thehelix112 Posted January 6, 2009 Share Posted January 6, 2009 Guys, I purchased some 1" 200b strut spacers thinking they were the same was zed strut spacers, not the case FYI. I can get 0.75" strut spacers for the zed, but I've taken 1.5" out of the strut in installing the P30 bilsteins. Is it reasonable to get two sets of 0.75" strut spacers and stack them? They have countersunk sections so there is no chance of lateral shift. They come with grade 8 bolts, would it be worth upgrading to 8.8 or higher grade bolts if I am going to stack them? Has anyone done this? Also, does anyone have any good recommendations for suppliers for these? So far all I've seen is TTT, and I don't really know how thick theirs are, just guessing. Many thanks, Dave Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 6, 2009 Share Posted January 6, 2009 Guys, I purchased some 1" 200b strut spacers thinking they were the same was zed strut spacers, not the case FYI. I can get 0.75" strut spacers for the zed, but I've taken 1.5" out of the strut in installing the P30 bilsteins. Is it reasonable to get two sets of 0.75" strut spacers and stack them? They have countersunk sections so there is no chance of lateral shift. They come with grade 8 bolts, would it be worth upgrading to 8.8 or higher grade bolts if I am going to stack them? Has anyone done this? Also, does anyone have any good recommendations for suppliers for these? So far all I've seen is TTT, and I don't really know how thick theirs are, just guessing. Many thanks, Dave I think you're talking about bumpsteer spacers here. Motorsport Auto has them in 3/4" and 1" thicknesses. I want to say that you can get one piece 1.5" tall spacers for 510s. I'm sure you could find them if you looked around a bit. Grade 8 metric bolts? Are you sure? Never seen metric bolts with SAE temper. Should be grade 8.8. Might also be the wrong bolts. In any event I think grade 8 rougly equates to 10.9 metric. http://www.warburtons.com.au/resources/Tech_Pages01.pdf You seem to be wanting to stack them to equate the size of the spacer to the amount you've sectioned from the tube. I think this is unnecessary and will probably cause interference issues unless you're running large diameter rims. Other options here are redrilling the pivot point on the crossmember, or even slotting the crossmember if you want to adjust bumpsteer and not just adjust what part of the stock bumpsteer curve you're running in. Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted January 6, 2009 Author Share Posted January 6, 2009 Jon, Bump steer spacers/strut spacers.. my apologies. The 1" spacers I have are for 510/200b, and they don't fit. Very sad. And no I am definitely not sure about the grade 8 metric bolts thing, I was just going by the advertisements which all state ``grade 8 bolts''. Thanks for the link. I'm not running particularly big rims, and I guess I'll get one set of 0.75" spacers and see how much clearance I have. I recall there being a thread about raising the inner LCA pivot point and how this negatively affects the anti-squat unless you likewise raise the radius rod pivot point, which is beyond my means at the moment. So I'll steer clear of that. Thanks for the input. Dave Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 6, 2009 Share Posted January 6, 2009 I recall there being a thread about raising the inner LCA pivot point and how this negatively affects the anti-squat unless you likewise raise the radius rod pivot point, which is beyond my means at the moment. So I'll steer clear of that. I never had a problem there. I had stock location TC rods with my LCA pivots raised to eliminate bumpsteer. What this would do is raise the roll center without increasing anti-dive. Without the pivot moved you have low roll center and the same amount of anti-dive. I see no harm in adjusting one without the other, and it certainly didn't cause any bind in the suspension. In fact my new setup has both slotted so I can adjust the RC and anti-dive independently. Quote Link to comment Share on other sites More sharing options...
johnc Posted January 6, 2009 Share Posted January 6, 2009 I recall there being a thread about raising the inner LCA pivot point and how this negatively affects the anti-squat unless you likewise raise the radius rod pivot point, which is beyond my means at the moment. So I'll steer clear of that. There's not a lot of anti-dive/squat built into the S30 suspension and freeing the suspension up is a better choice then retaining some level of anti. Springs, CG height changes, etc. can do a lot to reduce pitch changes. Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted January 7, 2009 Author Share Posted January 7, 2009 John, I'm not entirely sure what you mean when you say freeing the suspension up? Are you talking about binding? My inner LCAs are rod ends, so hopefully there is no binding there. Jon, you are, once again, correct I think. I was thinking only about the line from TC pivot to inner LCA pivot, thinking that if that angled downwards towards the back it would be a terrible thing. But the ball joint (outer LCA pivot) plays a larger, more important role in things as thats where the TC rod is connected to! I feel rather silly. I think I'll go re-read the thread on slotting the x-member. Thanks guys, Dave Quote Link to comment Share on other sites More sharing options...
260DET Posted January 7, 2009 Share Posted January 7, 2009 If the car is going to be lowered then relocating the inner LCA pivot is a good thing, keeping in mind that by so doing you are potentially changing the roll center and camber. Re those bump steer/roll center spacers, it would be best to assemble the suspension and steering at the preferred ride height and then check the bump steer. This can then be adjusted by using anything that will temporarily act as a spacer. Once the final spacer thickness is known do it permanently. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 7, 2009 Share Posted January 7, 2009 Re those bump steer/roll center spacers, it would be best to assemble the suspension and steering at the preferred ride height and then check the bump steer. This can then be adjusted by using anything that will temporarily act as a spacer. Once the final spacer thickness is known do it permanently. The bump steer spacers do not adjust bump steer. They only adjust what part of the bump steer curve your car drives in. This is because adding the spacer doesn't change the relationship between the inner pivot and the ball joint. If it did it would affect bump steer. Moving the inner pivot does change the relationship and that's why you can tune out bump steer with the inner LCA pivot but you cannot with bump steer spacers. When I confused myself on this issue, Black Beaut made up a very good .gif showing the relationship between the spacer and the pivot change. It's in the bumpsteer FAQ: http://forums.hybridz.org/showthread.php?t=103886 Quote Link to comment Share on other sites More sharing options...
260DET Posted January 7, 2009 Share Posted January 7, 2009 The bump steer spacers do not adjust bump steer. They only adjust what part of the bump steer curve your car drives in. This is because adding the spacer doesn't change the relationship between the inner pivot and the ball joint. If it did it would affect bump steer. Moving the inner pivot does change the relationship and that's why you can tune out bump steer with the inner LCA pivot but you cannot with bump steer spacers. When I confused myself on this issue, Black Beaut made up a very good .gif showing the relationship between the spacer and the pivot change. It's in the bumpsteer FAQ: http://forums.hybridz.org/showthread.php?t=103886 Yeh, from my S30 days I seem to recall that the suspension and steering links are not the same length though pivot to pivot. If that is so then the best that can be done with a S30 is to get the bump steer curve into a position where it has a minimum adverse effect, because BS cannot be entirely eliminated. So my comment on various thickness bump steer spacers was made in consideration of the above and the final ride height which is yet to be determined as I read the situation. And because Dave wants to track this car I think which may mean further changes in the future. Quote Link to comment Share on other sites More sharing options...
johnc Posted January 7, 2009 Share Posted January 7, 2009 I'm not entirely sure what you mean when you say freeing the suspension up? Are you talking about binding? Anti-dive takes some percentage of the load transfer under braking into the suspension itself (not the springs) as bind. Anti-dive is the ratio between where the a line drawn from the suspension instant center and the tire contact patch crosses the vehicle center-of-gravity/ground vertical plane. The ratio changes based on ride height and pitch so its low at the start of braking and gets higher under braking. 100% anti-dive means that all of the load transfer is being taken by the suspension components and geometry. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 7, 2009 Share Posted January 7, 2009 Yeh, from my S30 days I seem to recall that the suspension and steering links are not the same length though pivot to pivot. If that is so then the best that can be done with a S30 is to get the bump steer curve into a position where it has a minimum adverse effect, because BS cannot be entirely eliminated. They're pretty damn close. I had mine set up so that I could jack the suspension through about 3" of movement and not have any bumpsteer. I could have jacked it farther, but I figured that was good enough. If you do the JTR mod and move the LCA pivot out, then I think you might have more trouble. Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted January 7, 2009 Author Share Posted January 7, 2009 Yeah I've never understood why you would move the pivot outwards. You want the control arms to be as long as possible, to reduce the roll centre movement during suspension movement. So slotting the x-member upwards and extending the control arms to get them where you want seems like a much better option. johnc, yeah, I forgot that anti-dive was achieved with bind. I understand the words you're saying, but have never really wrapped my brain around it. Dave Quote Link to comment Share on other sites More sharing options...
260DET Posted January 8, 2009 Share Posted January 8, 2009 The control arms are moved out to give more negative camber and to widen the front track, both good things for the S30, if it going to be raced. Slotting the strut tops alone will not give you anywhere near the ~3.5* neg needed for a race car on radial semi slicks. Like everything to do with suspension its all about compramise and balance, altering one thing to give a benefit invariably produces a negative as well. Which is what makes it all so interesting. Quote Link to comment Share on other sites More sharing options...
drmiller100 Posted February 6, 2009 Share Posted February 6, 2009 Anti-dive takes some percentage of the load transfer under braking into the suspension itself (not the springs) as bind. . well, not really. Antidive is using the force of the brakes to "lift" the front of the car. Done correctly it can increase instantaneous braking force, reduce pitch. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 6, 2009 Share Posted February 6, 2009 well, not really. Antidive is using the force of the brakes to "lift" the front of the car. Done correctly it can increase instantaneous braking force, reduce pitch. Anti-dive works by using geometric leverage of the suspension to resist compression. This is bind for all intensive purposes. It may not be bind to the point of the suspension not moving at all, but anti-dive is the tendency is to resist compressing (aka jacking) which makes it "more bound" than it would be were the suspension set up neutrally. Or, to say another way, a suspension acting under any form of anti (squat, dive, roll) has reduced compliance. Carroll Smith: [Anti-dive] utilizes the upward force of brake torque reaction to oppose the downward force of load transfer. This opposition of forces means that the suspension becomes stiffer and less sensitive with vertical wheel travel and is so less able to absorb the shocks caused by track surface irregularities and load transfers In other words, the upforce from the jacking of the anti-dive and the downforce from the load transfer work against each other and in doing so they bind the suspension. Quote Link to comment Share on other sites More sharing options...
johnc Posted February 6, 2009 Share Posted February 6, 2009 Antidive is using the force of the brakes to "lift" the front of the car. No. Anti-dive is a suspension behavior not a brake behavior. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 6, 2009 Share Posted February 6, 2009 No. Anti-dive is a suspension behavior not a brake behavior. I think it's a bit of both. Anti-dive uses brake torque to affect suspension, anti-squat uses engine torque to affect suspension, high RC anti-roll uses centripedal torque to affect suspension. Or to say another way, the suspension compresses on the front of a car with anti-dive just fine when you aren't on the brakes. Quote Link to comment Share on other sites More sharing options...
johnc Posted February 6, 2009 Share Posted February 6, 2009 Well... I think its semantics. What really triggers anti anything (anti dive anti squat anti roll) is load transfer creating pitch and roll of the sprung mass. Depending on how the anti is setup in the suspension geometry, you can get anti-dive reactions in the suspension by abruptly lifting off the throttle, you can get anti-squat reactions by coming off the brakes abruptly, and you can get anti-roll reaction from side winds in a high profile vehicle.. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 6, 2009 Share Posted February 6, 2009 Well... I think its semantics. What really triggers anti anything (anti dive anti squat anti roll) is load transfer creating pitch and roll of the sprung mass. Depending on how the anti is setup in the suspension geometry, you can get anti-dive reactions in the suspension by abruptly lifting off the throttle, you can get anti-squat reactions by coming off the brakes abruptly, and you can get anti-roll reaction from side winds in a high profile vehicle.. Agreed, I think we're saying basically the same thing. The most efficient way to get these effects is to step on the brakes or gas or to turn the steering wheel, so it is a response to those inputs, but it is not the direct effect of those inputs. Anti-X is the effect of load transfer on the suspension geometry. Quote Link to comment Share on other sites More sharing options...
drmiller100 Posted February 7, 2009 Share Posted February 7, 2009 Well... I think its semantics. What really triggers anti anything (anti dive anti squat anti roll) is load transfer creating pitch and roll of the sprung mass. Depending on how the anti is setup in the suspension geometry, you can get anti-dive reactions in the suspension by abruptly lifting off the throttle, you can get anti-squat reactions by coming off the brakes abruptly, and you can get anti-roll reaction from side winds in a high profile vehicle.. Actually, No. Anti dive is caused by the BRAKES and suspension transfering a force into the chassis to lift the chassis. A great example is an old fashioned VW bug front axle. If you hit the front brakes, the torque of the brakes actually try to pull the front of the car down. They have "pro dive." If we were going really fast in a VW Bug backwards, and slammed on the brakes, you can visualize the torque of the brakes lifting the front of the car in addition to the weight transfer. Anyway, we can all agree the so called bump steer spacers don't do anything??? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.