With red Loctite, you don’t want to use too much of the stuff. This gel version is pretty cool because you don’t have to worry about it dripping all over the place.
I used the double-nut method to tighten the studs into the mounts.
I decided to go with the softest yellow mounts. Back in the day, I had Energy Suspension engine mount inserts in my Nissan and Hasport engine mounts in the S2000. I went with the softest, 62A durometer, mounts in the S2000 and I was happy with those for a dual-purpose street and track car. So, I decided to go with the softest 75A bushings in the Rennline transmission mounts. I used a dab of Loctite blue gel stuff to hold the fastener in place because this one has to be removeable in case I ever decide to change the bushings. Whenever Loctite red is used, that parts are not coming apart without a fight.
Nothing too exciting here, just tightening the fastener that locks the bushings in place. Note the orientation of the square feature; that’s roughly where it needs to be to get installed.
The Rennline instructions say to buy longer factory bolts for the 981 Cayman application. I figured that would also a requirement for the 718 Cayman as the 718 is not listed in the instructions. I test fit the bolts, but the diameter of the bolt flange is larger than the counterbore on the mount. That’s not ideal.
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You can actually get really accurate results using the equation if you have access to the actual springs:
:Using Coil Spring Dimensions and Material Properties
If you are designing a coil or want to find the theoretical rate from its physical build, use the Spring Rate Calculator formula:
Equation: \(k = \frac{G \cdot d^4}{8 \cdot D^3 \cdot n}\)
G: Shear modulus of the wire material (approx. 11.25 × 10⁶ psi for standard steel)
d: Wire diameter (thickness of the metal wire)
D: Mean coil diameter (Outer Diameter minus the wire diameter d)
n: Number of active coils (the total coils that move and flex)
https://www.thespringstore.com/spring-rate-calculator.html
I gave it a try, but a there is a large unknown of material. That said, I feel like the numbers the online calculator generated are about 60% above any reference numbers I have found for other generations and models of Porsches. Any numbers I post are just pure speculation, so I’ll just stay quiet on them. I could bust out my old college textbook and run numbers myself, but the unknown material is still a big uncertainty. Key observations of the factory coilovers, the rear is a linear rate spring and the front is a progressive. On the assemblies, Porsche labeled that the springs are under 1000N of load.
Do you have the old springs still? Apparently you can actually measure them. I found this old forum post:
“CC, the variables you listed are what makes a spring…spring. When I was involved in IMSA and NASCAR, I tested each spring before it went on. The reason was that even a spring from a very well established company could be off by as much as 5%, which was too much for dialing in a suspension. Sometimes the error was due to the spring being bent because of a wreck. Usually it was just off. It didn’t have to be out much to be off. Evenly wound coil springs are very linear. To sum it up, you can either trust the manufacturer to be close, or test them yourself. Put the spring inside a PVC pipe slightly larger in diameter and set on an accurate bathroom scale and zero the scale. Using a push rod like a wooden dowel, push down until the spring compresses 1 inch and read the scale. These springs are rated kg/mm so there will have to be a conversion from lbs/inch.”
I also have a 718 with swift linear springs in the same rate, 70 up front and 80 in the rear. Mine are on B16s so not as exciting as your Tractives. For me the biggest improvement came when I added low speed rebound damping to my DSC to compensate for the heavier springs.
Looking forward to your extended review of these as dual duty and what changes you make to the tune long term.
What is the operating mA range of the B16s? I bet they are quieter than my TracTives. It was a bit surprising to me how ‘loud’ the car is going over bumps with the full spherical setup and the TracTives. My S2000 was still basically quiet with the full spherical control arm setup and the KW Clubsports. I think the strut suspension setup on the 718 chassis transmits more shock loads into the chassis compared to the control arm setup of the S2000. I do think the spherical bearing adjustable camber plates of the TracTives is a major contributor to the noise over bumps and they may just be due to the bearing sizing selected.
I have another significant change to the turbo and exhaust setup coming in stages. And I will need a new tune. The new setup from Raggdoll will have better response and I think the same or better power and it’s all bolt-on. I designed a new exhaust tip to replace my x-pipe too which will flow better.
Damper operating range
• OEM dampers – 1500mA is full soft and 500mA is full stiff.
• Tractive dampers – 1900mA is full soft and 500mA is full stiff.
The OEMs and B16 are both made my Bilstein and are the same valve. For a Non GT4 owner the B16 is a fully threaded coilover with a an inverted body, very similar to what came on GT4s.
A friend of mine in another 718 has the Tracitves and also complains about the same noises, I have not ridden in his car long enough to get a feel for them. He said he is suspecting the mounts.
One thing he loves about the tractive is its ability to bomb over the curbing in the corners on the track, the car does not get upset or wiggle at all. I did notice in his calibration that he does not have as much compression damping as I do. Seems the the next step for me is to try taking some compression out of my car and see if it is more compliant over bumps and curbs.
What I did to be more compliant over the sharp bumps during street driving is take out high speed compression in the velocity tables. I did -5/-3/-1 on the front compression hi/med/low. I did around -3/-2/-1 on the rear.
That is a great reference!
Currently my friend with Tractive is at:
Front Comp 3/3/5 reg and 5/5/5 sport
Rear Comp -5/-5/- reg and -10/-10/0 sport
Front Reb 10/15/20 reg and 10/15/20 sport
Rear Reb 5/10/15 reg and 5/10/15
I am at:
Front Comp 10/7/7 reg and 12/12/7 sport
Rear Comp 10/7/7 reg and 15/15/7 sport
Front Reb 20/20/15 reg and 25/25/15 sport
Rear Reb22/22/15 reg and 28/28/15 sport
Note that the high speed does not come into play on the stock and B16 valve due to the slower response time.
If you email me at s2kmanifold@gmail.com, I’ll send you the calibrations I made for the factory SPASM setup and my Tractive setup as a reference. No clue if they would be any better or worse to your prefrences in handling.
Yours and your friends calibrations lean heavily on the velocity tables and I think the values would act to reduce the rate of roll and pitch. Reminds me of how enzocat on Rennlist liked to do the calibrations. I kept my values much more mild. I tweaked the rear values to eliminate some turn-in oversteer I was getting and I took out some high speed compression to reduce some of the sharp bump impacts.