Engine cradle and rear subframe assembly

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09-29-2018, 07:00 PM

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senor honda

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Engine cradle and rear subframe assembly

Engine cradle and rear subframe assembly Has anyone ever replaced the front and rear subframe assemblies? The ones I had on there originally were rusted to death, so I found a good set at the junkyard that I sandblasted and repainted. Everything will be new (polyurethane bushings, new ball joints, arms, etc)

Question I have is, how do I make sure it's put back on straight, not shifted to one side or another, etc. I could probably measure out things at different points, possibly mark the old position of the frames. But how do I know if the replacement ones aren't a little off? I've read that if the engine cradle isn't installed right that there could be camber issues, and I want to make sure the rear one is right t

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09-29-2018, 07:01 PM

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senor honda

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Originally Posted by ToppCat Has anyone ever replaced the front and rear subframe assemblies? The ones I had on there originally were rusted to death, so I found a good set at the junkyard that I sandblasted and repainted. Everything will be new (polyurethane bushings, new ball joints, arms, etc)

Question I have is, how do I make sure it's put back on straight, not shifted to one side or another, etc. I could probably measure out things at different points, possibly mark the old position of the frames. But how do I know if the replacement ones aren't a little off? I've read that if the engine cradle isn't installed right that there could be camber issues, and I want to make sure the rear one is right to avoid things like the driveshaft and the rear end not being aligned straight. Any ideas? Thanks.

My first reaction would be to mark where old cradle was attached to the car.
But you pointed out that the replacement may not be to the original specs.

After thinking a bit, a better measurement would be to carefully measure where the rear suspension points are, so the replacement cradle will be holding the suspension in the same place, even if the replacement cradle is a little off.

And you will need an alignment of the suspension anyway...presuming that you get the cradle back in the car so the suspension points are located in the original position.

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09-29-2018, 07:02 PM

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senor honda

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That's the thing though, the suspension on there is worn out. Bushings are blown out and it won't give me a positive variable to work off of. I mean, I may be splitting hairs on making this issue, but I'm a perfectionist when it comes to doing things. I could go by where the rims are I guess when it's finished. Measuring when everything is put together and making sure the spacing is correct in the wheel wells. But then I have to make sure the motor/trans is straight too (have new motor mounts and trans mount to install). I have to make sure the driveshaft is straight to the carrier, and from the carrier to the rear end. There are so many variables here that it makes my head hurt thinking about it.

The frames (front and back) were pulled from a 300 that didn't have a wreck, so I know they haven't been tweeked at all. They were in good shape. I'm guessing I'll have to pull out the tape measure and make my own "squareness" and hope for the best on the alignment. Initially when I started this project, I didn't figure in that the assembly could be shifted, but when cleaning out the frames on the car for rust, I noticed that the bolts for the frames could be shifted, which brought on this question.

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09-29-2018, 07:02 PM

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senor honda

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I would replace only one thing at a time.
Motor mounts.
Trans mount.
Drive shaft.
Carrier.

Before removing the old cradle,
I would measure where the old bushing had been in relation to a subframe point on each side, and if possible, another point front to rear.
That triangulates where the pivot point had been.

Then replace the rubber bushing....see if where I presumed it was is where the new bushing center is.

I would measure where the rubber bushing had been, to determine where the center is or will be with new bushings.
NAPA, machine shops, speed shops, race car shops, etc. can press bushings in with a hydraulic press

A good starting point is to get equal distances on each side.
If you already removed something, with new bushings, you can re-assemble
it and get bushing distances the same per side.....as a starting point.

You will need a new alignment anyway so get the distances the same per side, before you take it to alignment...if you did not measure in advance.

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10-12-2018, 08:58 AM

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senor honda

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Just an update on progress so far.Got the rear assembly in place. Not fun, but complete. When measuring out if it's straight or not, I measured from the sway bar end link (lower bolt) on both sides to the rear of the trans.

I was dead on, so there wasn't any front to back differences.As for side to side, it didn't change due to the nuts in the subframe are fixed position. So no change there. Dodge did a good job of aligning it right.

Next is the front subframe. I'll be doing the same triangulation once it's in place. It's been a fun job. But definitely an improvement. The prothane bushings in back has stiffened up things tremendously. The car has a much better launch with no wheel hop this time. Can't wait to get the front end done so it's all this way.