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

[JMortensen]

I think he means 5" of total travel, not 5" of bump travel. 2" of bump travel on Justin's car would be enough.

5" of travel at the shock is way excessive for his application in my opinion. If he's going to run the car super low, he'll HAVE to have very stiff springs. If you have very stiff springs, you don't need the travel. The droop travel on a car with 400 in/lb springs is going to be 1.5", I have a tough time seeing why he would need more than 3-4" total travel at the WHEEL with spring rates like that.

 

If he doesn't want spring rates that high then the only choice is to raise the car up. With a mismatch of very low ride height and soft springs I think hitting the chassis on the ground (hard) is a very real possibility.

 

In practical terms I think he wants to have 5" of shock travel but will run the car at the bottom of the available range. That's wasted effort. Having 5" of droop travel on a car with 7" of wheel travel and springs so stiff that it is only drooping an inch or inch and a half is just not useful, and the positive effects of droop limiting seem to indicate that it is a step backwards in terms of improving handling.

[JustinOlson]

I will be running the 245/40-17's (24.7") and the FA 23" tall slicks. I want a bit of extra range of travel in the strut so that I can adjust for each tire when its on the car.

 

I plan on running external droop limiters, because it just seems too difficult to droop limit with the struts without sectioning them several times.

[srgunz]

How can you really tell if one has a blown shock? I am running the older Koni 8641 gas adjustable shocks in my 240Z. On the rear it feels like one shock was bad and now I believe the other side has gone bad. I have pulled them. There are not leaking. They still have resistance when I push them down by hand and come back up on their own. Here's the deal. I turned the shock over and put the piston on the floor and pushed. There is virtually nothing there! No resistance. Does this sound right? Have any here noticed this on their shocks?

I run 225 lb springs so that is within the range of the shock I would think. I installed these in 1992 but they only have 12K miles on them.

[JMortensen]

How can you really tell if one has a blown shock? I am running the older Koni 8641 gas adjustable shocks in my 240Z. On the rear it feels like one shock was bad and now I believe the other side has gone bad. I have pulled them. There are not leaking. They still have resistance when I push them down by hand and come back up on their own. Here's the deal. I turned the shock over and put the piston on the floor and pushed. There is virtually nothing there! No resistance. Does this sound right? Have any here noticed this on their shocks?

I run 225 lb springs so that is within the range of the shock I would think. I installed these in 1992 but they only have 12K miles on them.

That shock is dead.

[srgunz]

That shock is dead.

 

Yep, thats what I figure too. These are not rebuildable and are under warranty yet. I will be calling Koni this week to see what they will do as these may be no longer available.

The fronts are still working good. (for now)

[srgunz]

OK, I talked to Koni tech and he said that if I turn these strut inserts upside down and test, they will have no resistance and this is normal for struts. (At least theirs anyway)He said to put back in and crank up adjustment to account for wear. Glad I only pulled one. Back together it goes and readjust.

[Floorless240z]

how does the tokico hts compare to the azc shock? I'm reading that the hts is rather lacking in range on rebound. sounds on par with adjustability though. comments?

[RTz]

how does the tokico hts compare to the azc shock? I'm reading that the hts is rather lacking in range on rebound. sounds on par with adjustability though. comments?

 

I've not messed with the AZC stuff, but I am currently running the HTS damper. The rebound range seems satisfactory for a 300lb spring, but I'm not getting enough control for a 350lb spring.

[tube80z]

I've not messed with the AZC stuff, but I am currently running the HTS damper. The rebound range seems satisfactory for a 300lb spring, but I'm not getting enough control for a 350lb spring.

 

If you have the dyno curve you can calculate the damping coefficient based on your unsprung weight.

 

Cary

[heavy85]

Since I started this thread thought I would add part II to my strut selection. After 3 years of autox, street driving to events (~10k miles), and ~10 track events the SA Koni 'Race' struts are dead. I think they are leaking but not at the lip seal rather where the housing is crimped to the cap and now started to wiggle around to the point one of the tires started kissing the spring. I noticed this weekend the front left had play in it and visible could see the strut rod moving around in the housing when I rocked the wheel in and out. They feel fine and smooth when I pull them out by hand which seems odd but? So whether I want to or not I need to buy new struts ... again. Gordon at Koni said these are on the low end of adjustment for 300/250 springs and that autox is the hardest on struts. I've been reading the past many pages of this thread and am considering changing to Bilsteins P30-0032-MO. However I still several questions I cant seem to find:

 

- Do they fit in 240Z strut tubes (sectioned ~2" front and rear) other than the rears need a spacer?

- Do they come with gland nuts that fit or do you need to order them separately?

- Do they work UNVALVED up to 300-350 lb/in springs?

- What is the valving compared to Koni SA on their light settings?

 

Thanks

Cameron

[JMortensen]

- Do they fit in 240Z strut tubes (sectioned ~2" front and rear) other than the rears need a spacer?

- Do they come with gland nuts that fit or do you need to order them separately?

- Do they work UNVALVED up to 300-350 lb/in springs?

- What is the valving compared to Koni SA on their light settings?

They should be 2" shorter than stock. I think the Konis are 1 5/8" shorter, so you'll probably need a spacer front and rear.

They do come with gland nuts, but they're the wrong ones. See earlier in this thread for the correct part number.

They should work fine with stock valving, which really wasn't that far off from what guys were having them revalved to.

No idea on the Koni vs Bilstein comparo question.

[heavy85]

Diameter wise they fit? Reason I ask is the Koni's are TIGHT and need massaged to fit the smaller 240 tubes. I really like the larger shaft diameter so hopefully I wouldn't wear these out as fast as the Koni.

 

Cameron

[johnc]

Why not have Koni rebuild the shocks you have. $100 to $150 a corner and you can work with Gordon on valving more appropriate for your specific autocross setup.

[heavy85]

He said standard shop rate is $167 for labor - which I assume excludes parts - per strut which is what the damn thing costs to begin with. I'm really frustrated by the whole thing not wanting to spend more money on struts when I need a rollbar, radiator, real brake pads,etc. I'm thinking of just getting the Bilstein which since the rod is larger in diameter should last longer. I'm disappointed how quickly the Konis wore out and dont want to dump more money into them or another set just like them.

 

Cameron

 

PS: This thread is terribly confusing with a mix up of guesses and lack of follow up and 240 vs 280. Best I can tell the 240Z Bilstein gland nuts are B629-A1 - is that correct?

[JMortensen]

Bilsteins are much looser in the housings, no need to grind paint off or any of that. Here is the gland nut:

[heavy85]

Looks to me that says B30-629 with an A1 on the other side so that should help. Thanks Jon. Did you have these revalved and have you run them yet to get an impression?

 

Cameron

[HowlerMonkey]

How can you really tell if one has a blown shock? I am running the older Koni 8641 gas adjustable shocks in my 240Z. On the rear it feels like one shock was bad and now I believe the other side has gone bad. I have pulled them. There are not leaking. They still have resistance when I push them down by hand and come back up on their own. Here's the deal. I turned the shock over and put the piston on the floor and pushed. There is virtually nothing there! No resistance. Does this sound right? Have any here noticed this on their shocks?

I run 225 lb springs so that is within the range of the shock I would think. I installed these in 1992 but they only have 12K miles on them.

 

When you pump a shock or strut insert upside down, you are trading fluid for air.

 

No shock will operate properly if the valving is full of air.

 

When I sold shocks at electrodyne in the mid 80s, I had people trying to return expensive bilstein, boge, koni...etc shocks because they didn't purge the air from the shock.

 

I would cycle them a few times, hear the gurgling, and hand them back a perfectly operating shock.

 

Remember that the top is sharp and anybody fooling around with a shock will naturally rather push on the smooth bottom than the sharp top.

 

Also....shocks are stored horizontally so purging is necessary as your car might not fully exercise the shock to the point or purging all air.

 

Here's the factory recommendation.

 

 

Now this is for a Z31 but shocks are the same.

 

Also....not all shocks require you to put it upside down for the compression of the routine......most important is to have it right side up while the shock extends.

 

Most can be purged by cycling them right side up.

[heavy85]

Should they come back out on their own because mine do not? Is this an indicator of being 'dead'? I'm starting to think about limping along with these for the rest of the year. They have good resistance pushing and pulling them in but as you describe if flipped over or even held horizontal while stroking you will get air pockets which I thought was a bad thing until now. The fraction of an degree of camber change due to them being a little loose I could probably limp by with if the damping is still there.

 

Cameron

[JMortensen]

I have mine valved differently than most. I was talking to a guy who does shock valving in OR and he suggested that I worry about the unsprung weight instead of the sprung weight, the idea being that what is important is to keep the wheel on the ground and what is not important is to make the car ride smooth. If you have lots of rebound damping it controls the oscillations of the car body (more comfortable, feels more stable) but it also tends to pick the tire up off the ground and reduce traction on corner exit. My Bilsteins are valved 100/100. I'm quite sure they would beat the piss out of me if I intended to drive the car on the street, but I won't. My Z will go to the track on a trailer, so I have no concern for ride quality on the street whatsoever.

 

I was starting to second guess my valving choice until I got into this discussion over at corner-carvers.com: http://www.corner-carvers.com/forums/showthread.php?t=41374

 

If you see holes in my analysis of the BMW vs my valving let me know, but I think it looks at least similar in concept, and I would expect the Z has more unsprung weight, so could use a little stiffer valving...

 

I want to say that Konis are not gas charged, I think that means that they do not extend all on their own. I'm not sure what to make of Howler Monkey's bit about "purging" air. Where does the air go? My struts are sealed, air doesn't come out of any vents or anything. Plus the picture shows compressing the strut upside down. I don't think the original Z struts were actually sealed. They just had a (leather?) seal at the top of the housing. I've never had a problem with compressing the struts upside down causing trouble with the strut's operation. In fact, this article says to turn them upside down and right side up and check for dead spots:

 

http://findarticles.com/p/articles/mi_qa3828/is_200309/ai_n9278028/

To bench-test a shock absorber, position it in the same direction it's installed in the vehicle, then extend it fully. Next, turn it upside down and fully compress it. Repeat several times. Replace the shock absorber if there's a lag or skip near the midstroke as the shaft changes direction, the shaft seizes at any point in its travel (except at the ends), any noise other than a swish or click is heard when the stroke is reversed rapidly, any leaks are observed or the action remains erratic after purging air.

 

IME, if the shock has a dead spot, regardless of whether it is right side up or upside down, it needs to be replaced.

[HowlerMonkey]

Compressing a shock upside down is fine.

 

Extending it upside down is not.

 

No strut/shock ever made is fully liquid filled.

 

There has to be an air (or gas filled) void within the shock to deal with expansion of the oil as it goes from 50 degree temps in the fall to near 200 on a bumpy section of road.

 

If there were no air void, then shocks would be blowing up from the thousands of PSI that a non-compressible liquid would exert as it's volume grew when temps came up.

 

Turn a brand new shock over, pump it upside down, and you will hear this "air" gurgling through the valving along with the effect of losing damping.

 

Now as far as 8641 series KONI shocks, they are low pressure gas meaning you should experience at least a weak amount of self extension after being compressed but it's nothing like a high pressure gas shock.

 

If you don't have oil leaking, gas pressure loss should have minimal effect on damping since the pressurized gas exerts very upward pressure and SRGUNZ has already stated they do self extend after being compressed.

 

What I've found with the 8641 series is that most owners use the adjustment knob to tighten them up the day they get them rather than use it to compensate for wear or adjust damping to balance a car since turning it fully tight nets you way too much damping.

 

This overzealousness by the original installer will wear a shock out pretty quickly so.....if you've determined that the adjustment of all shocks are even, then you should have damping close to the same.