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Oct 15, 2018 16:11:04 GMT
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I need a bit of advice about how to proceed with my RX7 FC. I already posted a thread about crushed rails under the car and the consensus seemed to be a slide hammer to pull them out. However since then i've stripped all the underseal off and can see that its not just the rails, but the floor itself. I've taken off the carpet so the problem can be seen from on top:       Now I've already had a go at absolutely smashing it from the top with a lump hammer and a block of wood, but its had absolutely no effect, I didn't want to weld, but it looks like I'm going to have to in order to this properly, so the options as I see it unless anyone has other suggestions are to. - Drill out the spot welds on the rails, and and interior cross member, knock it back down flat (should be easy with them gone). Straighten the rails, cross member etc. And spot weld them back on again. I'm sure it won't be as easy as it sounds. - Go absolutely OTT and do what this guy has done, cut out the rails completely and weld in proper box section which should hopefully never dent again. A fairly major operation, but its not exactly complicated fabrication work. Well within my skills I think, well after I've learned to weld.   Of course there's always option 3, which is to just pretend it isn't there and paint over it! (That's not an option by the way) Any thoughts on how I should proceed? |
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Oct 15, 2018 17:48:50 GMT
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So, are you saying that the floor should be flat, and that the chassis rail *and* the floor has bent upwards? It's hard to tell from the photos, as the floor in the lower ones also seems to be ridged. If it's the back end of that chassis rail, and the floor is where it should be, I'd drill out the spotwelds and remove the back section, flatten it out, and weld it back on. On this version of your photo, I'm saying cut it roughly where the red line crosses the chassis rail, and remove the section in the direction of the arrow.  But that's assuming it's only that part. Once the chassis rail is removed, you would be able to re-shape the floor as a lot of the strength will be gone. |
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Oct 15, 2018 18:15:04 GMT
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I THINK it should be flat and its been bent up.
If you see the photos, the left hand one is noticeably flatter than the right hand one, and honestly I don't see why it would be pushed up from the factory. It must have been seriously hit hard one something to that to be honest.
I think tomorrow I'll have to get a straight edge on it and start measuring some gaps on either side.
The chassis itself seems straight, all the suspension pick up points line, up as does the subframe. No sign of any body damage at all.
I'll try and find some floor pan photos of similar cars.
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Oct 15, 2018 18:26:41 GMT
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Oct 15, 2018 18:52:17 GMT
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Put a piece of wood up the chassis rail a long a piece as will fit. Put screws through the a valuable holes and bang each one in turn with your slide hammer repeatedly working along.
That might bring the rail out. If it does I would then think of taking out the seat rail if its bent or first trying with it in the
mk1 two footed boot stomp on a piece of board that's about the same size of the front a rear sections appropriately.
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Oct 15, 2018 20:57:05 GMT
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On our mx5 I managed to straighten the rails using a slide hammer with a piece of bar bent to 90 degrees attached to it and used through the holes in the bottom. On other panels I have welded strips of metal to the damaged areas and pulled on these.
If you need to hammer the floor down try reacting the load under the sill and tunnel with length of wood and axle stands before using a lump hammer and block of wood on the pushed up area from above.
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It's hard to imagine what kind of impact would cause it to bend in that way, without noticeably altering anything else. The intersection of the lower longitudinal rail and the upper crossmember would make it very difficult to shift - possible with a massive press, but who would be doing that? Jacking the car up badly causes the damage on the lower surface of the lower rails, but the fact that bit has distorted suggests that the next bit along did not. But it's really hard to tell just from the photos.
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vanpeebles
Part of things
I am eastbound in pursuit of a white Lamborghini, this is not a recording.
Posts: 978
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Makes you wonder if someone has jacked it up in the wrong place? I'd vote for drilling out the spot welds, then knock the floor flat, and straight out the rails with some square hammers/dollies.
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Oct 16, 2018 10:55:14 GMT
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Hi, I would say that's been done by bellying it out. Possibly by driving over a kerb putting two wheels up on the pavement or driving over a mini roundabout that has a more pronounced CROWN. Maybe, if there's no paint damage, driving off road in a field and putting a wheel in a hole. The possibilities are endless, it's not just the weight of the car but some speed would be involved and it doesn't need to be much.
Colin
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Last Edit: Oct 16, 2018 10:57:20 GMT by colnerov
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Oct 16, 2018 12:42:29 GMT
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To be fair it had underseal on it, and that's easy enough to recoat after you've had a ding.
I've looked more closely today, the right hand side is noticeably up inside the car compared to the left hand side, so its had some kind of impact.
Anyway, I've decided to bite the bullet and do it properly. And by properly I mean of course going way OTT. So I'll be cutting out the old rails and having a local welder who was recommended to me come down and weld in through floor subframe connectors like the photos I showed earlier. That way it will be way stronger, I can jack the car from it. Add some rigidity and fix the problem once and for good.
I would like to have had a go at welding it myself, but its not worth me buying the equipment for a few hundred quid, having to practice loads and still making a worse job than someone who does this all the time.
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Oct 16, 2018 14:37:02 GMT
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adding new rails is *ok* but my advice looking at those example pictures is reinstate the drain holes. one of the only things i have learned when doing body repairs is when you think you are stopping water getting in, you are actually preventing it getting out  |
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Oct 16, 2018 14:54:22 GMT
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We've come to a compromise. I wanted to chop a hole in the floor, the welder was worried it would weaken the chassis and possibly cause it to flex before the reinforcement was welded in.
So instead I'm cutting the bottom out of the rails which should remove most of their rigidity. Straightening the floor, then welding box section inside the old frame rails. Hold it in place with a jack and plug welded from the top, then seam weld the edges of the old frames onto the new box section. So it butts to the floor, but doesn't go through.
That's the theory anyway.
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