Koni Racing strut conversion...

Suspension and other discussion

Koni Racing strut conversion...

Postby MWP » Sun May 29, 2016 9:00 am

So im currently in the process of converting my factory struts to using Koni Racing (8611 series) inserts and weld-on coilover sleeves.
When done, ill have a setup that rivals any off the shelf $4k+ coilover kit, for about 1/2 the cost.

Is anyone interested in me doing a bit of a write up on the process?
Its a similar process to the stickied AGX conversion thread, but a bit more involved & technical.
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Last edited by MWP on Sun May 29, 2016 6:25 pm, edited 1 time in total.
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Re: Koni Racing strut conversion...

Postby CMS-GT4 » Sun May 29, 2016 12:04 pm

These kind of write ups are always welcome. It might encourage people to choose better setups as well.
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Re: Koni Racing strut conversion...

Postby underscore » Sun May 29, 2016 3:31 pm

I love writeups, especially ones that can save big money, so if you're willing to make one then please do!
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Re: Koni Racing strut conversion...

Postby MWP » Sun May 29, 2016 5:49 pm

Okie dokie.
I'll do it in parts, as it'll end up being quite long, and i doubt ill get it all written at once.
Maybe when done, ill re-edit and turn it into one big write up.

I'll first say that im no pro. I dont re-valve my dampers, i dont have suspension travel data logging gear (one day maybe), i don't have a mechanical engineering degree, etc, etc.
What i know is from my experience and reading as much as i can on this topic over the years.
So don't take what i write as fact, how i my modify my suspension as being fool-proof, it being the best way to go about it, or that its safe to follow.

It'll be a bit random, with some general information why cheap coilovers are crap, why what im doing i believe is decent, etc, etc.

----------------------------------------

Part 1.

Why i'm doing this...

I *love* hills driving!!!
I live in a decent sized city, that is surround on two sides by comparatively low mountain ranges with lots of twisty, challenging roads, that are often quite bumpy and unpredictable.
Occasionally some of these roads also get closed off for rally, sprint and hill climb competitions that i compete in when i can.
An example of one of our fun roads: https://www.youtube.com/watch?v=M31hXZ339hk (that sound!).
Me competing in a hillclimb last year: https://www.youtube.com/watch?v=DNqdvFOQDco

The bumpy and unpredictable nature of the roads (and most public roads in general) means you need quite compliant suspension that wont give you any surprises.
You should be able to hook around a corner almost at the limit, hit a bump in the road, pothole, etc, and not be thrown into the other lane, or worse, off the side of the road.
Suspension like this is what we should all aim for: https://www.youtube.com/watch?v=zZQKepbGKiI (absolutely incredible!)

What we commonly use...

There is generally three problems that come up with the type of suspension modifications we do.
Not enough bump travel - you hit a bump, the suspension travels all the way to its limit hitting the bump stop (bad!).
Springs that are too stiff - stiff springs are great for a smooth track, but not for normal bumpy road driving.
Dampers (shock absorbers) don't match the springs/car - causes a lot of problems, like making the car bounce and not settle after hitting a bump.

Off the shelf lowering springs actually do the job reasonably well for the price. They normally use variable rate springs that lower the car, but also increase the spring stiffness as they are compressed.
The downsides of them is the reduced suspension bump travel, and not having a damper that is matched to the variable spring rate.

Cheap aftermarket coilovers have a bunch of problems (it appears the Japanese tuning market is mostly to blame. "Its Japanese, it must be good!", nope!).
Tein, JIC, and then later the other aftermarket Asian brands like BC, etc make coilovers that look pretty, have high spring rates that make the car feel like a go-kart, but actually do a pretty bad job of providing more grip on the road.
Basically they hide the poor quality of the product by using a high spring rate. A super high spring rate means dampers don't have to work as hard (so they can be cheap and crappy), and the normal suspension travel issues are not a problem.
Those million-way damper adjustment levels they provide are very unpredictable and inconsistent.
Alloy housings, no thanks! Even steel housings have been known to crack. Trusting your life on cheap alloy housings is a really bad idea (in my opinion).
Just think about it... say you are paying $1200 for a set. That's $300 a corner for a blingy housing, the strut top, the spring, the damper, etc. It's too cheap, its just not going to work that well.
Even at twice that price you may not get decent quality springs, quality dampers that are matched, and damping rates that are setup to suit the specific car.

For decent coilovers that use decent quality parts, are made to suit the specific car (to some degree), etc start at around $3000 a set.
If you think that's expensive... top end, professional racing team coilovers are often worth >$40,000 (like in that what we should aim for youtube video above).

Home made coilover conversions can do the job well if done right (like hopefully i am).
Doing it properly is quite a challenge though. Simply fitting a sleeve to the existing housing, and sliding in a damper that will fit is not ideal (sorry rear AGX conversion thread, but this applies to you).

----------------------------------------

Next up, my plans...

BTW, comments are very welcome :)
It may be some time between instalments.
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Re: Koni Racing strut conversion...

Postby aus jd 2703 » Sun May 29, 2016 9:10 pm

I own bc coilovers so I may have some bias.

Murray coote of mca actually said the bc arnt bad they are how ever missing low speed rebound. Apart from that are an ok off the shelf coilovers. This was for a mx5 doing time attack Murray is pretty hard to please so that's as good of a review as a off the shelf coilovers will get. And they will do coilovers for st185. My car was possibly a test muel until funds dried up.

So my point is bc arnt bad.

But what your proposing mark is the next level, a proper adjustable strut set up. I'm very curious on your finding and subsequent results. Although I lack the funds currently do copy what you end up with I will be interested to see your results.

What's the plans for anti roll bars?
My car has has kmac front and rear bars. My mate has stock front and white line rear. His car is so much more predictable than mine. A lot of other variables but I'm beginning to think front swar bars are best left stock 24-27mm depending on year.

Watching with great interest!! Keep up the good work!
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Re: Koni Racing strut conversion...

Postby TRDTurko » Mon May 30, 2016 12:20 pm

I did something similar in my build thread but with KYB inserts (came with the car). When I get back to my new build I will be going with the Koni race inserts as well.
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Re: Koni Racing strut conversion...

Postby Aaron » Mon May 30, 2016 12:31 pm

aus jd 2703 wrote:I'm beginning to think front swar bars are best left stock 24-27mm depending on year.


You're probably right about this. The Whiteline article mentioned it too, but if you think about it, it makes sense. Our cars are already more prone to understeer than oversteer. By stiffening the front bar, you're just transferring even more weight to the opposite side in a turn -- more understeer. By stiffening the rear, you introduce more oversteer which is exactly what we need.
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Re: Koni Racing strut conversion...

Postby MWP » Mon May 30, 2016 12:39 pm

Aaron wrote:
aus jd 2703 wrote:I'm beginning to think front swar bars are best left stock 24-27mm depending on year.


You're probably right about this. The Whiteline article mentioned it too, but if you think about it, it makes sense. Our cars are already more prone to understeer than oversteer. By stiffening the front bar, you're just transferring even more weight to the opposite side in a turn -- more understeer. By stiffening the rear, you introduce more oversteer which is exactly what we need.


Yup, also agreed on this.
I found a Whiteline rear bar helped, but have found no need to install a larger front bar yet.
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Re: Koni Racing strut conversion...

Postby MWP » Mon May 30, 2016 2:32 pm

aus jd 2703 wrote:So my point is bc arnt bad.


Yeah, i may have been a little unfair with what i wrote above.
For the price BC's are great, you do get a lot for little money.
It's just for anything more than a daily street car, or low-mid club level track car you do really need a setup that's more capable.
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Re: Koni Racing strut conversion...

Postby celicast184 » Mon May 30, 2016 3:45 pm

Koni's are great Combo 'd with ground control kit. I have never owned a set, but I have ridin in my buds accord on the same setup. Over n all, it's good for what it does. Only thing that turns me away from them is that they are not ride height adjustable without sacrificing shock stroke and preload on the springs. This worries me because as a daily/weekend worrier, there will be lots of stress on the shocks. Especially when the spring basically just floats around if the springs are lowered to get the desired ride height. So, I am building my ultimate setup.. I'm gonna sacrifice some used coilovers I have laying around and hollowing them out to do the same exact conversion. This way I can preload my springs, lower my car, have travel, use camber, select spring rates, possibly get rid of sway bars, etc...
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Re: Koni Racing strut conversion...

Postby MWP » Mon May 30, 2016 4:13 pm

celicast184 wrote:... I have ridin in my buds accord on the same setup. Over n all, it's good for what it does.


No offence, but this is the other problem with the internet & suspension... you really cant trust anyone's opinion on what is good, and what is not without some kind of decent tech reasoning, or results to back it up.
Hopping in some guys cars and saying it feels good really means absolutely squat. You don't know the car, don't have somewhere you are familiar with to really test it, or lap times to compare it to.

... and i do realise its a bit ironic that obviously what i'm saying is on the internet, and is just my opinion with nothing to back it up (yet) :P
I'm hoping i can explain the tech reasons behind what i'm doing well enough that it makes sense as to why its a decent setup.
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Re: Koni Racing strut conversion...

Postby celicast184 » Mon May 30, 2016 4:40 pm

I get that. I can't say that your setup is absolutely the best without ever driving one with that setup. Have you driven BC coilovers equipped celica? Also, determining your setup also reflects on what the car is used for. ex) track prepped car will have chassis mods to stiffen the frame while daily driven cars can go without. Im setting out to build the most all around coilovers for daily/weekend warrior! Plain and simple.
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Re: Koni Racing strut conversion...

Postby celicast184 » Mon May 30, 2016 4:49 pm

Also, not all coilovers come with cheap alloy. Only early ksport came with alloy lower hubs and those things were junk! I don't mess with those at all. BC/Megan's/apexi all use great materials for their setups. I do agree that the shocks are crap. That's why I'm using coilovers for the external equipment and hollowing out and converting to Koni's inserts for the coils.
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Re: Koni Racing strut conversion...

Postby MWP » Mon May 30, 2016 4:58 pm

celicast184 wrote:That's why I'm using coilovers for the external equipment and hollowing out and converting to Koni's inserts for the coils.


Make sure you put up some progress photos of that in another thread... it will be good to see :)
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Re: Koni Racing strut conversion...

Postby underscore » Mon May 30, 2016 9:35 pm

I'm assuming Koni shock dynos their dampers?
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