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1991 roof repair

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I'm New to the nsx gonna build one from a shell found a shell only problem is the roof needs to be replaced as its damaged but there's another spare roof from another car I hope it's as straight forward as tig welding it up with a aluminum filler rod and grinding down and leveling and blending the areas of repair or if there's more to it than what I thought. that's why I'm asking if someone with experience can help me and what to do to proceed.
 
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Gonna repair/replace the roof on my 91 nsx by cutting the damaged roof then replacing and welding the "new" undamaged roof
I see the Service_manuals say to mig weld the but I'd rather tig since it's better. Is there any reason why they would use mig in the first place for repair my guess it's for costs or is there more to it.
 
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As a former confirmed snot-ball / ugly welder, I will speculate that there are fewer welders who can lay down a good bead with TIG than can make an acceptable bead with MIG. The service manual wording may reflect the fact that in an autobody shop environment the number of welders who can lay down a 'pressure certificate' perfect TIG weld are few. MIG was also probably the process used in the factory assembly line . If you are running a continuous bead, TIG (with a skilled welder) would seem to be a better choice because a skilled welder can do better heat control on thin materials.
 
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Gonna repair/replace the roof on my 91 nsx by cutting the damaged roof then replacing and welding the "new" undamaged roof
I see the Service_manuals say to mig weld the but I'd rather tig since it's better. Is there any reason why they would use mig in the first place for repair my guess it's for costs or is there more to it.

This has been done a few times and to it properly, you need to measure the control points, very very accurately and follow the repair manual exactly. Otherwise, you'll have door seal leaks, wind noise and rattles. I assume you are looking at page 4-27, etc. of the body repair manual? You may want to reach out to [MENTION=4046]pbassjo[/MENTION] for the best possible advice, but I see no reason tig wouldn't work just fine. It's about getting a good weld/bond. Definitely less cleanup with tig vs mig.

If you have time, please document it on the build forum!
 

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MIG is the preferred choice. It is what was used in the manufacturing process. If you are insisting on doing TIG you should disconnect all ECU's, better yet remove them while TIG welding as the waves and frequencies emitted by TIG can damage surrounding and connected ECU.

The pulse MIG welders are the best. With a instructor you could be welding like a expert in no time. Here's one.
This has three torches. Aluminum, steel and bronze.SP-5.3-product-large.jpg

You should consider adhesive bonding that is now available for aluminum panels like roofs.
That would be the cleanest. I would sometimes be able to refinish a panel and THEN bond it on and bam you're done.
 
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The car has no electronics, it’s a shell right now. What your saying is mig would be more forgiving to weld with as a welder with less experience than one that would with tig in this situation? Now is this where you would cut off the old roof to replace the “new” one?
 

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LJSB

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The car has no electronics, it’s a shell right now. What your saying is mig would be more forgiving to weld with as a welder with less experience than one that would with tig in this situation? Now is this where you would cut off the old roof to replace the “new” one?

The cars contained no electronics when welded at the factory so that was not a consideration on their choice of welding. They had had many plug welds in the process which is another reason for their choice of MIG.

Are you planning on cutting where the red lines in your picture are?
 
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[MENTION=38940]1967z[/MENTION] Joe is the expert here, but you need to measure first to determine where the damage extends to. Ideally you do not want to remove the A and B pillars. If they are bent, you may be able to pull them back into position using the control points as a guide. Honda wants you to weld the roof to the intact roof rail that connects the A and B pillars.

Page 4-28 describes the process. You need to drill out the spot welds and cut the mig weld fillets where they are marked. This should allow the roof to be lifted off of the rails:

AL9nZEUxmOKIOwWyiu8L7yoE65H8ZlDL61D8SxtW_EMzglD1ncSHpZOac0R00izDNeRcLT7fRIrAMPcTIx7iWQfRmjFi5nDdwtTKa15TmbNQCZmaTjCaw8oNTZqURa18Q3ZMZME0G9erqRORdRdFagh79S3SfQ=w553-h1223-no


Once the roof is off, it should look like this on both sides of the car:

AL9nZEX9uWpY6_k2t2ZDseTkfHDlr8jaUST6Hqo82qYeRffZ-5enJPs3oq6l3vaIusOTdtI0xv0tXmIsORjKQNEF5IthaukUiP_8QogjPqsanvhBxDsvacTfzf-OH7muAMXPZHrkekm54y7Cl_hIK-zfyWd8Hg=w497-h374-no


If your donor roof still has these rails attached, you'll have to cut them off too. Joe can explain it better than me, though.
 
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Well I think cutting the red lines where it’s marks would be ok for this operation but if I’m wrong and there’s a better way with minimal cutting that would be good here’s pictures of what I’m dealing with.
 

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this is turning into a fun exercise...these copart esque wrecks deserve to be reimagined...
 
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Ah I see. You've taken on quite a project! :) Since the A pillars are wrecked, I think the factory correct way to do this is to cut and replace the side panels along with the roof. The issue I believe is structure. If you cut and weld at the A and B pillars, those seams become the new failure point. Think of folding a piece of paper over and over- the seam is the weak point. God forbid the car ever flips again and that could become a potentially lethal problem for the driver and/or passenger.

Maybe Joe can think of a way to do it safely, but that's why Honda says replace the side panels. The hoop shape is the rollover crush protection for the driver and passenger. See the shaded area below.

AL9nZEXGx-qNs8bBF20PV2P9ocODo1VI-VjbNB4RfFj_Yth4-tfbcT0iUtR2_M7ecrzbclVWKLYzViLvU42Y0PmKdvOUUAQDBuEIGwPfnpobqUXyw8Cq8lV0eBYsGAix2m8_qPibWSacoOC3J5sRKg_Y5vIspw=w647-h570-no
 
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If there’s a better way with minimal cutting that would be good I’m just trying to figure out the best way to do this, here’s pictures of this project to better understand what’s happening here.
 

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From the photos, it looks like it may be possible to pull the right side pillar back into place. But, the left side pillar is damaged beyond repair. So, IMHO, you need to:

1. Cut the roof out following the repair manual method;
2. Cut the left side panel out following the repair manual method;
3. Pull the right side panel back into position, using the body control points to measure;
4. Weld the replacement side panel into place; and
5. Weld the replacement roof into place.

Unfortunately, it's a lot of cutting and welding, but it is fixable if you have the equipment and time. Before taking the drill/grinder to any of the car, I would measure the entire chassis to make sure the rest of it is straight. It's hard to tell from the pictures, but it looks like the left front frame rail is bent toward the centerline of the car.

*EDIT*

You may want to just give Joe a call. This repair is likely going to be more complex than can be adequately described on a forum. He can walk you through what is required. Let us know if you need a copy of the body repair manual.
 
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I'm not a body guy, but the first thing I would do is get that frame on the jig machine (or even just a level surface) and spend a couple days measuring to build a 3D picture of where it is out of spec. Then, you need to source a donor frame(s) to cut the pieces needed for the repair. You have to cut them out in the shapes described by the repair manual. Just from the pics, you're going to need a left side panel in addition to the roof. It may be possible to pull the rest of the frame into spec. I've seen that done at Joe's shop and in Japan.

I love seeing a NSX get saved, but man this is a big job.
 
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a photo of the replacement roof is shown above the side panel thing is something I would consider. You did say that welding up the A and B pillars wouldn’t be ideal as replacing the left side panel because it would cause a weak point for car flip overs. That potential new weak point in the A and B pillars after the roof swap would be irrelevant in my situation with this car as it’s getting a roll cage. All that matters to me is getting the cars roof/pillars and whatever else dimensionally correct to factory specs if that means cutting a roof and pillars as a assembly and swapping out for a doner pillar/roof assembly than I’ll do that if that means changing out the side panels than I’ll do that.
 
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Off topic real quick is there anywhere on this place where I can know where the type S badge placement is on the rear bumper??? Exact factory spec dimensions for the pin holes. Since one of you is doing a tribute type S
 

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Off topic real quick is there anywhere on this place where I can know where the type S badge placement is on the rear bumper??? Exact factory spec dimensions for the pin holes. Since one of you is doing a tribute type S

So, no one in the U.S. knows the answer to this because Honda never sold a Type-S bumper here. Thus, we have no donor part to use as a measuring tool to punch the holes. As a result, most people have cut off the studs and just used the included tape to stick it on there with their best "eyeball" guess based on pictures. My plan is to reach out to MITA or my buddy Nick in NZ (who has a real Type-S) and see if they can measure for me...

On the roof issue- the cage changes everything. If this car is going to have a full tubular roll cage, then that becomes your rollover protection. I think welding at the pillars is ok under these circumstances, since at that point it's just cosmetic. Though, you might still have issues if using it on a public road, etc. Are you building a race car? Or a ricey SEMA-style Type-S tribute? :D
 
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Just a street car with a type S badge basically being a “poser” but I don’t care, I like the badge.
 
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