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Driver
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Joined: 26 Jan 2004
Posts: 6627
Location: SW Ohio
1991 Mercury Cougar XR7
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 Posted: Thu Feb 04, 2010 9:28 am Post subject: Risk assesment: Do I begin this job.... |
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So I've had a nice rust-free and seam-welded subframe in my possession for about 3 and a half years now. Every winter I say "I'm going to put it in this year, and get that rusty POS out of there."
For those years, I've been tripping over the new subframe in my garage, I really want this done.
Problem: Age and rust.
Broken bolts seem to be common in this swap. and I mean the 6 bolts that hold this to the car. Meaning, if they break, there is no going back, no "just put the old stuff back in".
Mid Ohio is 2 months off and paid for... I'm not so sure I want to begin such a major surgury and risk not making the event, but I have the time and the parts now, and the subframe in there is nasty-rusty. What to do?
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ninetyfourintegra
Joined: 16 Sep 2008
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Location: Pittsburgh
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| Posted: Thu Feb 04, 2010 10:04 am Post subject: |
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If the bolts break can they be extracted and re-tapped?
I hate working rusty parts (which is why I never work on my DD). Every time the rusty stuff breaks on the race car and I can't fix it. I put it on the trailer and take it to my mechanic.
It seems, sans sub-frame, the car might not be movable to have some professional assistance given to it though.
Perhaps the bigger question is. Is the car safe to drive as it sits now?
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Ron Dodson
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Freiheit
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| Posted: Thu Feb 04, 2010 10:19 am Post subject: |
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Can you start pretreating things now? Like get out there with the PB Blaster and a wire brush and get things cleaned up so you can see what you're getting into?
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Driver
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Joined: 26 Jan 2004
Posts: 6627
Location: SW Ohio
1991 Mercury Cougar XR7
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| Posted: Thu Feb 04, 2010 10:43 am Post subject: |
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| ninetyfourintegra wrote: |
Perhaps the bigger question is. Is the car safe to drive as it sits now? |
BWHAHAHA HAHAHAH HAHAH!! I mean yes, yes it is. 
I don see any signs of eminent failure down there. The rusyness makes things a pain in the ass, though, and there are acouple of studs that have beome trhough-bolts over the years because of failure.
Putting this off for 3 years has only made it worse, I'm sure things are slightly more stuck now than they used to be.
I've begun shooting PB on the bolts, but the threads themselves can't be reached... without drilling holes from above, which I am more than willing to do.
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ninetyfourintegra
Joined: 16 Sep 2008
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Location: Pittsburgh
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| Posted: Thu Feb 04, 2010 10:54 am Post subject: |
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Gawd I hate the smell of PB Blaster. I remember when I did the first tear down on my car after it left its DD status, I would soak things down and that smell just permeates the whole house.
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Ron Dodson
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Driver
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Joined: 26 Jan 2004
Posts: 6627
Location: SW Ohio
1991 Mercury Cougar XR7
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| Posted: Thu Feb 04, 2010 11:40 am Post subject: |
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| ninetyfourintegra wrote: | | Gawd I hate the smell of PB Blaster. I remember when I did the first tear down on my car after it left its DD status, I would soak things down and that smell just permeates the whole house. |
Better than gasoline. I was elbow deep in that crap last year, buggering with my fuel pump and a minor leak. I'll be happy never to smell it again. I think I spilled almost 2 gallons into the catch pan... in completely unrellated news, there is still a huge black spot out in our asphalt culdesac. the morning it first appeared, it smelled oddly like gasoline. 
I think I'm going to sit on this descision for a week. I have a 3-day weekend comng up, I'll just do odds'n'ends until then. That's not the only project that needs done. Actually, the only "need" is to have a draveshaft of a proper length.
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ninetyfourintegra
Joined: 16 Sep 2008
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Location: Pittsburgh
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| Posted: Thu Feb 04, 2010 11:48 am Post subject: |
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My dad's street has a few of those... and his driveway has a hole in it from where the car sat on the trailer leaking gas...
Last year when I was replacing the brake lines I had to drop the gas tank. I thought I had threaded the right side strap enough to hold but when I dropped the left side the whole tank dropped. The result was that the fuel lines snapped. At that point I got the tank reattached and put it on the trailer... Another example of having the mechanic finish the job.
When I bought a winch on clearance I thought I would use for the "just in case" unfortunately it was an omen and I lost track of how many times I had to use it last year.
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ansonivan
Joined: 09 Dec 2004
Posts: 95
Location: Columbus OH
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| Posted: Wed Feb 10, 2010 6:05 pm Post subject: |
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I would start by heating the bolt heads and giving them a little trial turn to see if they're inclined to move. Failing that you might try your drilling from above idea to allow for penetrating oil soakage.
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1996 328i
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Driver
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Joined: 26 Jan 2004
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1991 Mercury Cougar XR7
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| Posted: Wed Feb 10, 2010 9:21 pm Post subject: |
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I thought about that, but I didn't want to mess with the heat treat of the bolt unless it was desperate. Heating it can loosen it, or can make ti snap easier.
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Freiheit
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| Posted: Thu Feb 11, 2010 11:43 am Post subject: |
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Lets ask the question a different way:
Is there something inherently wrong with the current subframe?
Would the new subframe correct a problem? Generally improve something?
Can the current part be driven on until it breaks, then do a break-fix rather than an upgrade?
Given the time and work involved can some other work be done in that same timeframe for other benefits?
Given that its now February and competition starts in April or March, this job should have started in October by making room in a garage for the car so the work could be done between November and now.
| Driver wrote: | | I thought about that, but I didn't want to mess with the heat treat of the bolt unless it was desperate. Heating it can loosen it, or can make ti snap easier. |
Just think of the reputation you'd have at NASA if you lost the entire subframe on the track at Mid-Ohio!
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"I'm looking at this like art I don't understand" - Eric, re: the internet
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Driver
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Joined: 26 Jan 2004
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Location: SW Ohio
1991 Mercury Cougar XR7
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| Posted: Thu Feb 11, 2010 12:09 pm Post subject: |
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There are most certainly benifits to having the new peice in there, apart form the slight performance gain of being stiffer.
The old unit is... old. It's rusted. During its last alignment, on of the LCA bolts snapped because it could rotate in it unthreaded cam-hole-alignment thing. The Differential Mounting studs broke free of their positions long ago, and I've since been using grade-8 through bolts to hold it in place. Plenty strong, but adds time and hassle to differential swaps.
Replacing it with the new peice and new hardware will make the aft section of car infinately easier to work on.
I was busy in October. 
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ansonivan
Joined: 09 Dec 2004
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Location: Columbus OH
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| Posted: Sat Feb 13, 2010 12:00 pm Post subject: |
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You don't need to go overboard with the heat, even 30 seconds with a mapp gas/propane torch will help immensely and won't come close to changing the temper.
Also, use a mini sledge to give each bolt a few serious whacks to the top of the head, this helps break the rust bond plus it's satisfying.
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1996 328i
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Noisy Cricket
Joined: 06 Sep 2005
Posts: 2093
Location: Cleveburg
1989 Volkswagen Golf
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| Posted: Sat Feb 13, 2010 4:07 pm Post subject: |
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| Driver wrote: | | I thought about that, but I didn't want to mess with the heat treat of the bolt unless it was desperate. Heating it can loosen it, or can make ti snap easier. |
If you only knew how many alignment shops heat tie rods or other threaded adjusters in the suspension to bright orange in an effort to get them to turn...
I would not worry about it. Heck, I've done that to the pinion on a Dana 70 in an effort to get the nut off. No problems ever. |
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