Rear end "jumpy" when first started

[5.0Moe]

I have a track pack '14 GT with the torsen diff. When I start my car I usually let it warm up for a couple minutes and when I start driving my rear end is very jumpy. Could this be that its just not warm yet? I dont have any problems once i go a block or two.

The reason im posting is to see if this is normal or something is potentially broken.

Any input would be appreciated! thanks!

 

[5.0Moe]

No one else experiences this. Ive been thinking and it has happened since the car was new, so I'd think its normal cause of the LSD.

 

[5PNTSLW]

what do you mean by "jumpy" do you mean it feels like it floats around a lot and sways?

 

[Darufe]

Do you mean wheel hop? Like you get on the gas and the rear ends seems to jump up and down? If so...theres alot of people (well everyone with a 5.0 really) who have experienced this and theres many ways to cure it.
Lowering the car and slapping on stickier rubber cured kt for me.

 

[rfopt]

5.0Moe,

Do you notice when you start from a stop with the wheel cranked to one side(an example is when you back out of a driveway and then start to go forward or when you turn onto a street from a parking lot) that the car bucks few times after going forward a little? I wondered if in my case it was from accidentally touching the clutch pedal or I didn't have my foot on the gas pedal right, This has happened to me a few times, however your posts have me wondering if my torsen diff caused this.

 

[5.0Moe]

5.0Moe,

Do you notice when you start from a stop with the wheel cranked to one side(an example is when you back out of a driveway and then start to go forward or when you turn onto a street from a parking lot) that the car bucks few times after going forward a little? I wondered if in my case it was from accidentally touching the clutch pedal or I didn't have my foot on the gas pedal right, This has happened to me a few times, however your posts have me wondering if my torsen diff caused this.

It is not wheelhop, and nothing seems loose, it just seems like its bucking a bit as rfopt mentioned.

I always park with my wheels straight but it happens once my foot is off the clutch. Just coasting down my block with my foot barely on the gas or not at all.

 

[SteveC]

My car does something similar. When I first start the car and drive off (everything cold), the car bucks pretty bad if barely on the throttle in first gear. Usually I either just give it more gas or shift it into second and I don't have a problem after that. I have never had it happen with my foot off the gas but with the engine braking you won't coast too far.

 

[el jefe 302]

Yup if the "jumpy" feeling goes away after a block or two I had the same thing with the stock tune.


BTW moe, that 13 is clean as hell. Nice job man! :coolman:

 

[BMR Tech]

I'm going to step on the edge of a cliff, and say it is your tires causing it.

When a car sits for long periods of time, and even sometimes just overnight....the flat spot created by the colder rubber compund and weight of the car, can and will cause the rear of the car to bounce when initially starting your commute.

To test this, simply suspend your tires overnight, and see if it happens when you drive the car.

 

[5.0Moe]

My car does something similar. When I first start the car and drive off (everything cold), the car bucks pretty bad if barely on the throttle in first gear. Usually I either just give it more gas or shift it into second and I don't have a problem after that. I have never had it happen with my foot off the gas but with the engine braking you won't coast too far.

Thats exactly what mines doing also, guess nothings broken then. :dancenana:

Yup if the "jumpy" feeling goes away after a block or two I had the same thing with the stock tune.


BTW moe, that 13 is clean as hell. Nice job man! :coolman:

So once you tuned it it stopped? That would mean its the actual motor as opposed to the diff, that's interesting.
and thanks! Im happy with it right now.

I'm going to step on the edge of a cliff, and say it is your tires causing it.

When a car sits for long periods of time, and even sometimes just overnight....the flat spot created by the colder rubber compound and weight of the car, can and will cause the rear of the car to bounce when initially starting your commute.

To test this, simply suspend your tires overnight, and see if it happens when you drive the car.

Yeah thats what I thought it was at first but its way different. I have a drift car also, so driving with flat spots in no rare occurrence for me! lol

 

[INEEDA_TERMI]

Thats exactly what mines doing also, guess nothings broken then. :dancenana:



So once you tuned it it stopped? That would mean its the actual motor as opposed to the diff, that's interesting.
and thanks! Im happy with it right now.



Yeah thats what I thought it was at first but its way different. I have a drift car also, so driving with flat spots in no rare occurrence for me! lol

My car does it, but I have the traction lok rear with clutch packs. It is the fluid and friction mofifier separating when it sits for a while. Usually if I let it sit over a day it does it. Feels like an uneven clutch slipping and trying to grab at the same time.

 

[5.0Moe]

My car does it, but I have the traction lok rear with clutch packs. It is the fluid and friction mofifier separating when it sits for a while. Usually if I let it sit over a day it does it. Feels like an uneven clutch slipping and trying to grab at the same time.

yes exactly, so it seems to be the diff then. thanks for clearing it up guys!

 

[bdcardinal]

My Track Pack does it too on first drive-off. Remember even though you are warming up the engine oil, the differential fluid is just sitting there not moving or being warmed until the vehicle is in motion.

 

[MKSVT]

Mine does it also, once it gets somewhat warm. It goes away.