Pennock's Fiero Forum
  Technical Discussion & Questions
  The suspension mystery continues, and I don't know where to go from here.

Post New Topic  Post A Reply
Email This Page to Someone! | Printable Version


next newest topic | next oldest topic
The suspension mystery continues, and I don't know where to go from here. by Threedog
Started on: 08-01-2020 05:09 PM
Replies: 17 (291 views)
Last post by: Threedog on 08-04-2020 02:26 PM
Threedog
Member
Posts: 1198
From: Denver, Colorado
Registered: Jun 2013


Feedback score: (1)
Leave feedback





Total ratings: 62
Rate this member

Report this Post08-01-2020 05:09 PM Click Here to See the Profile for ThreedogClick Here to Email ThreedogSend a Private Message to ThreedogEdit/Delete MessageReply w/QuoteDirect Link to This Post
Car: 3800SC 87 Fiero

Issue: The car bounces back and forth like there are no shocks on acceleration above 20 mph.

Basically, I will be accelerating and everything will be fine and dandy until I hit a bump or jerk the steering wheel back and forth quickly. Then the back of the car gets WAY out of line. It bounces back and forth so much that if I don't let off the accelerator I would lose control of the car. If I let off the accelerator, the car straightens itself back out after a bump or two. If I brake, the issue stops immediately (the harder I brake, the faster the bouncing stops).


This started when I went to lower the car. I had it on lowering springs, I took it to the alignment shop, drove it home and had this issue. I also replaced literally every part of the suspension.

What I replaced:
- Struts in back twice, shocks in front twice, didn't fix it. I currently have coilovers on the rear, but going back to stock in the rear did NOT fix the issue.
- Springs: I have tried lowering springs, stock springs, did not fix the isssue
- The bushings in the rear are old poly ones, the front are new poly ones
- All ball joints are brand new and from Rodney Dickman
- Rear tie rod ends are brand new
- I replaced all bolts(A-Arm, Cradle, and Strut tower bolts) with metric 10.9 and grade 8 bolts of the exact same size and length. I have tried going back to the stock bolts everywhere, didn't fix the issue.


Does anyone have any idea what could be causing this?
IP: Logged
PFF
System Bot
IMSA GT
Member
Posts: 8671
From: Nazifornia
Registered: Aug 2007


Feedback score: (5)
Leave feedback





Total ratings: 241
Rate this member

Report this Post08-01-2020 05:23 PM Click Here to See the Profile for IMSA GTClick Here to Email IMSA GTSend a Private Message to IMSA GTEdit/Delete MessageReply w/QuoteDirect Link to This Post
I know this may be a stupid question but are you sure the upper frame rails haven't rusted through? It seems like you covered all the bases with the suspension so I would look at the frame just for the hell of it.
Here is a pic from someone in Canada who had issues. You need to remove the wheel well liner to see this part of the car. If this is the issue, unfortunately the car is finished.

You can see that when this occurs, the only thing holding the entire rear of the car together is the front cradle mounts.

[This message has been edited by IMSA GT (edited 08-01-2020).]

IP: Logged
Threedog
Member
Posts: 1198
From: Denver, Colorado
Registered: Jun 2013


Feedback score: (1)
Leave feedback





Total ratings: 62
Rate this member

Report this Post08-01-2020 05:36 PM Click Here to See the Profile for ThreedogClick Here to Email ThreedogSend a Private Message to ThreedogEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by IMSA GT:

I know this may be a stupid question but are you sure the upper frame rails haven't rusted through? It seems like you covered all the bases with the suspension so I would look at the frame just for the hell of it.
Here is a pic from someone in Canada who had issues. You need to remove the wheel well liner to see this part of the car. If this is the issue, unfortunately the car is finished.




So, they have certainly not rusted through, there is next to ZERO rust on the vehicle (it is from New Mexico and the body has like 50k miles).


The only way I could see those nut housings being loose is if they got over torqued and broke the welds, but I was able to get them as tight as ever when I checked just now.
IP: Logged
Rickady88GT
Member
Posts: 9240
From: Central CA
Registered: Dec 2002


Feedback score: N/A
Leave feedback





Total ratings: 195
Rate this member

Report this Post08-01-2020 05:44 PM Click Here to See the Profile for Rickady88GTClick Here to Email Rickady88GTSend a Private Message to Rickady88GTEdit/Delete MessageReply w/QuoteDirect Link to This Post
When you say "bounce" is this up and down or does the car sway back and forth?
IP: Logged
Threedog
Member
Posts: 1198
From: Denver, Colorado
Registered: Jun 2013


Feedback score: (1)
Leave feedback





Total ratings: 62
Rate this member

Report this Post08-01-2020 05:46 PM Click Here to See the Profile for ThreedogClick Here to Email ThreedogSend a Private Message to ThreedogEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Rickady88GT:

When you say "bounce" is this up and down or does the car sway back and forth?


Honestly, its both. Or the up and down is so severe I can't tell. If I continue to accelerate and let it get worse and worse the front suspension bottoms out.

It is definitely not a "sway". I currently can't do more than 30 miles an hour because it is so bad.
IP: Logged
Threedog
Member
Posts: 1198
From: Denver, Colorado
Registered: Jun 2013


Feedback score: (1)
Leave feedback





Total ratings: 62
Rate this member

Report this Post08-01-2020 05:48 PM Click Here to See the Profile for ThreedogClick Here to Email ThreedogSend a Private Message to ThreedogEdit/Delete MessageReply w/QuoteDirect Link to This Post

Threedog

1198 posts
Member since Jun 2013
I did shorten the front bump stops by about an inch. Could that have caused it? I have stronger springs in the front now, and I feel like because it only happens under acceleration the issue has to be in the back.


Edit: Nevermind, the issue existed before and after I shortened them.

[This message has been edited by Threedog (edited 08-01-2020).]

IP: Logged
qwikgta
Member
Posts: 4493
From: Virginia Beach, VA
Registered: Jan 2001


Feedback score:    (21)
Leave feedback





Total ratings: 83
Rate this member

Report this Post08-01-2020 07:47 PM Click Here to See the Profile for qwikgtaClick Here to Email qwikgtaSend a Private Message to qwikgtaEdit/Delete MessageReply w/QuoteDirect Link to This Post
Not sure if you covered the rust issue or not but I guy in the local club had an issue like this and it was b/c his cradle was loose b/c of rust issues. All new parts and it could not hold an alignment. Front cradle was the issue. Car felt loose all the time. Even put in a new front cradle thinking it was bent or something but it was the space frame that was shot. He parted the car b/c it had a lot of great stuff on it and thru the frame away.

Rob
IP: Logged
Threedog
Member
Posts: 1198
From: Denver, Colorado
Registered: Jun 2013


Feedback score: (1)
Leave feedback





Total ratings: 62
Rate this member

Report this Post08-01-2020 09:11 PM Click Here to See the Profile for ThreedogClick Here to Email ThreedogSend a Private Message to ThreedogEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by qwikgta:

Not sure if you covered the rust issue or not but I guy in the local club had an issue like this and it was b/c his cradle was loose b/c of rust issues. All new parts and it could not hold an alignment. Front cradle was the issue. Car felt loose all the time. Even put in a new front cradle thinking it was bent or something but it was the space frame that was shot. He parted the car b/c it had a lot of great stuff on it and thru the frame away.

Rob


Yeah, everything is good in terms of rust, not a spot on it.

I did have the front cradle removed and powdercoated..but I have checked. All bolts are right, it was put together correctly.
I am going to change the front inner and outer tie rod ends as well, to see if that fixes the issue. Maybe it is more back and forth than up and down?
IP: Logged
cmechmann
Member
Posts: 963
From: Baltimore Md.
Registered: Dec 2012


Feedback score: (1)
Leave feedback

Rate this member

Report this Post08-01-2020 10:41 PM Click Here to See the Profile for cmechmannClick Here to Email cmechmannSend a Private Message to cmechmannEdit/Delete MessageReply w/QuoteDirect Link to This Post
You state this is a 3800 swap? And you have lowered it?
This may may be an off the wall check, but check to make sure none of your cv joints are binding. Pay close attention to the inners. You could have took out one of the inner cup bearings when taking apart the suspension. Or one could be pushing in too far into the tripot. This will give a loping feel. And sometimes very violent.
Recently replaced the center section on the right side. I had forgotten what I had used before and installed one that was about 1 inch too long. Every time the car loaded down the rear(over bump, acceleration, etc.) would have a violent vibration.
IP: Logged
Will
Member
Posts: 13340
From: Where you least expect me
Registered: Jun 2000


Feedback score: (1)
Leave feedback





Total ratings: 234
Rate this member

Report this Post08-02-2020 03:29 PM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
Did you have the car aligned after you installed the lowering springs?
Check the torque on the big bolts that join the strut to the suspension upright. I've known alignment technicians not to torque those fully, which results in big handling problems when they slip
IP: Logged
Threedog
Member
Posts: 1198
From: Denver, Colorado
Registered: Jun 2013


Feedback score: (1)
Leave feedback





Total ratings: 62
Rate this member

Report this Post08-02-2020 04:54 PM Click Here to See the Profile for ThreedogClick Here to Email ThreedogSend a Private Message to ThreedogEdit/Delete MessageReply w/QuoteDirect Link to This Post
My diagnostic is going to be the following:

- First I am going to replace the front tie rods (inner and outer), as it might be a "side to side" thing.
- Then I will have it aligned (even though the issue first showed up when the car was aligned)
- Then I will check the CV axles. They are brand new, and were the same length as the old ones, but it is possible one isn't in all the way or there might have been a small difference in length(is it possible to over torque the axle nuts on the bearing side? I just made those tight instead of putting them to a specific torque).


When I took my front inner and outer tie rods ends off, I discovered this. Is it normal? (this is the passenger side of the steering rack, tie rod removed, the bolt I am pulling on is the outside steering damper bolt)

video: https://drive.google.com/fi...IDF/view?usp=sharing

If it is not normal, could it be causing major issues? And should I be rebuilding or replacing my steering rack?

[This message has been edited by Threedog (edited 08-02-2020).]

IP: Logged
PFF
System Bot
Threedog
Member
Posts: 1198
From: Denver, Colorado
Registered: Jun 2013


Feedback score: (1)
Leave feedback





Total ratings: 62
Rate this member

Report this Post08-02-2020 04:56 PM Click Here to See the Profile for ThreedogClick Here to Email ThreedogSend a Private Message to ThreedogEdit/Delete MessageReply w/QuoteDirect Link to This Post

Threedog

1198 posts
Member since Jun 2013
Edit: Double Post

[This message has been edited by Threedog (edited 08-02-2020).]

IP: Logged
Rickady88GT
Member
Posts: 9240
From: Central CA
Registered: Dec 2002


Feedback score: N/A
Leave feedback





Total ratings: 195
Rate this member

Report this Post08-02-2020 05:57 PM Click Here to See the Profile for Rickady88GTClick Here to Email Rickady88GTSend a Private Message to Rickady88GTEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Threedog:

My diagnostic is going to be the following:

- First I am going to replace the front tie rods (inner and outer), as it might be a "side to side" thing.
- Then I will have it aligned (even though the issue first showed up when the car was aligned)
- Then I will check the CV axles. They are brand new, and were the same length as the old ones, but it is possible one isn't in all the way or there might have been a small difference in length(is it possible to over torque the axle nuts on the bearing side? I just made those tight instead of putting them to a specific torque).


When I took my front inner and outer tie rods ends off, I discovered this. Is it normal? (this is the passenger side of the steering rack, tie rod removed, the bolt I am pulling on is the outside steering damper bolt)

video: https://drive.google.com/fi...IDF/view?usp=sharing

If it is not normal, could it be causing major issues? And should I be rebuilding or replacing my steering rack?



My opinion is that that is to much play. But that is not causing your rear end bouncing problem.
How much play do you have in your steering wheel? Turn the steering wheel back and forth slowly to see how far it turns before you feel it statr to turn your front wheels. The play in that rack can cause some slop in the steering wheel or mushy feeling steering.
IP: Logged
ag9123
Member
Posts: 247
From: Chicago, IL USA
Registered: Sep 2013


Feedback score: (1)
Leave feedback

Rate this member

Report this Post08-02-2020 07:40 PM Click Here to See the Profile for ag9123Click Here to Email ag9123Send a Private Message to ag9123Edit/Delete MessageReply w/QuoteDirect Link to This Post
Did you replace the rear lower ball joints? They're hard to check for looseness without getting a pry bar in there and checking for play. My left rear lower ball joint was shot but seemed ok when tugging on the wheel up and down and side to side. When I took the control arm off to install poly bushings, I could see the ball joint was dry as a bone and ready to pull out of the socket! Was getting a MAJOR wiggle when doing any type of steering maneuver at highway speeds. Bad enough that I would need to slow down til it stopped. Verify that the cradle bolts are torqued properly and check ALL the suspension bolts for tightness including the rear tie rods.

------------------
1984 Indy Fiero

[This message has been edited by ag9123 (edited 08-02-2020).]

IP: Logged
Threedog
Member
Posts: 1198
From: Denver, Colorado
Registered: Jun 2013


Feedback score: (1)
Leave feedback





Total ratings: 62
Rate this member

Report this Post08-02-2020 07:44 PM Click Here to See the Profile for ThreedogClick Here to Email ThreedogSend a Private Message to ThreedogEdit/Delete MessageReply w/QuoteDirect Link to This Post
I replaced all ball joints, and have checked every bolt.

The more questions I answer, the more I think about this..

Is it possible that an improper alignment has been the cause of all of this? It actually started after I got it aligned.

I rebuilt the whole suspension, drove it to the shop, then when I left the shop it started doing this. I can’t quite remember if it was doing this before I went to the shop (it was a short drive, and months ago)...but could they have caused this somehow? Even though the machine said the car was aligned?
IP: Logged
ag9123
Member
Posts: 247
From: Chicago, IL USA
Registered: Sep 2013


Feedback score: (1)
Leave feedback

Rate this member

Report this Post08-02-2020 07:52 PM Click Here to See the Profile for ag9123Click Here to Email ag9123Send a Private Message to ag9123Edit/Delete MessageReply w/QuoteDirect Link to This Post
Did you check all the nuts and bolts after the alignment? It's possible they left something loose...it happens. Hopefully they gave you a before and after printout of the alignment specs. Can you post those here if you have it?

------------------
1984 Indy Fiero

IP: Logged
Blacktree
Member
Posts: 20297
From: Central Florida
Registered: Dec 2001


Feedback score:    (11)
Leave feedback





Total ratings: 349
Rate this member

Report this Post08-04-2020 08:52 AM Click Here to See the Profile for BlacktreeClick Here to visit Blacktree's HomePageClick Here to Email BlacktreeSend a Private Message to BlacktreeEdit/Delete MessageReply w/QuoteDirect Link to This Post
I know from personal experience, if the rear toe is set wrong, you'll have a wild ride. This is especially true if the rear wheels are toed out. Every time you hit a water puddle or a bump or something, the rear end will step out.

Also, once an alignment shop forgot to tighten the bolts on one of the rear struts after setting the camber. It was like riding a bucking bronco! I got a free alignment out of that...
IP: Logged
Threedog
Member
Posts: 1198
From: Denver, Colorado
Registered: Jun 2013


Feedback score: (1)
Leave feedback





Total ratings: 62
Rate this member

Report this Post08-04-2020 02:26 PM Click Here to See the Profile for ThreedogClick Here to Email ThreedogSend a Private Message to ThreedogEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks for the help guys! I went ahead and got a steering rack anyway, figured it couldn't hurt (I also didn't like the play in the current one, and it was the last mechanical part that was 30+ years old!). Gonna install this week and hopefully get it aligned by Friday, will report back.
IP: Logged

next newest topic | next oldest topic

All times are ET (US)

Post New Topic  Post A Reply
Hop to:

Contact Us | Back To Main Page

Advertizing on PFF | Fiero Parts Vendors
PFF Merchandise | Fiero Gallery | Ogre's Cave
Real-Time Chat | Fiero Related Auctions on eBay



Copyright (c) 1999, C. Pennock