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AkumaNoZeta

Idea for front knuckles.

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Posted (edited)

I came across these on the interwebs https://www.gktech-usa.com/v3-super-lock-s-chassis-front-drop-knuckles.html and I if you look at their image of the steering arm placement, it looks to be pretty much in line with the balljoint. Making me think they can be swapped sides and be able to run with the front steer of an S30, versus the 240SX's rear steer. Maybe move the rack forward to add a little more ackerman. Control is nothing, just build one with a 240SX balljoint on one end and a heim on the other.

 

I'm thinking the main advantage would be serviceability. Now more having to remove the wheel bearing to change out rotors, be able to adjust the bottom knob on those fancy coil-overs without disassembling anything, and I personally like replacing sealed bearings more than having to repack individual pieces with grease. Plus, looks how strong the aftermarket is for 240SX, and I'm sure it will only get stronger so you don't have to worry as much about certain things becoming obsolete in the future.

 

Speaking of the future, I'm hoping to be working on finally getting my car to be able to sit on it's own wheels one day in the near future so I've been exploring my options. I don't want to re-design for double A-arms since I already tied in my strut towers to the cowl and I feel that would be a waste of time if I don't retain the strut design. Tell me what you think.

Edited by Grim

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Hmm definitely benefits to be had.

 

You can do even one better and get the race oriented ball joints and not have to worry about regreasing or tearing a boot on a ball joint. 

 

But shorter knuckles usually translates to more steering effort. While at speed it might not be bad, but without some kind of assist that would make low speed driving a bit more difficult, then that begs the question do you swap in an electronic kit or swap in a power steering kit, then the options for S13 start to make a lot more sense, then you get to why not swap in the whole front crossmember and such.

 

Another concern would be the track width, if you kept the S13 style front mounting it is going to push the hub further out from the body. You could run some high positive offset wheels, but that brings up the concern with hitting the tension arm. So you would have to run a neutral or negative offset wheel most likely which would push the wheels quite outside the body. Alternatively you could make the pocketed style S13 arms. Then again, you could also just buy the S13 arms at that point and bolt it onto the S13 cross member and do a full transplant of that setup.

 

My problem with this line of thinking is that if you take a step back it doesn't really make sense to do all this to an old car (granted this is the forum of not making financial sense :D). Like running someone pointed out once you swap in a V8 and start to consider a live axle you are basically building a muscle car/corvette. Alternatively swapping to S13/14/15 suspension front and back kind of makes those cars really viable looking, like you can buy an S13 and have access to cheap big brake kits, a plethora of axle and differential options, coilover options, wheel options etc. 

 

I guess it depends on how far you want to go with it. I mean swapping to the S13 suspension with the 7m recessed far back probably won't be as difficult if you were trying to retain the L28 in stock position or run a front sump 4 cylinder. Swapping to S13 parts would be a safe bet for parts availability, but the fabrication work involved, does it offset maybe paying a bit more for S30 specific parts? There are more options now more then ever compared to say 4-5 years ago. My big 0.02 lol.

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Posted (edited)

You do bring up some good points. Not only is there the less leverage with the shorter arms, but I think scrub radius would make a bigger effect on slow speed steering effort and that would be an unknown factor, especially since it also changes with tire height and wheel offset. I also have an 260Z model and I believe they have a 17 or 18:1 ratio vs. the earlier 15:1 so that would probably help negate some of the effort.

 

I wouldn't use the rest of the 240SX suspension, for all I know the knuckle may already fit on the Z's balljoint, I doubt it though. I'd want to keep the flange to flange distance the same so making control arms to transition between Z and SX would be better, but depending on the inclination of the SX knuckle that could result in a shorter arm which means bigger camber changes through the suspension travel. Another thing that worries me is since it's a dropped knuckle, would it require an unusually long coilover to get proper ride height?  I wish I knew how to use CADD so I could make a digital model before finding out everything is a waste of money, haha. 

 

I'll be making a new crossmember for my car anyways, the factory one looks wierd on it now so I need to make one out of square tubing to match the rest of the car considering I don't have any of the stock sub-frames or crossmembers anymore. I even thought about going ahead and making it a rear steer, but when I swapped the Z knuckles side to side and eyeballed it, it didn't look like it would have sufficient clearance from the oil pan.

Edited by Grim

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Give me a Taper roller bearing any day over a Cartridge style dual ball bearing. Taper roller bearing will take much higher side loads than a Cartridge BB. This pops up all the time on cars that run track days.  Track day corner loads and high brake temps can take a heavy toll on cartridge style front bearings. Drifting is easy peasy in comparison. 

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Posted (edited)

Use a separate Hub with Taper roller bearings and a Hat system for mounting rotors. No need to remove hubs to change rotors.

 

Here are the front front rotor and Hub ( 1 piece ) from my  1986 Camaro. Rotors were machined off leaving a separate hub, Then I bought off the shelf WilWood aluminium rotor Hats that fit over machined hub. Longer 1/2" studs installed ( ARP )

 

 post-44147-0-23409100-1494795782_thumb.jpg

 

post-44147-0-49418300-1494795834_thumb.jpg

 

post-44147-0-57666400-1494795880_thumb.jpg

 

post-44147-0-84693300-1494796033_thumb.jpg

Edited by Chickenman

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Posted (edited)

I never understood why nobody makes a slip on rotor for a Z. I suppose the rotor hat would have to be stupid deep to work on a stock hub, but with all the aftermarket hubs, nobody has done it. Probably screws everything up: change the hub, then the LCA hits and snowballs everything else from there, but that seems like something that would have been figured out by now.

FWIW, you would move the rack BACK to increase Ackerman. I did it, then actually mapped it out on paper. It didn't help much unfortunately, really the difference was negligible. All the details on what I measured and what the results were are in this thread: http://forums.hybridz.org/topic/97092-toe-changes-for-track-use/page-4

 

Totally agree with Chickenman on the tapered rollers. If you really want to DIY your suspension, look at circle track parts. They've got everything: BIG bearing hubs (wide 5), adjustable upper and lower control arms, many different steering rack configs, tubular sway bars, cheap (good) shocks, good brakes, etc. 

Edited by JMortensen

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Well, mine's not going to be a race car anyways. More like an overkilled daily driver. I don't think I'd ever run tires soft or sticky enough to run into pre-mature bearing failure like that. I've been planning to run 245/50/16 tires, I got one mocked up on a 16X8 0 offset wheel and I like how it looks. Like I said before too, I already tied my strut towers together so I rather keep with the strut design. I did that before the full extent of the rust was revealed. If I knew ahead of time that nothing was usable, I would have just built a tubed chassis and make a fiberglass copy off the body. Probably would be done by now if I did that.

 

post-3229-0-45274700-1494803941_thumb.jpgpost-3229-0-07963100-1494803989_thumb.jpg

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Posted (edited)

Or, maybe working of a Mustang knuckle would be better? https://www.stangnet.com/mustang-forums/attachments/94-95vs96-98spindle-jpg.153405/

They're already front-steer cars, tapered bearing hubs with slip-on rotors, and still uses bolt-on strut allowing access to bottom knobs on double/triple adjustable struts.

 

Edit: I guess the later model, the one with better geometry, actually uses a barrel style bearing so there's go that advantage.

Edited by Grim

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I may be officially overthinking this now. I just had the idea of making a bracket to attach to the bottom of the S30 spindle that relocates the ball joint outside the unit, towards the center of the car. Seperating it from the steering arm allows the possibilty easily swapping out different arms to try different set-ups, and the relocation of the balljoint should allow a lot more ackerman without having to put the tie rod inside the brake rotor.

 

I spent a little time looking at the front hub of the Z and can't see why no one just throws a slip on rotor hat over the wheel studs. With a 1.25" thick rotor, I don't see why it would need to be more than a 2" offset and Wilwood has pretty much any size you could need. Eliminate 4 bolts in the process, so less weight there. I also don't see why not just fab a bracket coming off the strut tube/knuckle joint for bolt on style struts. All this should equate to ample more inside wheel clearance as well with the strut bracket and ball joint bracket both moving the hub outwards.

 

Ya'll can tell me to shut up at any time. lol

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I'm gonna second with the amount of work that would need to be done, you'd probably be better off taking a the whole crossmember and front suspension off another car and making that work.

 

Bonus points if you can make it work off a car that uses a commonly swapped engine to add in the engine mounting points.

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One problem that you will have with using another spindle is that it was designed for the strut angle in the car that it came from. If you put a 280ZX front strut on a Z, for example, the camber is all F'd up. I can't remember which way it goes, it's been 25 years since I did it, but I want to say it had 4 degrees positive camber or something like that.

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Unless you plan on legitimately just taking the spindle and trying to graft onto the stock hub, then your connection points would need to altered was what I was in reference to. Yes the ball joint on the bottom and the tie rod are fairly simple to sort, but the coilover is a macpherson type. You could go out and find the brackets, cut it off, then transfer them onto the stock strut, but then you don't get all the aftermarket goodies like coilovers to choose from. So it kind of snowballs.

 

I mean unless this is going to be a one time fabrication and done type of deal, I would say to work your way up to it. You don't have to dump a ton of money into a stock type setup, but find what you actually want to change and then tackle it later? 

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It would be a one time fabrication thing. The whole car has been a one time fabricaton thing. In fact today I had a conversation with myself, telling me that I need to stop over-complicating everything. It's bad enough I have to completely fab up the rear suspension, at this rate I'll never get to drive the car. At least I still have most of the provisions for the front. Plus, I'm not a race car driver so I'd probably never notice a differance anyways, and like you said I can always change it up later.

 

On a side note, has anyone ever thought about Johnny Joints by Currie Enterprises? I was looking for an alternative to rod ends and came across them. They look real promising, albeit quite bulky, but I haven't came across anything negative about them through Google. In fact one guy on an off roading forum said he has something like 70,000 miles on his lifted truck (both trail riding and daily driving) and none have developed any slack yet. They have weld in ones and bolt in ones, but it seems they don't came with threads smaller than 3/4"-16 which would be alright if you don't mind bulky control arms.

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http://forums.hybridz.org/topic/120418-arttu%C2%B4s-240z-never-ready/?do=findComment&comment=1127576

 

Something like that in your mind? My FLCA is about same lenght as S13. This is what get´s you in trouble, KPI increases a lot if you keep strut upper mount in original position. Ackerman related mods are also done, if you scroll down a bit. 

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Posted (edited)

Here's a crude drawing I did. The scale is as accurate as what 20 minutes of eyeballing can be, but it gets the idea across. It's only a thinking exercise at the moment so no need to take actual measurements yet. The idea is with a S30 knuckle with a welded on pedestal for a 3/4" stud to use a 3" Johnny Joint and then another extension welded on the top for bolt-on struts.  Of course it throws the spindle out more, but should allow more backspacing. Theoretically, the top extension can be made to put the KIA wherever you want, bottom one too I guess but you don't want to make the control arm shorter than necessary. Scrub radius will depend on tire height, KIA, and wheel offset. Moving the ball joint inwards like that I think would give you more room to play with Ackerman, and separating it from the ball joint makes it easier. 

 

post-3229-0-50676000-1495250942_thumb.jpg

Edited by Grim

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The problem with your drawing is that you didn't include the hub and where the wheel face will go.  Ideally you want to go all the way down to the ground and see where this falls in relation to the tire's center on the ground.  One problem that often arises is the front track grows when you try and make all this work.

 

For a street car a ball joint is probably going to be lower maintenance.  The joint you're looking to use is huge overkill for what's needed.  One thing to remember is that you might want things like ball joints to bend or break if you hit a curb or other large object.  If you don't have a "fuse" to blow then all that force will go find the next week link.  You don't want that to be the frame rails.  

 

Hope that helps,

Cary

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