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-   -   2006 ford escape hybrid rear vibration (https://electricvehicleforums.com/forums/ford-escape-hybrid-26/2006-ford-escape-hybrid-rear-vibration-27482/)

fishbob 12-19-2011 07:52 AM
2006 ford escape hybrid rear vibration
 
I just purchased a 2006 ford escape hybrid with 130,000 miles, I test drove it up to 55 MPH and it drove great.. After i bought it I got on the freeway and at 60 MPH or more it has a very noticable vibration seems to be from the back of the vehical. Just wondering if anyone has had this happen to theirs before I bring it in. Thanks

wwest 12-19-2011 09:12 AM
Re: 2006 ford escape hybrid rear vibration
 
F/awd..?

In which case rear driveshaft u-joints or a rear half-shaft CV joint(s).

At that mileage I would vote u-joints.

travelover 12-19-2011 05:28 PM
Re: 2006 ford escape hybrid rear vibration
 
Could be just tire balance. I'd check that first.

fishbob 12-19-2011 06:35 PM
Re: 2006 ford escape hybrid rear vibration
 
It is a awd, The vibration seems faster than a tire out of balance more like a u joint that I have had on other vehicals but I will sure check the balance, I got under it and tried to move the joints seem to be tight although the left rear axcel seemed to move in and out some. Thanks Guys

wwest 12-28-2011 10:37 AM
Re: 2006 ford escape hybrid rear vibration
 
Originally Posted by fishbob (Post 239926)
It is a awd, The vibration seems faster than a tire out of balance more like a u joint that I have had on other vehicles but I will sure check the balance, I got under it and tried to move the joints seem to be tight although the left rear axle seemed to move in and out some. Thanks Guys
At those speeds the rear drive clutch should NOT be engaged so that leaves us with U-joints. Unless the rear drive clutch has failed in some manner wherein the rear drive is continuously engaged, even slightly engaged. That could result in pretty severe vibration of so.

wptski 12-28-2011 04:15 PM
Re: 2006 ford escape hybrid rear vibration
 
Originally Posted by wwest (Post 240074)
At those speeds the rear drive clutch should NOT be engaged so that leaves us with U-joints. Unless the rear drive clutch has failed in some manner wherein the rear drive is continuously engaged, even slightly engaged. That could result in pretty severe vibration of so.
It can still engage if you accelerate but not at a constant speed unless it detects front wheel slippage.

fishbob 12-29-2011 05:33 AM
Re: 2006 ford escape hybrid rear vibration
 
Thanks for the info, I changed the rear u joint and it helped some but especially when cold it is worse, The rear u joint was dry and I plan to change the rest and will post the result after.

wwest 12-29-2011 10:27 AM
Re: 2006 ford escape hybrid rear vibration
 
Originally Posted by wptski (Post 240079)
It can still engage if you accelerate but not at a constant speed unless it detects front wheel slippage.
It has long been my understanding that the rear drive clutch is NEVER engaged above 20-25MPH regardless of acceleration level.

And I'm quite sure that should wheelspin/slip occur at ANY speed/condition the INSTANT result will be TRAC activation, engine dethrottling and front (logically presumptive) braking so as to most quickly restore traction to those all important front drive & directional control wheels/tires.

wptski 12-29-2011 04:44 PM
Re: 2006 ford escape hybrid rear vibration
 
Originally Posted by wwest (Post 240091)
It has long been my understanding that the rear drive clutch is NEVER engaged above 20-25MPH regardless of acceleration level.

And I'm quite sure that should wheelspin/slip occur at ANY speed/condition the INSTANT result will be TRAC activation, engine dethrottling and front (logically presumptive) braking so as to most quickly restore traction to those all important front drive & directional control wheels/tires.
That's incorrect. This can be easily seen using a Scanguage-II. I've even seen a slight engagement while coasting down a long gradual grade.

The AdvanceTrac would detect side to side slippage but back to front would engage the 4WD.

wwest 12-29-2011 05:51 PM
Re: 2006 ford escape hybrid rear vibration
 
Originally Posted by wptski (Post 240100)
That's incorrect. This can be easily seen using a Scanguage-II. I've even seen a slight engagement while coasting down a long gradual grade.

Coasting downhill, or even simply coasting, I can understand. It's always a good idea to have as much of the engine compression braking as is possible applied at the rear rather than all at the front. Back in my days in MT, pre-ABS, on a slippery downhill I would slip the automatic transmission into neutral and then use e-brake judiciously to maintain a slower speed and help stabilize the vehicle laterally at the same time.

The AdvanceTrac would detect side to side slippage but back to front would engage the 4WD.

Yes, I agree, the way I read the shop manual along with TRACTION control activation as described the rear drive will be simultaneously engaged.

But keep in mind that this is always primarily, predominantly, a FWD vehicle. So if conditions are such that wheelspin/slip is likely to occur, it will almost ALWAYS present itself at the front first, initially. So yes, couple in the rear drive INSTANTLY, but the more important function is to return those front wheels/tires to a tractive wherein directional control is not threatened or can be asserted as/if needed.

Thus you will almost always encounter TRACTION control activation simultaneously.
The thing to keep in mind is that the rear drive is engaged at low speed, low speed acceleration, regardless of roadbed conditions. For the clear majority of us that would mean that most of the time, tractive roadbed, that action is not only needless it will also unduely stress the driveline. So why would Ford make matters ever worse by needlessly, even on a low traction surface, engaging the rear drive, even partially, above 20-25MPH.

wwest 12-29-2011 06:12 PM
Re: 2006 ford escape hybrid rear vibration
 
Originally Posted by wptski (Post 240100)
That's incorrect. This can be easily seen using a Scanguage-II. I've even seen a slight engagement while coasting down a long gradual grade.

The AdvanceTrac would detect side to side slippage but back to front would engage the 4WD.
Is your Scanguage reading the actual ECU command or is it simply indicating the PWM dutycycle %..?

Electromagnetic actuators that are controlled used PWM voltages often have a "keep-alive" minimum pulse duty cycle to overcome the "striction" effect often present in these devices, especially if hydraulic control of some kind is involved. Many systems even "dither" the PWM dutycycle at a low frequency rate, low enough frequency to allow the device to remain in a constant "vibratory" motion.

wptski 12-30-2011 07:27 AM
Re: 2006 ford escape hybrid rear vibration
 
Originally Posted by wwest (Post 240110)
Is your Scanguage reading the actual ECU command or is it simply indicating the PWM dutycycle %..?

Electromagnetic actuators that are controlled used PWM voltages often have a "keep-alive" minimum pulse duty cycle to overcome the "striction" effect often present in these devices, especially if hydraulic control of some kind is involved. Many systems even "dither" the PWM dutycycle at a low frequency rate, low enough frequency to allow the device to remain in a constant "vibratory" motion.
Back in '09 when I first looked into this, I used a scope to monitor the actual PWM signal output from the 4WD module. This was before I got a SG-II which reads the 4WD PID PWM signal. On the scope, it did go to zero. Comparing the scope to the SG-II, it showed about 50% of the SG-II reading. Desert Dog rethought his coding which was based on 100% max which it can't be to prevent drivetrain wind up, wheel hop, etc. He modified the coding then to reflect the change based on 50% being max.

wwest 12-30-2011 01:00 PM
Re: 2006 ford escape hybrid rear vibration
 
Originally Posted by wptski (Post 240123)
Back in '09 when I first looked into this, I used a scope to monitor the actual PWM signal output from the 4WD module. This was before I got a SG-II which reads the 4WD PID PWM signal. On the scope, it did go to zero. Comparing the scope to the SG-II, it showed about 50% of the SG-II reading. Desert Dog rethought his coding which was based on 100% max which it can't be to prevent drivetrain wind up, wheel hop, etc. He modified the coding then to reflect the change based on 50% being max.
Take an actual 4WD, R/awd, and have it in full, 100%, locked mode ONLY for/during low speed acceleration, straight-forward (or even slight turns) acceleration, and you will not experience wheel hop at all and not enough driveline windup to seriously degrade drive line component life cycles. Maybe some slight tire scrubbing.

The problem arises from running it fully locked on a tractive surface continuously.

So I see no problem in the use of 100% lockup, 50/50 F/R torque split under these restrictions. And keep in mind that the SH-AWD system goes into 50/50, or even 30/70, F/R torque split under these same conditions via the ~7% over-driving of the rear.

I suspect the only true way to determine the F/R torque split under varying throttle conditions is on a 4-wheel dyno.

wptski 12-30-2011 04:08 PM
Re: 2006 ford escape hybrid rear vibration
 
Originally Posted by wwest (Post 240134)
Take an actual 4WD, R/awd, and have it in full, 100%, locked mode ONLY for/during low speed acceleration, straight-forward (or even slight turns) acceleration, and you will not experience wheel hop at all and not enough driveline windup to seriously degrade drive line component life cycles. Maybe some slight tire scrubbing.

The problem arises from running it fully locked on a tractive surface continuously.

So I see no problem in the use of 100% lockup, 50/50 F/R torque split under these restrictions. And keep in mind that the SH-AWD system goes into 50/50, or even 30/70, F/R torque split under these same conditions via the ~7% over-driving of the rear.

I suspect the only true way to determine the F/R torque split under varying throttle conditions is on a 4-wheel dyno.
Well, of course but most of the time it's driven on hard dry pavement and that's what I was refering to.

A function test right from the Ford manual is for the tech to command 100% rear wheel torque and make hard low speed turns. If it resists turning, it's working properly.

wwest 12-30-2011 05:49 PM
Re: 2006 ford escape hybrid rear vibration
 
Originally Posted by wptski (Post 240136)
Well, of course but most of the time it's driven on hard dry pavement and that's what I was refering to.

But not continuously, only under acceleration.

A function test right from the Ford manual is for the tech to command 100% rear wheel torque and make hard low speed turns. If it resists turning, it's working properly.
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