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


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Ran across this today: http://www.summitracing.com/parts/afc-30030?seid=srese1&gclid=CjgKEAjwwPabBRCXo46OtM_RhGMSJACgCeqAA9DCl1Sw3lzo2cgYUD32oz7bxD9WADM-YcuqIU3-QPD_BwE

 

It's a double adjustable AFCO strut for a Mustang. Because it's a Mustang strut it isn't compatible with a Z (has ears on it to attach at the bottom, but if that were available without the ears and just a threaded body, could screw into any of the adapters that people use for cheap Chinese struts. AFCO has a very good reputation with the Miata crowd.

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Going with the Bilstein Sport cartridge insert for the 280Z Chumpcar. These things are really heavy duty as evidenced by the chrome shaft being about twice the diameter of stock.

 

old # P30-0032, new # 34-184530. This is a VW insert

 

It's a smaller outer diameter at 1.5" so clearance is no problem.

 

the average price is about $150 ea but I found them at 2 places on the East coast for $135.

 

I got them HERE

 

These came with a blue dust boot and according to the instructions you don't need a bump stop because it's built in internally.

 

Also these came with two gland nuts each with included seal, one has an internal thread and the other is external thread, but they are a smaller (VW) thread.

 

What's really neat though is these two gland nuts screw into each other. So instead of sectioning the strut housing I'm just going to cut two inches off the top and weld the internally threaded gland nut on the top. Then just use the supplied external thread nut to hold the insert. First though I've taken the seal out of the internal thread gland nut (being careful to save it without damage) and opened up the inside bore step where it's too small to fit over the cartridge.

 

In addition the internal thread nut has a outer step on it that fits down inside the housing and a larger diameter step that stops it from going inside. So it's almost like made for it.

 

So this solves two problems. First it's much easier to just weld the internal gland nut on top of the cut off strut than it is to section the strut housing and keep it aligned. Second there's no need to source a gland nut that fits the stock thread and is a small enough I.D. to hold the smaller dia insert.

 

The lower spacer is going to need an O.D. near the 1.7" of the housing and an I.D. smaller than the 1.5" of the insert. Plus it will need a recess to hold the insert centered. Nothing too hard on a small lathe, best to use some aluminum tube.

 

Not going to change the valving at first, just run it and see what happens.

 

Nice Chris, good thinking and thanks for the info!

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These things are really heavy duty as evidenced by the chrome shaft being about twice the diameter of stock.

 

 

What you are seeing is not the shock shaft.  That's the shock body - the Bilsteins are an inverted shock.  The actual shaft is at the bottom inside the yellow tube.

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  • 2 weeks later...

Ran across this today: http://www.summitracing.com/parts/afc-30030?seid=srese1&gclid=CjgKEAjwwPabBRCXo46OtM_RhGMSJACgCeqAA9DCl1Sw3lzo2cgYUD32oz7bxD9WADM-YcuqIU3-QPD_BwE

 

It's a double adjustable AFCO strut for a Mustang. Because it's a Mustang strut it isn't compatible with a Z (has ears on it to attach at the bottom, but if that were available without the ears and just a threaded body, could screw into any of the adapters that people use for cheap Chinese struts. AFCO has a very good reputation with the Miata crowd.

 

At that price point, AST had quaoted me ~$3000 for a custom set made specifically for the 240z. Too rich for my blood, but in all honesty it's a pretty good deal.

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  • 1 month later...

interesting, I did not know that but it make perfect sense.

 

Chris,

 

Have you had a chance to drive the car with the Bilsteins yet? Wondering how they feel without the re-valve. Thanks!

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  • 3 weeks later...

Chris,

 

Have you had a chance to drive the car with the Bilsteins yet? Wondering how they feel without the re-valve. Thanks!

Yes, they are pretty stiff. We raced The Ridge, 19th, 20th July. Got pretty lucky on the set up it handles awesome in the dry and the wet. We've got 2 drivers with decades of experience and they were impressed it was this good on the first race.  The spring rates are 150# in the front and #190 in the rear. This may sound soft in the front but it made it work in the wet. The Ridge is a really smooth track, we'll know more after we race at Pacific which really tests the suspension.

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Yes, they are pretty stiff. We raced The Ridge, 19th, 20th July. Got pretty lucky on the set up it handles awesome in the dry and the wet. We've got 2 drivers with decades of experience and they were impressed it was this good on the first race.  The spring rates are 150# in the front and #190 in the rear. This may sound soft in the front but it made it work in the wet. The Ridge is a really smooth track, we'll know more after we race at Pacific which really tests the suspension.

 

Thanks for the feedback! I just had my VW P30s dynoed and will also be running them without a re-valve. Looks like they should do the trick on paper but there's nothing like actually driving the car to find out. I'm glad to hear how well it went!

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The Bilstein P30’s work ok with the stock valving.  I ran a couple races with them before I had them revalved.  I really liked the “feel” of them which is purely related to their low speed performance in transitions.  I initially had them revalved 100/300 which was too stiff and killed the transitional feel of the car.  I then worked with a Bilstein engineer to revalve again based on my measured data. Turns out my current valving is not too far off the stock numbers.  My car weighs 2450# wet with me in it.  I think if you were around 2100-2300# the stock valving would be really close.  My comments are for road racing of course.

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  • 4 months later...

The Koni 8610 1437 Race inserts have a stroke of 6 inches.  If you have sectioned your tubes and lowered the car, chances are that you have no droop in the rear.  The Tokico 3015 has the same issue if used on a sectioned strut.  Be carefull before sectioning as, if some day you want to go Koni all around, No droop may be an issue.  Ask me how I know. 

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Missed my point Jon.  The amount of droop is determined by the height of the the strut tube where the gland nut attaches.  It is assumed that you will use spacers to appropriately fasten the insert no mnatter how long or short you make the tube.  If you shorten the tube too much, you will have more bounce than droop and if you are not careful with these short stroked shocks, you can run out of stroke in the droop direction.  I respect your knowledge, I think I just didn't say it properly.

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I'll try again.  Ideally, at ride height, you want the shock to be extended enough to accommodate the bounce you expect with the springs you have, and enough droop to handle  the same.  In other words, let's say you have the shock equally centered with 3 inches of compression and 3 inches of droop, for example. Using this example, imagine now we section the strut even more, say another inch and reduce the spacer by that same inch.  We now have 4 inches of compression with 2 inches of droop all else being the same.  The issue of spacers is only to properly mount the shock.  the size of the spacer depends on the length of the shock body and the length of the strut tube.  Is that any clearer ???

Edited by ww2winger
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The spacer is not only used to properly mount the shock. I've seen a Z at an autox with the rear sectioned to fit the strut insert with no spacer. The rear end was much lower than the (pretty damn low) front end. The guy had cranked in a bunch of preload to try to raise the rear up. Thing spun about 10 times that I saw. If that same car used a 2" spacer, it would have driven fine. 

 

I guess what I'm trying to say is that if the shock is in the middle of its travel at ride height, you probably don't need to section the strut. As to the amount of droop necessary, I don't think you really need more than the amount of sag you have. So to simplify, if you have a 500 lb corner and a 500 lb spring, you don't need 3" of droop. You need 1 inch, because that's the amount of sag that you have. Stock Z's (and just about every other production car I can think of outside of leaf sprung vehicles) don't have as much droop as they have sag. Of course, you don't need 5" of bump travel with 500 in/lb springs either, because you'll never use it. For my own car, I've got the rears sectioned 2" and I'm using camber plates which drop the car down another 1" or 1.5". At the ride height I intend to run, I'm using droop limiters to eliminate the extra droop that exists after the spring comes loose on the perch. When I eventually get better struts I'm going to try and find something with a 3 or 4 inch stroke. The rest is wasted on a really low, stiffly sprung car.

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You hit it on the head Jon. His strut was sectioned too much !!  Had he sectioned it 2" taller and used a spacer, no problem.  Since his strut was sectioned too much, he couldn't use a spacer with that shock. I sectioned my struts (rear) to fit the Tokico 3015 BZ shock (at the advice of Ground Control) which has a stroke of a little over 7 inches. Now that I am running this car exclusively on the track, I would like to go to Koni or some other adjustable shock.  However, when mounting a Koni 8610 1437 Race shock in the same strut, it requires a spacer.  Using a spacer is no problem but at the height of the strut, the Koni has very little droop.  I would like to have a taller strut and use a taller spacer.  This would give me more droop.  I don't need much more, but it would be nice. The Koni has a 6 inch stroke.  Bottom line, if I had it to do over,I would use more calculations before sectioning.  This would insure that I would have sufficient bounce and droop.  Now I have way more bounce than I need and barely any droop.

I run Konis on the front and Tokico 3015 BZ on the rear. I would like to do an altogether re-do. Any ideas for sources for shocks, struts, etc would be appreciated.  I have read this and many other forums and most guys are street drivers or autocrossers.  I run only on the track. Any ideas where I can acquire a set of struts ? Seriously.  

Thanks for all your time.  Jim

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As you go up in spring rate you also need less bump travel. At tarmac racing spring rates (300 to 400 lb. in.) 1.5 to 2" of bump travel at the shock shaft is plenty.  That works out to about 2.5 to 2.75" of wheel travel.  

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 However, when mounting a Koni 8610 1437 Race shock in the same strut, it requires a spacer.  Using a spacer is no problem but at the height of the strut, the Koni has very little droop.  I would like to have a taller strut and use a taller spacer.  This would give me more droop.  I don't need much more, but it would be nice. The Koni has a 6 inch stroke.  Bottom line, if I had it to do over,I would use more calculations before sectioning.  This would insure that I would have sufficient bounce and droop.  Now I have way more bounce than I need and barely any droop.

 

Same here - 2" is too much for the Koni's

 

See http://mcscc.org/Gal.../DSC0085?full=1

 

from this thread

 

http://forums.hybridz.org/topic/119304-may-have-figured-out-corner-exit-wheel-spin-issue-now-how-to-fix/?hl=cameron&do=findComment&comment=1118089

 

Not in that thread but I am still having corner exit wheel spin issues in one particular corner even with roll center changes. 

Edited by heavy85
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