moehler

iTrader: (12)

I have an ACT SS clutch and a 9lb RB flywheel. Recently I have been getting "shudders" (don't know how else to discribe it, car shakes and jerks slightly) at low RPMs (less than 2k). I have to slip the clutch pretty hard to get out of it. It only happens once in a while (usually after driving the car for a while), but it has been happening more frequently.

Any Ideas?

Thanks,
Matt

SPICcnmGT

I dont' have a light FlyW in my 7 yet but I do in my other car and it shudders basically like yours, below 2k rpm on take off. Its about a 9lb with a Spec stage 3, which is street/strip. I figure its mostly the clutch trying to grab since it is a higher performance clutch, think about a race clutch if you actually try to slip it, it studders really bad, or it just goes or goes dead. Mines been doing it for probably 2 yrs now with no problems, I just kinda deal with it.

BTW I have had my tranny back apart, and I didn't see anything abnormal.

dubulup

sounds like one of the cons of drivablity with a light (9lb) flywheel...

moehler

iTrader: (12)

I'm not too sure about that. I had this setup for about 10k miles with no problems. After I got my new engine installed I started to notice this.

dubulup

well, that's no good


hmmm...only time my car acts as you describe is decel when fuel cut is existed. Fuel is cut (via haltech) during decel until 1500rpm, but no slipping of the six puck has to occur


when does it shudder? cruising, accel, decel

if its crusing, your cold fuel map might be too rich/lean with the cooler weather...

moehler

iTrader: (12)

It doesn't seem to be fuel related, but you never know. It feels as if the clutch doesn't was to fully catch the flywheel only when starting from a stop. If I rev it up to about 2100 rpms and slip the clutch everything works out fine. It's pretty strange actually.

California Dreaming

Mine does the same thing below 2k RPM's, only on deceleration though.

dgeesaman

iTrader: (7)

Clutch and/or flywheel. I'm guessing the flywheel needs resurfaced, or if it has those removable plates that they were installed improperly (can those plates warp from being overtorqued like brake rotor hats? I'm just fishing on this idea)

My only suggestion - is when engaging the clutch, make sure the clutch pedal is always on the rise, and the throttle is always going down. You can do it slowly if you want more slip, but if you pause either one, the springs in the disc unload and grab and lead to that shaky engagement.

Dave

DaveW

Shudder is a vibration at the natural frequency of the engine/transmission mass on its mounts, similar to a tuning fork. It takes very little input to excite a vibration at a system's natural frequency. The things that can make this worse are a change in mass, less damping, mounts that are stiffer or softer, causing the natural vibration frequency to match some input (clutch puck engagement, engine rpm or firing frequency, etc.)

Therefore, if the onset of the vibration coincided with the installation of a new engine, the new engine mounts may be more flexible. aligned differently, etc.

When I had my FB, I had a severe clutch (stock clutch) shudder which only occurred in 1st gear from a stop. If I used 2nd to start up it was not there. I replaced the entire clutch, the engine mounts, the rear shocks, and probably some other stuff that I've forgotten. Nothing worked. Finally, in desperation, I attached a VW Bug steering damper between the engine and the inner fender (similar to where a torque brace would mount). Problem solved.

On the FD, a damper (or even a rigid torque brace) in the location that engine torque braces attach would probably solve the problem.

moehler

iTrader: (12)

I was thinking maybe the surface of the flywheel as well. It probably is possible to over torque it, but then I probably would have noticed this over the first 10k miles that I drove the car. On another note, when I bought the Flywheel I asked RB if I should buy an extra surface as well and he basically said that he very rarely sells the surfaces by themselves because they rarely wear out or go bad.

I'll try your suggestion. Now that you mention it, it might be only occurring when I give her a little more gas or clutch while holding the other pedal constant. Thanks .



Thanks for your input... I do have stiffer engine mounts, but I already have a solid engine torque brace as well.

DaveW

If that's the case, maybe the strut bar and the more rigid mounts (different natural frequency, and less damping) are causing the problem. IIRC, I've seen a damped strut bar somewhere that might work.

s1mpsons

iTrader: (5)

Would this happen if a new clutch was mated with a used "not-resurfaced" flywheel. This is what I am dealing with now, using an new Exedy Racing Stage 2 Thin Pad Cerametallic Clutch Kit part 10900 and my reused lightweight flywheel. Flywheel was allegedly resurfaced by Racing Beat, but it came back looking used with surface imperfections. I didn't see it when it was sent out to RB, only when it came back.

Does anyone think that bedding in the clutch to flywheel (similar to new brake pads) would work to fix shudder?