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Jerks to left then right... by Mantioch
Started on: 06-19-2014 09:32 PM
Replies: 15 (236 views)
Last post by: 84fiero123 on 06-21-2014 08:28 AM
Mantioch
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Report this Post06-19-2014 09:32 PM Click Here to See the Profile for MantiochClick Here to Email MantiochSend a Private Message to MantiochEdit/Delete MessageReply w/QuoteDirect Link to This Post
'86 SE V6 4spd

First - thank you, everyone, for the support while I restore my Fiero. I've loved these cars since I was a wee lad and I am giddy every time I drive her.

After patching my coolant pipe...ehem... I decided to try her out on the interstate with my new wheels and tires. She drives fantastic! However....

Something I noticed before this whole tire ordeal was that at lower speeds, say 45MPH, there was a slight pull to the left when decelerating. It would pull then let go - it was not constant. However, at 65+MPH it is jerking to the right when accelerating and jerking to the left when I let off the throttle. This is a momentary jerk, not a constant pull, but it is severe at those speeds. I know very little about suspension. Any ideas what this may be?

Thanks again for all of the expert advice.

-Chris
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Mantioch
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Report this Post06-19-2014 09:33 PM Click Here to See the Profile for MantiochClick Here to Email MantiochSend a Private Message to MantiochEdit/Delete MessageReply w/QuoteDirect Link to This Post

Mantioch

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Member since Mar 2014
Oh, one thing to mention - it is not the steering wheel jerking. This is the entire car doing that. The steering wheel stays put.
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gtoformula
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Report this Post06-19-2014 09:44 PM Click Here to See the Profile for gtoformulaClick Here to Email gtoformulaSend a Private Message to gtoformulaEdit/Delete MessageReply w/QuoteDirect Link to This Post
It could be the rear cradle mounts or a loose or worn suspension component. If you aren't familiar with the suspension you may want to have a shop put it up on a hoist and inspect for loose parts. If everything is in good condition then have the rear alignment checked. Keither worn parts or belonging out of alignment can cause this condition.
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Gall757
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Report this Post06-19-2014 10:10 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
It also could be a broken motor mount. Sometimes you have to jack up the engine a little to see a rip in the rubber mount. Do you hear a noise when this happens?
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Mantioch
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Report this Post06-19-2014 10:36 PM Click Here to See the Profile for MantiochClick Here to Email MantiochSend a Private Message to MantiochEdit/Delete MessageReply w/QuoteDirect Link to This Post
No noise of any kind and no vibration. It is just like the car points that way. The car also seems to drift this way and that as well a those higher speed under constant acceleration, but it is very mild.
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lordbg0205
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Report this Post06-19-2014 11:00 PM Click Here to See the Profile for lordbg0205Click Here to Email lordbg0205Send a Private Message to lordbg0205Edit/Delete MessageReply w/QuoteDirect Link to This Post
Rear tie rods? Have an 87 that would roam, jacked up the rear and found the tire wiggled at the 3 and 9 position
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olejoedad
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Report this Post06-19-2014 11:39 PM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post
Control arm bushings, rear ball joints, toe links, engine/trans mounts will all cause the symptoms you are describing.
Cradle bushings are blamed for a lot of problems, usually not the culprit unless everything else is perfect.
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f85gtron
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Report this Post06-20-2014 06:05 AM Click Here to See the Profile for f85gtronSend a Private Message to f85gtronEdit/Delete MessageReply w/QuoteDirect Link to This Post
Too much toe in or out at the back wheels will create this condition. I had that problem with mine. While cornering, under heavy acceleration, it would pull outside the corner, then i would let off the gas and it would dive into the corner. I finally measured my alignment with a tape measure and it measured out crap. I adjusted it the best i could at home and that alone made the condition go completely away.
Check and make sure everything it tight first, if it is, suspect the rear toe values.
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TONY_C
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Report this Post06-20-2014 09:08 AM Click Here to See the Profile for TONY_CSend a Private Message to TONY_CEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by f85gtron:

Too much toe in or out at the back wheels will create this condition. I had that problem with mine. While cornering, under heavy acceleration, it would pull outside the corner, then i would let off the gas and it would dive into the corner. I finally measured my alignment with a tape measure and it measured out crap. I adjusted it the best i could at home and that alone made the condition go completely away.
Check and make sure everything it tight first, if it is, suspect the rear toe values.


I agree. These cars, can be quite scary when the rear toe is not set correctly. It's very unsettling to feel the rear of the car get as loose as it does when the rear toe is out. And it doesn't take much either. Inspect everything for worn parts and then have it aligned.
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Mantioch
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Report this Post06-20-2014 01:16 PM Click Here to See the Profile for MantiochClick Here to Email MantiochSend a Private Message to MantiochEdit/Delete MessageReply w/QuoteDirect Link to This Post
Okay, I have the front jacked up right now. Nothing seems loose, but I really don't know what I am supposed to be checking. Can anyone diagram one of these pics for where I should be looking for looseness? Sorry - I am just not sure what to look for. I was able to wiggle both wheels a bit while holding at a 6 and 12 o'clock position.







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Gall757
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Report this Post06-20-2014 02:37 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
Everything will be nice and tight when you jack up the body and let the wheels drop. Support the car under the spring to compress it, and things will get loose.
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Mantioch
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Report this Post06-20-2014 04:32 PM Click Here to See the Profile for MantiochClick Here to Email MantiochSend a Private Message to MantiochEdit/Delete MessageReply w/QuoteDirect Link to This Post
Ooooooh. Well, yes - that makes sense.
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gtoformula
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Report this Post06-20-2014 05:58 PM Click Here to See the Profile for gtoformulaClick Here to Email gtoformulaSend a Private Message to gtoformulaEdit/Delete MessageReply w/QuoteDirect Link to This Post
Both the front and rear suspension should be inspected, but the condition that you describe is most likely caused by a worn part or an out of alignment condition with the rear suspension.
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Patrick
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Report this Post06-20-2014 06:27 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Mantioch:

Okay, I have the front jacked up right now. Nothing seems loose...


As has been mentioned previously, I'd say the problem is at the other end. I'll guess that it's a worn rear ball joint.

Raise the rear end and grab each tire/wheel at 3 and 9 o'clock and really reef on it violently back and forth. (Obviously you're pushing with one hand while pulling with the other.) The tire/wheel shouldn't move. If it does, get someone else to reef on the tire/wheel while you're watching closely from the other side to see where the play is.

[This message has been edited by Patrick (edited 06-20-2014).]

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Mantioch
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Report this Post06-21-2014 06:30 AM Click Here to See the Profile for MantiochClick Here to Email MantiochSend a Private Message to MantiochEdit/Delete MessageReply w/QuoteDirect Link to This Post
Got it. Thanks, guys! I'll check it out this weekend.
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84fiero123
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Report this Post06-21-2014 08:28 AM Click Here to See the Profile for 84fiero123Click Here to Email 84fiero123Send a Private Message to 84fiero123Edit/Delete MessageReply w/QuoteDirect Link to This Post
Bring it in for a 4 wheel alignment at a reputable alignment shop, it is usually free if they find a bad part during the pre alignment inspection. that is the easiest and best way and will give you a good idea of your problem by a competent alignment tech, hopefully he is a competent alignment tech anyway. If they find a bad part they will not do the alignment until that part is repaired, by them or you or someone else. When they do find the problem and tell you the part and how much its going to cost tell them thank you very much and I will have to think about having you do it. Then buy the part and replace it yourself and bring it back for an alignment, you will have to bring it back for an alignment after replacing any suspension parts that affect the alignment anyway unless you use the procedure outlined extensively in the frequently ask questions part of the forum and even then it is recommended to at least bring it in and have your work checked.

http://www.fiero.nl/forum/Forum9/HTML/000031.html

Steve

------------------
Technology is great when it works,
and one big pain in the ass when it doesn't



Detroit iron rules all the rest are just toys.

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