ej6sir-t

iTrader: (1)

View Video to see problem

My rear end and senses tell me the problem is coming from the right side of the car but who knows usually things are the exact opposite. Rear shocks are brand new, no excessive play in any suspension bushings or ball joints when tested

please help
cant find any problems

ej6sir-t

iTrader: (1)

Problem happens only above 65 when turning left hard

TunerN00b

Caveat, not an expert in regards to trying to identify issues from video like this.

Is this one of the Preludes with 4 wheel steering (I don't remember which years had it)? If so, start there.

Is this a Type-SH? Those lack a true differential and depend on correct operation of the "acceleration device" to allow the car to turn. Incorrect front wheel speeds relative to each other could produce such behavior as well. Verify correct operation if possible.

No 4 wheel steering and not an SH? Check for anything that could be causing dynamic toe issues in the right rear.

ej6sir-t

iTrader: (1)

No 4ws , is sh, no problem with sh diff. Rear tight track bar BJ and bushing ok, no play

ej6sir-t

iTrader: (1)

bump

TunerN00b

I hope we're playing fast and loose with terms here. The Type-SH doesn't have a diff, at all. One axle is directly driven off the the transmission output, and the other has the ATTS unit to allow speed variation. It's a "spool".

And since it is an SH, I'd recommend checking the wheel speed sensors and the steering angle sensor. The ATTS's control unit (unsure if main ECU or separate) needs accurate information from those to adjust axle speeds correctly.

m4xwellmurd3r

This thread made me look up the atts and how it works. I found a dude who ripped one apart. It uses dual clutch packs and a planetary gearset to actually change the gear ratio between the actual axles so they rotate at different speeds. One clutch pack is for left hand turns, the other for right hand turns.

It seems like the system to engage the clutch pack to engage the gearset for thr right wheel (to make it rotate faster) is rapidly engaging and disengaging. It could be an issue with the solenoid for that circuit, dirty/bad fluid, or a worn out clutch pack. Though the guy that tore his apart said he had an atts light on with it, and I dont think he ever got into what caused the system to fail, but the clutch packs themselves had very little wear.

The atts uses a system of fluid pressure, a big spring, and the clutchpacks to engage the gears. It works a lot like an auto transmission actually.

I hope something I post can be of some use. The atts is a complex animal. Im suprised honda would go to such lengths to design it. It was fun reading about it for the 2 or 3 hours I spent on the subject

TunerN00b

It was a prelude (pun intended) to the SH-AWD systems that followed in the larger Acuras.

RT-4WD, SH-AWD, and Haldex Traction units (similar concept as Honda's RT-4WD) all allow pseudo-AWD functionality without need for a center differential, which is a huge space / packaging saver for a transverse oriented engine arrangement.

ej6sir-t

iTrader: (1)

It does have a diff. The atts is not the problem.

m4xwellmurd3r

https://docs.google.com/file/d/0Bxeu.../preview?pli=1

It has no diff. The planetary gearset had a locking and unlocking function to alter the wheel speed left to right.
The transmission itself has a spool in it. A solid bar straight through. (Actually, it has a bunch of planeyary gears to transfer power to the right axle, the left acle, and the atts unit. The more I look into it the more conplicated it looks lol)
When you go straight, the wheels are locked. When you turn left, the clutch pack slows down one axle, cauding the planetary gearset to rotate. Since the gears are of different sizes, it causes the outer wheel to accelerate
When you turn right, the opposite occurs.

If you had a normal differiential, the atts wouldnt work.

Read the google doc I posted, it has a lot of good infoy that might be of some use.

The atts is acting up in your car. The fact that it does it in a long sweeping turn (where the atts has been determined to be at its strongest advantage) is proof enough.

ej6sir-t

iTrader: (1)

It's not acting up. The atts light would come on if it were. And to double check I pulled the atts fuse. The system only activates when slip is detected. And the car does have a diff if it was a spool you wouldn't be able to lock on side and spin the other. It's a dif that has locking clutch packs on each side. That's the definition of differential. A device that allows a speed differential from side to side.

ej6sir-t

iTrader: (1)

Bump

ej6sir-t

iTrader: (1)

So the front tie rods (inner and outer) barely had any play but the boots were bad so I replaced them. At the same time I got new rear tires and an alignment. After that the problem has disappeared.