installed power steering, in the process the rack ended up a little higher than it had been so I either need to move the inner pivot up or the outer end down (in relation to the tie rod end). That is if I even want to mess with it, the bump steer is not bad (haven't actually measured it, driving impressions), it's just there and will bother me until I can do something about it. It is the "safe" direction though, toe out on compression, so thats at least one positive to the whole thing. I was thinking it may be a simpler job to place a spacer between the ball joint and the control arm than mess with the steering arm and tie rods. I'll have to ponder it some more, it may have other "bad" side effects than a change in anti-dive as I suggested in my first post. Sorry, I read Tyler's reply and thought it was from you. Any ideas on what such a spacer would look like? I'm not able to picture this in my mind and not have it be just like a standard bumpsteer spacer. If you put the spacer between the control arm and the ball joint, it would do the same thing as the regular bumpsteer spacer; change the roll center but it wouldn't change the actual pivot points on the outboard end. [EDIT--Actually it wouldn't even do that, because the pivots would be in the same place. It would make no difference at all.] What matters is the location of the ball joint relative to the tie rod, so what you would need is a spacer between the ball joint and the steer knuckle (or a bent steer knuckle). I just don't see a way to do a spacer there unless you modified the steer knuckle to take a ball joint with a larger shank and put a spacer in between to take up the space. I'm sure you could have the steer knuckles bent, I know Design Products racing does that for 510's to correct bumpsteer. The problem is knowing how much change you need. That's why I like slotting the crossmember, because you can then adjust however much is necessary to minimize the bump steer. For a crude idea of anti dive, you can just look at the TC pivot to the ball joint. If this imaginary line points up from the TC to the ball joint, you have some anti. If it is level, you're neutral, if it points up, you have some pro-dive. You want them level or slightly down, I think a lot of really lowered Z's have pro-dive. I know mine did. Edited March 31, 2011 by JMortensen Quote Link to comment Share on other sites More sharing options...
wheelman Posted March 31, 2011 Author Share Posted March 31, 2011 Not sure what the spacer might look like but it would be sandwiched between the control arm and the ball joint mounting pad. The 4 bolts that hold the ball joint to the arm would go through the spacer and thread into the pad just like they do now. Obviously the bolts would have to be longer to accomodate the spacer. Is that a little clearer description of what I'm thinking? I was thinking that by increasing the distance from the control arm to the ball joint it could make the control arm and tie rod more parallel which is the same thing the Pinto kit, moving the inner pivot or bending the steering arm can do, in my case anyway. The idea is to make the tie rod and control arm as parallel to each other as possible so they follow the same arc through their motion, after all isn't it the differing arcs that cause the bump steer? You verified my thoughts regarding the anti-dive characteristics. Wheelman Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 31, 2011 Share Posted March 31, 2011 (edited) Not sure what the spacer might look like but it would be sandwiched between the control arm and the ball joint mounting pad. The 4 bolts that hold the ball joint to the arm would go through the spacer and thread into the pad just like they do now. Obviously the bolts would have to be longer to accomodate the spacer. Is that a little clearer description of what I'm thinking? I was thinking that by increasing the distance from the control arm to the ball joint it could make the control arm and tie rod more parallel which is the same thing the Pinto kit, moving the inner pivot or bending the steering arm can do, in my case anyway. The idea is to make the tie rod and control arm as parallel to each other as possible so they follow the same arc through their motion, after all isn't it the differing arcs that cause the bump steer? Doesn't work that way. Think of the control arm as the pivot to pivot. We know where the inner pivot is. If you put a spacer under the ball joint, you haven't moved the outer pivot, you've basically just "bent" the control arm further (the line between the ball joint and inner pivot is further from being perfectly straight, but the pivots have not moved). Edited March 31, 2011 by JMortensen Quote Link to comment Share on other sites More sharing options...
wheelman Posted March 31, 2011 Author Share Posted March 31, 2011 Ok, now I see why you said it wouldn't work and I agree, it won't. I guess I'll either have to move the inner pivot or go the Pinto route at some point. Wheelman Quote Link to comment Share on other sites More sharing options...
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