Thread: Car jerks as I slow down to stop.

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Sorry to bother you all again. Just when I get one problem fixed, here comes another. Just started a few days ago. When I slow down to come to a stop the car begins to jerk. It only happens when I let off the gas and Just coast at slow speeds. I can give it gas and the jerking stops immeidiately.

Does anyone have an Idea where I should start in order to diagnose this problem?

Thanks,
John

Or if your running disc brakes an out of true rotor, or maybe uneven drums or out of adjustment pads on one wheel. Does it jerk the steering or come from behind, what brake set up are you using(drum/drum, disc/drum, or disc disc? Lastly have you modified anything lately, or changed any parts? Alignment?
Just the first things that come to mind. I'd add clutch, but Allen beat me to that one.

Sorry, It is a 1985 cutlass supreme with a chevy 350 in it. It is an automatic with a rebuilt transmission.

Ah.. have you checked your fluid level in the transmission?

possibly a warped rotor... Maybe low on rear end grease and binding up the ring and pinion? has any work been done on the rear end?

Ok, Sorry I was in a hurry earlier. It is a rebuilt TH-350 trans. The jerking takes place around 20 mphr and lower. I do not have to apply the brakes for this to happen.It just starts doing it around this speed, I can ste3p on the gas and it stops instantly. There is no slip in the transmission at all and other than this the car is running fine. Although it does seem to be idling a little rough at the stop lights.

Frozen u-joint?

1985, it seems to me, was in the final throws of wrestling with carburetors. I remember a buddy of mine who had nightmares with this very problem you are describing on a 1984 Ford and traced it to the decel equipment that was designed to reduce emissions as the motor came down in rpm's. I don't remember the name of the whole mess, but someone on here will know.

im thinking it might have to do with the front disk breaks cuse my truck dose the same thing like when getting off freeway exits or slowing down from high speeds as i slow down it starts to jerk and it started after i got a few rotors from the local junkyard here so like toofast_28 it might be a warped rotor?

If it is the rotor you will fell it when you put on the brakes your pedal will pulse up & down. At least thats what happens to me after a warpe one

Hey, Does this have a lockup torque converter in in? Sounds like it could be locking up and not releasing.....just a guess.

When you say jerking do you mean (it jerks forward)? I think you are also saying that it only does this with no load on the drivetrain (coasting) and when you apply load it goes away? When it is jerking is there any noise associated with it (or when you step on the gas). Have you checked to make sure everything is still bolted down good from the bell housing back?

The last thing you worked on was the trans? sounds like your torque convertor may sticking- not fully releasing,

Post 13: Yes it seems to jerk forward when coasting, but there doesnt seem to be any noise associated with this. I have not been able to check anything on it yet as it has been raining here all week.

Post 14: The last thing that I did was to replace the flywheel, 3 bolts on it had backed out. Apparently the guy I bought this car from did not tighten down anything correctly. A little while after this I had to take it to the shop because of some more loose bolts it jumped time, not only that but the distributor wasnt even tightened down.

The funny thing is that along with the jerking I describe, it sometimes acts like it doesnt want to run. It idles ok in neutral but gets rough when put in drive.

I wonder if you got the converter engaged all the way with the pump? Trans bolted to the cross member all the way? Does the rough idle in drive clear up when you give it gas?