Jerking

[bill77ocean]

Hi, i have the 2010 fusion hybrid, lately been noticing, when at a light and slightly letting off the brake pedal, theres like a jerking or a small surging feel, also noticed that with slight gas pedal acceleration on a hill was same kinda jerking feeling, is this normal? it does not do it during normal driving though....been wondering if its the transmission clutch slipping a bit..was thinking about taking it in to have it serviced anyway soon, but this does seem a bit odd.

[lolder]

Hi, i have the 2010 fusion hybrid, lately been noticing, when at a light and slightly letting off the brake pedal, theres like a jerking or a small surging feel, also noticed that with slight gas pedal acceleration on a hill was same kinda jerking feeling, is this normal? it does not do it during normal driving though....been wondering if its the transmission clutch slipping a bit..was thinking about taking it in to have it serviced anyway soon, but this does seem a bit odd.

This is probably normal. There is no clutch; there is no torque converter. When you have the brake on at very low speeds or at a stop, there is no electrical power being applied to MG2, the traction motor. When you release the brake, the system applies a small amount of power to MG2 to simulate the "creep" of an automatic transmission with a torque converter . Under certain circumstances, you may notice this transition, especially if you slowly release the brake. They system does not apply any voltage to the motor when the brake is on as it would be wasteful. There is also a transition during braking at about 5 mph from regen to friction braking that can sometimes be felt.

Edited May 4, 2010 by lolder

[bill77ocean]

This is probably normal. There is no clutch; there is no torque converter. When you have the brake on at very low speeds or at a stop, there is no electrical power being applied to MG2, the traction motor. When you release the brake, the system applies a small amount of power to MG2 to simulate the "creep" of an automatic transmission with a torque converter . Under certain circumstances, you may notice this transition, especially if you slowly release the brake. They system does not apply any voltage to the motor when the brake is on as it would be wasteful. There is also a transition during braking at about 5 mph from regen to friction braking that can sometimes be felt.

Thanks for your comment on this, but like i said i also noticed this on a hill at a red light, i was giving very slight pedal acceleration, and felt the same thing with the brake pedal released..but hmmm, no clutches huh, i realize its a CVT, but thought there would be some sort of clutch on it.. but okay

Edited May 4, 2010 by bill77ocean

[lolder]

Thanks for your comment on this, but like i said i also noticed this on a hill at a red light, i was giving very slight pedal acceleration, and felt the same thing with the brake pedal released..but hmmm, no clutches huh, i realize its a CVT, but thought there would be some sort of clutch on it.. but okay

There is lots of information available about the hybrid Power Split Device (PSD) that many hybrids use. The Toyota and Ford systems are very similar differing mostly in geometry and size. They were developed separately but closely resemble each other in function for the same reason many jet passenger aircraft look alike; the best designs yield similar results. If you pursue learning about these systems, you will realize how revolutionary they are. If you are holding the brake, you can make the ICE start by pushing on the accelerator. This can cause some observable shudder. No hills around here.

[funny]

I have had my car for about 5 weeks now and have experienced a similar jerking phenomenon about 2-3 times. It is a bit unpleasant and different than the minimal sensation of the ICE transition. My initial thought was "transmission slippage" but was not too worried as the car is new.

[ralteredstates]

Ambulance chaser in a different type of suit. Just increases my respect for the profession.

[gemdc]

Don't know about Prius but Fusion Hybrids do have a clutch. Take a look at fordparts.com fusion transmission assemblies and scroll down to the eCvt image. Both the 2013 and the 2010-2012 show a clutch plate between the ICE and the transaxle. Does anyone know what activates that clutch or what purpose it serves? I was surprised yesterday when I saw a CLUTCH in our hybrids.

[acdii]

My guess, it disconnects the ICE from the tranny when in EV mode. I doubt the THSD doesn't use a clutch type mechanism, it has to disconnect the ICE somehow in EV.

[gemdc]

Looking at the various Power Split Device simulations on the Web with regards to the Toyota Prius, it doesn't really appear that it is necessary to disconnect the ICE from anything. It is amazing how the planetary gear setup is able to allow the sun, planets, and ring gear spin at varying speeds. So far as I can determine, the 2010-12 Fusion Hybrid Aisin transmission is almost a duplicate of the Prius transmission. With the exception of the clutch plate of course. The 2013 HF35 evidently connects the main Traction Electric motor via an additional shaft and gear set.

 

Although these transmissions look simple on paper there is a lot of metal there. I read a post on another forum where a guy replaced a burned out Prius transmission with one from a salvaged Prius for about $500. Then he broke out all the copper, aluminum, and steel in his old transmission and sold it as scrap. Got $53 for the metal. Also, the total weight for the metals combined to over 200 lbs. No small chunk if you dropped it on your finger. Those electric motors have a bunch of copper.

 

I am guessing the Ford clutch plate is how they transition between a stopped ICE and the spinning gears so smoothly. People usually say Ford starts and stops the ICE more smoothly than Toyota. I haven't driven another hybrid except my 2010 and now the 2013. That plate may be passive with no actuating mechanism but just allows some slippage when the ICE starts and stops.

 

Could a defective clutch be the source of my rattle when my ICE starts pulling or slacks off pulling? I only hear it below 30 mph so I try to drive over 30 (I wish, then it wouldn't be a problem). I am still waiting for my dealer to get a "comparison" vehicle in inventory.

[gemdc]

The 2010-2012 Fusion Hybrid parts list image shows a clutch plate between ICE and Aisin transmission as well.

[BradS7535]

I just started noticing this on my 2013 HyTi. It has happend 3 times so far. I will be sitting at a stop light, with my foot LIGHTLY on the break and there will be a quick surge. Fist two times it happened I thought someone had bumped into my rear! Any other thoughts on what this could be?

[acdii]

Press harder on the pedal. The computer may not be seeing the brake pedal being depressed, and kicks the EV. It may be something as simple as an adjustment to the brake light switch.

[fusionTX]

I sometimes notice a little jerking in my 2013 just sitting in the garage with the car on in Park.

Edited April 28, 2013 by fusionTX

[terryb]

Darn it! I was sorely tempted to tell you to put down the sun visor and look in the mirror until you said "jerkING" You ruined it. :cry:

 

Joking of course, the only source of motion in the machine would be the ICE providing a HVB charge.

[Nick P]

Is it possible you're feeling the Hill Assist function? When you stop on a hill and remove your foot from the brake to start to move, the brakes remain applied for about 2 seconds to allow time for your foot to travel from the brake to the accelerator without the car rolling. As soon as you press the accelerator, then the brakes release and you move forward. Could that be the jerking you feel? The car doesn't do that on level ground, only on hills. And I believe all Fusions have this.

[corncobs]

I have expierenced the jerking at least twice always with a fully charged HVB and coming to a stop at a traffic light. It doesn't happen all the time and I have not found any real cause that would explain it.

[lolder]

Sometimes at the first application of the brakes when they are wet or cold when you transition below 5 mph, there is a small, momentary discontinuity in the braking action. It usually is not repeated.

[acdii]

Oh you mean that smacking your head against the windshield when too slow for regen and the brakes are real grabby? :) I dont recall the 13 being like that, but man does the 10 like to get grabby! Just touch the brakes going 4 MPH and BAMM your stopped!