# Steering shudder at constant speed



## teum (Jul 27, 2007)

I have a 1994 Sentra 1.6L, 160K miles.

Recently whenever I am at a constant speed, (that is if I am on a flat ground, I'd press the accelerator slightly such that I am neither gaining nor losing speed), the steering assembly shakes badly. It seems to be happening at speed faster than 20mph, but I am not sure if it cannot happen at lower speed.

It feels like the shaking is happening all along the drive axle from the left to the right wheels including the transmission (an automatic). I really cannot pinpoint the source to any single part. As long as I maintain the constant speed, the shaking remains. The shaking is really bad that it feels like it could drop the transmission and rip the drive axles.

I've ruled out the CV joint by driving backward with steering wheel at full left or right position and not hearing any clicking. The CV boots are still intact without any grease seeping out.

I tried searching the archive and have been googling for sometime now, but vibration and shudder problems are not exactly easy to accurately describe to a search engine. So, apology if the question has been ask before.

Thanks in advance.


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## i r teh noobz (Apr 26, 2007)

My '92 did that for a while. I had to change the steering rack to fix it. For the longest time, I was sure it was a CV joint or a wheel bearing.

Does your car leak power steering fluid?


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## Tavel (Aug 21, 2004)

could also be a broken belt in one of the tires. Rotate them and see what happens.


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## teum (Jul 27, 2007)

i r teh noobz said:


> My '92 did that for a while. I had to change the steering rack to fix it. For the longest time, I was sure it was a CV joint or a wheel bearing.
> 
> Does your car leak power steering fluid?


No. The fluid is black, but at normal level and I have not refilled ever.

I am not sure if this is related the vibration problem, but when I turn the steering wheel even a little, I heard what seems to be squeaking sound like plastic rubbing rubber or other plastic somewhere around the other end of the steering shaft. I can try to flush the fluid to see if that will fix the squeak.

Anyway, the steering wheel's freeplay is not any looser than in a newer car (1999). So, how do I know that the steering rack (the whole steering rack?) is the culprit? Any test for that?

Thanks.


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## i r teh noobz (Apr 26, 2007)

Grab one of the wheels and try to move it with your hands. My driver side wheel moved when my rack was bad, but I think its also a sign of bad bearings.


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## teum (Jul 27, 2007)

i r teh noobz said:


> Grab one of the wheels and try to move it with your hands. My driver side wheel moved when my rack was bad, but I think its also a sign of bad bearings.


There wasn't any give.

I exchanged the tires, per Tavel's suggestion, with another sentra's (I have two of them) that does not have this problem. No luck, the problem still exists.

Since I posted here, I took better note of the problem. It happens only at 40 mph or faster. The vibration is almost as if a cylinder is dead. But I'm pretty sure that is not the case as accelerating or decelerating even slightly vanishes the vibration.

I also notice that when starting from stop without overt acceleration, the vibration, in a much smaller intensity, appears too. But accelerating more or less vanishes the vibration. From 5mph to 40mph, I cannot reproduce the vibration.

I drained the ATF and a lot came out, about 1 gallon. The last time I drained it, it was not that much. I don't know if this matters.


Any other clue?


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## i r teh noobz (Apr 26, 2007)

Check your tie rods and struts.


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## teum (Jul 27, 2007)

i r teh noobz said:


> Check your tie rods and struts.


Tie rods and struts are fine. I swapped them (shop realign afterwards) with ones from the other sentra and didn't notice any improvement. While I was down there I checked the balljoints too and found they didn't have any give.

This makes sense since I don't have handling problem at any speed. It is just that damn front-end vibration at a certain accelerator position. Go faster or slower and it's gone.

I have been dreading the possibility that the problem is with the auto transmission. Is there other possibilities beside the auto transmission? (oh please say yes, servicing AT is expensive!)


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## Tavel (Aug 21, 2004)

what about a worn engine mount? that can cause unusual harmonics (vibrating at 40mph but not 42, lol)

I don't think you mentioned that in your troubleshooting.


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## HATEnFATE (Dec 24, 2002)

Have you replaced the wheel bearings yet? I'd put money on it. 

I went with a friend to MA to pick up a nice Sentra. Drove it back to IA with two bad wheel bearings. Couldn't go over 65 mph because the car would shake so voilently. I was waiting for the engine and trans to fall out from under the car the whole way back. replaced the bearings once we returned home and the ride was smooth as glass.


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## dragontoy22r (Jun 27, 2007)

Whenever vibration is present at high speeds, not low, it is 99% of the time balancing of the wheels. I had vibration from the rear of my minitruck, figured it was the driveline somehow. Had that balanced and replaced the u-joints and got nothing out of it. It ended up being the wheels all along. Even Wal-Mart can balance your tires.


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## teum (Jul 27, 2007)

Tavel said:


> what about a worn engine mount? that can cause unusual harmonics (vibrating at 40mph but not 42, lol)
> 
> I don't think you mentioned that in your troubleshooting.



Not worn engine mounts. The rubbers are still bouncy as I just replaced them about 2 years ago.

The vibration is not speed-related. I just went 90mph this morning and the car handled well. The vibration comes at a certain acceleration: about 0 mph^2. IOW, if I go constant speed, it vibrates like a dead cylinder.

I also have come to notice that the vibration exists at all speed, it just that it is barely noticeable until you're doing a constant speed of 40mph or greater.


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## teum (Jul 27, 2007)

Here is another way to visualise the problem: engage the cruise control at any speed and as the speed is stabilising, the vibration becomes more pronounced. When the speed has stabilised, it vibrates so bad it feels like there is a dead cylinder there. Brake or accelerate even a little and the vibration immediately goes away and the car is rock solid.


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## dragontoy22r (Jun 27, 2007)

Man, you have a bad problem, one that takes tearing too much sh*t apart to find, only to find that it's right in front of you.
Try running a high detergent fuel injector cleaner through your system. If you have a bad injector or slightly plugged, you'll end up with a problem like this. 
Have you checked your cap, rotor, wires and plugs? Just possibly you have some fault there. A short, if you will, in a plug wire or a bad contact in the cap and rotor, though you mention speed relation to complicate things, will cause the sensation of a dead cylinder as well.
Good luck friend, trial and error are about all that's on your side in this kind of repair, especially when you've you've narrowed out the most plausible of candidates.


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## HATEnFATE (Dec 24, 2002)

Wheel bearing

a wheel bearing can/will do EVERYTHING your describing once it gets bad enough.

What part of the US do you live in? Close enough for a fellow owner to ride along and give you a second opinion?

P.S. Sentra's are awesome at shelling out wheel bearings. I've replaced them on every B13 sentra I and my friend have owned and a few we didnt' own.


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## dragontoy22r (Jun 27, 2007)

Yeah, but a bad wheel bearing won't let him ride okay at 90 mph, but give him grief on acceleration at any speed. It's something else. I'm sure you and I are gonna kick ourselves in the a** when he finds out what it is. Unless of course we guessed it right.


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## HATEnFATE (Dec 24, 2002)

hopefully it's something stupid but i'm sure your right about us kicking ourselves, unless one of us is right.


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## teum (Jul 27, 2007)

*Problem solved.*



HATEnFATE said:


> hopefully it's something stupid but i'm sure your right about us kicking ourselves, unless one of us is right.


Hah! You may now kick yourself 

I found the cause after numerous experimentation and time wasted, and it is a very unlikely cause. It's the EGR valve! Talk about having a stomach operation for a toothache.

Apparently googling it seems to return many similar reports like this one: Foreign service Motor - Find Articles 



> "When the EGR valve opens during light-to-moderate acceleration, the excessive exhaust gas either kills the No. 1 cylinder totally or causes a severe misfire. The resulting quiver, shudder or shake is most noticeable on automatic transmission Accords. Once you encounter this on a road test, you'll never forget it."


So, when I said earlier that the feeling was like a dead cylinder, I was not that far off. I am glad that after spending ungodly amount of hours swapping various suspension & steering parts, plugging and unplugging misc. small parts, I finally stumbled into this *STOOOOOPID* EGR.


Thanks for the support!


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## HATEnFATE (Dec 24, 2002)

Have you confirmed thats the issue yet?
If it is, kick ass. I'm surprised, I've never heard of this being an issue.


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## dragontoy22r (Jun 27, 2007)

Yeah, kick my ass too. Makes a bit of sense though I've never heard of this causing a shuddering. I guess excess pressure in the EGR system could force pressure against valves...maybe?

Very nice that you found it though!


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