steguis

I did two test "launches" (ok maybe they were half-assed launches) but in both cases the rear just hopped as I tried to launch. I think the rpm wasn't high enough (it was around 2-2500rpm). I don't mind trying launching at a higher rpm but before I do I just wanted to ask how everyone else does it? This is for a ProSolo launch. For normal autocrosses I just do a standard "stop light" start then accelerate to avoid creating undue stress on the drivetrain.

spdracerut

Hmm... seems really low launch rpm to be getting wheel hop. My observation isn't based specifically on caymans, but having launched many different types of cars. I'm inclined to think your control arm bushing are worn out along with any other engine and drivetrain bushings. I've never found that launching at a higher rpm helps, but typically hurts from my experience.

chriswd62

I had the same issue with my 981 a few years back at the Pro in DC. I tried to launch everywhere from 2,000 RPM to 6,000 RPM, and had wheel hop every time. Maybe try stiffer bushings and motor mounts (if allowed in STU).

edfishjr

I've had two relatively powerful cars that both were bad about wheel-hop on launch as delivered from the factory. In both cases the wheel-hop disappeared after I installed shocks with increased levels of damping. In one case with Koni single-adjustables the car would wheel-hop if the damping was set fully soft, but went away as soon as the rebound was increased. My conclusion was that it was cheap OEM shocks that allowed it to happen.

I think that wheel-hop is a resonance effect where the natural frequency of the tire (which is basically bouncing) couples to the car suspension or subframe frequency. Changing the stiffness of any of the elastic components could possibly cure the problem. However, if the frequencies in play are related to the spring-mass system consisting of the suspension spring and the unsprung mass (wheel/tire/hubs/brakes/half the control arms, etc.) then new or different bushings is unlikely to help. The shocks are the only components that can extract significant energy from the resonance. If the resonance is in the entire subframe and its mounts, then bushing changes could be the cure (because newer rubber has more damping and may change the natural frequency of the subframe system) but shock absorber damping might still also fix it because the shocks can still take a lot of energy out of the system and damp the resonance.

Grantsfo

Yeah I’d check motor mounts. They go bad quickly. My car never hopped but I had very firm mounts.

steguis

I have both brand new motor mounts and transmission mount so I don’t think that’s it. I suspect I just need to try launching at higher RPMs so I was more asking this to see what rpm and technique are you doing to launch (clutch dump, side step, etc).

steguis

I’m also running MCS double adjustable shocks.

fast1

It's been over four years, but my recollection is that I launched at between 5500 - 6000 RPM. Typically low torque engines like a Cayman require high RPM launches to get the quickest time. 2500 RPM is far too low for a Cayman.

Sprockett

Breaking the tires loose on launch is better for the car than launching hard without breaking them loose. On concrete, I launched the 987.1 at like 5500 or more RPM to break them loose. Wheel hop is a killer...go higher RPM.

Sprockett

I'll add that the new manual Cayman's 981/718 are both severely handicapped in this regard as they implemented a lower rev limiter in first gear. With the GT4 I had a real hard time breaking tires loose even at the 6000k limiter on concrete. A couple of weekends ago, Kit found it impossible to launch his manual 718 on Crows concrete with the 4xxxRPM limiter of the 718.

sl951

The movement is mainly from the cayman transmission mounts. New OEM transmission mounts are too soft and won't stop this. If you take a slo-mo video you'll see the center exhaust oscillate up and down.
- Launch at around 3500 - 4500.
- Since you can't change your transmission mounts for stiffer aftermarket versions (class rules etc). You could try to fill in the space between the bottom of the transmission and the aluminum cross member bar by zip tying a rubber/stiff foam block on the cross member. Don't completely fill in the gap, but instead think of this more like a shock bump stop to limit the amount of transmission travel (wheel hop).