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

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Guest JAMIE T

I spoke with Gordan last week about struts for our cars. I was particularly interested in the 2817's which are a custom build struts. You basically get a strut that can be valved basically anyway you want it and it comes with a steel housing that you weld you own bracketry to. After finding out that they are about $1500 EACH. Gordan talked to me about the ones you mentioned and seems to feel they are improved and would be suitable for our needs.

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"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"

 

And Gordon told Bryan Lampe early this year that compression damping had been increased. Doug from Koni told Erik Messley that Koni changed both rebound and comrpession damping on the 8610-1149 to better meet the needs of the biggest market for those inserts (European VW racers).

 

I have a shock dyno graph for the 1149. I'm going to try and get one for the 1437RACE.

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Just got an e-mail back from Gordon Benson with a mixed dyno chart of the 8610-1149 and the 8611-1257. He says:

 

I don't have a full chart for the 8610 RACE but the 8611 RACE has the exact same valving for the rebound side.

 

So, that means the rebound valving on the 8610 was changed to match the rebound valving on the 8611 double. That is a big change from 8610-1149:

 

1. The 8610-1149 rebound full hard is about 1600nm at velocity .330mps while the 1257 rebound full ahrd is about 2400nm at velocity .330mps. That's 33% stiffer rebound at full hard.

 

2. The 8601-1149 rebound at full soft is about 600nm at velocity .330mps while the 1257 at full soft is about 1250nm at velocity .330mps.

 

So, that means the rebound valving range on the 8610-1437RACE has been moved up about 33% compared to the 1149. That's probably fine and would allow contorl of higher rate springs but it also means that it probably won't work for springs rates any less then about 300 lb. in.

 

For the compression (bottom of graph), the 8610 1149 and 8610 1347 RACE uses the _same_ footvalve and will build the same amount of compression force.

 

From this we can assume that the compression did not change on the 8610-1437RACE from what was on the 8610-1149. Checking the dyno charts confirms that there really isn't any change in compression damping for the 8610-1437RACE compared with the 1149. Its still a bit low (around 250 to 500nm in the .132 to .198mps range where cars usually work) so revalving to around 750nm is still a good idea.

 

The only other difference between the 8610 1149 and 8610 1437 RACE is that the top mount is different. Whereas the 1149 was 5/8" in diameter, the 1437 RACE is 14mm but includes a hat bushing to work with 5/8" bearing camber plates.

 

A minor change but one to keep in mind when sourcing camber plates.

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Shocks dyno graphs (thanks to Cary for extracting them from a .pdf and making them large enough for us guys with old eyes to see). The first is for the 8610-1149. The upper half is rebound force and the lower half is compression force. Both forces are measures based on the speed of the shock shaft. Force is measured in Newton Meters and velicity is measured in meters per second.

 

86101149.gif

 

The second graph is an overlay of two. The 8610-1149 curves along with the rebound curve of the 8611-1257RACE which is supposed to match exactly the curve of the 8610-1437RACE that replaced the 8610-1149.

 

8610-8611comp.gif

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For someone like me getting ready to source some race struts, this thread is AWESOME!

 

And by the way, here is the quote I got from Shox.com

 

8610-1437RACE $159.00 eac strut insert

8611-1259RACE $249.00 each

 

Koni & Tokico have free shipping, for retail customers, to the continental USA and Canada. Further discounts are usually available when purchasing more than one item at the same time.

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So' date=' that means the rebound valving range on the 8610-1437RACE has been moved up about 33% compared to the 1149 ... means that it probably won't work for springs rates any less then about 300 lb. in.

[/quote']

 

Uh Oh - I already ordered a set thinking they would work based on Gordons reply ..... but I'm running 225F / 250R 'cause it also runs on the street some and you're saying they are too much for anything less than 300 lb/in :(

 

Looking at the graphs the old ones at about two turns is where the new ones are at full soft which would imply (based on your comment) that the old struts had to be run near the softest settings at my springrates - is that where people were running them? Does this mean I'm screwed or just have to run them on the softer(est) settings?

 

Thanks

Cameron

 

PS - my first sticky 8)

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Cameron:

 

I already have a set of the Koni 8610-1437RACE inserts installed on my car. I ordered them before they were even available in this country. The car is being prepared for SCCA ITS but at the moment I'm driving it around on the street with the exact same spring rates you have. The ride is firm but not harsh. It never bottoms out. Typical Zcar rear end squat upon hard acceleration is completely eliminated. Nose dive under hard braking gone as well. And handling is awesome. With 40 series Toyos the car is on rails. You have to pitch it wildly into corners at stupid fast speed to even get it to slid. I personally am still coming to terms with the limits of the car. And this is with NO sway bars, I have a set of fatory sways but they are not even installed. I wanted to see how it handled without them. What John is talking about is road race handling on the track. Under those conditions handling is a very individual thing and his path of development and yours may not be the same. I don't think you are going to be disappointed with your Koni's.

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HEY JOHNC

Heres the secret sports setup,

have fun unless your a translator

www.sissk.co.jp/secretsports.htm

they offer a adjustable drop in, i belive 1.8 inch short stroke and valved very agressive..but im told there to be the hot setup these days in japan for s30

TRY WWW.TECHNOTOYTUNING.COM gabe tyler makes some parts for the z cars, like rca's "ROLL CENTER ADJUSTERS, "AKA" BUMP STEER SPACERS. some one mentioned the spacers, hes got great products and is pretty reasonably priced...

nice of you to bring that topic up by the way....

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I'll probably end up with the 8610s. I will need to replace the rear struts as my new Tokico Premiums on the rear have on that has failed, and I had to "resize" the fronts for a little custom top hat experiment I was trying...

 

Mike

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I have actually talked to the guys at technotoytuning and they seem to know their stuff.

 

Can't tell that by looking at their TC rod. Again, as discussed many times on this site, shortening the TC rod pivot length increases bind in the front suspension and affects the camber gain in bump designed into the 240Z's front suspension. It hurts rather then helps handling.

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Can't tell that by looking at their TC rod. Again, as discussed many times on this site, shortening the TC rod pivot length increases bind in the front suspension and affects the camber gain in bump designed into the 240Z's front suspension. It hurts rather then helps handling.

I'll say it again, my TC rods with a similar design allowed me to run a lot more caster, and I think that the caster more than offset the camber gain or the increased dive. By a very large margin. I'm sure that anyone who uses Mike Kelly's or AZC's control arm and TC rod would back me up.

 

EDIT-I guess I should also state that I am redesigning the rear pivot to get rid of the shortening of the TC rod. I agree that shortening that rod is detrimental, but the increased caster is HUGELY beneficial.

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I'll say it again' date=' my TC rods with a similar design allowed me to run a lot more caster, and I think that the caster more than offset the camber gain or the increased dive.

 

snip

 

I agree that shortening that rod is detrimental, but the increased caster is HUGELY beneficial.[/quote']

 

I haven't ever done a back-to-back with caster being the only variable, but I have never found the need to add any more than stock on our 240Z's or BMW's that we race in ITS, and there isn't anybody out there beating us. Years ago we started out in the "race cars need more caster" mode and couldn't tell the difference between weekends with more and weekends with stock (never did a same day test). When I took over the BMW suspension program at ARC/Sunbelt I removed the ton and a half of caster that Ground Control had recommended, however, the plethora of other changes I made would negate any conclusions about the contribution of caster to transformation of those cars from undriveable to ARRC champs. I just don't see more caster being necessary for good handling on a 240/260/280Z. I could be wrong. I usually agree with everything else you say. :)

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Might be a road course vs autox thing too, but the front end will ACTUALLY TURN IN at an autox if you have more than 5 degrees. I did have an instructor who drove my car with 3 degrees at a road course say to me: "This car is great at the road course. How the hell do you autox it???"

 

Ground Control recommended 3 degrees last time I checked with them for what that's worth, but my own experience is that doubling that works a LOT better.

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Steve and Ian were very successful with their setup at many autoX events. They were running over 7 degrees positive caster. The added benefit in the front was less static camber, which in their case made for a better contact patch on the front tires.

 

I'll be playing around with mine this spring and summer and will be able to tell you what works better, more or less...

 

Mike

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Might be a road course vs autox thing too' date=' but the front end will ACTUALLY TURN IN at an autox if you have more than 5 degrees. I did have an instructor who drove my car with 3 degrees at a road course say to me: "This car is great at the road course. How the hell do you autox it???"

QUOTE']

 

Interesting, what front toe do you run? Turn in on low speed corners can be an issue, but a smidge of toe out usually takes care of that for us.

 

When I built Chet Wittel's first ITS 240Z he took it to a few autox's to get more familiar with it, and being former Atlanta Region BSP champ he did very well with it, so not unusual for a properly set up road race 240Z to also autox well.

 

Looking forward to Mike's tests.

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Another variable in this caster debate is tire size. When I ran 275/45-16 S04 Hoosiers on the front I got rid of a lot of caster (down to 4) which helped even the tire temps out. I also reduced camber from 3.5 to 3.0 in front. Back when I was running 225/50-15s I had a lot of caster (about 7) and camber to make the S03 Hoosiers work.

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Steve and Ian were very successful with their setup at many autoX events. They were running over 7 degrees positive caster. The added benefit in the front was less static camber, which in their case made for a better contact patch on the front tires.

 

I ran a similar amount on my car using bias ply slicks (13" FA fronts). In the motec seminar it was pointed out that caster is very tire dependent. Claude's example of how to think of a tire was as a number of interconnected springs. If you coilbind any of them you slide the tire. Some tires need a lot more caster than others.

 

Claude told us that one car they run uses 29 degrees of caster. The trick in testing this is to also realize that you'd need to change the caster trail as you increase the angle to test just caster. And the trail will change with tire diameter. It's the caster trail that leads to increased steering stiffness as you add more caster.

 

Cary

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OK, let me pull this sticky post back to the original topic. I have some updated info on struts.

 

I followed the Katman's advice and went with Bilsteins. I like to be a little different and I think a non-adjustable strut more closely matches vintage racing intent. I was also swayed by this post and Katman's posts on the IT forum. In addition the Bilsteins are cheap and the Carreras are no longer available.

 

The full part number on the box is F4-P30-0032-MO. This is the "sport" shock used for 75-84 Rabbit and others. From Bilstein website:

 

SPORT

For the performance-minded driver, Bilstein “Sport†shocks deliver absolute mastery of the road surface. Designed to push a car’s suspension to it’s performance peak, these super-firm shocks are well suited for use with special

springs, anti-sway bars or other suspension upgrades.

 

Measured data (by me with +/- 5% tolerance) is as follows:

Shaft dia: 1.315

Shaft dia. at top: .550

Shaft length: 8.5 to top of gland nut

Body dia: 1.519

Body length: 13 to top of gland nut

gland nut is 1/4 thick

Overall Length: 21.5

Stroke: 5 - 5/16

Color: Bilstein Yellow

Gland Nut (240Z) - p/n B30-629

Gland nut - 48mm x 1.5 thread

Cost: $99 ea. + $15 gland nut

 

The gland nut was a sticking point. P/N 450424 gland nuts listed earlier in this post are no longer available. Bilsteins take a special nut that has an oil seal. The closest replacement is p/n B30-629 with the correct threads but too long. You will need to order this nut and cut about 5/16 of the threads off to get correct fit. I did it carefully with a cut off wheel and a little sanding. I will try to get a p/n for a 280 (52mm x 1.5) nut at a later date.

 

So far, Bilstein has been a good company to work with and future re-valves are indeed $65 ea.

 

Of course, as detailed in earlier posts, cut a spacer to fit into the bottom of the tube so the gland nut tightens up within 1-2 mm's from the strut housing, but not bottoming. I used 3/4 pipe. And depending on what you are attaching it to at the top, you may need to drill out or obtain a bushing for correct fit to your camber plates or spring perch.

 

As I build this one up in preparation for the Walter Mitty, I will try to post a static alignment thread.

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hi just a question here ive been running std strut length bilsteins with 1" lowered std heavy duty springs for many years quite happy with this but wanting more camber adjustment i have now bought arizona z camber plates and coil over kit with 250 ib springs

 

my question is will the camber plates and coil overs drop the overall height or do i still need to section struts to get the lowered look as well as full suspension travel

 

mick

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The answer is: it depends. Camber plates let the strut rod extend further and the 240 struts are already a little shorter, which helps a lot. Again, shoot for static ride height around mid-point of strut travel. If you slam it, you will bottom out the struts.

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