Converting Koni Yellows to Coilovers
 

I was wondering if anybody has actually done this. I did a search and found Team saying this:

What is the issue with the rears? Doesn't the rear shock tower just act as the upper spring perch? It seems like with a regular coilover sleeve and a spring adapter, it should go together just like any other coilover conversion. I haven't had my rear shocks out yet, so I can't be sure, but I've looked at every picture I can find to see what the difficulty is. Please shoot me down if I'm wrong though.

I'm getting my Konis in the mail tomorrow, and the first thing I'm going to do with them is put them in CAD. Then, when I go to install them, I'll CAD the stock upper perches too and see if I can find a way to make this work.

I suppose I should also ask the all important question of "Is this worth doing at all?" It seems like for less than $1000, the converted Konis with the proper spring rate would be better than Teins or K-sports or Megans. I don't even really need coilovers as I just got some R-compounds and was planning to run in BS, but it's winter, and I like to tinker.

Anyway, any input would be appreciated.

The rear shock towers have a built in spring mount, but it's sized for the factory spring and wouldn't work with a 2.5" ID spring. I'm developing a solution. Check my Bilstein thread for more information.

Find out where he got this part:http://www.hi-impact.org/ryang/modif...k_moton_10.jpg

http://www.hi-impact.org/ryang/modif...ock_moton.html

I was actually just looking at that. If that's the only problem, then that's pretty great because I can turn one of those out on a lathe rather quickly. I'll try to put up some CAD drawings within the week to get some feedback.

LionZoo: I did see your Bilstein thread and I didn't realize that that was the part you were talking about. Do you have any pictures of yours?

Nope, they're still in development. I'm going to do one more test fit this weekend to make sure nothing is rubbing. If you want to turn a piece on the lathe I can just send you a copy of the drawing after I'm done. What material do you plan to use?

That would be great! I was planning to make mine out of delrin. I'm very interested to see how your setup turns out.

https://www.rx8club.com/showpost.php...6&postcount=44

Feedback would be appreciated.

What are your adapters made out of? Have you considered using steel? You could make a welded assembly using some thinwall tube and a a plate, or just machine the whole thing out, but that would be a lot of boring. Then, make a plastic or rubber bushing to sit between it and the stock perch. Without doing any analysis, I'd trust a piece of steel as thin as 0.035", which may just give you the clearance you need.

Welding would be too much work. This is not just for me; it's designed to be a kit for other people that want to buy their own race springs. At this moment my own personal pieces are aluminum, but the production pieces will be urethane. My design is a bit different from what Robin has in that I'm feeding my spring forces into the original spring perch area while his has the spring forces fed onto the lip of the top mount. I was thinking about going that way until I realized the lip isn't actual level; it's a fairly low tolerance cut. I feel feeding the forces into the original mount brings with it a bit more peace of mind.

Does your design somehow yield less clearance than Robin's? It seems like the irregularity of the cut on the lip of the top mount would be insignificant compared to the misalignment of the shock to the top mount that comes with suspension travel. I'd understand if you had reservations about the integrity of the structure of a part designed only to locate the spring, but if either way gives the same clearance, then I guess it doesn't matter much.

How thin would the walls of your adapter have to get to clear the damper? If it's really close, you could try a tapered bore to give a little bit more clearance lower down where the shock is moving more, and it should hold up fine since the stresses should be much lower as you move away from the spring seat.

Right now the lip to locate the spring is 0.075". Previously it was at 0.125" and I bored it out 0.1" and so took away 0.050" from either side. I can bore at out another 0.050" to give a wall of 0.050", but that starts getting into territory where it's pretty thin. At this point I feel the much more elegant solution would be to go to a bigger spring in the rear rather than try to make it work with a 2.5" spring as even if I can get it to work with the bored opened up just a little bit more, a couple hundredths clearance (at max) is very very small and I'd feel pretty uncomfortable.

Personally I have misgivings about whether the current 2.5" adapter designs on the market actually have clearance. From what I've seen, even if they don't rub they'd be very very close to rubbing. The rubbing isn't obvious during installation; the rear damper moves in its mount through it's travel and only starts tightening up after it gets past static ride height. My rubbing on the latest design occurs about 1" from full compression; if you don't test your installation you might never notice it. This might not be an issue with some of the kits as they're delrin and delrin can slide a bit, but my own personal anal-ness means I'm not willing to accept anything that will be rubbing.

Ok, third idea: How about making the adapter so that it mounts the spring a little bit off center (offset toward where your clearance issue is)? I know it's not ideal for loading of the spring, but it shouldn't be much worse than what it already is. You would need some method of indexing the adapter and keeping it there, like a setscrew or something, but it seems like it could be a better fix than low availability springs.

Also, what coilover setup are you using? I'm looking at getting some cheapie sleeves on eBay and decent Eibach or Hyperco springs. I'm also a little concerned about how high the perches will end up on the front shocks without cutting off the existing one and putting on another. With the perch in the stock location, it looks like a coilover sleeve would restrict me to some pretty short springs with not much travel.

I'm not sure I'm up for indexing the spring. Yes I realize the spring already isn't loaded on center, but trying to make it worse is not something I would want to do. I think what I'm going to go is end up opening up the bore a bit and design for a 70mm spring in the back with an insert on the top mount so that it can take a 76mm spring as well.

I'm not actually sure what spring perch I'm using yet; probably just something off the shelf. I remember talking with Shaikh and figuring out what perch type we needed; I'll have to ask him again. I'm going to try some Swift springs and see how I like them. It's not quite the safe choice that Hypercos are, but I have a friend who's a serious tracker that swears by them so I'm curious and I can get a good deal on them.