im sure everyone has experienced this to some extent regardless of whatever car you are driving... but i wanted to if there were any quick fixes or solutions such as a lighter flywheel, not as stiff springs, etc? if you cant picture what i mean, just imagine you put a car in reverse and go backwards rather fast... then immidiatly let your foot off the gas. it will buck a few times before things settle back down.

thanks, heath

(BTW ive got a stock ecu that is functioning properly)

 

heavier flywheel would help... more rotating mass would smooth the deceleration.

 

Heath, its normal. One of the car magazines back in '92 or '93 did a shootout w/ the Supra, 300ZX, FD, and another car (I forget), and I remember one of the reasons they marked the FD down was b/c they said it was very jerky...either it was stopped or it wanted to go WOT. Very jerky in low gears. So I just learned to live w/ it

~Ramy

 

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Yup - I just got used to it - even my 1st-gen did that.

 

My second gen didn't have any bucking at all untill you got it under 500rpm in 1st or second. But I have heard that getting a good tune will help out alot with the FD's not sure though.

 

The only answer I know is to tune your foot And yes it's annoying. It comes from driveline windup and release, (which the springs in the clutch can affect to some extent) but mostly gear lash and the flexibility in the driveshaft. Plus, it can be hard to keep your foot perfectly still, perpetuating the bucking motion.

Of course, the stock ecu doesn't help a bit, so good tuning will help make it all more predictable.

Dave

 

The car was bone stock when the magazine tested it. And mine was on the stock ECU when I first noticed it. And that's also prob why Heath mentioned in his post

~Ramy

 

My RX-3 wagon does some wicked bucking, I thought it was the driveshaft. Then again I think a 6 puck clutch doesn't help either.

 

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LOL

 

Never driven a puck clutch...so are you talking about around engagement (right afterward)? Cuz I thought Heath was talking about when you're already engaged, say you're driving, and slowing down as traffic is building up ahead. As you stay in the gear but slow down, the car will hesitate and jerk based on MINUTE changes in throttle. Not bogging...the car's def. still going fast enough not to bog. But it just jerks. I can do this on purpose by VERY slightly pressing on the throttle, and VERY slightly easing off a tiny bit. There's just a point where it'll jerk forward or back... Oh and from my experience, this is most pronounced in 2nd gear.

 

YES. nail on the head ...thats exactly what im trying to describe. so everyone agrees its from drivetrain slack? i dont suppose theres much to do to fix that. also someone said it could be from the spring clutch... i dont know, it seems like more than just a sprung hub could account for. i know that every car does this to some extent... but it seems more pronounced in the FD.

 

don't quote me on this but i've heard urethane motor mounts help cut down on this as the engine is the end of the drive train. and if it twists when getting on and off the throttle, the rest of the drivetrain will follow suit and rebound causing bucking

 

and i wonder if the PFF plays any role in this as well. i get this effect both in my 97 miata and FD which both have PPF's

 

my fd does this bucking bs too, but thats in acompaniment of a klunk from the rear end bushings being shot to all hell. i have a feeling anythign that will tighten up the rear end and engine, anything from flywheel to differential, will help. if you make the whole system solid and dont allow any flex from one end to the other, im sure it will react better. also possible that the fuel system is not decelerating its fuel supply in a smooth enough manner. not sure but isnt there a deceleration solenoid or something that helps bring the engien down smoothly on closed throttle? thought i read something like that at some point. nto too sure though

 

under 500rpm in 1st or 2nd?

o_O!!

My old FC did it if it was below 2,000RPM in any gear, really.

My FD seems to do it a little more violently though, but again, it's basically ~2,000RPM or below, if my foot's completely off the pedal, regardless of gear.

I always thought of it as "a rotary thing".

heh...