My other odd problem...

[Eric VerValin]

OK, I swore I had a bad mount, because it feels like the motor is moving when I'm above 1500 rpm or so in gear, and let off the gas. And or step on the gas. It almost "bounces" into position it feels like if that makes much sence. Its not like it rocks once, kinda back and forth before it settles.

Anyway.. I got it up in the air yesterday, and all my mounts appear to be fine. I put a block under the oil pan, and slowly raised the jack, and I picked up the car and the motor didnt budge. Sooooooooo... what am I left with here? The only thing I know of that "NEEDS" replaced is an inner tie rod end on the drivers side.. could that be enough to cause these strange things?

 

[Phoenix]

A loose subframe can cause this , double check the 4 bolts + Bushings.

 

[93rev2sev]

slop in drivetrain from high miles.

Do you have the engine roll dampers in place? are they any good?

 

[Eric VerValin]

Both dampners are still good, my drivetrain / cv shafts are new / reman with less than 2000 miles on em. Subframe bushings are aluminum, and appear tight. I have a big flat washer, and a lockwasher on them, and they're still flat, didn't put a TQ wrench on it or anything. I just get nervous tightening those sometimes, as they require more torque than my wrench can do, but I do have a nice 5 foot long peice of steel I use as my cheater, I'm just afraid to push the bushing thru the sheet metal, or something "fun" like that. I don't trust rusty cars.. lol I get nervous anytime I gotta mess with the subframe.

 

[93rev2sev]

I can't deny that I have the same type of issue. It feels like the engine is "spring loaded". I attributed it to the fact that I removed the engine roll dampers when I reinforced my mounts. Now, I've begun to think that there is just too much slop in the drivetrain.

I can turn one wheel/tire 5 or 6 degrees before meeting the resistance of the other one. That kind of slop will definately make for some engine mass jounce. I've learned to eliminate most of it by altering my driving habits but "throttle tip-in" and "tip-out" is where it's kind of annoying.

Does it sound like the same thing?

 

[frosho]

Mine has done the exact same thing since I got it. "Bounces" back and forth when I touch or let off the throttle. I just do my best to ease on/off the gas to keep the bouncing to a minimum.

 

[Eric VerValin]

LoL.. oh yea its almost non existant when you know how to use the clutch.. I just noticed how big of a difference it was after driving my truck around for a day... what a difference that is..

 

[93rev2sev]

your truck is north south engine...that makes a diff too.

 

[FastAndFurious]

Mine does same thing. I just easy on the gas and clutch, but it is very very annoying..

 

[itwonder]

My guess is that movement that is normally isolated from the car body by the SFB is not being isolated by your aluminum ones. You may still have motor mounts that are allowing more motion than they should. You might consider installing limiting bolts on them. I did that and filled mine with liquid urethane. If I had to do it over again, I would not do the urethane fill on the rear mount as it makes the mount so stiff that vibration is transferred , most noticeable at idle.

 

[Eric VerValin]

Ok yea, the way the car is now with the ALSFB's you can definately feel the motor in the floor, and the shifter. I kinda like it, feels like I'm driving a machine, and not a commuter car. The werid thing is that it was ok for a while, then it just started happening.. Getting the alternator rebuilt today, will start picking at the suspension here in a few days. Stupid snow makes it kinda hard to crawl around on the ground checkin things..

 

[93rev2sev]

The engine was designed to move. They used that movement to help cut down on harshness and vibration. By allowing a little movement, they can dampen the vibrations more easily, change their frequency, etc.. the mounts are SUPPOSED to work in "harmony" with the roll dampers. As the engine mass is forced to the rear of the car under accelleration, that energy is absorbed by the roll dampers.

Now think about reinforced mounts(even WITH roll dampers), the mass of the engine still shifts rearward under accelleration, and since the laws of physics state that it is impossible for a material to have "100% elastisity"(this is what we are TRYING to acheive with hardened mounts), the mass rebounds. Since you are using very little torque, as soon as the mass rebounds, it starts to shift rearward again...and you get that bouncy, jouncy, sloppy feel.

this is why the effect is minimal in your truck. It's a north/south configuration, so it does not care that the engine mass is moving rearward or forward...the engine spins sideways...not front to back with the motion of the engine mass of a FWD car.

Capisch?