What's the deal with this body mount?

[Mastiff]

When my truck flexes, the body seems to be moving a lot. Check out the bumper here:

I flexed it a little in the garage to see what I could see, and the passenger front body mount (under the rad) is pulling up:

The rubber doesn't look rotten or anything, and the nut/bolt look like new. I thought maybe it just needed to be snugged up, but I can't budge the nut either direction. The only thing I haven't done is apply an impact to it. What do you guys think?

 

[63chevyll]

The mount might be a little rotten on the inside, but I'd say that about normal chevy frame and mount flexing

 

[Mastiff]

The mount might be a little rotten on the inside, but I'd say that about normal chevy frame and mount flexing

Only does it on that side. The other side stays tight, the top mount doesn't pull away like that.

 

[K85 Octane]

<-- curiously wondering where the thread stops on that bolt. Maybe the nut is bottomed out because the rubber has compacted or some such nonsense. Maybe stack a bunch of washers under the nut temporarily and see what happens.

I've got poly throughout, zero flex in all my pictures Going to be even better once the front half cage is done

 

[colbystephens]

<-- curiously wondering where the thread stops on that bolt. Maybe the nut is bottomed out because the rubber has compacted or some such nonsense. Maybe stack a bunch of washers under the nut temporarily and see what happens.

Here's a pic of the condition of my bolts when removed for my 1" body lift + new body mount bushings. Stock, the core support bolts are 5" flange bolts, Grade 5, 1/2 diameter, 13 thread count. Shown as bolts 3 and 4 (L to R) in the pic below. I don't think you're bottoming out the threads on the shoulder of the bolt.

My truck has no rust, and has lived in NV its whole life. Those bolts are in bad shape, and I suspect you could be getting some body/frame flex as a result of that.

This thread might help you out:
http://coloradok5.com/forums/showthread.php?t=308391&highlight=body+lift

 

[Mastiff]

The exposed part of the bolt looks beautiful here. Maybe it's hard to tell in the pic. It could be rusted up inside I guess.

Anyway, I'm not sure you guys are seeing what I'm seeing. If you look closely in the second pic, you can see the bottom part of the rubber, where it sort of mushrooms down. It's pulling up away from the frame like I'd expect it to if the lower rubber was shot or something. On the other side if I lift the truck the same way, it all stays compressed together. The flex visible in the bumper is surely coming from this mount allowing the body to pull up from the frame.

I know this probably just means I need to replace all the mounts, but I'd like to at least try tightening it up in case that's all it needs. Is the bolt tack welded or something on the top? Can/should I put the impact on it to see if it'll loosen up? Is it possible to get a wrench on the bolt without removing the radiator?

 

[6.2Blazer]

There is some play in the mount and I agree that tightening it up may fix it. I'm thinking you need to put a wrench on the top part to hold it...been a few years since I did mine but thinking that is the way it was set up. Also remember needing an impact on most of the bolts.

 

[colbystephens]

You do need a wrench on the top. Actually, if I recall right, you need a socket/extension/etc. to get down inside the core support. I liked using an impact on mine.

 

[Mastiff]

You do need a wrench on the top. Actually, if I recall right, you need a socket/extension/etc. to get down inside the core support. I liked using an impact on mine.

I posted on your other thread, but did you remove the radiator?

 

[Hogback Fabrication]

The frames on the straight axle Chevy trucks are REALLY flexible, I've been there for sure



I actually addressed the issue because my mechanical clutch linkage wouldn't work with the suspension flexed out. Poly body mounts completely fixed it.

Don't expect them to take the frame flex out, they'll just reduce it some.

 

[chulisohombre]

Lolls like the bolt is staying in place with flex. Possible the bolt has rotted inside and is broken? Mine had a couple shims and a bolt head up top. But it's a 72. I have zero flex now with poly bushings and everything stays put.

 

[colbystephens]

I posted on your other thread, but did you remove the radiator?

Nope. You put a socket wrench into the vertical channel/box tube next to the radiator. They're kind of a pain to get to.

 

[Mastiff]

Lolls like the bolt is staying in place with flex. Possible the bolt has rotted inside and is broken? Mine had a couple shims and a bolt head up top. But it's a 72. I have zero flex now with poly bushings and everything stays put.

Good call. I haven't seen it all apart, but maybe the bottom half is seized in place to a sleeve, which is why it won't turn either? I'm going to have to apply some impact power to this thing and see what gives...

 

[dremu]

I'm going to have to apply some impact power to this thing and see what gives...

I see what you did there.

-- A

 

[Stomis]

Just wait until it all starts pulling through the mount! I second that the rubber is probably rotten inside.

 

[scottladdy]

There are two access holes in the radiator core support, accessible from the front when you remove the grill. You will need a wrench to reach in and down onto the top of the bolt to engage the hex. Apologies but I don't recall the socket size. Very easy to see where they are once you remove the grill. A second set of hands is helpful here, but not required.

IIRC torque spec was 40 ft lbs. but please confirm.

For any body mounts that have a captive nut on top, do not use an impact wrench on these. The nut is a large square deal trapped under a steel cage that is spot welded to the surrounding steel. Very easy to spin the nut free of the cage after all these years. These are the mounts where the bolt head is exposed from underneath.

 

[Mastiff]

Well, I got it apart. The bolt is rusted quite a bit. The bushing itself doesn't look real bad, not sure I can totally explain the way it was pulling apart. I think I see some body mounts in my future though. Any preferences out there? Energy, Daystar, Prothane, whatever ORD sells?

Here's some pics of the access holes, just for the record. The nuts and bolts both take a 3/4" socket.

 

[rebelgregory]

I used the ORD poly mounts along with their 1" BL. Don't know if you're interested in the body lift, but it will help you with your fender trimming issue with your new tires.

 

[63chevyll]

The ORD ones quality stuff, and with the 1 inch body lift you gets new bolts also

 

[Mastiff]

I used the ORD poly mounts along with their 1" BL. Don't know if you're interested in the body lift, but it will help you with your fender trimming issue with your new tires.

A lot of people advocate the body lift, but I'm going to pass. It's already a bit higher than I want, and I think I'm willing to do the little bit of trimming required.

Looks like I'll either do ORD or Prothane. Daystar and Energy either don't offer kits for 83 K5, or are going out of their way to make it hard to figure it out. Every place I look for these kits they just give some crazy long part # and won't say what it's supposed to fit. Prothane has a good site and I found the part right away. $75 on Amazon, not sure the extra $45 is worth it for the ones from ORD (not that $45 means much given the frustration I expect during install)?

http://www.amazon.com/Prothane-7-110-Body-Mount-Bushing/dp/B003AVT2H8