Koni Shock Perch Redesign for 7075 | FerrariChat

Koni Shock Perch Redesign for 7075

Discussion in '308/328' started by redline76, Dec 8, 2023.

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  1. redline76

    redline76 Formula Junior

    Feb 26, 2008
    349
    Venice, CA
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    Warren V
    Hi all,

    So, my new Konis arrived and...there's been some changes.

    1) They put a sticker on the lower 1/4 instead of the stamping per the original (lame)
    2) The perch support is now one giant c-clip instead of the two halves (okay)
    3) The included perch is made of aluminum and sits pretty high. When I tried to slide it on to test the fit it's extremely tight, to the point of scuffing the paint and destroying the sticker. (super lame). I'm going to call Koni on Monday to confirm. For reference, it's part set number: 7150016770

    So.... I think I found a supplier to make me some perches but I'm thinking of 7075 for cost reasons. To support the different material I thought maybe the perch would need to be reinforced somewhat. Attached are my new numbers based on the dimensions of the included Koni aluminum perch, but I've thickened it up considerably from the original stainless model spec.

    Any thoughts on this?

    Cheers and happy Friday!

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  2. redline76

    redline76 Formula Junior

    Feb 26, 2008
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    Warren V
    Brian A likes this.
  3. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Jan 11, 2001
    25,413
    30°30'40" N 97°35'41" W (Texas)
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    Steve Magnusson
    So is the groove for the giant c-clip much lower on the new shock body than the groove on the original shock body for the half-rings? (Or stated differently, when assembled, is the distance from the center of the lower mounting "eye" to surface on the perch where the spring sits the same for the new and old shock?)
     
  4. redline76

    redline76 Formula Junior

    Feb 26, 2008
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    Warren V
    Steve,

    Awesome to see you've noticed the thread- thanks so much for your input. Great question; I happen to have a spare set of older dissasembled Konis so I was able to get some measurements ('m a creative, not an engineer so of course I didn't even think to measure the obvious). By my unsteady hand it looks like the new Konis have a perch rest that's <at least> 3mm lower than before (105mm v. 108mm from center of perch indent to center of shock eye. The delta could be more; it's late and I've had a couple :p The angle of the photo makes it look funky; I'll remeasure tomorrow in better light. Image Unavailable, Please Login Image Unavailable, Please Login
     
  5. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Jan 11, 2001
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    Steve Magnusson
    Glad to help out, but now it looks to me that the two Koni designs are completely different:

    On the old shock, the stock lower perch surface that the spring sits on is 8.3 mm below the groove on the shock (i.e., the lower perch spring surface is below the feature that holds the half-rings).

    On the new shock, the lower perch surface that the spring sits on seems to be above the groove on the shock (i.e., the lower perch spring surface is above the feature that holds the giant c-clip)

    First, IMO, you should measure the distance from the lower eye center to the surface where the spring sits when assembled on each = could be that Koni just messed up.

    If they are the same, then you need to make a cross-section drawing of the new lower spring perch to determine its L1 dimension and then change the design (while keeping the feature that holds the giant c-clip in the same place) to get the drop that you desire -- I don't thing you can use my old L1 dimension for a 25mm drop at all.
     
  6. mk e

    mk e F1 World Champ

    Oct 31, 2003
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    Don't try to guesstimate to the center of the holes for design work. Measure from the edge of the hole, then measure the hole diameter and add 1/2 to the length. It will be much more accurate, especially with large holes like the shock eyes.
     
    waymar likes this.
  7. mk e

    mk e F1 World Champ

    Oct 31, 2003
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    Also, the old rubber bush will likely be deformed, best to measure to the shock eyelet directly to get reliable numbers.

    On the the c clip end I'd suggest using the c-clip, seat it and measure to the side you care about so you have a hard edge to put your caliper on and know you're measuring to the same spot every time.
     
  8. dave80gtsi

    dave80gtsi Formula 3
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    Nov 3, 2003
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    Steve - What about the proposed use of 7075?

    When I went thru this same exercise recently, I recall that you had some very specific minimum alloy strength requirements.

    DM
     
  9. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Jan 11, 2001
    25,413
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    I'd certainly use 7075-T6 and increase the various wall thicknesses as the OP has done (but this might interfere with the lower a-arm). Overall, I don't like it much -- mostly because Aluminum doesn't have a fatigue limit (although that particular alloy does have a yield strength slightly above what I specified) -- unless done how Koni has done it. Note that the new Koni design is a solid block of Aluminum that sits on top of the c-clip as is fully supported on the whole ID by the shock body. Whereas, once you try to increase the L1 dimension down (and leave the c-clip where it is), it becomes more of a "bell" shape (unsupported on most of the ID). I'd need to see a scale cross-section drawing to decide if OKish or not OK (but I still think that Koni messed up where the spring sits relative to the bottom eye) so will await more info from Warren.
     
  10. redline76

    redline76 Formula Junior

    Feb 26, 2008
    349
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    Warren V
    Great feedback guys. Steve, I share your concerns with most of the perch being unsupported which is why I thickened the top, sides and bottom ring to 7mm. Still leaves most of the perch hanging lower but Brian A's 7075 perches look similar and he seems to be doing ok with them.

    It's fun cosplaying as an engineer; take a look at what I "discovered" for both front and rear, clearly I suck at this.

    Per my amateur measurements from bottom of shock eye to c clip groove:

    OLD Front: 95mm (+/- 1mm)
    NEW Front: 91.5mm (+/- 1mm)

    OLD Rear: 133mm (+/- 1 mm)
    NEW Rear: 128.75mm (+/- 1mm)

    I've attached pics taken by my lovely assistant while I tried to keep everything aligned :p

    Note the machined groove in the shock body to accommodate the flat c ring. Conceivably one could simply chuck these up in a lathe and machine a new groove, saving the need for a perch? Yet another vendor to source...

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  11. redline76

    redline76 Formula Junior

    Feb 26, 2008
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    Warren V
    Side note: Are shocks considered wear items when it comes to Classiche or concours? For now I DGAF, but down the road when these cars are worth millions?

    <that was a joke but my car is pretty original, haha >

    Starting to wonder if I should just chuck the original assemblies into a box and get the GAZ coilovers. I love the ride of the Konis which is why I ultimately decided to go down this route but dang if it isn't a pain just to get my QV a bit down from the 4x4 stance...

    Cheers all,

    -w-
     
  12. mk e

    mk e F1 World Champ

    Oct 31, 2003
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    If you add a square to your technique so you know the shock is straight up and down or just lay the shock on the table and put the square at the end you will get more repeatable numbers. Then you'll be +/- 0.01mm :)



    In the pics groove looks like its a seam where they put 2 pieces together so I don't think you can just cut a new groove. On the original shock I think the groove is rolled, meaning they deformed the tube pushing the metal to the ID not by cutting metal away.

    Years ago I lowered my car a bit by making new perches for the konis but I also swapped springs to standard 2.5" ID coil-over springs that were a little stiffer and shorter so the perches ended up just 1/2 thick Alum with a groove on 1 side because the shorter spring meant the perch had to move forward not back. I can't for the life of me remember exactly what springs I used though. Not relevant to you plans other than you mentioned considering other shocks that would come with 2.5 ID springs.
     
  13. redline76

    redline76 Formula Junior

    Feb 26, 2008
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    Warren V
    Yes, my measurement skills definitely need work haha, but at least you can get an idea of what's changed, if not 100% accurate :)

    (Side note: I followed your 308 V12 build right from the beginning including platform transfers. You're a madman, and I mean that in the best possible way)

    I guess Superformance "uprated" springs are an option as well; per Steve's comment about clearance I'm concerned there just may not be enough room to work with using my proposed design.
     
  14. maurice70

    maurice70 F1 Rookie

    Jan 25, 2004
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    Just a heads up,
    I bought the Superformance updated springs for my 328 and the rears were actually a bit higher than my original springs
     
  15. mk e

    mk e F1 World Champ

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    Many years ago I read about "bulldozing" the springs to lower the car. They put them is a big vise and fully compressed them, then hit them with a hammer to kind of stress relieve them and they come out shorter. They had before/after pics of the springs to prove it worked. If you can come up with a way to compress them safely it might be worth a try...I've never tried this and it seems a bit uncontrollable though so trial and error to get about the 25mm you want and have a mostly matched set.
     
  16. redline76

    redline76 Formula Junior

    Feb 26, 2008
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    Warren V
    UPDATE TIME!

    I spoke with Koni and explained my predicament that the tolerances were too tight on the 1983SP6 perches and in trying to get them on they ruined the decals.

    They looked into it and found the same condition on the units in stock, so an engineering order is in place. They confirmed that the grooves should be the same height as the originals.

    In the meantime, they generously sent me 4 NOS perches made of steel and 4 new decals, which I thought was pretty cool of them.

    Well, they came today and the NOS perches are dimensionally very similar to the new aluminum ones, but they do fit. They also are grooved quite low but that groove could be machined higher, albeit it won't come close to Steve's version.

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    Lemme know what y'all think.
     
  17. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Jan 11, 2001
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    My thought is the same as my first thought: if the groove is in the same place on the shock body (but your measurements in post #10 don't seem to indicate that), using the new perch on the new Konis on a 308 would raise the car a bunch (unless the upper end of the shock is also significantly different than the old design) -- i.e., Konis' new design might not be the same as the old design. However, the important thing is the distance from the lower eye to where the spring sits on the lower perch on the two designs (you've never posted this), and the distance from where the upper end of the spring sits to the upper eye. IMO, you'll probably need to do a new lower perch design with some new L1 dimension to get what you want (as even the diameter of the new c-clip looks smaller than the old half-rings), but you've got all the parts to compare, and know the plan ;).
     
  18. redline76

    redline76 Formula Junior

    Feb 26, 2008
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    Warren V
    Steve,

    A very comprehensive response, thank you. Now that I have perches that actually fit on the shocks, I have to get the old units disassembled so we can compare apples to apples. I sure as s**t ain't going to trust Harbor Freight $34 spring compressors, so time to find a local shop to do the work for me.
     
  19. waymar

    waymar Formula 3

    Sep 2, 2008
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  20. dave80gtsi

    dave80gtsi Formula 3
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    Oooohhhh! I've been looking for one of these bespoke compressors, suitable for use on a 308, for quite some time.

    Most cheap compressors that I've seen to date use exterior coil hooks which appear extremely sketchy (I'm looking at you, Harbor Freight, as was already noted), to the point of being dangerous.

    To the OP, should you end up buying and using this better design, please Be A Brother and post a pic along with any relevant useful thoughts for our future archive 'Search' use.

    Thanks - DM
     
  21. redline76

    redline76 Formula Junior

    Feb 26, 2008
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    Warren V
    Dang, that looks way better, never seen one before. @waymar: can this still be used while mounting on the vehicle? My understanding of extended spring perches is that the rears units will need to be compressed to fit.
     
  22. Brian A

    Brian A F1 Rookie

    Dec 21, 2012
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    I used this type (although not this brand) of spring compressor on my 308. It worked well and it seemed safe.

    https://a.co/d/78Wix4J
     
  23. Imatk

    Imatk Formula Junior

    May 6, 2007
    394
    I just found this thread and had the exact thing happen to me. One of the shock perches is the correct size. The other doesn't fit and I wound up destroying the sticker as well trying to get it to fit, before I had the thought of trying another one.

    Also one of my shocks was missing both the stickers and the perch entirely.

    I have an email into Koni, but haven't heard back from them yet.

    http://www.samjam.com/Ferrari/PerchWontFit.m4v
     
  24. redline76

    redline76 Formula Junior

    Feb 26, 2008
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    Warren V
    They were really good about getting back to me.

    If you don't get what you need from them I'm happy to send you the four steel perches they sent me.

    -w-
     
    Imatk likes this.
  25. Imatk

    Imatk Formula Junior

    May 6, 2007
    394
    They got back to me this morning actually, going to send me perches and stickers :)

    Also, did you have difficulty pressing in the bushings in your shocks?

    I've only done one so far and it was a BEAR to say the least.

    I've since bought the Hillman bushing tool and I'm now waiting on a press. I thought the control arm bushings were hard to press in until I did the shock!
     

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