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Rear Suspension Steers under throttle (1988 notchie) by Figero88
Started on: 07-10-2013 12:15 AM
Replies: 7 (266 views)
Last post by: Figero88 on 07-11-2013 07:22 PM
Figero88
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Report this Post07-10-2013 12:15 AM Click Here to See the Profile for Figero88Send a Private Message to Figero88Edit/Delete MessageReply w/QuoteDirect Link to This Post
I have enjoyed my 1988 LS3/F40 6-speed (Archie swapped) Fiero as a fair weather driver for the past 2 years. Within the last month, I have noticed that the car steers to the left under throttle (feels like it is steering from the rear) and when I release the throttle, it straightens back out. I have had the vehicle aligned at the local Chevy dealer (where they checked suspension components for looseness). Once aligned to specs, they found no further issues. The Fiero does have a Quaife LSD, and there are no abnormal sounds emanating from the car or powertrain.

This is my first post. I have enjoyed my highschool dream car thoroughly so far and hope to tap into the incredible knowledge base of this forum. Does anyone know what may be causing this rear steer issue? I am afraid that continued driving may cause something to snap (the "rear steer" is most noticable on the highway). Before this started happening, I did hear/feel a pop from the back of the car.

The specs of what was done during the alignment is listed below:

Alignment:
1. Rear cradle alignment checked, adjusted to specs, tightened.
2. Toe, Camber, Caster, Alignment checked, brought back to specs, tightened-front and rear.
3. Shocks and struts visually inspected. No issues.
4. Steering components and linkage checked. No issues.
5. Front and rear brake pads checked. No issues.
6. CV drive axle boots leaking a little.

I appreciate everyone's help on this topic (tried the search engine here and nothing pertaining to this issue popped up...even when searching the archives)!
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trotterlg
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Report this Post07-10-2013 12:33 AM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
I would look at the left rear suspension. I would say that somehow the left rear wheel is shifting forward when it pulls, that pushes the rear to the right and causes the car to try to go left. It may take quite a load on the wheel to shift it, but I bet you find something. You may try blocking the front wheels and then pulling up against them with the car stationary and see if you see the wheel shift forward. Larry
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Raydar
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Report this Post07-10-2013 12:46 AM Click Here to See the Profile for RaydarClick Here to Email RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
I don't know about the popping noise, but the classic cause of the "throttle steer" issue on the 88 is that the long bolts that go through the knuckle and lateral links will get loose.
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aaronkoch
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Report this Post07-10-2013 01:21 AM Click Here to See the Profile for aaronkochClick Here to Email aaronkochSend a Private Message to aaronkochEdit/Delete MessageReply w/QuoteDirect Link to This Post
Have you verified that the wheel bearings are torqued down to 200 ft lbs?

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fieroguru
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Report this Post07-10-2013 12:03 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
Check the long bolt that attached the lateral (side to side) links to the rear upright. It can work its way loose and allow the wheel to toe in/toe out.

It they are tight, you should probably consider a rod end lateral link upgrade for the rear. With the available torque from the LS3, you could very well just be deflecting the bushings and causing the toe in/toe out. The rod end lateral link upgrade eliminates bushing deflection so no more torque induced toe changes.
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Marvin McInnis
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Report this Post07-10-2013 05:06 PM Click Here to See the Profile for Marvin McInnisClick Here to visit Marvin McInnis's HomePageSend a Private Message to Marvin McInnisEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Raydar:

... the classic cause of the "throttle steer" issue on the 88 is that the long bolts that go through the knuckle and lateral links will get loose.


 
quote
Originally posted by fieroguru:

Check the long bolt that attached the lateral (side to side) links to the rear upright. It can work its way loose and allow the wheel to toe in/toe out.



Yes!


 
quote
Originally posted by aaronkoch:

Have you verified that the wheel bearings are torqued down to 200 ft lbs?



Careful! If you mean the big prevailing-torque nuts that retain the axles in the hubs ... 200 ft-lb is correct. If you mean the bolts that attach the hubs to the knuckles ... No!

[This message has been edited by Marvin McInnis (edited 07-11-2013).]

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FieroMaster88
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Report this Post07-10-2013 06:33 PM Click Here to See the Profile for FieroMaster88Click Here to Email FieroMaster88Send a Private Message to FieroMaster88Edit/Delete MessageReply w/QuoteDirect Link to This Post
Mine does the same thing. I think my bushings in the arms are worn. I plan on changing them soon.

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88 Coupe: 2.0L Turbo 4 Cylinder, W2A, T25 Turbo.
84 Indy #64: Restoration Project, Super Duty 4 swap

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Figero88
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Report this Post07-11-2013 07:22 PM Click Here to See the Profile for Figero88Send a Private Message to Figero88Edit/Delete MessageReply w/QuoteDirect Link to This Post
I appreciate all the responses provided. I won't be able to check the root cause immediately (I will be starting my 2-week annual training period for the reserves in 2 days) but I will use all the responders' expertise to figure out what is wrong and effect a repair. I will post the results here to aid future Fiero enthusiasts going through a similar situation. Thank you!
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