randy 77zt Posted February 17, 2005 Share Posted February 17, 2005 i moved to control arm bolt holes up 3/4" and out 3/4".then i heated the tie rod ends to remove the kink and make them straight.the pivot point for the control arms is very close to the pivot point of the ball sockets on the rack.car drives very good-cars is very easy to drive at the track.this changes the roll center of the front suspension.this is not a common modification because if the car is used for racing most rules (scca) bump the car up into a very expensive(gt2) class.but my car is just a work car/track school car so i dont care.some day i should remove the springs and move the car up and down to check bump steer . Quote Link to comment Share on other sites More sharing options...
260DET Posted February 17, 2005 Share Posted February 17, 2005 As you probably know, a car can be checked for bump steer when getting a wheel alignment by moving the front of the car up and down on the suspension, at the same time checking for any change in toe due to that movement. What I have wondered about in relation to the 'bump steer' spacers is if they have any other effect besides altering the roll center. Because they raise the outer pivot in relation to the axle. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted February 17, 2005 Share Posted February 17, 2005 Don't they lower the pivot point by, in essence, extending the length of the bottom of the strut housing? Quote Link to comment Share on other sites More sharing options...
2126 Posted February 18, 2005 Share Posted February 18, 2005 Don't they lower the pivot point by, in essence, extending the length of the bottom of the strut housing? Terry is correct! IIRC, the real purpose for installing the bumpsteer spacers is to reposition the transverse links back to or near the original geometry...when a Z has been lowered a significant amount...and thats about it! I'm currently hunting for a front crossmember for my 1970 so I can do the pivot point mod without having the additional down time, if I were to use the one in my Z. Anyone help me out with a spare (straight) crossmember? I may even do the adjustable ball-joint mod to the transverse links as well. Ah hell, the next thing you know I'll be doing the CV drive axle mod....only time and $. Quote Link to comment Share on other sites More sharing options...
260DET Posted February 18, 2005 Share Posted February 18, 2005 OK it wasn't put very well :neutral: what I was getting at is the 'change in distance' between the front axle and the outer pivot point. With bump steer spacers that distance is increased. Moving a pivot point up or down alters the roll center, what I was wondering was whether the 'change in distance' by itself alters anything that affects handling. Quote Link to comment Share on other sites More sharing options...
johnc Posted February 18, 2005 Share Posted February 18, 2005 Moving a pivot point up or down alters the roll center, what I was wondering was whether the 'change in distance' by itself alters anything that affects handling. The most significant change is that it affects the camber curve as the suspension moves in bump. It tends to flatten the curve so the normal gain from stock ride height (about 1/2 of a degree) gets reduced to less then a 1/4 degree (assuming a 25mm spacer). But that drawback is more then offset because without the spacer properly locating the control arms you would get a camber loss as the suspension moves in bump. Quote Link to comment Share on other sites More sharing options...
Ricky Posted February 28, 2005 Share Posted February 28, 2005 I have lowered the front of my Z 50mm by shortening the Struts and fitting Koni 8641 1115 sport inserts. I have been following this thread and am not sure weather I should fit bump steer spacers or reposition the lower control arms. If I do reposition the LCA is there a magic distance up and out or just up? Quote Link to comment Share on other sites More sharing options...
buZy Posted March 1, 2005 Share Posted March 1, 2005 From my research there is no magic set distance. I'm doing the LCA mod right now and just went up 3/4 inch. That's all I could get before interfernce with the V8 mounts. Have heard of others going .875 to 1". Going out i'm using AZ car adjustable transverse link and caster arms. Reinforcing the caster arm tab to transverse mount for insurance....Never heard of straightening the tie rod ends, interesting... I suppose it depends on your ride height/set up. Two questions do come to mind here though. Would the strength of the tie rod ends be compromised when heated and straighted?? Have not fully drilled yet my LCA holes maybe I will sneak the pivots out too just a bit. Would .375 be ok?? I dont care about racing. I'm on the street scence. Thanks everyone! Quote Link to comment Share on other sites More sharing options...
Doug71zt Posted March 1, 2005 Share Posted March 1, 2005 You may want to look into Z31 tie rod ends. I had a quick look at a pair as they don't have the kink, and are close to the same length as the 240 ones. Doug Quote Link to comment Share on other sites More sharing options...
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