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heavy85

The Strut thread - Koni / Illumina / Tokico / Carrera / Bilstein / Ground Control

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BZ3099 is what I used in the front. That is a rear 88 MR2 strut. Then I used the 240 front strut in the back, but I don't have the number for that one.

 

When my strut blew it looked like someone took a squirt gun full of shock oil and sprayed it all over the inside of the fenderwell. If you have the struts out the way to check them is to compress them and extend them and feel for "dead spots" on my Tokico that blew you could compress it all the way then pull on the strut when it was compressed and it would pull up about an inch and a half with NO resistance, then it felt normal again. The bluing on the shaft is not an indication of a bad strut, but the ones that were blued on my car also had the paint bubbling off, so they did get HOT.

 

Some people bend the top of the strut for camber. Sounds like yours might have been bent on purpose. I have a friend who had a local suspension shop do that for her, so I don't think it's uncommon at all. I honestly don't know how they do it with anything like accuracy, but it might be that this is the reason why your struts are all bent at the top.

 

EDIT--You can get all the same struts and then put a spacer in the back if you want.

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Katman: How did it come to light that the Konis had worn out their upper bushings? Did their performance drop off noticably on the track or were they removed from the car and inspected and found to be bad? In other words, how could you tell they were bad? I think I remember you saying it wasn't just one strut or one set, that you tried several and they went bad. Elaberate please

 

thank you

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Katman: How did it come to light that the Konis had worn out their upper bushings? Did their performance drop off noticably on the track or were they removed from the car and inspected and found to be bad? In other words' date=' how could you tell they were bad? I think I remember you saying it wasn't just one strut or one set, that you tried several and they went bad. Elaberate please

 

thank you[/quote']

The shaft gets wobbly in the body so camber and toe were not controlled.

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Guest nitr0

katman did you try a polyurethane upper bushing kit or solid strut top with the Koni? I've got Koni's (not in yet) F + R and will probably only run soft springs in a coilover, but they will get alot of abuse on the street. I trust the Koni name but every car works different and i'm open to suggestions.

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I believe the bushing Katman is refering to is the one inside the strut tube insert housing. Not the bushings on the tophat assembly you would traditionally associate with "bushing" kits for the street.

 

In road course "stuff", the energy transfer and heat are significant enough in most applications that is isn't uncommon to heatsoak shocks and struts, which is why any series that allows external dampers (Ohlins and Penskys) does just that.

 

This is also the same reason you read here that we tell people not to run cross drilled rotors, then go to ALMS or other professional racing series and see... Cross drilling on the rotors. Big budgets and special treatments allowed for in professional (And more and more amature) racing does not translate well to the street.

 

You'll be fine with Konis or Tokicos on the street. You'll never abuse them the way 30 minute road course session will... Nothing hurts suspension and brake parts like doing road course laps.

 

Mike

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Guest nitr0

Thats actually what i first thought but dismissed it because - its a Koni, they shouldnt do that..... Another question, what condition were the valves in? and were the Koni's gas charged?

 

The stock Koni's for the 240/260 (86-1811 -F and 86-1812-R i think) are not gas charged so will heat up quicker, and are designed to work at the cars standard height, they are part of the classic range. At 25-35mm (1 to 1-1/4 inch) lowered, the struts are working at their lowest safe range, any more than 35mm even in a street application the travel is too much and the shock will bottom out...

 

People here in Australia are using Z31 300zx inserts Front and Rear with great results on the track, they are gas charged and externally adjustable, and are also about 35mm (1-1/4 inch?) shorter than the 240/260z inserts so will work properly with lowered cars.

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All my former Koni friends always complained about the upper bushing wearing out prematurely, and Truechoice hammers you on the rebuilds. Otherwise I like them.

 

Is it possible to install a linear bearing instead of a bushing?

 

Cary

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Like MKelly said it's the shaft bushing inside the shock body. I don't know what Koni might be able to substitute. It is possible they no longer have that problem, its been several years since I knew anybody intimately familiar with them on a Z. I agree with everything else he said as well.

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Koni (and other) shock bushing failure is almost always cased by only a couple things:

 

1. Bent shock shaft.

2. Binding in the normal articulation of the strut.

 

For this discussion we'll ignore number 1.

 

The strut/shock combination is designed to primarly take vertical loads. Inherent in the design of a strut are some lateral or bending loads but they are not as great as most people think. ANY lateral or bending load increases the bind in the movment of the shock shaft and is a bad thing.

 

Because the length of the strut/shock assembly and the angles of the strut in relation to the vehicle and the LCAs change as load changes, the front and rear strut installations on the 240Z need to have free movement at the top and bottom of the strut. The freer the better because these are the places when most of the suspension bind occurs. If this articulation is restricted then the side loads on the shock bushing increase dramatically.

 

If shock bushings are wearing out prematurely then I would check for binding in the ball joint/steering arm (or the spindle pin at the rear) and at the upper strut mount. A classic failure example was (is?) the Polyurethane OEM upper spring isolator that MSA sold (sells?). The stiffness of the poly restricted articulation at the upper strut mount and it would destroy shocks very quickly. A lot of Tokico Illuminas were killed with this "performance" part. Another example was GC's camber plates from about 10 years ago. They used monoballs without much articulation and these would bottom out near maximum compression, causing bind.

 

Other contributing factors can be (very, very vehicle specific):

 

1. Rear toe-in beyond about 1/8".

2. Really big caster numbers in front (8+).

3. Shortened TC rods (TC rod pivot moved forward).

4. Excessively shortened steering arms that bind up the tie rod end.

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A friend reminded me of trait of the Koni 8610 (and I think 8611) inserts that I had forgotten about. The upper bushing/seal is crimped in place with three tabs off the housing itself. The bushing/seal is not a tight fit and can feel loose/sloppy. Its designed that way by Koni and everything tightens up fine when the gland nut is torqued to spec. If the gland nut loosens at all then the bushing/seal gets a little bit sloppy. Also, the Koni shock oil is only good for 2 years of monthly racing. Upgrading to Silkolene will give 4 years of racing before the oil needs replacing.

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'Bump steer' spacers increase cornering force leverage exerted by the wheel on the strut, the bigger the spacer the more leverage. Don't know if that makes an appreciable difference to shock shaft wear and binding but it could.

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As an update to this post, I'll call it...............

 

ECONOMICAL RACE STRUT INSERT OPTIONS

Bilstein (VW sport insert) non-adjustable - P30-0032 - $99 ea. Plus $70 for revalve at Shox.com

Advance Design - double adjutable - $399 ea. - Ground Control

Koni 8610-1437RACE - single adjustable - may need revalve - $160 - Summit

Koni 8611-1257RACE - double adjustable - $256 Summit

Carrera 32748 - non-adjustable - Still supported by QA-1? I'm still waiting on quote/answer.

Tokiko - Not suitable for higher spring rates.

 

For the price, I'm thinking seriously about the Koni 8611's. Any other users of this shock out there?

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Thanks John for some excellent information concerning the Konis.

The upper bushing/seal is crimped in place with three tabs off the housing itself.

I can confirm the Koni 8610-1437RACE do indeed seem to have this set up. It's actually the housing cap that's crimped. Will make sure the gland nut stays tight.

Clarkspeed: I am running the Koni 8610-1437RACE on my car (78 280z). Did not have them revalved before installation. I have not driven the car on the race track yet, so can't comment on there perfornance on the track. Also, I got mine at shox.com and they were only $130 each.

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I would like to hear how the 1437RACE works on the track. The dyno charts us west coast guys have seen show a doubling of compression (to over 200) but others have said that Koni executives refute this.

 

I've sold a few sets of 8611s to customers. The compression adjuster is at the bottom of the shock so you need to machine a couple spacers to keep from crushing it. Drilling a hole in the bottom of the rear strut tubes makes it easy to get at the comp adjuster. Doing the same on the front tube just makes it easier to get at once the strut is unbolted from the steering arm.

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Hey John-

 

Checked my notes and we ultimately ran lower spring rates on the EP car with the slicks than we had on the ITS car that won the ARRC twice, so I stand corrected. We had tried higher and didn't like it. 400F/350R on the ITS car, 'bout 100lb/in lower on the EP car. Before we got the ShockTek's we only went 325/285 on the ITS car.

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I would like to hear how the 1437RACE works on the track. The dyno charts us west coast guys have seen show a doubling of compression (to over 200) but others have said that Koni executives refute this.

As soon as I get the car on the track I will let you know. I am considering running the car at a couple of autoXs just to shake it down.

 

I've sold a few sets of 8611s to customers. The compression adjuster is at the bottom of the shock so you need to machine a couple spacers to keep from crushing it. Drilling a hole in the bottom of the rear strut tubes makes it easy to get at the comp adjuster. Doing the same on the front tube just makes it easier to get at once the strut is unbolted from the steering arm.

I am considering the 8611s for the next upgrade. I don't think having to unbolt the steering arm would be that big a deal. Thanks again for all the information you have provided on these inserts.

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Also, the Koni 8611 shock to use is the 8611-1259RACE. The dimensions are:

 

Stroke: 6.02"

Max Length: 21.26"

Min Length: 15.24"

Body Length: 13.07"

Body OD: 1.71"

 

Dimensionally its exactly the same as the 8610-1437RACE and the old 8610-1149. They will also work with the OEM gland nut.

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Last night I e-mailed Koni about the difference in damping characteristics between the old and new struts. Following is that e-mail along with their response. It appears that the new struts should work just fine without revalving if I read this correctly.

 

Response from Koni:

 

"Cameron,

 

The compression damping did not change from the 8610 1149s. The rebound

damping, however, was changed to be more digressive so we could give the inserts a greater range of spring rates to work with than the out going 8610 1149s. I'm sorry that you have been mis-informed. Thanks for writing.

 

Gordon"

 

Original Message from me:

 

"Sent: Tue 12/20/2005 7:05 PM

To: [email protected]

Subject: Koni Web Site Contact

 

Comments : I autocross a 240Z and am in the process of shortening the strut

housings to run shorter struts and gain back some suspension travel. 8610-1149 used to be the strut of choice for this application but they are no longer available from Koni. I've been told the replacement is 8610-1437RACE but that the compression damping has been doubled. If this is the case the

'replacements' really are not direct replacements and require revalving to work properly in this application. Can you please confirm the damping

characteristics of the 8610-1437RACE in comparison to the old 8610-1149 and recommend a strut to use in place of the 8610-1149s."

 

Woo-hoo sounds like we may still have a decent low cost strut available from Koni unless I'm missing something.

 

Cameron

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