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Hi guys need your opinion before i start welding the frame rails in, currently i have a made the rail from 70x25 with 1.5 wall but was wondering if i should make a lip for them (so i can spot weld them like factory) or just weld the corner to the bottom of the floor,

I can't spot weld from the top as the bulge runs along just above where the frame rail will land. 

 

So what do you guys think i should do?

1009524255_2020-01-2415_59_11.jpg.dc7785280b6c1403cbb6da1ce9361df2.jpg303186976_2020-01-2415_59_08.jpg.8ad7813e2d362c0392b9b660e602f6db.jpg

 

And yes i know there is some gaps but that will be taken care of when i get ready to start welding in the frame rails.

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Depending on how good of a welder you are flanges are easier to weld in using the drilled hole filled with weld method and will look more original or you could stitch weld it the way it is right now.  How did you end up with Zedd Findings floor pans and not the rails, they are usually sold as a kit?

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Since you have a tube, and not the U shaped rails from the factory, I think I would drill a bunch of holes in the floor pan and spotweld to the topside of the rail, and also stitch them on the side on the bottom side of the floor. Use a weld thru primer on the top of the rail and bottom of the floor so you don't end up with rust in that joint, since if water gets in, it's unlikely to get out. 

 

What you could also do, is cut the floor in half longways, and bend the edges 90 degrees to make your flange, and spot/stitch weld as needed. That way you don't end up with the possibility of moisture gathering between the floor and rail. 

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Stitch weld it as is. if you want the extra welding, weld it from above as well. Keep your welder focused on the frame rail so that the majority of the heat stays away from the floor pans and you dont end up punching holes through them. weld nice smooth U shapes building up a puddle at the top of the U (on the frame rail) and then dropping down to the frame rail and back up. this will also help prevent distortion. And when i did mine, i welded the frame rails together to make one solid piece prior to welding to the floor pans to ensure the joints were not weak. Once you are done seam seal it and call it a day.

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well i did buy factory style frame rails but wasn't really pleased with how it was turning out so i decided to do some full length rails and it was cheaper to buy material i needed than to go for bad dogs extra piece . But i think i will just stitch weld it as some of you suggested. 

 

here are some more pictures

its almost final fitment, need to get it down a little in the rear but otherwise i'm ready to start welding the first one in. 

1431111065_2020-01-2515_48_51.jpg.4506c0602cb624f231a8e33eabfa3ef3.jpg13937991_2020-01-2515_48_47.jpg.b43e6634cbc0227be4246f1f534a5c8e.jpg

 912401718_2020-01-2515_48_57.jpg.223f0aae2341e68815c8ca38b3df6c9f.jpg

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7 hours ago, ubergumgum said:

its almost final fitment, need to get it down a little in the rear but otherwise i'm ready to start welding the first one in. 

You should know that when you finish off the rails with extensions going right to the sub frame at the back, sometimes you'll will have difficulty with a forward mounted rear sway bar.  It can rub or you may need spacers to bring it down away from the bar, a sway bar that goes around the back works fine.

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10 hours ago, grannyknot said:

You should know that when you finish off the rails with extensions going right to the sub frame at the back, sometimes you'll will have difficulty with a forward mounted rear sway bar.  It can rub or you may need spacers to bring it down away from the bar, a sway bar that goes around the back works fine.

My car acctually have a rear mounted swaybar from when i bought it. 

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When I replaced my frame rails I cut out the section of floor that included the frame rail flanges, making the opening 4.25" wide.  I then had stainless frame rails made with tops (see drawing - as-is at top, new design at bottom) and welded them in, but I'm not really liking them now, so I will likely redo them.  The rails and tops are each u-shaped with one fitting inside the other.  I welded the edges of the floor pan to the sides of the frame rails because the OEM pans are not flat and I couldn't figure an easy way to deal the changes in height - in other words, I could not figure out to butt weld the pan to rail flanges.  This resulted in the side of the frame rails protruding above the floor by about 1/2".  After welding (continuous by joining all stitches) I ground off the protrusions, but they still are about .25" above the floor.

 

The reason I am redoing them is I ended them the way the originals ended, so no tie-in to the rear frame; and the tie-in at the front is completely cocked up because the new rails are wider than the members to which they need to be attached. 

On the next go, I'll have them made to the factory width, extend them to the rear frame area, and include flanges of the sides that reach out to the floor pan edges.  This means I will have to flatten the area of the floor where they meet so I can get good butt welds.  My primary objective in all of this is to avoid faces of two pieces of carbon steel being pinched together in any way by plug or spot weld in order to avoid rusting at the weld (even with weld-through primers - not 100% on-board with how they hold up over time after having burned off at the weld site).

 

Can you post pics of your rear-mounted sway bar, and also, how are you tying in the new rails at the front?

 

 

1903758076_FrameRailConcept.png.d0e65044ae6407d5bb1969377587506c.png

 

 

 

Frame Rail Concept.png

Edited by ETI2K
Did not mean to include bottom image. That was an old concept.

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9 hours ago, ETI2K said:

I then had stainless frame rails made with tops (see drawing - as-is at top, new design at bottom) and welded them in,

Just know that welding dis-similar metals together will result in corrosion at the weld regardless of how well you seal it up.

9 hours ago, ETI2K said:

After welding (continuous by joining all stitches)

On long stretches like the frame rails you should try and avoid continuous welds with no gaps, it makes it too ridged and can lead to stress cracks in the body.  A stitch weld is very strong and allows the body a certain amount twist and bend and helps avoid cracking.

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Hmm, very good to know that about cracking.  Thanks

 

My reasoning for stainless was that the upside down hat design provides no way for moisture inside the profile to drain or evaporate well, so eventually, water will collect and settle at the bottom of the frame rails.  The OEM spot welds assure there will be no 'coating' to stop corrosion at the weld sites either. 

So the obvious question becomes, how do you prevent your repair from rusting out again?  I have no experience with weld-through primers in that regard and wonder about how they can protect if they've been burned and never get a top coat.

 

Uncoated continuous butt welds can only experience surface rusting since there are no small cavities for water to collect as there would be using stitch welds.  Also it would seem butt welds would endure better than a "pinch" weld (spot or plug).  So that's for the continuous floor pan to side of frame rail welding rationale. 

As for corrosion, I agree dissimilar metals can have great potential.  My strategy there was, after welding, to spray (with an undercoating spray system - fan, reverse slash, shotgun type nozzles, etc.) ZRC into every cavity until it started to drain from the weep holes.  I had holes placed in the bottom of the frame rails for that purpose, besides letting water out.  The rationale for stainless comes from my belief that you can't really see inside a cavity where several pieces of sheet metal come together to be certain you've coated the metal thoroughly, and I was intent on fixing this car only once.  So I reasoned the dissimilar metals potential was less of an issue than the potentially uncoated carbon. Further, I had planned to lower the car and believed eventually those frame rails will become skid pads.

 

Of course, that thinking is know more than 20 years old and I know new coating materials, processes, and tools (can you say borescope?) are available.

 

I'd love more feedback on the corrosion issue.  Maybe there's a (many?) threads out there already.  I just haven't looked yet.

 

Edited by ETI2K

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3 minutes ago, grannyknot said:

Personally I have stopped using weldthru primer, useless.  Stitch weld, clean everything up well, 2k epoxy prime, continuous bead of seam sealer just the way OEM does then paint and undercoat.  Good for another 40yrs.

 

Exactly. If you seal out the air, it'll run out of oxygen pretty quickly and any miniscule amount of corrosion will stop. 

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@ETI2K, since you asked about corrosion control...these are two good products to consider.  Have used both for several years with good results.

 

https://www.eastwood.com/internal-frame-coating-aerosol-black-14oz.html

 

https://www.3m.com/3M/en_US/company-us/all-3m-products/~/Dynatron-Auto-Seam-Sealer-Caulk/?N=5002385+3293193911&rt=rud

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8 hours ago, jhm said:

@ETI2K, since you asked about corrosion control...these are two good products to consider.  Have used both for several years with good results.

 

https://www.eastwood.com/internal-frame-coating-aerosol-black-14oz.html

 

https://www.3m.com/3M/en_US/company-us/all-3m-products/~/Dynatron-Auto-Seam-Sealer-Caulk/?N=5002385+3293193911&rt=rud

I've used the Eastwoods internal frame coating and it's pretty good but it comes out of the can very quickly, I bought 3 of those big cans thinking that would be enough to do the sub frames on the Z, not even close, you really need 6 cans.

As you can imagine it makes bloody mess under the car so use a tarp or lots of newspaper.

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Posted (edited)
On 1/29/2020 at 3:25 PM, ETI2K said:

When I replaced my frame rails I cut out the section of floor that included the frame rail flanges, making the opening 4.25" wide.  I then had stainless frame rails made with tops (see drawing - as-is at top, new design at bottom) and welded them in, but I'm not really liking them now, so I will likely redo them.  The rails and tops are each u-shaped with one fitting inside the other.  I welded the edges of the floor pan to the sides of the frame rails because the OEM pans are not flat and I couldn't figure an easy way to deal the changes in height - in other words, I could not figure out to butt weld the pan to rail flanges.  This resulted in the side of the frame rails protruding above the floor by about 1/2".  After welding (continuous by joining all stitches) I ground off the protrusions, but they still are about .25" above the floor.

 

The reason I am redoing them is I ended them the way the originals ended, so no tie-in to the rear frame; and the tie-in at the front is completely cocked up because the new rails are wider than the members to which they need to be attached. 

On the next go, I'll have them made to the factory width, extend them to the rear frame area, and include flanges of the sides that reach out to the floor pan edges.  This means I will have to flatten the area of the floor where they meet so I can get good butt welds.  My primary objective in all of this is to avoid faces of two pieces of carbon steel being pinched together in any way by plug or spot weld in order to avoid rusting at the weld (even with weld-through primers - not 100% on-board with how they hold up over time after having burned off at the weld site).

 

Can you post pics of your rear-mounted sway bar, and also, how are you tying in the new rails at the front?

 

 

1903758076_FrameRailConcept.png.d0e65044ae6407d5bb1969377587506c.png

 

 

 

Frame Rail Concept.png

You asked how i will tie my new framerails to the old in the front, made the plates just need to get some gas for my welder before i burn them in. 

 

you also asked about my rear swaybar, its connected to the part that holds the rear control arms in the rear part by the mustache bar. Can take a picture when i mount the swaybar.

 

Some pictures of the plates. they need some bending to sit flush but almost finished, made them out of 1.5mm sheet metal

1412566883_2020-03-2618_27_12.jpg.2a3d31c58bafdc7bc5f3e8d469306bae.jpg1263415881_2020-03-2618_27_04.jpg.76c95eb47e5f5e0817efff7927be03c0.jpg

1739440675_2020-03-2618_26_53.jpg.f01a324085fde78d36017f64a912db38.jpg1863137484_2020-03-2618_27_01.jpg.8eec252790c84124a2983f6b6e1cab0c.jpg

 

Edited by ubergumgum

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