Z-train Posted December 17, 2013 Report Share Posted December 17, 2013 Yes,it is.Having the steering wheel turn when you hit a bump is not a good thing. Quote Link to comment
Icehouse Posted December 17, 2013 Report Share Posted December 17, 2013 Yes,it is.Having the steering wheel turn when you hit a bump is not a good thing. In an extreme case. During suspension travel the wheel will toe in or out. Bump steer gets a bad rap because in our lower cars its exaggerated. I just don't see how looking at the previous picture of the 620 with rack and pinion it can so easily be dismissed as "wong"...?..?.... Quote Link to comment
orangie Posted December 17, 2013 Report Share Posted December 17, 2013 Look at the picture of the cobra frame picture I posted earlier. When the rotation points of the steering rack are not in the imaginary line of the upper and lower control arms, meaning the tie rods are not parallel with the lower control arm, the horizontal distance will be changing differently so the effect will be the car will toe in and out depending on how far up or down the front suspension travels. I could calculate the distance and give you the angle changes, but you cannot really understand the effect without getting in the truck and driving it. The worst case scenario I can think of would be a hard corner and braking hard where you get nose dive. I would guess you wouldn't even notice the effect braking hard and going straight. I can't say I like the way the car is set up, but if you insist on running it that way I would take the car out into a parking lot and see what some hard cornering and braking will do to the car. Will it make it unpredictable or is it controllable? 1 Quote Link to comment
yello620 Posted December 17, 2013 Report Share Posted December 17, 2013 I just don't see how looking at the previous picture of the 620 with rack and pinion it can so easily be dismissed as "wong"...?..?.... Spend 15 years doing suspension and alignments for a living and it pretty easy to see that it isn't RIGHT. Quote Link to comment
Icehouse Posted December 17, 2013 Report Share Posted December 17, 2013 Look at the picture of the cobra frame picture I posted earlier. When the rotation points of the steering rack are not in the imaginary line of the upper and lower control arms, meaning the tie rods are not parallel with the lower control arm, the horizontal distance will be changing differently so the effect will be the car will toe in and out depending on how far up or down the front suspension travels. I could calculate the distance and give you the angle changes, but you cannot really understand the effect without getting in the truck and driving it. The worst case scenario I can think of would be a hard corner and braking hard where you get nose dive. I would guess you wouldn't even notice the effect braking hard and going straight. I can't say I like the way the car is set up, but if you insist on running it that way I would take the car out into a parking lot and see what some hard cornering and braking will do to the car. Will it make it unpredictable or is it controllable? Regarding the picture you posted: That is the most simple suspension setup possible. Look at the rear of a S13/Z32/R32. You guys may be right, To me the rack in the datsun Setup is at full droop. Also the camera angle isn't anything like the picture you posted. Spend 15 years doing suspension and alignments for a living and it pretty easy to see that it isn't RIGHT. Designing suspension? Quote Link to comment
BenJammin Posted December 17, 2013 Report Share Posted December 17, 2013 Let's get something straight here for purposes of this thread.... are we talking about precision race car correct geometry or Ratsun level "let's find something that will work reasonably well.... for a decent price ... and be reasonably safe at normal speeds and loads ?". For the record, personally I want RnP simply for the purpose of having room to get my KA A/C compressor in there by eliminating the existing steering box and I already have the updated Xterra u-joint collapsible column. I'm not talking about a $1600 custom setup, nor am I talking about a $50 ghetto cut and chop just to get something to turn the wheels. But to make it just a little more difficult here.... I want it power and to work with the stock KA pump. Any ideas on those limitations / requirements ? Quote Link to comment
thisismatt Posted December 18, 2013 Report Share Posted December 18, 2013 If you did a setup like the one posted above, you should essentially be able to use any rack you want. 1 Quote Link to comment
BenJammin Posted January 7, 2014 Report Share Posted January 7, 2014 If you did a setup like the one posted above, you should essentially be able to use any rack you want. Which "setup posted above" are you talking about .... post #43 ? Quote Link to comment
orangie Posted January 7, 2014 Report Share Posted January 7, 2014 He was talking about the Chevelle rack where you use an outer bar to tie the two ends together and run the tie rod on the outer bar. Quote Link to comment
thisismatt Posted January 7, 2014 Report Share Posted January 7, 2014 Which "setup posted above" are you talking about .... post #43 ? Post 47. What orangie said. You could position the tie rod joints anywhere you needed to get the correct geometry. Quote Link to comment
Z-train Posted January 7, 2014 Report Share Posted January 7, 2014 Let's get something straight here for purposes of this thread.... are we talking about precision race car correct geometry or Ratsun level "let's find something that will work reasonably well.... for a decent price ... and be reasonably safe at normal speeds and loads ?". For the record, personally I want RnP simply for the purpose of having room to get my KA A/C compressor in there by eliminating the existing steering box and I already have the updated Xterra u-joint collapsible column. I'm not talking about a $1600 custom setup, nor am I talking about a $50 ghetto cut and chop just to get something to turn the wheels. But to make it just a little more difficult here.... I want it power and to work with the stock KA pump. Any ideas on those limitations / requirements ? Ben,I was quoted in the $600.00 range by Flaming River.Group buy.....? 1 Quote Link to comment
orangie Posted January 8, 2014 Report Share Posted January 8, 2014 It's not cheap, but it doesn't have to be as expensive as the way I did it. The rack was only the first kick in the nuts. I happend to get a rack with 9/16 - 18 thread, oddly enough nobody makes heim joints in that size. You can find tie rod ends, but then you have no adjustability for bumpsteer (if that's important to you or not). Now, what do you do for a column?? Ever price those univeral u-joints? Some of those are a hundred bucks a piece and you need at least two of them. Maybe you could find something out of boneyard to work, but you get my point. All the little things add up and I would guess you're going to be in it for about a grand. Quote Link to comment
Icehouse Posted January 8, 2014 Report Share Posted January 8, 2014 Just find some junk yard parts and make it happen. I bet a 240z rack would work. That and a 720 column is where I would start. There are also zillions of small cars coming out. Maybe you could find one the right width with electric power. That would be cool. Quote Link to comment
abbylind Posted January 8, 2014 Report Share Posted January 8, 2014 91 Toyota MR2 uses electric activated rack and pinon IIRC....Might be worth exploring.... Quote Link to comment
76*620 Posted January 8, 2014 Report Share Posted January 8, 2014 Over on hybrid several guys converted their 240z's to power steering using Subaru racks, From the drivers seat a z feels a bit wider, I have never taken measurements but the Subaru rack may work. Quote Link to comment
ggzilla Posted January 8, 2014 Report Share Posted January 8, 2014 Yes, many racks can be made to work, and those who have done it are often happy with the results. But none are the "correct" length. Using the fully adjustable type like Matt's makes a lot of sense. You just need a rack like the one I have...mount the tie rods anywhere you want. Quote Link to comment
orangie Posted January 8, 2014 Report Share Posted January 8, 2014 The 240z rack is way to wide. I saw some electric racks that might work as far as width, but it has a bunch of junk around the pinion area and I'm not sure how much heat it can take since the exhaust is on that side and it would run right up against the engine. I looked the 92'ish pontiace grand am and it has a rear steer power rack that is similar to the above posted rack, but rear steer puts the pinion up near the firewall. I've seen a chain drive hooked up to make it work, but it's not something I would attempt. Quote Link to comment
orangie Posted January 8, 2014 Report Share Posted January 8, 2014 There's a guy who converted a miata rack to manual and shortened it by 5.5 inches, but they don't tell you how to do it. I guess, you have to buy the book! http://www.cheapsportscar.net/diary.php?UID=6 Quote Link to comment
]2eDeYe Posted January 8, 2014 Report Share Posted January 8, 2014 There's a guy who converted a miata rack to manual and shortened it by 5.5 inches, but they don't tell you how to do it. I guess, you have to buy the book! http://www.cheapsportscar.net/diary.php?UID=6 December 6, 2003: I started by modifying an extra steering rack. This is a power rack from a Miata, but in order to avoid bump-steer it needs to be shortened. I sectioned the rack and the housing and shortened it by 5.5". I also converted the rack to manual operation instead of power. You can see where he sectioned it on the long side and ground down the welds. Seems like a decent solution if you have the capabilities required. :) Quote Link to comment
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