Rear Underbody Inspection

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Inspired by the recent conversation over in the daily threads, I took a look at my rear underbody. Generally speaking, I consider myself lucky - although I hate saying it for fear of jinxing myself.

For a car originating from Long Island, NY, I think it looks pretty good down there. Some components, such as springs, show significant rust, but the body, subframe, and structural reinforcements all look fully intact (probably thanks to some sort of protective undercoating done by the original owner).

Here are a few observations, none of which concern me, unless anyone else tells me otherwise.


This fuel line actually make contact with the tank here. Doesn't wear through it, but seems like a poor installation.
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Does the tank really just hang on this one strap?! What's there seems solid; I just find it odd that I cannot make out any other attachment points.
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Moving on to whatever this thing is called, it looks fine. Not sure what it does; I'm guessing it restricts movement of the subframe (?).
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Moving further back, is it normal that this hanger doesn't have rubber all around but instead has that empty hole at the bottom?
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I really would like to change the differential oil at some point. I understand it's good for 100,000 miles (?), but it's old; I'm guessing it's original. I saw a video of someone siphoning out the old oil through the filler hole without taking off the cover, which seemed pretty easy. Is the tube at the top just a breather? I may have to replace that tube; it looks like it's falling off...
20250416_122921.jpg


These control arms seem to sit differently. See how one sits further forward than the other?
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Few more random pics:
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Looks pretty solid to me. I wish mine was that clean... :bawling:

The rear differential mount is normal. If you've had a 4-wheel alignment done, ask them for the printout of the spec of the rears (most shops don't know the rear has adjustment points).... but unless you've changed out control arms or bushings, it's probably the factory alignment. Gas tank has two straps - 4 attach points.
 
There is a slight difference side-to-side in the rear uca's, the body attach points are different to match. You have marginally more rust than Lazarus; If it bugs you, drop the irs, scotchbrite the parts and paint them.New bushings are available from RA.
Body to IRS bushings are only available in delrin, from bill.
 
I will also mention that if you do want to change the diff fluid, when I did it, I took the rear cover off since it was original fluid and got all the shmoo out of the pumpkin and magnet and it was definitely worth it for me, although it does take some effort since you gotta remove that rear differ carrier that you showed, either method is good, its always better to get some of the old fluid out than nothing. I got a new fel-pro gasket and as the manual states I added Permatex gasket bond and had no leaks whatsoever, also yes that is just a vent for the diff and to be honest mine doesn't have a tube (probably fell off as some point) and its been fine, although now I will probably look and find one but it is just supposed to vent to atmosphere as yours is.
I really would like to change the differential oil at some point. I understand it's good for 100,000 miles (?), but it's old; I'm guessing it's original. I saw a video of someone siphoning out the old oil through the filler hole without taking off the cover, which seemed pretty easy. Is the tube at the top just a breather? I may have to replace that tube; it looks like it's falling off...
View attachment 11404
 

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