Frame primarily spot welded?

[Ashyukun]

I'm working on drawing/modeling up the parts that I'll need to fabricate/have fabricated for repairing the extensive rust on 16655's frame and at the same time looking at how to weld everything in so it's as seamless as possible and as close to (or higher than the) strength of the original frame. Looking closely at the original frame though I realized that for the majority of the parts I can't see any weld lines- for things like the captive nut cages and the top edge of the reinforcing... trapezoid? inside the front suspension box frame- where there's just an edge or a short flange- you can see the weld line, but pretty much everywhere else there isn't one. Looking really closely at some of the joints it looks like I can barely make out the small circles from presumably spot welding them- so is the majority of the frame just spot-welded together? It's really hard to make out any of the weld spots on the majority of the frame, but there are a few spots where it is.

If so- does anyone have any idea of the general spacing of the spot welds so if I and up needing to also spot weld some of the repair parts I'll be able to keep the joints as strong as the original?

Thanks!

[Rich]

That's quite a challenge you're investigating.

No, the majority of the frame isn't spot welded. Most of it is brake-formed and continuously welded. Several of the subsections look like stampings. Spot welds are here and there but if much of your frame is toast then that evidence is gone.

Try finding a good frame you can lay eyes on somewhere. There are frame-off restorations going on all the time in the DeLorean community.

Classic DMC (Houston) has whatever original parts drawings exist. No idea whether they'd share them.

Try any of the USA vendors/shops and ask what they can show you, assuming you can travel to look at something. Speaking of that, DeLorean Midwest is planning a weekend open house event in early August.

Meantime here's a webpage from DMC FL showing some primo frame sections. Enlarge the pics by clicking them. https://www.dmcflorida.com/restoration.html



I'm working on drawing/modeling up the parts that I'll need to fabricate/have fabricated......Looking really closely at some of the joints it looks like I can barely make out the small circles from presumably spot welding them- so is the majority of the frame just spot-welded together? It's really hard to make out any of the weld spots on the majority of the frame, but there are a few spots where it is.

If so- does anyone have any idea of the general spacing of the spot welds so if I and up needing to also spot weld some of the repair parts I'll be able to keep the joints as strong as the original?

Thanks!

[David T]

The frame is made of 16 GA cold rolled mild steel. Cut out the sections that are rotten and fabricate new pieces to weld in. If you want it "pretty", grind the welds smooth. If the rot is really bad, maybe as suggested, you see if you can find another frame but realize that it may also be in need of at least some repair too. Don't forget to factor in not only the cost of another frame but the cost of transportation, the frame is large and heavy. With enough time and patience almost any frame can be repaired. It is not about the cost of the materials, it is the time you will have to put into it. If it is really bad you have to lift the body off and remove the drivetrain to get to all of the areas. There is a good line drawing with dimensions in the very last section of the Workshop Manual. If you wind up disassembling everything you increase the cost because you will want to replace all of the bushings, seals, hoses, etc. Remove the fuel tank if you weld anywhere near it (it's plastic and it doesn't take much heat to damage it). The frame is especially susceptible to rot in the front around the shock towers and crumple zone, and in the rear around the engine cradle.

[Rhye]

If so- does anyone have any idea of the general spacing of the spot welds so if I and up needing to also spot weld some of the repair parts I'll be able to keep the joints as strong as the original?


Yes, there's quite a lot of spot welds. You can find some on the blueprints that I've collected here:

https://drive.google.com/drive/folders/1XO47YUfR0KnhnUexj2F7eqdvF5GMsf7j?usp=drive_link

The famous "Shroud of Dunmurry" shows them as well:

https://dmctalk.org/showthread.php?17902-The-Shroud-of-Dunmurry

I'll be making a reproduction frame some day and I'm considering replacing the spot welds by a regular welds put on the edge of blind holes.

[dn010]

I'll be making a reproduction frame some day and I'm considering replacing the spot welds by a regular welds put on the edge of blind holes.

DeLorean Go in Europe is already making reproduction frames in either mild steel or stainless (they also have replacement parts like the front extension). DPI sells reman mild steel frames or new stainless frames (front frame extensions also).


Yes, there's quite a lot of spot welds.

Depends on what frame you're looking at. Early frames have parts riveted together, later ones don't.

[David T]

A properly done spot weld can be just as strong (even stronger) than any other type of weld. A much smaller heat affected zone. The key is "proper" and the correct placement and spacing. Usually other methods are used because you just can't get the electrodes where you have to. As for repairs, MIG, TIG, or Oxy-Acetalyne will do just fine. If you want to replicate spot welds there are ways to do that for the appearance of spot welds but nobody is going to look that close! You can buy spot weld cutters and drill out spot welds. They look like mini milling cutters with a spring-loaded pin to hold it centered. To build a frame "from scratch" is a monumental job if you do not have a jig.

[Ashyukun]

The frame is made of 16 GA cold rolled mild steel. Cut out the sections that are rotten and fabricate new pieces to weld in. If you want it "pretty", grind the welds smooth. If the rot is really bad, maybe as suggested, you see if you can find another frame but realize that it may also be in need of at least some repair too. Don't forget to factor in not only the cost of another frame but the cost of transportation, the frame is large and heavy. With enough time and patience almost any frame can be repaired. It is not about the cost of the materials, it is the time you will have to put into it. If it is really bad you have to lift the body off and remove the drivetrain to get to all of the areas. There is a good line drawing with dimensions in the very last section of the Workshop Manual. If you wind up disassembling everything you increase the cost because you will want to replace all of the bushings, seals, hoses, etc. Remove the fuel tank if you weld anywhere near it (it's plastic and it doesn't take much heat to damage it). The frame is especially susceptible to rot in the front around the shock towers and crumple zone, and in the rear around the engine cradle.

Thanks- thankfully my frame isn't that bad that it needs to be outright replaced. Granted- it would be a LOT simpler/easier to do so but also exponentially more expensive. I need to replace essentially the lower half of the front crossbeam/box, frame extension (already have a replacement one- I decided early on that it was just too complex to try and fabricate myself), a small spot on the front 'wishbone', a fairly large length of the passenger-side rear 'wishbone' will need to be repaired, and (of course) the bottom of the engine cradle.

I already have the frame stripped down completely and sandblasted- I didn't figure on doing things halfway so it made sense to strip it, repair it, and then protect it from rust from scratch. I am going to be replacing a lot of things along the way, but given I'm also converting it to a BEV (https://dmctalk.org/showthread.php?20244-Massive-overhaul-of-16655-including-planned-BEV-conversion) I'd be doing that anyway.

[Ashyukun]

Yes, there's quite a lot of spot welds. You can find some on the blueprints that I've collected here:

https://drive.google.com/drive/folders/1XO47YUfR0KnhnUexj2F7eqdvF5GMsf7j?usp=drive_link

The famous "Shroud of Dunmurry" shows them as well:

https://dmctalk.org/showthread.php?17902-The-Shroud-of-Dunmurry

I'll be making a reproduction frame some day and I'm considering replacing the spot welds by a regular welds put on the edge of blind holes.

Holy CARP! :jawdrop: That's immeasurably helpful!!! Thank you!!

[dn010]

I had no trouble making this plate when I had to repair my first frame, it's pretty simple to replicate but if you want a good replacement without all the work involved:

https://www.deloreango.com/us/dog-bone.html

[Ashyukun]

DeLorean Go in Europe is already making reproduction frames in either mild steel or stainless (they also have replacement parts like the front extension). DPI sells reman mild steel frames or new stainless frames (front frame extensions also).

Depends on what frame you're looking at. Early frames have parts riveted together, later ones don't.

My new front frame extension came from DeLorean Go. Mine is an '83, so pretty far from being an early frame. :)

[Ashyukun]

I had no trouble making this plate when I had to repair my first frame, it's pretty simple to replicate but if you want a good replacement without all the work involved:

https://www.deloreango.com/us/dog-bone.html

I debated ordering that as well when I ordered my front frame extension from them but decided against it since I wasn't sure (and still am not... I won't know until I can see how the motor/gearbox/inverter will fit...) whether I'd be needing to design and fabricate a new cradle for the electric drivetrain or if I'd just need to make an adapter for it.

[Rhye]

DeLorean Go in Europe is already making reproduction frames in either mild steel or stainless (they also have replacement parts like the front extension). DPI sells reman mild steel frames or new stainless frames (front frame extensions also).

Depends on what frame you're looking at. Early frames have parts riveted together, later ones don't.

Yes, I'm aware of the vendors' offers. Judging from the photos, D-go seems to not use spot welding at all (not sure what DPI does).

Never actually seen a riveted frame (apart from a photos of some small components attached to it).

[Rhye]

Refreshing/extending (and hijacking - hope the OP doesn't mind) the frame topic a little bit. Does anybody here have an access to BS 1449 Part 1 1972 standard? I'm particularly interested in CR4 GP (Cold Rolled General Purpose?) steel properties from that era, namely the yield strength and tensile strength (it's the exact material specs the majority of frame seems to be originally made of). I'm aware it's available as PDF for ~$280 but I don't think I'm ready to spend that amount of money just to get those 2 numbers. (;

[Rich]

Does anybody here have an access to BS 1449 Part 1 1972 standard? I'm particularly interested in CR4 GP (Cold Rolled General Purpose?) steel properties from that era, namely the yield strength and tensile strength (it's the exact material specs the majority of frame seems to be originally made of). (;

I don't have the BS book or access to it but I have a workaround for you.

Refer to the EU-area spec EN DC01 (1.0330). It is for a mild carbon steel which shows as equivalent to BS CR4 steel:

https://www.steelnumber.com/en/steel_composition_eu.php?name_id=199

Since the yield strength in this standard has a wide spec range use it carefully or get a certified spec from an EU steel supplier for their DC01 (1.0330) steel.

[Rhye]

Thanks a lot for sharing this. Yes, there are at least several references to CR4 GP on the web and the one you've found may probably be the most accurate. But it's still "for reference only" so the numbers I'm looking for may be a little off - that's why I'd like to look into the original standard (just want to know the exact material properties assumed by frame designers back then).

[Rhye]

I've managed to find a 1983 edition. The numbers for CR4 are a bit of a surprise to me...

71809