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Discussion Starter · #1 · (Edited)
I have been recently looking into upgrading to some better dampers considering the recent threads on chassis tuning and spending a little time wrenching with the PDG gang on the race GTM.

Being of scientific nature I delved into experimentation mode and did some backyard testing. I climbed up on the rear transmission mount and jumped up and down and mentally recorded my experience. I then marked my hood hinge bolts and took the hood off and did the same on the front frame bar. The front feels like a wet noodle compared to the rear! I know the spring rates are 66.6% higher in the rear, but the difference seems to be the damping, I can compress the front suspension far more than the rear and the front feels like a spring whereas the rear hardly moves and does not feel like a spring.

To have a control group, I popped the hatches on my Cayman S and repeated the procedure, no wet noodle here (my neighbor caught me doing this and must think my noodle has issues though).

I just removed my suspension to swap to Pfadt poly bushings and had some time to play with the black konis. I removed the springs and compessed the shock againsed the floor with the body up and was supprised there is virtually no compression damping. I repeated at least 20 times thinking it might just be bubbles, no change. Invert the body down, shove, some bubble noises for the first two cycles and then plenty of compression damping. Invert, repeat, invert repeat, grab another shock- same thing, no compression damping with body up.

Could this be part of the handling woes of this beast? I know this isn't a road test but maybe sombody with a runner could flip their fronts and see if it makes a difference?
 

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It is definately something worth looking into. The definitive answer would be to put the shocks on a shock dyno and compare the force vs, speed curves inverted vs. conventional. I hope FFR/Koni did this before spec'ing the shocks. Maybe post on the other board and someone from FFR would respond.

If not, maybe someone with access to a shock dyno could run a test and post the results.
 

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I know for a fact AIR SHOCKS that dont run springs REQUIRE the body in the up position. Never read that on any other kind though.... but if it is true that would be nuts !
 

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Discussion Starter · #6 ·
Well, I don't expect to hear back from Koni over the weekend, but I'm fairly sure they don't stamp an orientation arrow on these things for nothing.

None of the part numbers turn up any results on the Koni site search engine (3408 8245 1209). It is interesting that every single picture of a shock on their site that I saw has the body on bottom unless it is specifically an 'inverted' design. Further investigation in their motorsports catalog I found the following note on a twin tube design:

"Please note that
the mounting angle may not be more than
45 degrees from vertical as otherwise air
might be sucked into the working cylinder.
When this occurs, the damper does not
function properly."

There is also diagrams of twin tube and monotube design which show a 'foot valve' and various orifices at the bottom of the body on the twin tube. If you invert the twin tube design, it appears the gas would go into this foot valve- orifice area. Monotube design does not have this valve area and I think are not sensitive to orientation because the gas is separated from the working fluid by a 'floating piston'. Here's the link to the catalog, the diagram is on page 1:
http://www.koni-na.com/pdfcatalogs/KONIMotosportCatalog.pdf

Here's a pic of the shock, TOP arrow is at the bottom. Note- the threaded spring skirt is slipped up over the piston rod so the body is on bottom in the photo (although it may not look like it).

Mark
 

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Ok, based on this info, we are actually supposed to install the rear shocks "body down" or "the spring towards the top shock mount" according to the manufacturer? So this means the front shocks should also be flipped around? Is that right?
 

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Discussion Starter · #8 ·
Rev, I Just sent Koni an email so I haven't got any official word yet but yes, it appears the spring should be on top just like the rears.

Here is my email to Koni:

Dear Koni rep,

I'm building a Factory Five GTM kit car that comes with Koni FSD coilover shocks. The instruction manual from FFR has the front shocks mounted with the body up and the rear with the body down. People on the Forum have long been complaining about Ill handling cars and the people that have replaced the shocks state there is a huge improvement in the handling.

I recently removed my suspension to install poly bushing and started playing with the shocks. I discovered that there is virtually no compression damping with the body up- as they were mounted. Turn it over and plenty of compression damping. I then slid the threaded sleeve up over the piston rod and discovered the TOP arrow pointing to the piston rod end. I'm guessing that arrow is there for a good reason?

The part numbers on the shock body are:

3408 8245 1209

Thanks,

Mark
 

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how about the older yellow ones??? I have those on my car does not ride bad but wondering if it could be better?? also I remember reading on here a long time ago the rears can only go on one way due to clearance problems with the axle boot.
 

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this is from KONI, look like the old one can run inverted. 30-5436 old part number.

"Our 30 series shock is a single adjustable mono-tube design that can be used on Asphalt or Dirt Applications. There are four distinct rebound adjustments that allow you to adjust the shock to suit your needs, chassis setup and track conditions. The compression forces are pre-set. It is lightweight, very consistent and affordable.


This design offers a wide rage of valving options to fit a variety of applications at an economical price. The 30 series dampers are available with a variety of valvings to meet your specific damping requirements and can be utilized with a coil-over kit if necessary. Attachments are 1/2" ID bearing on both ends. The 30 Series can be run inverted to reduce unsprung weight."

Mostafa
 

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Reply from Koni this morning:

Those shocks can't be inverted!!!

Paul McLaughlin
Koni Shock Absorbers
ITT Corporation
Racing Technical Sales Rep.
1961A International Way
Hebron, Ky. 41048
800-922-2616 option 6
Well I guess I know what I will be doing this weekend!
Thanks for looking into this.
 

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Ok, based on this info, we are actually supposed to install the rear shocks "body down" or "the spring towards the top shock mount" according to the manufacturer? So this means the front shocks should also be flipped around? Is that right?
I second this question.

If this is the case, is anyone close enough to their GTM to see if there is room for the spring between the upper A arm?
 

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Those meaning yellow or black shocks? Eitherway, what do we do for the rear suspension then? If we mount the shocks correctly according to the FFR manual, then the spring will eventually rub through the CV boot. But if you invert the shocks, then you screw the shocks and potentially have an accident. Either way, we're chomping on a s$%t sandwich...



Reply from Koni this morning:

Those shocks can't be inverted!!!

Paul McLaughlin
Koni Shock Absorbers
ITT Corporation
Racing Technical Sales Rep.
1961A International Way
Hebron, Ky. 41048
800-922-2616 option 6
 

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Those meaning yellow or black shocks? Eitherway, what do we do for the rear suspension then? If we mount the shocks correctly according to the FFR manual, then the spring will eventually rub through the CV boot. But if you invert the shocks, then you screw the shocks and potentially have an accident. Either way, we're chomping on a s$%t sandwich...
Um, I believe the rear, with the body DOWN are "normal", and the fronts, with the body UP would be considered "inverted".

Simply turn the fronts over.
 

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Is there room between the upper control arm for the front coilover to be installed correctly? I just recall there not being a lot of space between the control arm and the coilover body.
 

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Thanks Keith.

I just took a look at the front coil-over (Gen2) and it does not look as if it can be flipped to the correct position as is. The upper control arm mounts are more aft (more caster) and there doesn't seem to be enough space between the coil-over and the upper control arm mount. Just looking at it, it appears that if the spacers on the upper coil-over bolt are shortened in the rear and lengthened on the front, bringing the top aft there may be clearance.
 

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Vidal
I have about 1/2" between the coil over and the upper control arm mounting tabs. I can see your point if they relocated the tabs more than a 1/4" aft on the Gen 2s you will have clearance issues.
 
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