Dropping the Subframe on 1st Gen and Bushing Replacement

[GOT2B GM]

So, I was working on my CS vert today. Put 2 new balljoints and 2 tie rod ends on it to fix a nasty clunk. All of them were worn to a degree, so I replaced them all.

Still had a nasty clunk when turning the steering wheel back and forth.

I got under the car while my girlfriend was moving the steering wheel and found that the rack and pinion bolts were loose where it bolts to the subframe.

Tightened them up, and now the clunk is gone, but the rear of the subframe moves side to side about 3/16" total when turning the steering wheel lock to lock.

I checked the rear subframe bolts with my Snap-on torque wrench and they are torqued to spec, at least 110 ft/lbs.

Could the spacers/retainers/bushings be worn? Or is the nut that sits in the unibody/floorpan supposed to move like that?

Thanks

[Brian P]

the frame is essentially isolated from the car body by the rubber mounts, so if they are worn, or screwed in some other way, you may need to replace em.

[Crazy K]

you don't need ramps. YOU SHOULD NOT USE RAMPS... if you cannot support the rear of the frame.

yes, you can lower the rear frame, a max of about 4 inches without issues.

I would break loose ALL the frame bolts first, in and out maybe one turn.
then raise the car, placing the body on jackstands.
support the rear of the frame with a hydraulic jack.
remove rear bolts, and turn the front bolts about maybe 2 or 3 turns.
let the frame drop some. keep it supported, or you could disconnect the steering intermediate shaft or break a coolant line.
remove the old bushing, install new... pre-greasing everything.

jack it back up and tighten all the bolts.


You should by some Dielectic or sligel or whatever silcone grease, you can get a large tube of dielectic at advanced, or sliglide at NAPA or carquest.

[Bake82]

Here’s the way I just did this on my car.

· Jack up car
· Support on jack stands
· Support engine with engine lift
· Unbolt motor and transmission mount
· Unbolt power steering lines from subframe
· Unbolt steering rack from frame
· Unbolt/pop Ball joints out
· Grab a 3-4 ft 2x4 or 2x6 and put it length wise on your jack and bring it up to the subframe SEE NOTE BELOW
· Loosen and take out all 4 subframe bolts
· SLOWLY lower the subframe, making sure you are not bring the motor down with you and that you have unbolted everything
· Once subframe is down on ground, pull out and do the work you need to do.


*NOTE: if you do not have a 2x4 of 2x6 and have extra jack stands, you can put one or two stand(s) in the rear frame, about 3-4 inches lower than the frame.
-unbolt the 2 rear bolts, and slowly lower the frame to the stand(s), it will balance on the one stand.
At this time remove the two front bolts, and lower all the way to the ground, jack up rear and remove jack stand(s) and lower to ground,

For re-installation do the reverse


NOTE 2. While you have the subframe out, I would replace the following

4 subframe mounts
engine mount
transmission mount
Oil pan gasket, if there is a hint of it leaking, I would CHANGE IT! You need to lower the subframe to change the oil pan gasket, now might be a good time to do it. It’s fairly cheap and easy to do with the subframe out, and you would kick yourself if you had a leak and had to do this all over again!

It took me between 8-10 hours to drop the subframe, change oil pump, and motor mount, and re-install everything. But I had a few other issues to work out.

I would expect to take a full day to do this, if not 2.

Good luck!

[GOT2B GM]

Subframe bushing replacement. Approximately 2 hours for 2 bushings.

Unbolt dogbones from motor


Jack car up and support with jack stands

Remove rack and pinion to subframe mounting bolts.



Crack all four subframe bolts 1-2 turns

Support the subframe with a jack(back or front depending on which bushings you are replacing)


Remove 2 subframe bolts from the side supported by the jack.

SLOWLY lower subframe with the jack, watching for any interferences. You should only have to lower it 3-4 inches at the most.

Pry lower rubber bushing out using a hammer and large flat blade screwdriver. The steel sleeve in the bushing may be rusty and cause some resistance, but it will eventually break loose.

The top bushings should just slide out of the top. If you need to, lower the subframe a little more so can *just* slide them out.

Now you have this.



Clean away any loose rust or dirt from the bushing contact surfaces.

New vs. old


Lubricate all rubber contact surfaces with dielectric grease.

Insert upper bushings into the subframe and center in the hole.

Jack the frame back up so the frame sandwiches the upper bushings against the body.

Lubricate lower bushings and insert into the bottom of the frame, aligning it with the oblong hole and the upper bushing.

It may require to be tapped in with a hammer and a piece of wood.

Make sure it is fully seated against the frame.

Apply antiseize to the subframe bolts, apply dielectric grease to the inside of the bottom plate.

Slide the bottom plate on to the bolt, and bolt the mount up.

Torque bolts to 110 ft/lbs.

Remove jack.

Bolt up the rack and the dogbones.

Now you have:


Lower the car.


Hope that helps

[slick]

I merged hell raiser's dropping the subframe topic and 93luminaz34's subframe and bushing topic together. I'm deleting all extraneous posts.

[slick]

These posts were deleted, but I am re-adding them. If you feel that they are unnecessary for this FAQ, then lemme know and I'll take them back out.

Just wondering, will I be able to get away with lowering just the rear of the subframe enough to change these bushings out?

I plan on driving the car up on ramps, unbolting the rack from the subframe, unbolting the dogbones and then supporting the rear of the subframe with a jack while removing the 2 rear bolts.

Then I will lower the jack slowly until I can pop the bushings out of the frame and put the new ones in.

It's says in my GM service manual that rubber lubrication should be applied to the new bushings, anyone know what product to use?

Florida car so I'm thinking its not frame rot. Gonna have to hit up the dealer this week.

If you replace ALL the retainers bolts and bushing....expect to pay $330CDN at the CDN dealer. I got everything for $200 USD in the states from a dealer down there. It worked out well..I didn't even need to make the drive(friend lives down there and was coming back home!)

[hell_raiser]

the subframe bolts can be a pain!!!

[regalguy26]

inner tie rod ends are making the clunk noise, not the frame mounts, and you can have the rear frame lower than 4 inches, just your stering will seperate my mounts fell out a few months back



you dont need to take anything off but the rear mounts to change them, while it is down do the inner tie rods too, its much easier

[ekim17mr]

Where did youbuy you replacement bushings im looking to replace them on a 1998 buick century

[BXX]

This topic is way old, but, call your local GM dealer to get them. That being said, its kinda rare for Gen 2 cars such as your Century to really wear our the subframe bushings to the point they have to be replaced.

[Addicted2bass]

The passenger side subframe mount is rotted out and essentially no longer there on my TGP. We found this out last night when we started to do the rack and pinion. They are discontinued at the dealership. Are the 94-96 mounts the same?
I found these: http://www.1aauto.com/1A/BodyMounts/...MX00062/363553

[locaste]

My 1998 Buick Century has similar issues with the passenger side rear subframe mount only much worse than illustrated here. The lower bushing is in advanced state of shredding and beyond this, the frame mounting point is very compromised due to corrosion. On my car, this mounting point is boxed rather than the empty tab I see illustrated here. The car has about 122,000 miles on it and otherwise runs great and still looks good. I am looking for recommendations with this situation and an opinion as to how long can I continue to operate the vehicle in this condition.

Thanks:
Lou

[tumbiola]

New to forum, Im going to try and post pics, wait till you see this mess!
I might just have to scrap the car, for all 4 bushings, 8 rubbers, 4 bolts, 4 retainers, ect. $500!
Passenger side
IMAG0188.jpg

Drivers side

IMAG0189.jpg

My wife took the kids to daycare and all four washers/ bushings in the back snapped!
How unsafe is that!

I don't know the diameter of the bottom washer to see if the hole in the subframe is rusted out.
If anyone could help me out with the size so I can fix this or just scrap it. It runs so well ,it's a shame.

[mra32]

Looks like the full set (front and back) can be had for $80 I think Dorman part numbers 924004 and 924005 on Rockauto.com. Oh wait. Those are W-Body ones. You have an H-Body. Completely different cars and it looks like the subframe bushing is similar but not the same.