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Thread: Fiero Cradle issue. Please HELP

  1. #1
    Senior Member MacGyver's Avatar
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    Fiero Cradle issue. Please HELP

    I was wondering if any of you guys have removed that thick rubber pad that lives between the cradle and the Fiero frame. It looks like it's over a 1/2" thick. I wanted to lower the rear end a 1/2" or so and thought if I removed the rubber pad the ground clearance would stay the same and just the body would lower. On the 88 Fieros the cradle is bolted directly to the sub frame. Is their any reason why you can't do it to the older Fieros as well?

    Comments welcome

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  2. #2
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    It may be possible, but I don't think it'll be as easy as simply removing the rubber mount, nor do I think it's a good idea.

    For starters, the rubber mount is made of four sandwiched pieces: an integral steel hat & sleeve assy, two rubber bushings, and a large washer. If you take out the top metal hat & sleeve, and upper rubber mount, there isn't much that will maintain the alignment of the bottom rubber mount. I'm pretty sure it will be able to squirm around without the metal top cap & sleeve. Even very minor shifts in the cradle will give an uneasy rear wheel steering sensation. If you take out the bottom piece as well, then you'll be left with a large hole in the metal cradle. To ensure the cradle stays aligned, you'd need a large diameter metal bushing to center the cradle hole on the much smaller bolt hole in the frame. It's possible, but you'd need access to a lathe to turn a pair of proper alignment bushings.

    The reason I don't think it's a good idea is because unless you raise the front end of the cradle as well, you'll be changing the angle of the cradle in the chassis. That's going to change suspension dynamics, perhaps not significantly, but then again, you couldn't know unless you analyzed it. Most notably you'd lose some anti-squat, but a host of other parameters would likely be affected too.

    You also mention that you wouldn't lose any ground clearance, but that's not entirely true. The lowest part of the Fiero in the rear is the bottom of the cradle, which is also level with the bottom of the seat pan. If you raise the cradle into the chassis, then the chassis will sink closer to the ground. If you couple that with drop springs, you could easily find your seat pan within 3" of the street even though your cradle maintains 5" clearance. It simply won't be the lowest hanging part.

  3. #3
    Senior Member MacGyver's Avatar
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    Quote Originally Posted by Bloozberry View Post
    It may be possible, but I don't think it'll be as easy as simply removing the rubber mount, nor do I think it's a good idea.

    For starters, the rubber mount is made of four sandwiched pieces: an integral steel hat & sleeve assy, two rubber bushings, and a large washer. If you take out the top metal hat & sleeve, and upper rubber mount, there isn't much that will maintain the alignment of the bottom rubber mount. I'm pretty sure it will be able to squirm around without the metal top cap & sleeve. Even very minor shifts in the cradle will give an uneasy rear wheel steering sensation. If you take out the bottom piece as well, then you'll be left with a large hole in the metal cradle. To ensure the cradle stays aligned, you'd need a large diameter metal bushing to center the cradle hole on the much smaller bolt hole in the frame. It's possible, but you'd need access to a lathe to turn a pair of proper alignment bushings.

    The reason I don't think it's a good idea is because unless you raise the front end of the cradle as well, you'll be changing the angle of the cradle in the chassis. That's going to change suspension dynamics, perhaps not significantly, but then again, you couldn't know unless you analyzed it. Most notably you'd lose some anti-squat, but a host of other parameters would likely be affected too.

    You also mention that you wouldn't lose any ground clearance, but that's not entirely true. The lowest part of the Fiero in the rear is the bottom of the cradle, which is also level with the bottom of the seat pan. If you raise the cradle into the chassis, then the chassis will sink closer to the ground. If you couple that with drop springs, you could easily find your seat pan within 3" of the street even though your cradle maintains 5" clearance. It simply won't be the lowest hanging part.
    Thank you for all your input. I didn't know about the larger mounting holes in the cradle. Good to know that it's not like the 88s. My car has a sway bar mounted to the bottom of the cradle which currently makes it the lowest part of the car in the rear. Maybe I may end up removing the sway bar and see if it really makes that much difference. Then I'll be able to set the coil overs to drop the rear a bit.

  4. #4
    Senior Member Don's Avatar
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    Sean;

    I removed the rubber mounts for the rear cradle mounts and replaced them with 2x3 box metal welded to the tops of the cradle. I still kept the height though so that the front mounts also lined up properly. Aluminium front mounts from Rodney and solid rear mounts make the pre 88 cradle mount the same as the 88 for a more solid feel. I carefully measured where the rubber cradle mounts lined up when installed and then made the marks on the cradle and aligned the new metal box into the same place and welded. The nuts inside the frame move a certain amount and the front cradle mounts line up the cradle so you can move the rear nut a bit to line everything up when putting the rear nut in place.

    Have you thought about moving the sway bar to the upper part of the front cradle cross piece? You have all the exhaust coming out the rear on both your cars and there could be room to mount the sway bay on top rather than the bottom. I planned on having a look at that this week for my build so I can do the mounts and get everything aligned before painting the cradle.

    Cheers
    Don
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    Prova Countach 5000QV

  5. #5
    Senior Member MacGyver's Avatar
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    Quote Originally Posted by Don View Post
    Sean;

    I removed the rubber mounts for the rear cradle mounts and replaced them with 2x3 box metal welded to the tops of the cradle. I still kept the height though so that the front mounts also lined up properly. Aluminium front mounts from Rodney and solid rear mounts make the pre 88 cradle mount the same as the 88 for a more solid feel. I carefully measured where the rubber cradle mounts lined up when installed and then made the marks on the cradle and aligned the new metal box into the same place and welded. The nuts inside the frame move a certain amount and the front cradle mounts line up the cradle so you can move the rear nut a bit to line everything up when putting the rear nut in place.

    Have you thought about moving the sway bar to the upper part of the front cradle cross piece? You have all the exhaust coming out the rear on both your cars and there could be room to mount the sway bay on top rather than the bottom. I planned on having a look at that this week for my build so I can do the mounts and get everything aligned before painting the cradle.

    Cheers
    Don
    Don,

    That's a good idea worth looking into. I haven't really took the time to look it over all that well. I also need to change out the rear springs. Dave had put what looks like 450 to 475 lb springs back there. Way to much for the street. I think he was trying to keep from bottoming out. I think I put 325lb 12" springs in my 430 which is a bit stiff, but still gives me a good ride. Hopefully if I move or get rid of the sway bar I can get this to work with lighter springs.

  6. #6
    The best way to fix all the problems with the pre 88 cradle is to replace it with a 88 cradle. The only modification you need to do is to reposition the top mount of the strut which requires a adapter plate available from WestshoreFabricating.com.

    Joe Sokol

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