PUSHER Posted June 27, 2005 Share Posted June 27, 2005 How do some of these cars get so slow? From what I know you basically want the conrol arms to be parallel with the ground if you want it to not handle like poop. I know people reposition the mounting point for the front control arms.(anyone have a picture of that?) But what do people do for the rear? Not going to run out and my car and do it( i like clearing speed bumps) but mainly curious. Thanks. Quote Link to comment Share on other sites More sharing options...
tonycharger72 Posted June 27, 2005 Share Posted June 27, 2005 mmmmmmmm - im certainly no expert on this, but if you look at a stock 260z, the lower control arms arent horizontal, they go down towards the struts, i would imagine your best bet would be keeping this same relationship, This is what ive come across - the lower control arms travel in an arch, say for instance 15deg angle downwards and 15deg upwards (that might not be right, im just guessing), if you have the LCA horizontal you eliminate half of its allowed travel, which i dont think is a great thing, But if you lower the car as much as shown in the picture i dont think that would be possible to retain the same LCA angle as stock - but i could be wrong, If you do a search on this you will find alot of info on this site, alot of complex in-dept info If you buy the JRG V8 Conversion manual it has a step-by-step process of how to modify the cross-member and has pictures!!! Quote Link to comment Share on other sites More sharing options...
AK-Z Posted June 27, 2005 Share Posted June 27, 2005 I'm not really sure. I thought that there was only an issue with the bump steering and all you need to correct that is a bump steer spacer http://www.zcarparts.com/store/merchant.mvc?Screen=CTGY&Category_Code=PSDC11 Quote Link to comment Share on other sites More sharing options...
JMortensen Posted June 27, 2005 Share Posted June 27, 2005 How do some of these cars get so slow? From what I know you basically want the conrol arms to be parallel with the ground if you want it to not handle like poop. I know people reposition the mounting point for the front control arms.(anyone have a picture of that?) But what do people do for the rear? Not going to run out and my car and do it( i like clearing speed bumps) but mainly curious. Thanks. 99% of the people out there with their car slammed don't even understand what handling problems occur when you lower a car too much. They don't know that what they've done is bad for the car's handling, and most of them just don't care. They care about how it looks. Bigger wheels and lower suspension is the look right now, so that's what you're going to see, regardless of what it does to the car's handling. As to the rear suspension, there really isn't much you can do to fix the control arm angle without some major work. Moving the inner pivot is not easy in the rear since the front bushing of the rear control arm is located by the subframe itself. If you don't care to modify the frame you can weld up a new strut with the wheel bearing hole higher in relation to the bottom of the strut and that would work kind of like a drop spindle. JamieT was working on one. Also there is a guy who goes by the handle Panchovisa on classiczcars.com who has figured out a rear toe/camber adjuster that would help the rear control arm angle. Both are not easy solutions. The rear control arm angle isn't as important as the front regardless, and IIRC it doesn't go past horizontal nearly as quickly as the front. Quote Link to comment Share on other sites More sharing options...
PUSHER Posted June 27, 2005 Author Share Posted June 27, 2005 Was mainly referring to the z's I see at local autox's whom im sure know what theyre doing. So they just let the rear be? And where do they reposition the control arm pivot point? On a search someone said that you do either bumpsteer spacers or reposition control arm and that doing both would be to much overcompensation, wondering if thats true. Thanks. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted June 27, 2005 Share Posted June 27, 2005 I've moved the pivot and run a bumpsteer spacer. You just need to measure the bumpsteer when you're doing all this. If you just do the JTR pivot relocation and get xx thickness bumpsteer spacers, it's gonna be wrong. But if you measure everything first, you can make it right. Running the car really low can be done successfully, and can be made very fast. All it requires is VERY stiff springs and the expensive struts to control them. Search for Cary's posts (tube80z). He runs a low roll center, and according to some people who are faster than me, he is faster than them. Quote Link to comment Share on other sites More sharing options...
EZ-E Posted June 27, 2005 Share Posted June 27, 2005 That is one thing a lot of people forget as with lowering a vehicle, you also shorten the travel of your strut, and you will need much stiffer springs to compensate for this or you will "bottom out" as well. Its why the best choice when lowering is usually a coil over set up. Quote Link to comment Share on other sites More sharing options...
AK-Z Posted June 28, 2005 Share Posted June 28, 2005 so for the front you need adjust the "bump steer" using spacers? and for the back you just need to adjust the camber (angle of which the wheels are in relation the the ground) and one way is to change the pivot point of the control arm, and the other way is by getting a camber adjuster mount ( or whatever you call it)? I'm reasking what was posted to see if I'm understanding correctly. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted June 28, 2005 Share Posted June 28, 2005 What we're really talking about is roll center. If you want to learn more about them, search the suspension forum or google it. Bump steer has also been beat to death. Search either and you can read for hours. Hell, just search alignment, caster, camber, toe, and roll center. It's all in there. Quote Link to comment Share on other sites More sharing options...
johnc Posted June 28, 2005 Share Posted June 28, 2005 Was mainly referring to the z's I see at local autox's whom im sure know what theyre doing. Think so? I and the previous owner of my 240Z were always told by other Z autocrossers that the car was too high to handle well. We were both still told that after the car posted the fastest times in BSP event after event and won a few NTs and Pro Solos. Quote Link to comment Share on other sites More sharing options...
tube80z Posted June 28, 2005 Share Posted June 28, 2005 Think so? I and the previous owner of my 240Z were always told by other Z autocrossers that the car was too high to handle well. We were both still told that after the car posted the fastest times in BSP event after event and won a few NTs and Pro Solos. I'd agree. Pit wisdom often is not. John, on the ROD you ran it pretty much with the controls arm near horizontal didn't you? In that situation the ride height differences have a lot more to do with tire diameter. In my situation I'm running very short FA tires on 13 inch wheels. Did the ROD ever run against Vic Sias's BSP Z? I'd be curious how closely mathced they would have been. Cary Quote Link to comment Share on other sites More sharing options...
PUSHER Posted June 28, 2005 Author Share Posted June 28, 2005 Think so? I and the previous owner of my 240Z were always told by other Z autocrossers that the car was too high to handle well. We were both still told that after the car posted the fastest times in BSP event after event and won a few NTs and Pro Solos. Dont belive I've ever seen your car or read anything about it. Do you have a page or a post with build-up/ any other information. Would appreciate it. Quote Link to comment Share on other sites More sharing options...
johnc Posted June 28, 2005 Share Posted June 28, 2005 John, on the ROD you ran it pretty much with the controls arm near horizontal didn't you? In that situation the ride height differences have a lot more to do with tire diameter. In my situation I'm running very short FA tires on 13 inch wheels. Almost horizontal. They still pointed down at a 5 degree angle. One of my issues was the tire height (25.2"). Did the ROD ever run against Vic Sias's BSP Z? I'd be curious how closely mathced they would have been. In the ROD's previous BSP incarnation when Erik Messley owned it the car won a few NTs and Pro Solos. Erik never drove it against Vic and when I drove my first NT against Vic in BSP I was way behind. In its later configuration the car was a "beyond SM2" car so a comparison with a BSP car is unfair. Besides, with the road race gearing I had, first was good to 50 mph. It sucked at autocross! This is what it looked like in its BSP days: Quote Link to comment Share on other sites More sharing options...
johnc Posted June 28, 2005 Share Posted June 28, 2005 Dont belive I've ever seen your car or read anything about it. Do you have a page or a post with build-up/ any other information. Would appreciate it. Right here, but the car is no more... http://www.betamotorsports.com/products/rod4sale.html Quote Link to comment Share on other sites More sharing options...
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