Car "Slams" into Gear

[1989MustangLX]

I've been having this problem for awhile. The car idles nice, but as soon as you put it into R or D, it slams roughly into gear and sometimes stalls. On wet or smooth pavement, the tires squeek. I can't imagine this is good for any of my drivetrain. Would turning the idle down help out? I think its at 7-800 rpm. The tach is still the 4 cyl model, so I divide it in half. Thanks for any ideas.

 

[The Shape]

800 RPM should be ok, but from what you describe it sounds like it is idled way to high. Are you sure you can trust the tach you have?

 

[1989MustangLX]

I doubt I can trust many things with this car. It sounds higher than 800 rpm, more like 1000-1200. I forgot to mention, this is an FMX.

 

[The Shape]

Reason I ask is because my 4-popper does the same thing, but it is because it idles at 1100 (I don't know why it idles that high or do I care cause it's just my beater) But it does the same exact thing you are describing.

 

[nosmatt]

?????

why dont ya flip the switch to 8 cyl?? (or, do they have that after the 79-86 cars, i know they did...)


anyway, sounds like the idle is too high, and/or it has a mal adjusted tv cable.

 

[1989MustangLX]

Tach doesnt have a switch. I think I found what it is. I got under the car with the tranny in neutral, and the driveshaft moves back and forth a bit before the wheels start to move. This leads me to believe that the rear end may need to have something fixed inside.

 

[6SpeedLX]

maybe your U joints are going?

 

[1989MustangLX]

I can see the pinion gear moving too, before the wheels are moving. Well, I can't see the gear itself, but the shaft the driveshaft bolts to.