Removal/Installation Front SubFrame

[dex_hamilton]

I've Got a base 92 Lumina 3.1, I need to replace the Front subframe due to damage of the sway bar mounts ripping out of place. Quistion is, can i get away with just unbolting trans/motor mounts, and the A-arms from subframe (with proper engine support from top) ? Or will the A arms not have enough clearance to drop the frame? If thats the case I'm thinking I could take the top 3? bolts off that hold the strut/spring from each strut towwer?

[l67ss]

Itd b easier to just pop the balljoints loose, but if you cant you can drop the struts with it, just make sure to hang the calipers outta the way

I've Got a base 92 Lumina 3.1, I need to replace the Front subframe due to damage of the sway bar mounts ripping out of place. Quistion is, can i get away with just unbolting trans/motor mounts, and the A-arms from subframe (with proper engine support from top) ? Or will the A arms not have enough clearance to drop the frame? If thats the case I'm thinking I could take the top 3? bolts off that hold the strut/spring from each strut towwer?

[rich_e777]

There is a way to do the subframe mounts without having to completely lower the entire thing. The book and others recommend undoing the steering shaft pinch bolt to avoid damage. If you support the weight of the engine/trans from the top it will make it easier to use a jack to support the subframe from below and the just do the back then the front. I was able to lower my rear subframe enough to swap swaybars and It looked like I could do the rear mounts as well.

[rich_e777]

Itd b easier to just pop the balljoints loose, but if you cant you can drop the struts with it, just make sure to hang the calipers outta the way

If you do that you might need an alignment afterwards. When I installed my front tower brace I was also changing brake pads, and had the car up on stands. Well like the part-time genius that I am, I pulled the strut plate off the drivers side. Only a part-time genius and it was my day off. Had a wicked pull to the left that an alignment corrected.

[dex_hamilton]

Thank you all! I'll report back once I'm done!

[l67ss]

Good luck man

Thank you all! I'll report back once I'm done!

[Schurkey]

You're going to drop the subframe to fix SWAY BAR MOUNTS? The bolts ripped out of the subframe? Is the subframe structurally unsound due to rust or something?

 

I'd repair the existing bolt holes; spend 1/10 the money, and probably 1/10 the time. Less than that if oversize bolts and an appropriately-sized tap can be made to do the job.

[White93z34]

I've seen that damage before. Spencer posted pictures of his 89's subframe with the entire area around the swaybar mount ripped right out.

 

the holes for his inner swaybar bushings are not tapped, they are nut/bolted.

[GnatGoSplat]

If the nut/bolt holes are pulled out/enlarged, how about using the shackles from a DOHC sway bar? Not sure if shackles is the right word for them, but I can't think of what else to call them.

[White93z34]

I considered that. might be a bandaid fix, they do use the holes that the smaller swaybars are bolted on with as guides though... Maybe worth a shot to try, but I don't see it holding up well if that whole area is demoed.

 

You could pull it down, inspect it, if its good aside of that get someone to weld it up.

[SuperBuick]

Reviving this topic because it was the best in the search for subframe removal.

 

What is the best process for removing the subframe from a 1991 - the reason for removal is to remove rust/repaint/refinish, and to replace all the mount bushings.  Would prefer to leave the engine in.

[White93z34]

I would use a engine support fixture to hold the power train in place while the subframe is r/r

[SuperBuick]

How about the steering rack - is there a pinch bolt somewhere to disconnect?

[White93z34]

there is, right at the base of the column where it meets the rack, you could disconnect all the hydraulic lines and drop it with the rack or you could just unbolt it from the rack and tie it up while you work, either way works

[SuperBuick]

I got a really nice not rusty 1990 turbo grand prix front subframe. Can I use this on my 1991 STE with the 3.4 DOHC and manual transmission? I know the mounts are different but will the bolt up to the “basic subframe”??

[Bake82]

On 7/28/2024 at 2:30 PM, SuperBuick said:

I got a really nice not rusty 1990 turbo grand prix front subframe. Can I use this on my 1991 STE with the 3.4 DOHC and manual transmission? I know the mounts are different but will the bolt up to the “basic subframe”??

The subframes will fit the car no issues. Everything will bolt up(rack, control arms, sway bar) but I am not sure if the 90 subframe will have the proper mounting provisiions for the 3.4 DOHC.  

 

IIRC the subframes changed due to the different mounting of the 3.4 DOHC.  I can't remember what year they changed, but I am thinking it was probably in 1991 when they added the 3.4 DOHC into the lineup.  I believe it was mainly the rear mount that changed.  But I can't remmeber 100%.  

[rich_e777]

An LQ1less bay with the auto. The bracket this dude is pointing to bolts up to the Lq1 supported off the transmission, might be similar to the manual. The LQ1 mount is bolted more forward. If you've got the holes in the TGP sub frame in that spot then you should be good to go.

 

[Bake82]

17 hours ago, rich_e777 said:

An LQ1less bay with the auto. The bracket this dude is pointing to bolts up to the Lq1 supported off the transmission, might be similar to the manual. The LQ1 mount is bolted more forward. If you've got the holes in the TGP sub frame in that spot then you should be good to go.

 

 

Great pic of the 3.4 mounts!  
 

that bracket also bolts to a mount and then to the subframe. There is a support in the back that the older subframes don’t have.   it’s the same for the manual trans cars too!  (The metal mount is different but still mounts to the subframe the same).  
 

 

same with the front mount, I’m certain the older ones do not have those provisions.    

[rich_e777]

The embarrassing part is I removed that subframe and thought I did a good job taking off all the rust and coating it. I`m going to take it back off and have it properly sandblasted and slather it in POR-15 just to be sure. Its Galaxie500's Vert.

[SuperBuick]

I was able to drop and refurbish my subframe - updating here how.

All suspension was already removed from the car for powdercoating and full rejuvenation of ball joints, bushings, struts, bearings etc.

Had to support the engine with an engine holding "thing", unbolted the 15mm nuts on the engine mounts where the connect to the subframe.

Unbolted the 10mm bolt holding the steering shaft to the steering rack.

Undid the high pressure line (18mm wrench) on the rack, and unded the low pressure line (hose clamp) where the rubber meets the long metal loop of lines that runs around the subframe.

4 15mm bolts held up the subframe - undone slowly at the back and supported by a jack (then jackstands) and same process on the front.  It is super heavy.

 

Used a cheap tractor supply siphon feed blast gun and wire wheels/rust strip discs with a drill to prep the subframe, and then KBS rust blast, and then used VHT chassis epoxy paint to satin black the frame.

 

Putting the subframe back up alone is a pain in the butt - i found that doing up the engine mount nuts first was MUCH easier than trying to align the bushings/bushing bolts to the frame.  I crushed the low pressure line and had to order a replacement - because I just couldnt see - I highly recommend two people for this job if you have access to another person - I did not.

 

The difference between the 3.4 DOHC manual subframe and a TGP subframe is different engine mount hole locations, and the 3.4 has a plate on the passenger back inside corner of the subframe.  Not different enough to make a huge deal but you would need to weld to make one like the other.

IMG_3407.HEIC IMG_3408.HEIC IMG_3414.HEIC IMG_3423.HEIC IMG_3436.HEIC IMG_3454.heic

[White93z34]

I want to say post ~1991 all the subframes had that extra mounting point.