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Rear Suspension Questions by Ancient Mariner
Started on: 02-08-2019 05:09 PM
Replies: 5 (207 views)
Last post by: mender on 02-10-2019 11:36 AM
Ancient Mariner
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Report this Post02-08-2019 05:09 PM Click Here to See the Profile for Ancient MarinerClick Here to Email Ancient MarinerSend a Private Message to Ancient MarinerEdit/Delete MessageReply w/QuoteDirect Link to This Post

Three questions:

1. What is the height of an 84 - 87 rear spring with no load on it?

2. From what point to what point is the measurement taken?

3. For Toe-In adjustment: Is the toe-in adjusted to 0* with the suspension under normal weight load?

Any help greatly appreciated.

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theogre
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Report this Post02-08-2019 08:00 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post

most of Cradle should have same road clearance as front cross member. Just park on flat level pavement and measure them to ground.

Alignment should be done without anything in the car. No crap in front or rear etc. Most shops don't tell you to pull crap out before doing alignments.

But note that Static alignment done in a shop often won't matter for cars w/ bad suspension parts or lowered cars.
Example: Iffy Cradle and CA bushings alone can steer the car and often in random way as you hit the gas, brakes, or both, or just hitting a pot hole.

Note too many replace the front shocks and not the rear or other way around. If they install gas units then can change road clearance for the axle.

Fiero load rating (GVWR) is calculated w/ 2 adults and 100# cargo but doesn't tell the whole story...
The two adults = ~ 175 lb each = I think ~ 50-60 percentage male model adult (Male Crash test dummy) at the time.
If you and passenger are over then wave good bye to having 100# cargo w/o going over load limit. This will hurt engine and brake performance at minimum. If only a heaver driver in the car then can change alignment some to a lot because car is loaded lopsided. Worse if you have iffy bushings etc.
Many new Owners Manuals give less guessing and puts simple calc/charts saying GVWR − Total People Weight = Cargo Weight Available if any.

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Blacktree
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Report this Post02-09-2019 11:14 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

 
quote
Originally posted by Ancient Mariner:
3. For Toe-In adjustment: Is the toe-in adjusted to 0* with the suspension under normal weight load?

Yes. Alignment specs assume the suspension is at normal ride height. That's true for any car.

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olejoedad
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Report this Post02-09-2019 11:31 AM 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

Any time the front of the car is raised to make an adjustment during the alignment, the front suspension is to be jounced a few times and allowed to settle before rechecking the alignment.

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theogre
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Report this Post02-09-2019 01:20 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post

 
quote
Originally posted by olejoedad:
Any time the front of the car is raised to make an adjustment during the alignment, the front suspension is to be jounced a few times and allowed to settle before rechecking the alignment.
Often This will not help DIY alignment checks or road clearance measurements and applies to rear for many cars not just Fiero. Tires can grip pavement enough to prevent settling after lifting. Low Profile tires are often worse because little sidewall hold in the suspension more in turn keeps car sitting up.

Is part of alignment machines is to have floating sections so wheel can turn and move as you do an alignment.
Front axle is twist and float, back is only a float zone on most machine beds. The floating sections require operator to lock them when car is loaded on the bed too to "Zero out" the float so don't hit a float limit and bind the bed with wheel loads.

Front axle needs easy turning because some tests requires turning the wheels to both ends of steering travel.
Both axles need floating when you jack the car for clearance to adjust parts etc.

Is ways DIYs can "make" a float for an axle but most won't bother checking or even adjusting alignment.

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mender
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Report this Post02-10-2019 11:36 AM Click Here to See the Profile for menderSend a Private Message to menderEdit/Delete MessageReply w/QuoteDirect Link to This Post

I use two sets of floor tiles with grease between them for my DIY alignments.

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