Change your subframe bushings!

If you got over 150,000 miles and your Lumina feels kinda ponderous on the road, sloppy despite all the steering components checking good, and maybe you hear the occasional heavy clunk from under the front, especially on turns with hard throttle, or, as I found out since, a loud metallic shriek that occurs when the REAR wheels take a hard bump or dip, you may have the same rotted out and used up subframe bushing situation I did.

This is without a doubt the best money I EVER spent on a car, and even though it seems like major surgery, it's actually pretty simple to do. And with worn out mount bushings, there is not only vertical slop where the subframe moves up and down relative to the body, but little lateral control of the subframe's position under the car either, which is where the steering slop comes into play....see that frame section is the foundation of both your driveline mounting AND provides your entire lower suspension with a place to call home as well...if it moves, the steering moves around with it...conversely, if you steer abruptly, there is a delayed reaction you sense as slop while the subframe wallows around before the chassis can react...a very bad situation.

The most important thing to bear in mind is that as long as the bolts come out without any trouble, you're golden...break one off or spin the nut on the backside in the body, and you're in a world of shit. Not insurmountable, but definitely gonna ruin your day and make a few hour job into an all weekend project. So I'd advise you hit all of 'em with as much WD-40 or PB Blaster or whatever you like a day or two in advance if feasible...there's a "window" in the body where you can see the threads and nut of the front mounts, just remove the lower inner fender fillers to get a good look. You'll probably also find your vacuum reservoir ball laying in the bottom of the driver's side, good time to hang that sucker back up where it belongs.

The rear mounts' threads are a little harder to access, but if you look hard, you'll see where you can hit 'em with the spray...so SOAK the hell out of them all before you start...way before...if you can.

Now, to get prepped to tackle this, you'll wanna take the bolts outta your dogbone roll restrictors up top, take the engine side bolts out and swing them down outta the way. The motor will pitch back a few inches, that's normal. The 3.1 rocks around pretty easily by hand, I've never had trouble getting the bolts back in, I just grab the lift hook on the top of the engine and pull it forward as I feed the bolts through, no problem. You need to do this so you're not fighting the restrictors when it comes time to lower the subframe.

If you're just doing the front, this is all you gotta do for prep. If you're doing the rears, you'll need to unbolt the two large bolts that hold the steering rack to the subframe...this is because when you lower the rear of the frame, the rack will try to come with it, and more than a little motion here can separate the column from the rack, then you got trouble. With the rack free of the subframe, the tie rods will droop down with the frame and suspension when it drops, but the rack will stay in place relative to the steering column, see?

So you'll want the car sitting on two jack stands, as high as you can get it. I like to place them under the boxed channels under the front floor...and I use a thin piece of wood or cardboard between my jack or stands and the body, just so I don't break the paint, I'm a freak like that. I don't want to give rust a place to start.

As always, once you get it lifted high and sitting on the stands, grab and fender and ROCK THE HELL OUT OF IT....if it can be knocked off the stands, better now than when you're under it...safety first...it shouldn't move though. If it's solid, let's change some rubber. :)

You'll want to do one end at a time, front or rear, in my case the front were TRASHED, so I did them first. Need to place the jack now under the subframe, in the middle, be careful you're not putting strain on the oil pan by accident. You'll need the jack there to support the subframe and motor once the bolts come out of the mounts. You'll want to loosen them both a bit first, just to be sure you aren't gonna run into trouble with them, then take one side out completely and back the other off as far as you can while leaving it still threaded a bit...I suppose you could take both out at the same time, but I suspect doing one side at a time helps you line them up as you put them back together...both out, the frame could shift one way or the other, and be a bitch to get lined up again...

So once you got one bolt out and the other loose, SLOWLY let the jack down so the subframe drops, just enough that you can get the bushing between the subframe and body to slip out...and maybe a little more, since your new bushings will be a bit fatter. These bushings "nest" into each other, so pay attention to how they came apart...but putting them back together is just a matter of proper placement of the metal "cups' that support them, and getting the bolt back in...hardest part is having to force the lower to nest inside the upper, it's a tight fit when they are new, some grease or lube spray will help a bit if you find it difficult. I lubed mine and pressed them together BEFORE installing, to make the rubber relax and bit and be nice and slick...seemed to help me push them together once in place on the car. The nice thing is once pressed together, they stay in place in the frame hole while you pilot your bolt.

Jack the frame back up, get this bolt started, and then leave it loose like you did the other side, now remove the other side's bolt, and repeat. Once you have that one started, jack your frame back up, and run those bolts down TIGHT...I forget the spec but I think it was like 150-175 ft lbs ...in other words, damn tight...

If you're doing the rears also, work it the same way, using the jack to support the rear of the frame, and letting one bolt hold the frame's position while doing the opposite side...and just remember to drop the frame no farther than necessary to get the old out and new in, and you should have no problems...

And for corn's sake, don't forget to put the roll restrictors back together when you're done, or the steering rack for that matter too...both could make your test drive when done really exciting and tragic...seen people flip a motor into the radiator because they forgot the restrictors, and though I've never seen anyone try to drive with a rack disconnected from the frame, I can imagine the consequences...LOL....just check your work, remember what you did and don't get too excited to see how your car feels now...

But I'm telling you, it's great...it took 100,000 miles off the road feel of the car...steering is precise as new, and the ride is definitely more solid and competent feeling....

Should have done this back at 120,000 miles, instead of waiting until it felt like the subframe and motor were gonna drive out from under it one day....:iceslolan

What did you use for bushings? Genuine GM, or aftermarket? If aftermarket, what supplier did you use?

Part numbers?



I stuffed polyurethane body bushings on my '68 El Camino, and it was an extremely worthwhile project...but not at all fun.
http://www.chevelles.com/techref/body_bushings.html

What did you use for bushings? Genuine GM, or aftermarket? If aftermarket, what supplier did you use?

Part numbers?



I stuffed polyurethane body bushings on my '68 El Camino, and it was an extremely worthwhile project...but not at all fun.
http://www.chevelles.com/techref/body_bushings.html

I used GM parts from the dealer...I don't have the part #'s handy but I could get them for you....First they got me the set for the rear when I asked for the front...so I'm laying under there with the frame hanging, and realize I got the wrong parts in hand...they look the same but the rear are a bit larger....so I kept them because from my vantage point laying under there I could see the rear were also splitting but not mangled and missing like the front...but it was ok, I had no place to go, and it gave time for me to spray the hell outta the rears too and let 'em soak for two days before attempting to loosen them. Everything came apart real easy...all those times I sprayed the underside clean during the winter finally paid off :iceslolan

PS about $50 for each set (front, rear) and that was with employee discount through my friend who works there...definitely worth it...

Yeah on an old body-on-frame vehicle you could use just about anything that fits...these have to be able to nest into each other and have the right shapes to locate the frame laterally...believe me I considered options before looking to see how they actually worked...

We got an old Jeep out in the garage we're restoring from a big fire, I noticed all the body-frame mounts on it are hockey pucks with a hole for the bolt drilled through the center :rofl:

I was shocked how bad they were....besides the clunks and shrieks I had noticed it seemed like when you turned in hard to the right it yawed excessively, lotta body roll I couldn't quite account for, since the steering and stab bar bushings all checked great and I just replaced all 4 springs and struts last year...turned out the upper front bushing on the driver's side was almost entirely gone, so the body WAS diving, pinching closer to the frame when I really leaned into it (gotta bear in mind I drive this car HARD, not unusual for me to hike the inside rear tire off the ground when cornering, I've been told by persons trying to keep up with me)...the bushing on the other side had that shiny, "burnished" appearance from being scissored back and forth on, frame pivoting on that mount since the other was gone, and the frame hole for the bolt was actually "fishmouthed" slightly from contact with the bolt....pretty serious stuff...supposed to be about 1/2" of rubber center around that bolt, that's what locates the frame on the hole. Center of that bushing was wiped out, non-existent. Can't believe I was still able to drive it as hard as I did, LOL. Yes, I'm nuts, so they tell me.

Thanks Jeffco.
If you open a shop=-next time i,m in Arnold ,Missouri i,m going to see you .