The Novice's guide to mini-tubbing a 68-69 Camaro

[BBC69Camaro]

Repost from over at PT.
http://www.pro-touring.com/forum/showthread.php?t=46900

[WARNING Image intensive].

I recently finished mini-tubbing my 69 Camaro and I thought I would share my experience and photos. When I was attempting to do this project I found a few documented installs but it still left a lot of questions. Hopefully this guide will help answer a few more questions.

First I took a welding class in prep to be able to tackle this project. If you don't know how to weld I think you can still get 90% of the way there and then just hire (or bribe a buddy with some beer) to come in and weld everything up once you have everything fitting how you want it. Getting everything fitted properly was 90%+ of the battle.

Keep in mind I had never done any metal/sheet work before. The goal wasn’t a perfect show install but one that would pass as factory work so that you couldn’t tell a mini-tubbing had been done. I don’t claim to be an expert; I am novice and so take everything I say with a grain of salt. There also probably better ways of doing things. Feel free to make suggestions and corrections.

This is not intended to be a guide on how to learn to weld; I am too much a novice at welding, so I am going to gloss over the welding and technique.

Also keep in mind that in my install I didn’t have to deal with putting in a new upper shock cross-member as I was going with a G-Bar.

I am a visual person so I took lots of pictures during the project and will use them to describe how I completed the project.

Tools:
* Common automotive tools
* Plasma Cutter (if you can beg borrow or steal one), it will make this project go 10x faster than other methods. 2nd choice would be air cut-off wheel (buy lots of cut-off discs).
* Angle Grinder with cupped wire brush (for taking off undercoating and paint).
* Lots of C-Clamps and/or long bar clamps (like used in wood working)
* Protective clothing, mask and goggles.
* MIG welder if you are going to do your own welding.
* Drill and assorted drill bits
* Spot weld removal tool (makes drilling spot welds a lot faster, but you can do without it)
* Scribe (for drawing lines on metal).
* Rotisserie if you can manage it, it would make life super easy on a project like this. Not necessary but like the plasma cutter would make it go extremely faster.


Going to try to break this down in very short descriptive steps:

1. Properly support vehicle.
2. Remove all rear suspension component, gas tank etc.
3. Remove rear trunk lid and everything from the trunk.
4. Remove interior (front seats too you are going to be working a lot in here you need the room).
5. Now the fun starts, use the angle grinder with wire cupped brush and begin to clean off the paint and undercoating in the wheel wells:







In these pics I cleaned off more than I needed to. You really only need to find the welds that hold the rear seat brackets and deck lid braces. After that you can cut out the inner tub:

[BBC69Camaro]

6. Next find the welds on the inside of the trunk that hold the deck lid braces to the inner tubs:


One thing that wasn't clear is, you need to resuse the deck lid braces. Make sure you are easy on them or you are going to need to fabricate new ones (DSE doesn't give you templates for this).

7. Now drill out the welds. For the ones holding to the inner tubs it is probably easier from the outside to do but inside might be easier to make sure you can resuse the braces.



I drilled them out from inside where I could then finished by drilling outside:[



Drill out the rear seat braces as well where it is held in place inside:

[BBC69Camaro]

8. Follow the DSE instructions on drawing the lines you need. One thing that wasn't clear was how to get the radius at the end properly. What I did was take some paper and scribe the mini-tubs outline on the paper then take the paper and using it as a guide to scribe the same outline lining up with the lines I had already drawn:



I used to a scribe to draw all my lines.

9. Next is actually cutting out the inner tub. I cut just inside of the seam as my first cut:



Now you want to cut as close as you can to the inner tub so you can remove it cleanly. That will allow you make the additional cuts you need to make enough room for the new tubs:


Plan on being in the trunk a lot for cutting, grinding and welding:


Once you have the tubs out it should look something like this:

[BBC69Camaro]

10. Now cut on your lines to remove the upper shock mounts and cut back the rear frame rail. I would cut short of the line you scribed. You can always cut more later. You want to cut just enough to fit the tubs and nothing more. I would cut short and grind to fit. Takes a lot longer but gives a much tighter cleaner install.

Just a bit more room:


Make sure to grind flush the top edge where you cut out the inner tub. You want it nice and clean so you can mount the new tubs to that flange:


I found that I need to clearance bit the tabs that had the old seat brace brackets so I could fit the mini-tubs in properly:



11. Now fold over your flaps as directed in the DSE instructions:


12. Clean up the cutout areas of the frame rails. I used the DSE templates to make sure the proper area was clear, although you could just make different close outs. But I wanted to follow the directions as close as possible since I had never done anything like this before:



13. Try to get the cut lines as straight as you can. They don't have to be perfect as you can kind of bend the mini-tub into place once it is in. You just need enough room so you can pop it in and get it placed correctly:

[BBC69Camaro]

14. Now fabricate your close outs. This is where the plasma cutter or even a band saw with a metal cutting blade will really pay off. If none are available use your cut-off wheel. I drilled and counter sunk the holes for spot welding:


I also used a cutting torch (oxy acetylene) to heat up and bend the close outs to the proper radius to fit my open frame rails. It is much easier to bend 1/8" steel when it is red hot.

15. Now mock up the closeouts. This where the C-Clamps and Bar clamps come in really useful:






Grind flush as necessary.

[BBC69Camaro]

16. Now weld up the closeouts. Either do it yourself or leave that trail of mixed nuts to the six pack next to the welder for your buddy (dont WUI thou):








A comment on my welding. In the class I took I was decent at running a bead on a bench, but welding in the conditions for mini-tubbing is a complete different story. I am picky when it comes to my car and the work I do. So I had to grind down my welds a few times until I got what I considered acceptable looking welds. They still aren't what I would consider good, but this is all going to be painted anyways.

17. Now drill holes in the tubs for the spot welds. Draw the lines on the front back like in the DSE Video:



18. Mock it all up. Use the C-Clamps to get everything nice and tight. You want ZERO (0) gaps if possible:





You probably going to need a buddy help you an push down on the edges when you are ready to tack.

[BBC69Camaro]

19. Buy more beer for your buddy, since it is time to weld up the inner tubs:


I welded up the inside seam between the inner tub and the trunk floor. This wasn't explict that I could tell in the video, but other installs looked like they did it this way:











After grinding a bit and cleaning up with a wire cupped brush on a grinder:


20. Now take the old deck lid braces and shorten them (I had pictures but somehow got misplaced). You are going ot need to do some custom fitment to make them just long enough to reach but not too long so that you can get them flush and get a good weld:

[BBC69Camaro]

21. Time for welding in the rear seat braces:



22. Grind down all spot welds and clean them up with a wire-wheel. You will probably find some spots that need more welding like I did, fix those spots as you find them. Pretty much everything should be welded now and should look nice and tight:




23. Seam sealing, one of the most important steps (least if you care about rust):



I used Eastwood's Seam sealer.

24. Prime and Paint, I used Eastwoods Extreme Chassis black and primer on the tubs:


You probably want to consider what you want to do for undercoating to protect them. I went with Lizardskin soundproofing formula and their ceramic heat insulation formula:

before:


after:


It dries a medium grey but really darkens over the course of about a week to dark grey.


I cleaned the entire undercarriage as well and painted it too (might as well make everything match). In person it looks pretty close to a factory finish. It isn't perfect by any means but my goal was a stock look and I think I succeeded. I may paint the underside with my leftover chassis black paint not sure, want to see how much it will darken (right now putting in rear suspension going to need to weld in the G-Bar frame anyways so more painting will happen after).

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I hope others find this guide useful and informative. If you have any suggestions or corrections feel free to post them and I'll try and make updates.


A special thanks to my instructor at school. As well as Frank from Prodigy for setting me up with the Deep tubs, G-Bar and Moser 12 bolt.

[BBC69Camaro]

Here is a list of resources I found helpful as well:

Obviously the DSE instructions and Video I found actually helped (I can't count the times I watched the video). Also DSE support was very helpful during the install answering all my questions.

Here is list of other installs I found online (feel free to add your own):

ATS - Colin Onaka’s 69 Camaro
http://www.t56kit.com/projects/onaka/

SteveN nice writeup:
http://www.pbase.com/steven69/minitubs

Super Chevy Article
http://www.superchevy.com/tech/0409s...ses/index.html

Mike Provencher's 67
http://hometown.aol.com/__121b_7l7+c...GXwy6qjTTuzHo=

DSE FAQ
http://www.detroitspeed.com/faq/faq.htm

Lugnutz 67 Minitub
http://www.lugnutz.com/67mtub.htm

LS1 Nova's Minitub picture thread:
http://www.pro-touring.com/forum/showthread.php?t=45572

Additional Mini-tub pics from my install:
http://s328.photobucket.com/albums/l...sion/Mini-Tub/

[Swain]

Your post helped me out a lot, the video was kinda moving too quickly. I looked over the instructions and your post a few times and just started cutting one side is done so far. I will post some pictures up this week. Thanks for the great photos.

Jason