OK, what is it about the subframe on these cars? Do they just rot away from salt and crap and not being washed or is there an inherent weakness in them? Mine seems to be very solid, and anything in the way of preventative maintenance to keep it from going bad would be top of my list for Spring.

_________________
- 1993 "Medium Garnet Red Metallic" Buick LeSabre; '94 L67, 115k, Custom Intake, 3.07 FD, X Cat. Conv., GTP Exhaust, 5-note Horn; "The Supercharged Couch". Maybe it only runs on human blood... (which is almost as expensive as 93 octane these days).
- 1978 "Carmine Red" Cadillac Eldorado Biarritz "Lawn Ornament"; 38k, "A billowous black fog trails behind it, and its tailpipe farts a sooty skid mark on the pavement wherever its idling..."
- 1969 "Persian Aqua Metallic" Cadillac "Delores" Eldorado; 97k. "Ahh, the Eldosaurus!"
- 1989 "Two-Tone: Dirt and Curdled Milk" F*&d F-150 (I6, 5 spd., pwr. nothing); 165k, 2 qts. oil/300 miles, toggle switch fuel pump, tractor exhaust... $150 CDN
- Because GM loves money and we are all pawns... "If you build it, they will come!

It's not the subframe that you've got to worry about...it's the unibody that the subframe bolts to that you've got to worry about. Problem areas exist directly around the 4 rear mounting points of the frame. We've had a couple active members had theirs fail. I believe both cars got repaired, (one for SURE), but its serious stuff. My 89 LE had some of the worst visible damage I've seen to date, yet it remained intact.

But to directly answer your question, yes, it is the road salt that is directly responsible for this problem. Keeping every bit of the undercarriage salt free as much as possible is the only real preventative without using an undercoating/fluid film, etc.

_________________
John
Now: '15 Toyota Prius III | 134 hp 2ZR-FXE | Silver | 36k
Now: '03 Honda CR-V AWD | Slow 4-Cylinder | Dirt | 180k
Then: '07 Ford Fusion SEL | 221hp Gen I VVT Duratec 3.0 V6 | Tungsten Silver | 150k
Then: '99 Toyota Avalon XL | 200hp 1MZ-FE 3.0 V6 | Diamond White | 189k | Sold: July 2015
Then: '11 Ford Fusion SEL | 240hp Gen II VVT Duratec 3.0 V6 | Ingot Silver | 84k | Totaled: Oct 23 '14 (Rear-Ended)
Then: '96 Buick Park Avenue Ultra | 240hp Series II L67 | Medium Dark Lichen | Bought: JAN 11 @ 135k | Accident: FEB 3 '12 | Crushed: MAR 1 '13 @ 153K
Then: '98 Pontiac Bonneville SSE | 205hp Series II 3800 L36 | Topaz Firemist | Bought: NOV '09 @ 74k | Accident: MAY 28 '10 | Crushed: MAR 15 '11 @ 84k
Then: '93 Pontiac Bonneville SE | 170hp Series I 3800 L27 | Dark Yellow Green | Bought: JULY '07 @ 92k | Sold: JULY '12 @ 118k
Then: '89 Pontiac Bonneville LE | 165hp 3800 LN3 | Medium Garnet Red | Bought: JAN '05 @ 117k | Sold: SEP 30 '07 @ 152k

OK great, thanks for clearing that up for me. I've been seriously considering getting a good undercoating done. Seems like everyone I've met in Canada gets theirs done, and it isn't expensive at any rate. Cheap insurance, right? Would you recommend trying to remove the subframe bolts and lowering it, then sand-blasting the uni-body in that area and repainting it as well? Thanks again!

_________________
- 1993 "Medium Garnet Red Metallic" Buick LeSabre; '94 L67, 115k, Custom Intake, 3.07 FD, X Cat. Conv., GTP Exhaust, 5-note Horn; "The Supercharged Couch". Maybe it only runs on human blood... (which is almost as expensive as 93 octane these days).
- 1978 "Carmine Red" Cadillac Eldorado Biarritz "Lawn Ornament"; 38k, "A billowous black fog trails behind it, and its tailpipe farts a sooty skid mark on the pavement wherever its idling..."
- 1969 "Persian Aqua Metallic" Cadillac "Delores" Eldorado; 97k. "Ahh, the Eldosaurus!"
- 1989 "Two-Tone: Dirt and Curdled Milk" F*&d F-150 (I6, 5 spd., pwr. nothing); 165k, 2 qts. oil/300 miles, toggle switch fuel pump, tractor exhaust... $150 CDN
- Because GM loves money and we are all pawns... "If you build it, they will come!

I would just blast it off with a pressure washer and coat it with rust preventative every fall.

_________________
Bye Bye:

RIP sandrock

I take mine to the self-serve wash that's open year round and blast off the underside. No rust so far, and it costs 50 cents.

If plans get realized this summer (maybe, I'll have to see how crazy I get), mine will get a coating of POR-15 around the mounting points when some transmission and body work gets done.

Otherwise, run to your John Deere dealer and pick up a few cans of Fluid Film. Then spray the daylights out of the underside of your car. It'll make a nice oily mess that will keep out moisture, and slow down corrosion.

_________________
2012 Chevrolet Cruze Eco - Current car

1999 Buick LeSabre Custom - Former car

Learn from the mistakes of others, that way when you mess up you can do so in new and interesting ways.

I did mine in POR15 over 2 years ago and it's holding up great. I'd recommend painting it on the underside yourself. It'll be a messy job but VERY worth it.

I like the idea of the POR-15; sounds the most permanent. Perhaps get it all cleaned, sand blast any rust I can find, then POR it, plus an undercoating? Maybe that's overkill, but bodywork is new to me. I've put thousands into this car, far more than I'll ever see back out of it, and I want it to last as long as possible. Mechanically, I'm finished for now and would like to tackle the few body things I have going on; rocker panels and a weird hood problem that looks like someone screwed up Bondo REALLY bad, before getting it painted.

_________________
- 1993 "Medium Garnet Red Metallic" Buick LeSabre; '94 L67, 115k, Custom Intake, 3.07 FD, X Cat. Conv., GTP Exhaust, 5-note Horn; "The Supercharged Couch". Maybe it only runs on human blood... (which is almost as expensive as 93 octane these days).
- 1978 "Carmine Red" Cadillac Eldorado Biarritz "Lawn Ornament"; 38k, "A billowous black fog trails behind it, and its tailpipe farts a sooty skid mark on the pavement wherever its idling..."
- 1969 "Persian Aqua Metallic" Cadillac "Delores" Eldorado; 97k. "Ahh, the Eldosaurus!"
- 1989 "Two-Tone: Dirt and Curdled Milk" F*&d F-150 (I6, 5 spd., pwr. nothing); 165k, 2 qts. oil/300 miles, toggle switch fuel pump, tractor exhaust... $150 CDN
- Because GM loves money and we are all pawns... "If you build it, they will come!

POR15 is all you'll need after a decent cleaning...

While I'm on the topic, has anyone had luck with those bolts if it has to come out? I've heard they are about impossible to remove and have to be torched off (unless of course yours just falls off...)

_________________
- 1993 "Medium Garnet Red Metallic" Buick LeSabre; '94 L67, 115k, Custom Intake, 3.07 FD, X Cat. Conv., GTP Exhaust, 5-note Horn; "The Supercharged Couch". Maybe it only runs on human blood... (which is almost as expensive as 93 octane these days).
- 1978 "Carmine Red" Cadillac Eldorado Biarritz "Lawn Ornament"; 38k, "A billowous black fog trails behind it, and its tailpipe farts a sooty skid mark on the pavement wherever its idling..."
- 1969 "Persian Aqua Metallic" Cadillac "Delores" Eldorado; 97k. "Ahh, the Eldosaurus!"
- 1989 "Two-Tone: Dirt and Curdled Milk" F*&d F-150 (I6, 5 spd., pwr. nothing); 165k, 2 qts. oil/300 miles, toggle switch fuel pump, tractor exhaust... $150 CDN
- Because GM loves money and we are all pawns... "If you build it, they will come!

Subframe bolts? Mine were just fine...removed them to drop the frame a bit for a swaybar change...wasn't an issue.

OK so I was under the car this weekend and the subframe/unibody appear to actually be in very good condition; probably nothing a good cleaning and undercoating won't go a long way in helping. However, The rockers are completely loose where they were pinch-welded? to the body -- the flange that they were welded to is completely gone. Along with that, the rockers are starting to get a little rough, particularly the passenger side (Dug about 15 lbs of dirt and garbage out of there). The inners appear to be OK and so is the floor, etc. Has anyone found good replacements for the rocker panels? Guess GM discontinued them, so they don't have any.

_________________
- 1993 "Medium Garnet Red Metallic" Buick LeSabre; '94 L67, 115k, Custom Intake, 3.07 FD, X Cat. Conv., GTP Exhaust, 5-note Horn; "The Supercharged Couch". Maybe it only runs on human blood... (which is almost as expensive as 93 octane these days).
- 1978 "Carmine Red" Cadillac Eldorado Biarritz "Lawn Ornament"; 38k, "A billowous black fog trails behind it, and its tailpipe farts a sooty skid mark on the pavement wherever its idling..."
- 1969 "Persian Aqua Metallic" Cadillac "Delores" Eldorado; 97k. "Ahh, the Eldosaurus!"
- 1989 "Two-Tone: Dirt and Curdled Milk" F*&d F-150 (I6, 5 spd., pwr. nothing); 165k, 2 qts. oil/300 miles, toggle switch fuel pump, tractor exhaust... $150 CDN
- Because GM loves money and we are all pawns... "If you build it, they will come!

Check Ebay and your local body shop. My rockers are in desperate shape also, and are getting replaced this summer. I hope the local shop that fuxored my rockers due to improper lift placement comes through with new ones.

_________________
2012 Chevrolet Cruze Eco - Current car

1999 Buick LeSabre Custom - Former car

Learn from the mistakes of others, that way when you mess up you can do so in new and interesting ways.