: Lag in the transmission



weister42
09-30-06, 02:50 PM
Haven't drove in the rush hour traffic jam for awhile, and I noticed that my car "jerks" when I press on the gas pedal. It is especially noticeable when the car is in 1st gear. My car has over 110k so is it time to get the tranny serviced? What is causing the lag in acceleration?

Ranger
09-30-06, 03:47 PM
At 110K, maybe plugs and wires?

zonie77
10-01-06, 01:39 PM
Are the "dogbones" bad and letting the engine rock?

Easy to see.

weister42
10-01-06, 02:00 PM
The engine mount is 6 months old and so the spark plugs, wires, fuel filter are about a year and so old. But just in case how do I check for the engine mounts?

white97deville
10-01-06, 02:04 PM
I would check the 6 cradle bolts also to make sure that they are tight.

zonie77
10-01-06, 02:43 PM
The dogbones are top front of the engine.

Have someone "brake torque" the engine while you watch it and see how much it moves. Put it in gear, hold the brake hard, give it some gas. Don't hold the gas down long. You're looking for excessive rocking motion of the engine so on/off the gas is what you want. Tight motor mounts should hold motion to an inch or less.

weister42
10-10-06, 09:09 PM
Okay I did the brake torque and the engine only rocks about an inch and no lag while i was doing brake torque. The lag only happens when I press on the gas really quick, and when I let the pedal go it feels like my car's rocking back and forth a little bit. It is more prominent when I drive at the shifting speed say, 42mph in 4th gear. When I start my car it rocks back and forth a bit too. The same happens in my buddy's 94 Cavalier except it's much worse.

So what could it be? maybe the bottom engine mounts? Tranny work?

mtflight
10-11-06, 11:57 AM
I had the jerk going on for a while until I replaced the dogbones with generic ones from rockauto. Cheap fix, cheap try.

Tommy Deville
10-11-06, 09:33 PM
What r dog bones?

Ranger
10-11-06, 09:56 PM
They are the two dog bone shaped "torque struts" mounted on either side of your engine attached to the radiator support.

mtflight
10-12-06, 02:34 PM
They are the two dog bone shaped "torque struts" mounted on either side of your engine attached to the radiator support.


yup. They dissapeared on the 98+ Seville, and 2000+ Deville.

Ranger
10-12-06, 03:47 PM
Thanks Alex. I was wondering what years they did away with them. Now if I could only figure out why.

mtflight
10-12-06, 04:04 PM
Thanks Alex. I was wondering what years they did away with them. Now if I could only figure out why.

One possible theory is that the 98+ Seville and 2000+ Deville were based on a revised version of the K-Body platform which evolved from the very rigid G-Body Oldsmobile Aurora (1st generation).

It is said that the Aurora broke GM's body integrity testing machine, and they had to use a truck frame crusher to test it. It wound up exceeding federal standards twofold--that's how rigid the frame was.

Perhaps the abandonment of the dogbones was ok due to the better structural integrity of the new platform. It also isolates the engine vibration to the cradle alone (more luxurious).

One possible consequence of the dogbone elimination is broken motor mounts which IIRC kept happening to danbuc until he replaced it with an aluminum mount.

Ranger
10-12-06, 05:01 PM
Learn something new every day. Thanks :thumbsup: