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

[silver280zx]

my bad

[rudypoochris]

Hey guys! I found these shock dyno tests on honda-tech.com. Thus these are probably for Honda inserts, but might still be useful. Included are attachments of the shocks I thought were pertinent... full link here: http://honda-tech.com/zerothread/1104049

 

I was actually very impressed by the amount of adjustability in the Illuminas, albeit the curve is progressive at first, but ends up being digressive on the harder settings. There is still a bit of progressivity at the start in the first graph (for the fronts) no matter what. For the price (~$75/ea.) this makes me feel good about having chosen them as an entry level street/sport shock.

[JMortensen]

I don't know how useful that really is to us here. If you really want to analyze a set of struts you have to dyno EVERY strut to get an idea of how that particular one performs. So even one Z strut to the next from the same model and manufacturer can have significant variances. Check this post that John Coffey linked to this morning showing two K-sport struts. Looking at either graph one could make some conclusions about them, but when you compare the two you see that they are so far different that it's amazing they'd be for the same application.

 

Comparing a graph from some other model of car and trying to make some sense out of the resulting info and apply it to a Z is nearly useless in my opinion. It does tell you that the adjustments do actually adjust correctly (seen some dyno graphs where full soft is harder than full hard and vice versa), but that's about it I think. While that is important information, it would be better obtained from struts made for a Z, preferably several of them so that we could get an idea of how consistent they really are.

[rudypoochris]

I know what you mean. I just found it kind of cool. I found it really cool though when I saw consistency between the two Illumina graphs in relation to the settings. Setting 1 goes from progressive, 5 being digressive. I totally agree. If we got serious the entire set would have to be run through a shock dyno. Out of curiosity... anyone know what types of places might have an accurate shock dyno?

[JMortensen]

http://www.shock-shop.com has a dyno. I'm sure http://www.shox.com also has one.

[thehelix112]

Just got a little more info on the Bilsteins. Apparently the part number we're using is valved 256/72 in stock form. This looks to me like a very good setup for springs in the 2-300 in lb range right out of the box. I wish I had known about them when I was using my car as a dual purpose vehicle for street and track.

 

Jon,

 

Is this the F4-P30-0032-MO the exact PN you are talking about?

http://www.bilstein.com/mistore/productdisplayf.php?sku=109472&hdwt=31101&loc=101&dealer=no&company_id=100484

Also, what do the valving numbers mean? I'm assuming the higher the number the stiffer the valving, so which is which? rebound/compression or vice versa?

 

Also, any recommendations on where to purchase those ones would be great.

 

Thanks,

 

Dave

[JMortensen]

Here is a description of the valving from Wiisass who is a member here but hasn't been active for awhile (this quote is from another forum):

The inverted monotube strut inserts are nice pieces and if revalved properly, they would be very good dampers. You mention a 300/100 valving. That's Bilstein's notation for 3000N at 0.52m/s in rebound and 1000N at 0.52m/s in compression. I need to run some more numbers to tell you what that would actually mean for your car. But that's how they rate their linear valving. Which assuming that it is actually linear, you will end up having too many tradeoffs in the valving and either have too stiff of a ride or not enough compression damping for the low shock speed manuevers.

The dampers for our cars use 30mm pistons, and they are going to be pretty much linear no matter what. I am not so sure about the linear valving critique. I've been dealing with Chris Billings from the Shock Shop http://www.shock-shop.com and he was telling me that what he would prescribe for my situation would be very close to linear anyway, perhaps even PROgressive on the bump valving. He said it is possible to valve the Bilsteins to be slightly digressive or progressive, but with those pistons they're not going to have the sharp knee like a Koni or something that was designed digressive.

 

Chris would be a good source for purchasing the struts, as would http://www.shox.com, and he has some very interesting things to say about valving and spring rates. Basically what I got out of it is that we are using too much shock to compensate for not enough spring. When you get enough spring, then the shock valving can be reduced even though the spring rate goes up, and what this gives you at the wheel is a tire which stays more loaded all the time, because the rebound valving in particular isn't as stiff. Stiff rebound valving pulls the tire off the ground. He also says people valve the shocks to deal with the sprung weight, but they should be valving to handle the unsprung weight, since keeping the tire on the road is the goal. So he sacrifices ride quality for the ability to keep the load on the tire.

 

I'm going to try some struts revalved as he suggested with some pretty stiff spring rates (he charges $50 per corner for this service, so $100 for a roadracing Z since we only have front and rear valving, not usually left front/right front left rear/right rear). We'll find out how it all works out in 2025 when I get the car back on the road. He usually does road racing struts, so he wasn't sure exactly how the struts would work out for my application. What I'm doing is a pretty radical departure from what is "normal", so it may be that I'm heading down the wrong path, but if that is the case it's $65 per strut to fix it and I was willing to test his theory. Chris has a pretty good track record (he set up the shock/spring rates for the 4th place DSR car in last year's runoffs), but I guess I won't know for sure until I try.

[Carl Beck]

Hi Guys:

Someone mentioned.. in this very long and old thread... that when switching to non OEM type shocks, you may have to drill out the hole in the shock/strut isolators to accommodate the larger diameter threaded ends of the adjustable Illuminas.

 

That changes the original "D" shape hole in the isolator - to an "O" shape, and in so doing, does not provide a stop (so to speak), to keep the shock rod from turning while putting the top nut on/off. Nor does the Illimina have a stop anywhere close to the isolator. There is one an inch or so below, most likely for the original application - but I can't see how it can be used in the shortened struts of the Z.

 

Question is - what have others done, and/or what is best practice? Is a rubber strap wrench the only solution?

 

thanks,

Carl B.

[JMortensen]

Strap wrench works. I had the same issue due to having camber plates and what I did was to carefully grip the bump stop with a pair of channel locks and then hit the top nut with an impact (LIGHTLY!).

[thehelix112]

This is the link mentioned previously with a nice summary by katman.

 

http://www.improvedtouring.com/forums/showthread.php?t=16613

 

Jon,

 

Sorry to reiterate, but was the exact PN F4-P30-0032-MO or something different?

 

Dave

[JMortensen]

I gave Chris that part number and he gave me that valving as the stock valving, so yes, as far as I know that is correct.

[thehelix112]

Cheers.

 

Dave

[Carl Beck]

Here is a description of the valving from Wiisass who is a member here but hasn't been active for awhile (this quote is from another forum):

 

The dampers for our cars use 30mm pistons, and they are going to be pretty much linear no matter what.

 

Hi Jon:

"our cars" ??? is that as in "our race cars?"

 

"30mm pistons"?? is the "piston" attached to the shock rod, inside the tube or cartridge?

 

Just for some trivia - thought I'd post a picture or two - of the inserts that were in the Nissan Competition Struts circa 1970/73. On these the shock rod is 30mm.

 

Rather than attempt to have them rebuilt -for a car that will no longer be raced - I'm replacing them with the Tokico's for now.

 

FWIW,

Carl B.

[JMortensen]

Our cars as in Z cars. Most Bilstein struts use 36mm pistons which are more digressive in nature.

[240zdave]

I will try to get a p/n for a 280 (52mm x 1.5) nut at a later date.

I read through this entire thread the other day, and never could find where anyone came back with the part number for the strut gland nuts for a 280Z. I tried a search and came up with nothing. Did anyone ever find out what the correct part number is?

[Chino 240Z]

 

Sorry to reiterate, but was the exact PN F4-P30-0032-MO or something different?

 

Dave

 

FWIW....

Last year I did this conversion on our 240 track car, removing the Tokico shocks. With the info collected from this thread, everything went as planned. Strut tubes had already been shortened.

 

Bilstein Shocks # F4-P30-0032-MO (revalved 300/100), # B30-629 gland nuts milled down a few threads to fit flush with top of strut tubes. After playing with lower spring rates this setup (right or wrong?) 325lbs Front / 275lbs Rear is currently working for me. Tire temps and wear showed much improvement. You may need to add small spacer in the bottom of strut tube for best fit during assembly. Purchasing the gland nut wrench that fits this nut makes install and removal smooth.

 

The shock is listed on receipt as: P30-0032 VW 74-89 Front Sport. The revalve was an additional $75 performed at Bilstein. I also used Shox.com

 

I can also see that each install adjustments may be a bit different as there are many coil over hardware packages on the market.

 

craig

[MONZTER]

I have been running the Bilsteins for about a year now, re-valved 300-100. I keep having a problem with the gland nuts loosing up. I locktited them this time, I hope I can get them apart someday? Anybody else have a problem with them coming loose?

[thehelix112]

Craig,

 

Thanks for the info. Glad to hear they're working. Did you get them revalved to 300/100 also? I am considering getting them revalved to suit 240/200 springs. Is the adjustment linear? Ie, would 220/72 valving suit?

 

Thanks,

 

Dave

[JMortensen]

Thanks for the info. Glad to hear they're working. Did you get them revalved to 300/100 also? I am considering getting them revalved to suit 240/200 springs. Is the adjustment linear? Ie, would 220/72 valving suit?

I don't think the valving is proportional as it relates to the spring rates. When you talk to someone about custom valving they'll have questions about spring rate, but also about sprung weight, unsprung weight, motion ratios, etc. If the only thing that changes slightly is the spring rate and the rest of the variables don't change then I don't think that the valving will be really all that different. I'd run them with the stock valving or do the 300/100.

[Cutlass372]

Looking for a bad ass suspension setup for my 240z. I'm on a pretty tight budget so im not really sure what to get. I really like the idea of coil-overs, but do you think its worth it over a spring and strut setup? I would probably run 225f/250r with the tokico illuminas if I was to go the spring and strut way. This car is going to be my new daily driver so it is going to see a lot of street driving, but I want the best handling setup that I can get away with. I plan on tracking the car when I get the time so it also needs to be competitive on the track. I also like the way that the coilovers can adjust ride height as the springs sometimes don't seem to go low enough. What would you say is the best way for me to go?