Thread: B13 rear suspension re-assembly problem. Alignment all wrong. (Broadband only!)

Glad to see Coach, sqd, and SkySheperd chiming in. All of you gentlemen are waaaaay beyond my (current) mechanical abilities to understand the workings of our suspensions.

However, this thread will definitely be included in the (overdue) update to the Suspension Thread.

I did not like the idea of leaving the Suspension Bind Issue unresolved. However, I am not nearly mechanically adept enough to question either Steve (98sr20ve) or Mike K (choaderboy2). Hell, half the time I cannot follow their discussions except in a very general sense.

I would looooove to have them join in this thread and discuss this issue to a firm resolution point. A concensus of expert opinions including Ben, Darrin, Coach, Stephen (already included here)....Steve and Mike K would be superb. Perhaps getting Greg V's input for good measure, and some part numbers if those are indeed placement specific.

Uh...from my limited understanding, neither the ES bushings (not enough deflection) nor the stock bushings (too much deflection) are the right answer. The corrrect answer is heim joints, which are currently a "user built custom" type of solution? Ie...peice them together yourself from the Ingalls catalog? If so, Ben can you (eventually) provide the correct part numbers and a diagram of the assembly so that it could be reproduced by the masses?

I'm just the librarian, cataloguing "books" of information (ie. threads) that I don't always fully understand.

Me neither. =D

I do think this matter deserves another look by everyone involved. It was like clock work; I installed the parallel link bushings and what used to be a great suspension turned to crap from the moment it touched the ground, continuing on to bend bolts that should never be under that type of stress.

I spoke with Greg about the issue over the phone. He's the one who let me know the parallel links had different part numbers fore and aft. I'll get the numbers again from him very soon and update here.

For a stock-like experience, the stock bushings are fine. They aren't ideal, but they won't cause any known problems other than the typical loose operation of the rear suspension and all that goes with it's crummy geometry. The ES bushings (as far as I'm concerned) are right out. Awful at best. The control link could make due with them (even on both ends if you're feeling spry) but I wouldn't ever use them on the parallel links.

I know I'm going against Mike K. here by saying this. I honestly can't imagine how his car and the ones he's known haven't had similar problems to me. The only thing I can think of is the ride height of the cars involved. If all the cars he's talking about ride lower than mine and have less suspension droop permitted there's a decent possibility that the parallel links in these cars stay at the ideal 90 degree configuration (or near it) where my car and others like mine hang out more in the "droop", deflected condition which makes the situation much worse.

Although, I recall reading Mike put a suspension through it's entire travel by hand noting the resistance. He said stock was equivalent to 5 lbs./ft. of spring rate, and ES bushings were about 10 lbs./ft. I'd like to get more details on this. To do this by hand the strut had to have been disconnected. If the strut is disconnected you've removed a tension force trying to keep the hub from rotating. Depending on how much this is, it could throw off his experiment completely.

Yes. If you'd like to completely remove the binding from the suspension and tighten up the joints this is the way to go.

As far as I know, there is no off-the-shelf solution so you'd have to make your own. Frankly, the work involved with constructing the control link would be prohibitive for 99% of people as the bar is bent making construction more costly, and the gain is minimal. The parallel links would show the most gain, and would be relatively easy and cheap to do compared to the control link.

Not sure they have the right parts, but it's worth giving them a call and see if they'd put spherical/heim joints on their adjustable parallel links instead of the stock-style solution.

I'll see what I can do. I might end up back with a stock rear suspension bushing set-up. I'm thinking this is probably my best option, but I'm still interested in the proper solution so I'll let you know what I find.

i'm currently driving around in one of the b13's set up by mike kojima. i will snap some pics tomorrow if i can find a lift where the car stays on its wheels because IIRC the control links ARE at a 90 degree angle (parallel to the ground). i've been trying to get ahold of him to talk to him about this issue, but we keep missing each other. i will try again tonight.

IMHO, i think that going to a heim joint setup would cause the suspension to deflect significantly more although allowing for much more suspension travel.



i did not know there was any curvature in the parallel links, but i will be heading over to my warehouse where i keep the racecar in a few. i'll shoot some pictures of the links, but when i pulled them off to paint them, i lined them up and all four were IDENTICAL. (if not, i'm screwed )

now, there is an extremely affordable and easy way to manufacture the suggested links. there are weld in threaded bosses that are made to fit the ID of DOM tubing. all we would have to do is cut the tubing to the right sizes then weld a boss on each side. then a nut on each end with the heim joints and voila. fairly simple build. the only difficult part i would see would be the machining necessary for some sort of spacers to keep the heim joint from sliding back and forth on the stock bolts.

i've been dying to go to my fab shop to finish the master cylinder brace that i promised you all, so if ben wants me to throw together a rough draft piece minus the spacers, i can do so with his approval. this is his project however, and i do not want to take it away from him. either way i will try my best to be beneficial to this thread.

If the control links (what I'm calling control links, they might be called trailing arms, etc.) are parallel to the ground it would be at it's most "extended" when looking at my diagrams. If this makes the parallel links form a perfect rectangle with the chassis and hub (instead of a skewed parallelogram) then it could explain why the ES bushings aren't causing as much trouble for you. As the suspension rises and falls through it's motion you'd only be deviating a little bit from the perfect rectangle. A car with a higher ride height (assuming yours is quite low) would experience more of an issue with this problem.


The parallel links aren't curved, it's the control link that has a slight "S" bend in it. I have a picture I can post up if you need.

You and me both buddy. I spent hours measuring and comparing and couldn't find a difference between my set. I am going to give my brother's car the once over to make sure his is the same way.


That last part you mention was my exact worry. Just a bit tougher than the rest of it.

I'm not in a position right now to attempt any sort of manufacturing of these parts aside from possibly making my own and sharing the method/experience with the community. If you (or anyone else for that matter) want to take this project and run with it, you may find me as a buyer very quickly. =]

circle theory/sine and cosine wave models

and yes you are absolutely correct.



i realized what you meant by the curvature after i had posted. i know exactly what you mean now.



i didn't get a chance to take pictures today but i plan to go to the warehouse tomorrow to check it out.



i had a brief chat with Mike Kojima about this today and he said our cars are so limited in rear travel anyway and that it would not make much of a difference. he went on to back his case up by pointing out all of our racecars that run the ES bushings and have never had a problem. i think this is what really helps our cars kick out and oversteer in the rear when set up properly. he believes it is not worth the time or money to do something like this and suggests that we invest them in other modifications.

that being said, i'm still very curious as to how the car would respond to something like that.

I can see why there'd be no need/use to change anything in the cars set up with very aggressive drops and spring rates. This seems to be a stock or Road Magnet/Hyperco problem.

If so, then the Suspension Bind affects a whole lot of the vehicles on this forum.

You figure out how many RM/Hyperco springs sets have been sold altogether and we're talking at least three or four hundred, if not several hundred sets.

Not to mention it being a problem with stock set-ups.

Therefore if Stephen does manufacture a GB run of uh...whatever this "fix" would be named, I would step-up and be the first buyer.

I run ES bushings in my car and the NX has them. Cars rotate well and I have never had issue with it. I guess you just learn to drive what is available to you. IF someone wanted to do this for the trick aspect, you could do it without TOOO much issue.

Brent

I get the whole binding thing as the ES bushings don't want to deflect but I am having a hard time understanding how in your case it caused the bolt to bend. we are talking about the bolt that goes through both control arms and the hub assembly right. I put in ES bushing years ago and I remember that's no ordinary bolt, I think it was hardened and about 5/8" in diameter! How did that thing bend, you had to have done something else. What kind of rims and tires are you using, everything offset....etc. I think you might have installed the control link upside down, this is possible and I have done it. However when I did it the control link was barely touching the inside of the tire. If it wasn't touching the tire I would have left it that way. I bet if you had a low offset rim of about 20-25mm rim and a 205 tire it would be sticking out far enough from the car that it would allow you to install the control link upside down....with the bend facing towards the tire instead of around it. If the tire was not rubbing on it you would have thought nothing of it. I win.

Yep.


Yah, it's a monster.


Nope. Just went out and checked, there's no way they'd even go on the wrong way with my wheel/tire/offset.

I installed the rear control link ES bushings and all was well. Weeks later I installed the rear springs and dampers and all was well. Weeks later I installed the parallel link ES bushings along with all new bolts and the alignment was visibly off. I drove around on it for a week or two and disassembled it to find that both bolts were bent. I have pics I'll post later. I wish you had my answer, but that's not it. =(