Car jerk when in gear and let go Gas paddle

[jaydeep]

I have 92 Vert 5 spd tranny. When car is in any gear and if I let go gas paddle quickly car jerk. What that could be? I have felling it might be axle related issue.

[evandael]

oh grammar.. thanks for the lols.

i think it may be mount related.. specifically engine mounts or rear subframe mounts. they bind up with positive torque from the engine and when you cut the throttle and it begins engine braking, the drivetrain shifts forward.

[Thizzelle]

wait wait wait, if your in gear and you let go of gas, your car jerks which way, slowing down or speeding up? if it is slow down then that is normal manual operation because your using the clutch to brake the car.

[jaydeep]

wait wait wait, if your in gear and you let go of gas, your car jerks which way, slowing down or speeding up? if it is slow down then that is normal manual operation because your using the clutch to brake the car.

It happens when I slow down. Its not normal because my e46 does not do that. I know there is something wrong.

[Bimmerguy91]

Its is normal but only to some degree. I would suspect your motor and trans mounts are pretty bad. Especially if they are stock. Get some 80a poly mounts and it shouldn't do that anymore

[ak-]

Does it jerk or does it CLUNK?

You're comparing a manual e46 to a 25 year old manual e30 lol.

[Vivek]

It could also be your subframe and diff mounts flexing when you unload the drivetrain.

[rasputin]

It could also be your subframe and diff mounts flexing when you unload the drivetrain.

wouldnt it still be load if he is engine braking

[Vivek]

Yea, but its the other direction. Speeding the car up vs slowing it down.

[GillesBigCowboy]

strong decelerating jerk when lifting the throttle in a manual tranny is a good thing... I always do this as a testdrive purchase test/estimation... My grampa told me no jerk is a sign of bad compression.

[Earendil]

It happens when I slow down. Its not normal because my e46 does not do that. I know there is something wrong.

As a guy who owns a 328i (e46) and a 325i (E30) and maintains the shiet out of both those cars, the E30 is way more harsh during the transition to engine braking than is the e46... I've also driven them in very bad states before ;-)

First off, the e46 has far more engineering behind it to make it "smooth" and keep rich people happy. Letting off that gas in that car is nearly like doing so in an automatic if the RPMs are nice and low. Even if the RPMs are high, it transitions to engine breaking evenly and smoothly.

The E30 is a brat. From my house, I pull out onto a steep road and travel two blocks down hill. I usually just 2nd gear brake it all the way down. Sometimes I accelerate too long when I"m in a hurry and get the RPMs up, and then I neglect to let off the gas easy. Sucker will pull the eyes out of your sockets.

Now, one thing that can make it worse, especially at high RPM, is if your throttle position sensor isn't detecting the idle position. The E30 does have a tiny bit of smarts, and when you let go of the gas and the RPMs are really high, it will engine brake like crazy so that you can attempt to use the gears to slow down. It doesn't even give it enough gas to idle. As soon as the RPMs drop off it will kick back into the proper idling amount of idling gas, thus reducing the engine breaking. If the TPS is working properly, the harshness is reduced because the amount of gas goes from a lot, to idle. If it doesn't detect that position, it'll go from a lot to nothing.

Now, that's only if the slowdown is harsh and there are no clunks. If you hear clunking, it could be the things mentioned above, or possible the U-Joint on your drive shaft going out. I would get a distinct metal slapping sound when slowing down, especially in 2nd or 1st, and the extra movement in the drive train could cause some bucking.