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Front subframe bolts

Discussion in 'Driveline' started by Bdubbs, Jun 9, 2019.

  1. Bdubbs

    Bdubbs u even lift bro? Established Member

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    Hey guys,

    I'm looking to replace the front subframe bolts in my 90 notch. I'm not sure what's in there and if 9/16 will even fit.

    I'm not familiar with IRS swapped foxes. So I'm not sure if the holes need to be enlarged, or if 12mm is sufficient in these?

    Just looking for some pointers, I've heard this isn't fun.

    Thanks.

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  2. 04torchred

    04torchred Well-Known Member Established Member

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    Does it seem to have play or clunk when you beat on it?

    If its doing fine right now just leave it alone. I also wouldn't expect the fox to be any worse to get at those bolts then a 03-04 cobra. Put a jack under it and just tap out one bolt and measure its thickness if you want. Should be able to caliper the hole also and get an idea if you need to enlarge it.

    If it doesn't seem to clunk or feel like its got play I would leave it as is for now though.
     
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  3. Bdubbs

    Bdubbs u even lift bro? Established Member

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    I have a pretty loud clunking/rattling sound I'm trying to track down. This is while driving normal. I tried a couple more things, just need to take the car out again to see if it's still present.

    I may eventually add the subframe bolts and look into the diff bushings. But I don't want to just throw money at it.

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  4. 04torchred

    04torchred Well-Known Member Established Member

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    Is the IRS still stock as far as you know?

    There is a good chance its the diff bushings(fronts in particular). Mine is starting to make a clunk when I let the clutch out or on/off the gas.

    I have play in my upper control arm bushings so those are most likely my culprit because my diff bushings are already FTBR aluminum.

    You should be able to get it up on jack stands and verify bushings quickly. With the tires off and e-brake on just on/off the clutch and have someone watch the diff and control arms or video it.
     
  5. GodStang

    GodStang Well-Known Member Established Member

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    Depends on the size of the sleeve between the bushing. Dad and I were the first to do the 9/16" 20 years ago. We had brought the bushing to lowe's and was looking for a 14 mm. While we were there we tested the fitment of the 9/16" bolt compared to the 14 mm and we felt it was better plus it has better tensile strength and shear strength. Of all the ones I have done a few had to make the front holes a tad bigger but not all of them.
     
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  6. Bdubbs

    Bdubbs u even lift bro? Established Member

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    Found the source of the noise. It's the rear bumper crash absorber support. I'm having a friend tack weld hopefully this weekend.

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