fishtailing during deceleration!

[WayneIlfrey]

Hello all,

I have an interesting problem.

Yesterday, my oil line to the prelubber pump busted. So I fixed it, but not before almost all the oil dumped. OK that was no big deal. But no I have another problem (and im not sure if they are related or not).

Whenever im going down the road she drives fine, but when i let off the accelerator the truck fishtails, and I mean it swings about a foot or more.

I don't know what could be causing this problem, anyone have any suggestions.

Thanks

Wayne



'91 Dodge Turbo Diesel (BiGReD)

 

[MAX A/C]

Hi Wayne--

That's an interesting problem... My first guess would be that oil sprayed all over the rear tires, and during decel (due to compression holding them back) they simply slip. To test this, get up to speed and then without lifting the gas pedal, put it in neutral, then lift the gas pedal. You shouldn't have fishtailing doing it that way. Sounds like your tires just need a good cleaning!

Good luck. Be sure to post the results/fix... I'm curious!

Scott

 

[Midnite]

Originally posted by Scott Morgan

Hi Wayne--

That's an interesting problem... My first guess would be that oil sprayed all over the rear tires, and during decel (due to compression holding them back) they simply slip.

No, it's got to be something else. Even in the winter time without anything in the bed of my truck, I can't get the wheels to slide on glare ice by just backing off the throttle going down a hill. Maybe if I jammed it down into second gear while I was doing 40MPH or faster, but I've never tried that. Remember, with a diesel you get virtually no compression deceleration when you back off the throttle (unless you've got an exhaust brake of course).



Wayne--when you say the truck fishtails, do you mean the rear tires skid back and forth on the pavement? Or is the truck just swaying back and forth with no skidding?



If it's swaying without skidding, then I would take it to a mechanic immediately. I'm no mechanic, but it almost sounds like a suspension or rear end problem.



Mike

 

[WayneIlfrey]

I just put a new set of tires on the rear. One of the tires was getting pretty bad. This did seem to help the problem, but it still jerks to the left.

It dosent really slid so much, Jerk is a better word.

Now that the new tires are on it isnt as bad but i still fell a pull to the left when i decelerate.

It is worse if i decel. quickly. If I decel. slowly it dosent happen as bad.

Any other thoughts guys?

Wayne

 

[NuttyMopar]

Jerking to the left

Have you checked your rear brakes and/or Anti Lock braking system. One of my rear brakes were a tad to tight and though it didn't cause the truck to jerk to the left, it did make it want to steer left when I wasn't giving it power. Is your front end aligned? I don't see how it would make a difference but you never know. Frame bent? If sitting on level ground, check your back bed up against the cab. It should measure the same on both sides. Drive slowly through a water puddle and see what the tread marks look like on the other side. They should both be the same distance apart compared to being offset a little. Tire pressure the same all around? Can't think of why that might be happening to you but just throwing out different things that might help.

 

[RDavidson]

Fishtail

Make sure your transmission isn't downshifting when you lift off the throttle. Next check the fluid level in the rearend. If it's O. K. look at the bearings in the rearend.

 

[hdm48]

hi. I had this problem once with a Hemi dart. it turned out to be the center pin in one of the rear springs. a real bummer when your going through the traps at 140 plus.

on way to check it is to have someone watch the rear axel while you hit the throttle in reverse. see if it moves.

another way is to put some chalk around the spring perch and drive it and make it do the one-two shuffle. then look to see if the chalk is scuffed.

or it could be that the oil is allowing the axle to move because your hanger bolts are loose.



good luck. and i would limit your driving until you locate the problem.

 

[WayneIlfrey]

RE:fishtailing

Just to let everyone that is interested know, I did fix my jerking problem.

It was both a axle ubolt loose and the spring center pin was a bit loose.

Thanks to all you guys that helped me out. I apreciated it.



Wayne

***God Bless America***